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This work focuses on the synthesis and characterization of nanoscale nickel oxide (NiO) nanoparticles doped with manganese (Mn) utilizing the cost-effective co-precipitation technique. For extensive characterization, a range of analytical methods are used, such as photoluminescence (PL) spectroscopy, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, ultraviolet–visible (UV) spectroscopy, and Brunauer–Emmett–Teller (BET) surface area analysis. The findings demonstrate that the addition of Mn causes the synthesized nanoparticles' crystalline size to decrease, which narrows the band gap to 3.13 eV. Furthermore, compared to pure NiO (44.11 m2/g), the surface area of Mn-doped NiO increases to 178.87 m2/g. Also as compared to pure NiO the electron-hole recombination rate of % Mn-doped NiO has decreased and an increase in the defect is observed. The study of Mn-doped NiO nanoparticles' photocatalytic activity against Rhodamine B (Rh. B) demonstrates their improved efficiency under solar light irradiation, as evidenced by their degradation up to 97.57 %, which is higher than that of pure NiO (90.94 %) in 70 min. Numerous aspects are investigated, including pH, catalyst dosage, original dye concentration, and scavenger studies. Studies on regeneration show that 5 % Mn-doped NiO nanoparticles may be recycled effectively and steadily for up to five cycles. These results demonstrate how effective photocatalysts for environmental remediation applications may be made from Mn-doped NiO nanoparticles. [ABSTRACT FROM AUTHOR]

The electronic, optical, and photocatalytic features of a newly proposed 2D material-based van der Waals heterobilayer, formed by vertically stacking monolayered SiS and AlN, have been investigated. The feasibility of utilizing this heterojunction as a potential photocatalyst for spontaneous water decomposition has been predicted by using the ab initio calculations. The findings reveal that the SiS@AlN heterobilayer can be stacked in four different patterns, resulting in a direct band gap ranging from 2.11 to 2.70 eV, as determined by HSE-06 calculations. The SiS@AlN composites exhibit appropriate band-edge locations for the oxidation and reduction reactions of water splitting. Moreover, the photocatalytic activity of SiS@AlN composites is significantly influenced by the electrolyte's pH. At equilibrium, the composite displays a direct Z-scheme band alignment, which facilitates the effective spatial separation of photo-excited charges and extends their lifetimes. Additionally, a significant built-in electric field is generated at the composite interface, further preventing the recombination of photo-excited electron-hole pairs. Furthermore, the hetero-bilayers exhibit better absorption of sunlight in both the visible and ultraviolet regions compared to individual 2D-SiS and 2D-AlN. These findings highlight the potential of the SiS@AlN hetero-bilayer for applications in solar water decomposition and optical device technologies. [Display omitted] • The SiS@AlN vdW heterostructures possess a direct bandgaps. • The SiS@AlN heterojunction equipped with direct Z-scheme type. • Exhibiting outstanding optical absorption ability in the visible and UV regions. • The SiS@AlN vdW heterostructures show overall water-splitting capability. • The photocatalytic performance of SiS@AlN heterobilayer is affected by the pH of water. [ABSTRACT FROM AUTHOR]

CsGeI2Br-based perovskites, with their favorable band gap and high absorption coefficient, are promising candidates for the development of efficient lead-free perovskite solar cells (PSCs). However, bulk and interfacial carrier non-radiative recombination losses hinder the further improvement of power conversion efficiency and stability in PSCs. To overcome this challenge, the photovoltaic potential of the device is unlocked by optimizing the optical and electronic parameters through rigorous numerical simulation, which include tuning perovskite thickness, bulk defect density, and series and shunt resistance. Additionally, to make the simulation data as realistic as possible, recombination processes, such as Auger recombination, must be considered. In this simulation, when the Auger capture coefficient is increased to 10−29 cm6 s−1, the efficiency drops from 31.62% (without taking Auger recombination into account) to 29.10%. Since Auger recombination is unavoidable in experiments, carrier losses due to Auger recombination should be included in the analysis of the efficiency limit to avoid significantly overestimating the simulated device performance. Therefore, this paper provides valuable insights for designing realistic and efficient lead-free PSCs. [ABSTRACT FROM AUTHOR]

CeO 2 is renowned photocatalyst with 2.8 eV band gap energy and exceptional optical features. However, the slow charge transportation and the fast recombination of the electron-hole pair hindered the photocatalytic efficiency. In this pioneering research, S-scheme CuO/CeO 2 heterojunctions were engineered sonochemically with rational compositions of CeO 2 and CuO nanoparticles for enhanced the photocatalytic efficiency of CeO 2 in destructing rhodamine B dye under full solar radiations. Diffuse reflectance spectrum [DRS], photoluminescence [PL], high resolution transmission electron microscope [HRTEM], selected area electron diffraction [SAED], N 2 -adsorption-desorption isotherm, X-ray photoelectron spectroscopy [XPS] and X-ray diffraction [XRD] investigated the physicochemical properties of CuO/CeO 2 heterojunction. Monoclinic CuO nanoparticles of 8 nm size are facilely incorporated in cubic CeO 2 crystallites of 27.3 nm through substitution of Ce4+ by Cu2+ ions which ascribed to smaller ionic radii of Cu2+ compared with Ce4+ and Ce3+ ions. Homogeneous distribution of CuO nanoparticles on CeO 2 surface was further investigated by SEM and TEM analysis. HRTEM, XRD, SAED and XPS analysis recorded the co-existence of crystalline peaks of CeO 2 and CuO implying the successful construction of CuO/CeO 2 heterojunction. The depression in the surface area of CeO 2 from 91.4 to 83.6 m2/g with incorporating 5 wt % of CuO revealed the deposition of CuO on CeO 2 surface. XPS analysis implied the existence of Ce3+ and oxygen vacancies that provide more adsorption sites for oxygen, which are beneficial for enhancing the catalytic performance of catalysts. CuO nanoparticles with 1.3 eV band energy enhanced the visible light absorbability of the heterojunctions in deep visible region for broading the photocatalytic response. Significant reduction in photoluminescence signals intensity by 60 % with incorporation 5 wt % of CuO revealed the favorable reduction in the rate of electron-hole recombination. In particular, CeCu5 containing 5 wt % CuO expelled 96 % of RhB dye within 6-h under solar simulator compared with 13 % removal on pristine CeO 2 and CuO surface. Hot radicals and positive holes degraded RhB dye molecules on the heterojunction surface as elucidated from scavenger experiments and PL analysis of terephthalic acid. The exceptional removal of RhB dye under solar radiation was ascribed to the alignment in the band structure of CeO 2 and CuO nanoparticles and the successful production of an efficient S-scheme heterojunction with strong redox potential and better electron transportation and separation. [ABSTRACT FROM AUTHOR]

The polymer semiconductor material known as graphitic carbon nitride (g-C3N4) has been extensively utilized for the removal of pollutants in wastewater treatment due to its notable visible photocatalytic efficiency, cost-effectiveness, straightforward synthesis, and chemical robustness. Nonetheless, unmodified g-C3N4 still exhibits deficiencies including suboptimal visible light absorption, pronounced electron-hole recombination, and wide band gaps, resulting in constrained photocatalytic efficacy. Through extensive research efforts, diverse modification approaches have been devised to enhance its photocatalytic capabilities. This paper systematically introduces the development history, preparation methods, photocatalytic mechanisms, advantages, and disadvantages of novel g-C3N4 materials, the various modification strategies including morphology control, element doping, defect construction, semiconductor coupling, and hetero-structure construction. In this paper, the preparation process, characterization results, practical applications, and performance enhancement effects of various elementally doped g-C3N4 materials in pollutant removal are discussed in detail, indicating the advantages of multielement doping modification strategy have obvious advantages in improving the photocatalytic performance of g-C3N4, highlighting the future prospects of g-C3N4 materials. [ABSTRACT FROM AUTHOR]

The electronic and photocatalytic properties of a type-II ZnS/HfS 2 heterojunction are comprehensively analyzed through first-principles calculations in this paper. By calculating the binding energy and phonon spectrum of five potential stacking patterns, the stable structure of the ZnS/HfS 2 heterojunction is determined. The electronic structure calculations indicate that the heterojunction has a type-II alignment with a 1.26 eV band gap. The heterojunction exhibits high carrier mobilities (4387.36 and 9561.39 cm2V–1S−1 for X and Y directions). The photocatalytic water splitting process of the heterojunction can be explained by the direct Z-scheme mechanism. The built-in electric field enables rapid recombination of electron-hole pairs at CBM and VBM, while the hydrogen evolution reaction and oxygen evolution reaction can separately be achieved at the ZnS layer and HfS 2 layer to complete the overall water splitting. The free energy analysis indicates that the ZnS/HfS 2 heterojunction has high activity for overall water splitting under illumination. Moreover, the calculated solar-to-hydrogen efficiency of the heterojunction reaches 30%, ensuring its photocatalytic performance. Remarkably, the type-II alignment is maintained and the catalytic performance can be further improved under biaxial strain because of the enhanced optical absorption in visible light and the reduced band gap. This work reveals that ZnS/HfS 2 heterojunction is a potentially novel photocatalytic material for efficient overall water splitting. [Display omitted] • Proposed novel type-II ZnS/HfS 2 heterojunction with 1.26 eV band gap. • Achieves overall water splitting via direct Z-scheme mechanism. • High carrier mobility and 30% solar-to-hydrogen efficiency. • Enhanced catalytic performance under biaxial strain. [ABSTRACT FROM AUTHOR]

AlN and ReS 2 monolayers are the foundation for constructing the unique 2D vdW heterojunction. Based on density functional theory, the photocatalytic performance of AlN/ReS 2 heterojunction was systematically studied using first-principles calculation methods. According to the calculation findings, the AlN/ReS 2 heterojunction possesses a band gap of 1.79 eV, and the staggered band structure efficiently divides the holes and electrons produced by photo-generated light. The Z-scheme charge transfer mechanism is achieved via the AlN/ReS 2 heterojunction, allowing the recombination of electron-hole pairs within the heterojunction. In the AlN layer for reduction processes, this mechanism leaves highly reducing photo-generated electrons, whereas in the ReS 2 layer for oxidation reactions, it leaves highly oxidizing photo-generated holes. The AlN/ReS 2 heterojunction's band edge location also spans the pH = 1 to 7 water oxidation-reduction potential. The AlN/ReS 2 heterojunction exhibits good light absorption capabilities and charge carrier mobility. As a result, for applications involving water splitting, the AlN/ReS 2 heterojunction is a promising photocatalyst. • The existence of AlN/ReS 2 vdW heterojunction has been predicted theoretically. • The Z-scheme AlN/ReS 2 heterojunction can separate photogenerated carriers. • The AlN/ReS 2 vdW heterostructure enables photocatalytic water splitting. [ABSTRACT FROM AUTHOR]

For photocatalysis technology to be applied industrially, there has been a significant increase in the need for visible-light-driven photocatalysts that possess exceptional superparamagnetic characteristics to facilitate easy separation. Hence, in this study, rare earth elements (RE) (Sm, Yb, Dy, Er, and Ho) were systematically doped into manganese ferrite (MF) using the coprecipitation method to serve two purposes, namely, reducing the photogenerated electron-hole recombination during photocatalysis and modifying the magnetic properties of MF to become superparamagnetic. The synthesised Re-doped MF was found to be visible light active, as evidenced by the transient photocurrent response and the obtained band gaps, which were in the range of 1.84–1.93 eV. From the cyclic voltammetry, electrochemical impedance spectroscopy, and Tafel polarization plots, it was evident that different RE element dopants have different effects on improving the electrochemical properties of MF. Overall, fast electron transfer of the synthesised materials was found to decrease in the following order: Sm-MF > Dy-MF > Ho-MF > MF > Er-MF > Yb-MF. The g-factor and peak-to-peak line width were found to be in the range of (2.221–2.317) and (93.17–149.85 mT), respectively. The resonance field and hysteresis loop (H c) were found to be in the range of (289.2–301.86 mT) and (8.24–32.61 mT), respectively. Overall, the synthesised RE-doped MF exhibits ferromagnetic properties, and the obtained small H c values hint at these particles exhibiting superparamagnetic properties. In summary, doping MF with Sm, Dy, and Ho is more desirable as it alters the magnetic properties towards superparamagnetic and improves its electrochemical properties. Thus, this study is of importance in advancing the field of photocatalysis in water treatment and material science. • RE (Sm, Dy, Ho, Er, and Yb) were successfully incorporated into the MF spinel structure. • Sm, Dy and Ho dopants improved the electrochemical and optical properties of MF. • The magnetic properties of MF were improved. • The produced photocatalysts were visible light active. [ABSTRACT FROM AUTHOR]

Nanoparticles, considered building blocks of nanotechnology, are a topic of widespread research due to their extraordinary properties that are useful in diverse sectors. Among all nanoparticle types, TiO2 (anatase) has drawn the most attention, primarily because of its superhydrophilic properties and effective antibacterial actions. Its applications include self-cleaning of solid surfaces, treatment of water and air, production of clean energy, treatment of microbial infections, pesticide management, etc. making TiO2 a focal point of research in materials science. However, the lack of photosensitivity to visible light (>390 nm) reduces the scope for utilising TiO2 in photocatalytic processes. Therefore, most studies on TiO2 nanoparticles have focused on broadening their spectral sensitivity through band gap manipulation for effective photocatalysis under visible light. Researchers have doped/co-doped metals and non-metals, such as N, C, F, S, B, Cu, Fe, V, Pt, etc. to nano-TiO2 to shorten its band gap with varying degrees of success. This review paper mainly focuses on the mechanism and effectivity of N and Fe co-doped TiO2 nanoparticles. The progress of scientific research on TiO2 photocatalysis has introduced an array of new applications using TiO2 nanoparticles, and these applications have also been discussed in this article. [ABSTRACT FROM AUTHOR]

Element doping and construction of heterojunction composites are the most common ways to enhance g-C3N4, which are very attractive in achieving high photocatalytic activity. In this study, 2D nanosheet structured BCN was obtained by doping B atoms with graphite carbon nitride. Subsequently, Ti MOFs were loaded on BCN to obtain a Z-scheme heterojunction composite TBCN through calcination. Under simulated sunlight, the photocatalytic hydrogen production rate of the TBCN heterostructure was 1242 μmol h−1 g−1, which was 2.2 times higher than that of BCN and 9.34 times higher than that of bulk graphite carbon nitride (GCN). Experimental results showed that the construction of a Z-scheme heterojunction composite (TBCN) could effectively adjust the material band gap position, expand the light absorption range, enhance electron transfer and inhibit electron–hole recombination, which are crucial for efficient photocatalysis. This study not only provides a strategy for constructing heterojunction composites in the field of g-C3N4 photocatalytic hydrogen evolution, but also deeply analyzes the electron migration direction and the reasons for enhancing carrier separation in the Z-type heterojunction scheme, thus providing potential guidance for future research. [ABSTRACT FROM AUTHOR]

In this study, pure WO3 as well as doped with molybdenum (0, 2.5, and 5 at%) nanoparticles were successfully synthesized via sol-gel processing followed by a hydrothermal approach. The physicochemical characteristics of WO3 and Mo-doped WO3 nanoparticles were thoroughly characterized using techniques, including XPS, FESEM, HRTEM, UV–Visible, photoluminescence, cyclic voltammetry and electrochemical impedance spectroscopy. Results predicted that the insertion of Mo into the WO3 lattice had a prominent effect on morphology as well as microstructure. The addition of Mo ions in WO3 NPs narrowed the bandgap of WO3 and enhanced its ability of light absorption. Band gap energy of pure WO3 nanoparticles is reduced from 2.77 to 2.49 eV with Mo (5 at%) doping. The photocatalytic behaviour of prepared nanoparticles was investigated through the photodegradation of an organic dye (methyl orange, MO) in an aqueous solution in presence of UV–Visible light. Photocatalytic activity of WO3 nanoparticles could considerably be increased with Mo doping, which might be due to the redshift of absorption edge as well as the lowering of recombination rate of electron-hole pairs caused by the trapping of charge carriers through crystal defects. The degradation efficiency of photocatalyst against methyl orange (MO) dye is enhanced from 71.1 to 86.1% with the incorporation of Mo ions in WO3.The electrochemical properties of undoped WO3 nanoparticles, and Mo-doped WO3 nanocomposite, were investigated through cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance measurements and analysis. The specific capacitance is increased from 255.6 to 488.9 Fg−1 through Mo (5 at%) doping in WO3 NPs. The present findings recommend that 5% Mo-doped WO3 nanocomposite provides a promising direction for the development of high quality, effective and reliable photocatalytic and electrode material for organic dyes degradation and hybrid supercapacitors respectively. [ABSTRACT FROM AUTHOR]

CuO:Cu2O/Si heterojunctions have been prepared with different concentrations of Cu2O nanoparticles using the thermal evaporation technique. The X-ray diffraction (XRD) results show that the prepared films are polycrystalline with orthorhombic structure and preferential orientation (110) direction along the c axis at 2휃 = 32.82∘, which corresponds to the pure CuO with crystallite size 18nm, while the particle size ranged from 14nm to 34 nm (resulted from SEM test). The optical properties were studied by recording the absorbance spectra using the UV–visible spectrophotometer. The absorbance increased with Cu2O doping. The high values of the energy gap refer to the quantization effect. The electrical properties including the Hall effect were studied. CuO:Cu2O/Si heterojunctions have been prepared at different concentrations. I–V characteristics show that the Cu2O doping increases the energy conversion efficiency by retarding the electron–hole recombination and the improved device performance is caused by the high short-circuit current (Isc) and open circuit voltage (Voc) and found that the highest efficiency (η) at doping 0.006 Cu2O 3.471% with Voc of 2.20V, Isc of 0.0170mA cm−2 and F.F of 0.6497 at P = 100mW/cm2. [ABSTRACT FROM AUTHOR]

In this work we have narrowed the band gap of orthorhombic sodium tantalate by doping the perovskite structure with 5 and 10% of iron. The hydrothermal method was used in the preparation of the samples. Moreover, the evolution of hydrogen by photocatalytic water splitting is reported for first time for orthorhombic NaTaO3 mono-doped with Fe. The band gap was reduced from 4.08 to 3.24 eV for sodium tantalate doped with 5% of Fe, and up to 2.05 eV for the perovskite doped with 10% of Fe. The highest photocatalytic activity was obtained with the semiconductor that had 5% of Fe. Which was attributable to its smaller particle size, larger specific surface area and lower recombination of electron–hole pairs in contrast with the sample that had 10% of Fe. X-ray diffraction, energy dispersive X-ray spectroscopy, transmission electron microscopy, nitrogen physisorption, ultraviolet–visible diffuse reflectance and photoluminescence spectroscopies were used to analyze the perovskite materials. [ABSTRACT FROM AUTHOR]

Nanocomposite SnSeO3/ZnSeO3 has been synthesized by hydrothermal method. EDAX and XRD confirm the perfect formation of SnSeO3/ZnSeO3 nano composite. It shows an interesting morphology of rectangular bar. Particle size is determined as 137.3nm. It is an effective applicant for applications in optoelectronic field. The energy gap of SnSeO3/ZnSeO3 nanocomposite is 5.52 eV. Urbach energy value obtained is 0.0635 eV. Refractive index obtained from optical energy gap is 1.926. PL emission spectrum obtains a strong efficient emission in UV (387.7 nm) region, weak emission in green (520.7 nm) region, and moderate emission in red (788.7 nm) region. The UV emission at 387.7 nm shows radiative electron-hole recombination and it makes the candidate suitable for display applications. The emission peaks in the visible range may be attributed to different surface imperfections of Schottky and Frenkel kinds, oxygen vacancies and Sn -- interstitials or Zn -interstitials. The FTIR bands are well assigned and confirms Se-O, Zn- O, Sn-O bonds in finger print region. The sample exhibits diamagnetic nature at 300K and 5K. It also exhibits interesting super paramagnetic nature at 5K between -0.15Tesla to 0.15Tesla. [ABSTRACT FROM AUTHOR]

Photocatalytic oxidation techniques are promising for degradation of the highly ecotoxic and refractory isothiazolinone bactericides in relevant industrial wastewaters. However, low charge separation and directional transport efficiency under solar light radiation restrain their practical application. Here, we report a nanostructured photocatalyst doped with Gd and B in TiO2 with carbon incorporation and defect formation through incomplete calcination. The specific surface area, grain size, and hydrophilicity of TiO2 are improved, which is beneficial for the interfacial reaction between the photocatalyst and pollutants. The reduction of the bandgap, the broadening of the photo-absorption range, and the retarded electron-hole recombination promote the photocatalytic performance due to the improved oxygen vacancies based on the electron distribution modification. The difference in partial density of states (ΔPDOS) between the current catalyst and raw TiO2 indicates that the co-doping of Gd and B with incomplete calcination changes the electronic hybridization of conduction band and valence band near the Fermi level, and affects the band gap energy. It improved charge separation and directional transport efficiency and benefited the formation of main active species, including OH and O2−, for the pollutant decomposition. The rate of photocatalytic removal of benzisothiazolinone (BIT) by the current photocatalyst reaches 1.25 h−1, being 4.31 times that of TiO2. The current work offers a constructive approach to the design and synthesis of nanostructured photocatalysts for the photocatalytic degradation of refractory organic pollutants. [ABSTRACT FROM AUTHOR]

• Ag was atomically anchored on ultrathin carbon nitride by thermal polymerization. • Ag doping increased visible-light absorption and decreased the AgUTCN band gap. • Single-atom Ag favored O2 adsorption and subsequent O2•− formation. • O2•− was verified as the major contributor to photocatalysis by AgUTCN. • AgUTCN gives efficient photocatalytic degradation of various PPCPs. Carbon nitride has been extensively used as a visible-light photocatalyst, but it has the disadvantages of a low specific surface area, rapid electron–hole recombination, and relatively low light absorbance. In this study, single-atom Ag was successfully anchored on ultrathin carbon nitride (UTCN) via thermal polymerization, the catalyst obtained is called AgUTCN. The Ag hardly changed the carbon nitride's layered and porous physical structure. AgUTCN exhibited efficient visible-light photocatalytic performances in the degradation of various recalcitrant pollutants, eliminations of 85% were achieved by visible-light irradiation for 1 hr. Doping with Ag improved the photocatalytic performance of UTCN by narrowing the forbidden band gap from 2.49 to 2.36 eV and suppressing electron–hole pair recombination. In addition, Ag doping facilitated O 2 adsorption on UTCN by decreasing the adsorption energy from −0.2 to −2.22 eV and favored the formation of O 2 ·−. Electron spin resonance and radical-quenching experiments showed that O 2 ·− was the major reactive species in the degradation of Acetaminophen (paracetamol, APAP). [Display omitted] [ABSTRACT FROM AUTHOR]

Photothermal nanoparticles are recent materials which provide additional capacity supply during the photocatalytic reactions. Iron disulfide (FeS2) nanoparticles with unique chemical and optical properties effectively absorb the full broad spectrum and convert the solar energy into chemical energy owing to its small band gap energy of 1.5 eV. However, the fast electron–hole pair recombination reduces the efficiency of FeS2 and depresses the redox reaction. In this novel research, FeS2/CeO2 heterojunctions are prepared for successful decomposition of rhodamine B dye as toxic pollutant belonging to xanthene dye group. CeO2 nanoparticles are fabricated through sol–gel procedure via triton- × 100 as pore directing agent. Nanoparticle's FeS2 is developed by the precipitating process under a N2-atmospheric condition. Various amounts of FeS2 particles were deposited in ultrasonic bath onto the surface of CeO2. The nanostructures, crystalline and optical properties of the solid specimens are evaluated by scanning and transmission electron microscopy (SEM and TEM) with Energy-dispersive X-ray spectroscopy (EDS), x-ray diffraction (XRD), photoluminescence (PL) and diffuse reflectance spectroscopy (DRS) techniques. The photocatalytic efficiency of CeO2, FeS2 and various compositions of FeS2/CeO2 heterojunction was deliberated via following the decomposition of rhodamine B dye under UV radiation at 365 nm. FeS2 efficiently transfers the absorbability of the nanocomposite to deep visible region by decreasing the band gap energy of CeO2 from 2.3 to 1.5 eV revealing that FeS2 determines the optical properties of the nanocomposites. The charge transportation proceeds through type (I) heterojunction with accumulation of the massive charge carriers in the valence and conduction bands of FeS2 nanoparticles. The novel nanocomposite with strong absorbability of nearly full absorption spectrum could be an effective photocatalyst for decomposition of toxic organic dye from various sources of water. [ABSTRACT FROM AUTHOR]

Nowadays, environmental problems are increasingly varied and the development of various diseases. Due to its ability to create defect in band gap energy and strong antibacterial activity against a variety of microorganisms, ZnO is used to solve both issues. However, ZnO has a large band gap energy, so it is necessary to decrease band gap by doping. In this study, the synthesis of ZnO and ZnO doped materials (N- and (Mg,B,N)-doped ZnO) through the solid-state was carried out. The phases of doped ZnOs are hexagonal wurtzite, according to the results of the characterization using XRD, Raman spectroscopy, and HR-TEM. Surface morphology for N-doped ZnO does not form agglomeration, while in (Mg,B,N)-doped ZnO, agglomeration occurs due to the difference in charge of B with Zn. The existence of dopant in ZnO lattice was confirmed by EDS and XPS. (Mg,B,N)-doped ZnO has the highest specific surface area (14.388 m2/g) according to the BET analysis. The formation of peaks in 358 nm, 520 nm, and 650 nm during PL examination indicates a reduction in the rate of electron-hole recombination and defects. The recombination rate was confirmed by EIS Nyquist spectra result. The band gap energy owing to doping decreased from 3.13 eV to 3.10 eV and 3.12 eV for N- and (Mg,B,N)-doped ZnO, respectively. The lifetime of undoped ZnO, N-doped ZnO, and (Mg,B,N)-doped ZnO is 0.526, 0.610, and 0.695 ns, respectively. Photocatalyst test results showed that N-doped ZnO and (Mg,B,N)-doped ZnO materials were optimum for degradation of methyl violet for under visible light with degradation efficiency of 89.28 % and 93.24 %, respectively. N-doped ZnO and (Mg,B,N)-doped ZnO produce inhibition zone of 7.18 mm and 14.15 mm for Escherichia coli bacteria and 7.50 mm and 11.80 mm for Staphylococcus aureus bacteria. Additionally, molecular docking studies were used to explain a potential mechanism for in vitro bacterial activity. [ABSTRACT FROM AUTHOR]

Transition metal-based perovskites have emerged as highly promising and economically advantageous semiconductor materials due to their exceptional performance in optoelectronics, photovoltaic, photocatalysis, and photoluminescence. In this study, we employed a microwave-assisted hydrothermal process to produce a Cu-doped NiMnO3 nanocomposite electrode material. The appearance of a peak corresponding to the (110) plane with a 2θ value of 36.6° confirmed the growth of the rhombohedral NiMnO3 crystal structure. The presence of metal–oxygen bonds in NiMnO3 was confirmed through FTIR spectra. XPS validates the chemical composition, providing additional support for the results obtained from XRD and FT-IR analyses. FE-SEM affirmed the anisotropic growth of small sphere-like structures that agglomerated to form broccoli-like shapes. Cu doping modified the band gap, reducing it from 2.2 to 1.7 eV and enhancing its photoluminescent (PL) activity by introducing defects. The increase in PL intensity (visible light luminescent intensity) can be attributed to a concurrent rise in complex defects and the rate of recombination of electron–hole pairs. Finally, the electrochemical activity demonstrated the pseudo-capacitor behavior of the synthesized material, with capacitance values increasing as the copper (Cu) content in the parent lattice increased. [ABSTRACT FROM AUTHOR]

In the photocatalytic processes of ferroelectric semiconductor materials, how to induce a depolarized electric field (Edp) by polarization to reduce the electron–hole recombination rate is still a big problem. Here, the ABO3-type K0.5Na0.5NbO3 (KNN) material is modified by Nd and Ni elements at A/B sites to narrow the band gap and maintain the room-temperature ferroelectric behavior. The 0.96KNN–0.04NdNiO3 sample shows the narrowed band gap (∼2.75 eV) and high residual polarization value (∼11.56 μC cm−2). After high-field poling, the hydrogen production rate of the sample in the full spectrum reaches 926.28 μmol g−1 h−1, indicating an increase of approximately 5 times compared to the 170.45 μmol g−1 h−1 of the unpoled sample. The improved performance of photocatalytic hydrogen production mainly results from the reduction of band gap and the formation of Edp after polarization. The change in the position of the top of the valence band after sample polarization reveals that high-field poling can improve charge transport efficiency by energy band bending. [ABSTRACT FROM AUTHOR]

Hydrogen is becoming more widely accepted as a potential energy carrier due to zero emissions, superior energy capacity, and ecological sustainability. It can be produced in a number of ways, but photocatalytic water splitting using sunlight has recently attracted attention as a sustainable option. Photocatalysts based on semiconductors, especially TiO 2 photocatalysts, have been the subject of extensive study because of their desirable physicochemical properties. There are still obstacles to overcome, however, including a wide bandgap, sluggish electron-hole recombination, and the potential for excessive H 2 generation. Numerous strategies such as doping, defect engineering, dye sensitization, and semiconductor coupling have been investigated with the goal of improving the performance of TiO 2 by discovering solutions to these limitations. This article summarizes current research on the multiple parameters affecting the photocatalytic process in dynamic H 2 generation. Surface area, particle size, TiO 2 loading, pH, temperature, light source, light intensity, sacrificial reagents, and band gap energy are all important characteristics of photocatalysts. The techno-feasible analysis, current challenges, possibility for subsequent research, and the potential for H 2 production by the photocatalytic water-splitting process are further addressed in this article. [Display omitted] • Recent attempts involving TiO 2 -based photocatalysts to produce H 2 via photocatalytic water-splitting have been addressed. • Various strategies to improve TiO 2 photocatalytic efficiency have been proposed for practical applications. • Factors affecting the TiO 2 -based photocatalytic efficiency were reviewed. • Techno feasibility analysis water-splitting have been addressed for commercialization. • Several challenges, future perspectives and strategies for development have been proposed. [ABSTRACT FROM AUTHOR]

Direct Z-schemes for photocatalytic overall water splitting for hydrogen generation are constructed for Sc 2 CCl 2 /MoTe 2 and Sc 2 CCl 2 /Hf 2 CO 2 heterostructures on the basis of the calculated band alignment and built-in electric field. Solar-to-hydrogen efficiency (η STH ′), which is evaluated using the overpotentials of the band edges and band gaps, can reach 22.09 % for Sc 2 CCl 2 /MoTe 2 and 19.07 % for Sc 2 CCl 2 /Hf 2 CO 2. Tensile strains have little effect on η STH ′. Compressive strains substantially increase the η STH ′ of Sc 2 CCl 2 /MoTe 2 and boost that of the Sc 2 CCl 2 /Hf 2 CO 2 heterostructure only slightly. Nonadiabatic dynamics simulations reveal that the lifetime of the photogenerated electron in one of the stacking patterns of Sc 2 CCl 2 /MoTe 2 is much larger than that of the other configurations, indicating that the reduction ability of the electron is well protected. However, the interlayer electron–hole recombination in Sc 2 CCl 2 /MoTe 2 is faster than that in Sc 2 CCl 2 /Hf 2 CO 2 , implying that the Z-schemes with the former are more efficient than the Z-schemes with the latter. The hydrogen and oxidation evolution reactions with the two heterostructures are thermodynamically feasible but the reactions cannot proceed spontaneously. These findings provide a helpful guide for the development of photocatalytic materials for photocatalytic hydrogen generation from overall water splitting based on the title heterostructures. [Display omitted] • Maximum solar-to-hydrogen efficiency of the constructed schemes can reach 22.09 %. • 4 % compressive biaxial strain can boost the efficiency of Sc 2 CCl 2 /MoTe 2 to 33.77 %. • Reduction ability of SM-AA is well protected by its long electron transfer time. • Minimum Gibbs free energy of HER/OER on the heterostructures reaches 0.89/1.99 eV. [ABSTRACT FROM AUTHOR]

A novel rGO (Reduced Graphene Oxide)-ZnO/WO3 nanohybrid has tremendous commercialization potential for photocatalytic hydrogen generation because of its cheap production costs, specific optical properties, remarkable stability and conductivity. It decreases charge recombination, improves photoelectronic transit, and broadens visible light absorption with rGO. This study developed a simple nano-casting procedure to include WO3 nanocuboids into rGO-ZnO nanorods formed by hydrothermal treatment with the appropriate amount of ZnO grafted on rGO. Improved photocatalytic activity has been discovered in rGO-ZnO nanocomposite with 1:3 ratios. The optimized powder rGO/ZnO (1:3) nanocomposite paired with WO3 exhibits the maximum photocatalytic hydrogen production activity (13.29 mmoles g−1h−1), which is approximately 1.27 times more active than the powder rGO/ZnO (1:3) nanocomposite (10.46 mmoles g−1 h−1). The contributions of rGO/ZnO (1:3) and integrated WO3 to photocatalytic hydrogen evolution enhancement have been fully investigated through experiment and characterization. The logical design and bottom-up synthesis of eco-friendly energy conversion materials with high performance and low-cost lead to commercialization and become the focal point of this effort. Optimized rGO-ZnO (1:3)/ WO3 heterojunction: a robust photocatalyst with a low band gap exhibits a slow rate of electron-hole recombination and remarkable (13.29 mmole g−1 h−1) solar hydrogen production activity. [ABSTRACT FROM AUTHOR]

Photocatalysts show great potential as compounds for restoring contaminated water and wastewater resources. The study aims to synthesize a composite with high photocatalytic potential under visible light to photodegrade the organic pollutants. Ag/Ag3PO4@ TiO2 were synthesized by doping Ag and Ag3PO4 on TiO2. The composite was characterized using X-ray diffraction analysis (XRD), diffuse reflectance spectroscopy, Field emission scanning electron microscopy, and Energy-dispersive X-ray spectroscopy analyses, and its photodegradation ability was investigated by methylene blue. Utilization of pure TiO2 yielded a removal efficiency that was merely half of the efficiency achieved when using modified particles, owing to the reduction of TiO2 s band gap from 3.2 to 1.94 eV. In addition to its enhanced photocatalytic performance under visible light, the synthesized Ag/Ag3PO4@TiO2 photocatalyst demonstrated remarkable efficiency in removing dyes such as methylene blue from aqueous solutions. The removal efficiency at pH less than 7 in 50 ppm methylene blue solution using 3 g/l photocatalyst over 45 min visible light irradiation was approximately 90 percent. Under sunlight, photocatalytic reactions exhibited an efficiency of over 95 percent within 45 min. It can be concluded that the simultaneous introduction of metallic (Ag) and nonmetallic (PO43−) dopants significantly increases the efficiency of electron–hole recombination suppression in the photocatalyst and also decreases the band gap. [ABSTRACT FROM AUTHOR]

With the rapid development of external minimally invasive or noninvasive therapeutic modalities, ultrasound‐based sonodynamic therapy (SDT) is a new alternative for treating deep tumors. However, inadequate sonosensitizer efficiency and poor biosecurity limit clinical applications. In this study, we prepared an oxygen‐vacancy‐engineered W18O49−x nanobrush with a band gap of 2.79 eV for highly efficient SDT using a simple solvothermal method. The suitable band structures of the W18O49−x nanobrush endows it with the potential to simultaneously produce singlet oxygen (1O2), superoxide anions (⋅O2−), and hydroxyl radicals (⋅OH) under ultrasound irradiation. Additionally, abundant oxygen vacancies that serve as further charge traps that inhibit electron‐hole recombination are incidentally introduced through one‐step thermal reduction. Collectively, the in vitro and in vivo results demonstrate that the oxygen‐vacancy‐engineered W18O49−x nanobrush delivers highly efficient reactive oxygen species (ROS) for SDT in a very biosafe manner. Overall, this study provides a new avenue for discovering and designing inorganic nanosonosensitizers with enhanced therapeutic efficiencies for use in SDT. [ABSTRACT FROM AUTHOR]

Tandem photoelectrochemical cells (PECs) are devices useful for water splitting (WS) with the production of oxygen at the photoanode (PA) and hydrogen at the photocathode (PC) by adsorbing more than 75% of the solar irradiation; a portion of the UV/Vis direct solar irradiation is captured by the PA and a diffused or transmitted IR/Vis portion by the PC. Herein, Ti-doped hematite (PA) and CuO (PC) were employed as abundant and non-critical raw semiconductors characterised by proper band gap and band edge banding for the photoelectrochemical WS and absorption of sunlight. The investigation of inexpensive PEC was focused on the scalability of an active area from 0.25 cm2 to 40 cm2 with a rectangular or square shape. For the first time, this study introduces the novel concept of a glass electrode membrane assembly (GEMA), which was developed with an ionomeric glue to improve the interfacial contact between the membrane and photoelectrodes. On a large scale, the electron–hole recombination and the non-optimal photoelectrodes/electrolyte interface were optimized by inserting a glass support at the photocathode and drilled fluorine tin oxide (FTO) at the photoanode to ensure the flow of reagents and products. Rectangular 40 cm2 PEC showed a larger maximum enthalpy efficiency of 0.6% compared to the square PEC, which had a value of 0.37% at a low bias-assisted voltage (−0.6 V). Furthermore, throughput efficiency reached a maximum value of 1.2% and 0.8%, demonstrating either an important effect of the PEC geometries or a non-significant variation of the photocurrent within the scalability. [ABSTRACT FROM AUTHOR]

In this study, the structural and optical properties as well as the photocatalytic performance of Ni0.33Cu0.33Zn0.33Fe2O4 nanoparticles were investigated. These nanoparticles were prepared using the co-precipitation method by applying different calcination temperatures (773, 823, 873, 923, and 973 K). The X-ray diffraction analysis confirmed the presence of the cubic spinel ferrite phase without secondary phases. As the calcination temperature increased from 773 to 973 K, the crystallite and particle sizes of Ni0.33Cu0.33Zn0.33Fe2O4 nanoparticles increased from 12.84 to 20.19 nm and from 19.13 to 43.83 nm, respectively. Among the prepared samples, Ni0.33Cu0.33Zn0.33Fe2O4 nanoparticles calcined at 873 K revealed the highest value of band gap energy along with the lowest values of Urbach energy, refractive index, and optical and static dielectric constant. Additionally, the prepared samples were applied as photocatalysts for the degradation of aniline under ultraviolet irradiation. Improved photocatalytic performance was revealed by Ni0.33Cu0.33Zn0.33Fe2O4 nanoparticles calcined at 873 K. This was attributed to the slowest recombination rate of the electron–hole pairs as revealed from PL analysis. To further improve the photodegradation rate, the degradation reaction was studied by varying the catalyst amount, aniline concentration, pH mediums, and reaction temperatures. Increasing the pH and temperature boosted the degradation rate. Finally, the degradation reaction was carried out by incorporating Ni0.33Cu0.33Zn0.33Fe2O4 nanoparticles calcined at 873 K with different weight % of carbon quantum dots. The results revealed enhanced photocatalytic activity with k = 30 × 10−4 min−1 was achieved after combining 10 weight % of carbon quantum dots with Ni0.33Cu0.33Zn0.33Fe2O4 nanoparticles. [ABSTRACT FROM AUTHOR]

To address the inherent limitations of ZnS and MoS 2 as visible light photocatalysts, herein, we report a step-by-step tuning of mixed sulfide composite system (ZnS/MoS 2) to achieve enhanced visible light to hydrogen fuel conversion efficiency in the absence of any sacrificial agents. In the first stage, ZnS/MoS 2 composite was synthesized by using a single step hydrothermal route and the photocatalytic activity of the synthesized ZnS/MoS 2 composite was tuned by varying the ratio of Zn and Mo in the composite. In the second stage, the photocatalytic efficiency of the composite was further enhanced by tuning the band gap and visible light absorption characteristics of the material through cobalt doping (Co-doping) in the MoS 2 co-catalyst. The hydrogen generation activity of the tuned composition (1:1.3 ratio of Zn and Mo) of the ZnS/MoS 2 composite with 3% Co-doping is obtained as the best (1256 μmol of H 2 in 1 h) as compared to the other compositions of the doped composites (1%, 3% and 5% Co doping). The enhanced hydrogen generation through visible light induced water splitting of the developed mixed sulfide composite systems (ZnS/MoS 2 and ZnS/Co-doped MoS 2) even in the absence of any sacrificial agents is ascribed to their tuned band gap and low electron-hole recombination rate. • Step-by-step tuning of morphology and band gap of ZnS/MoS 2 photocatalyst. • Flower-like ZnS/MoS 2 composite with highly porous morphology achieved through a one-step hydrothermal method. • ZnS/Co-doped MoS 2 system with tuned band gap and low electron-hole recombination rate. • Mixed sulfide composite systems with enhanced photocatalytic activity even in the absence of any sacrificial agents. • Offers a facile strategy for the step-by-step tuning of the photocatalytic mixed sulfide composites. [ABSTRACT FROM AUTHOR]

We investigate anatase TiO 2 doping with Au to determine the change in the band gap energy and optoelectronic properties using experimental and theoretical analysis. The structural analysis using XRD patterns revealed that the synthesized materials primarily exhibited an anatase phase of TiO 2 , with no impurity peaks observed. However, as the concentration of Au increased, additional diffraction peaks corresponding to Au crystalline phases were detected, indicating successful doping. Furthermore, the crystallite size was found to decrease with increasing Au concentration. We observe that the band gap reduces through substitution of Au into the TiO 2 lattice from 3.09 eV to 2.78 eV, demonstrating the feasibility of bandgap tuning of the TiO 2 system. A redshift for Au doped TiO 2 is observed from absorption spectroscopy and optical absorption intensity using hybrid density functional theory, facilitating visible light absorption, although with potential electron-hole recombination limitations. To enhance a visible light photocatalytic activity for water splitting, we extend our work to explore the impact of N and Au codoping into TiO 2 lattice. It reveals that the combination between N and Au leads to a suitable reduction in the band gap width of pure TiO 2. Interestingly, Au–N codoping may decrease the effect of photogenerated carriers, produce a new optical absorption feature in the visible region, and enhance the photocatalytic performance of TiO 2. This codoping configuration is also a promising photocatalyst for the decomposition of water using visible light without inducing unoccupied states. • Analyzing Au doped TiO2's geometry and optoelectronic features experimentally and theoretically. • Favorable O-rich environments promote the formation of Au doped TiO 2 structures. • Substituting Ti with Au causes a redshift in absorption edges, impacting energy band gaps. • Using hybrid density functional calculations to compute electronic and optical properties. • Codoping Au and N atoms to narrow band gap of TiO 2 without introducing impurities, enhancing visible spectrum photocatalysis. [ABSTRACT FROM AUTHOR]

Efficient photocatalytic water splitting is of holds paramount importance in addressing contemporary energy and environmental challenges. The emergence of symmetry-deficient Janus two-dimensional materials has opened new avenues for advancing the field of photocatalytic hydrogen production. Using first-principles calculations, we investigated a novel Janus Zn 2 XY (X = S, Se; Y Se, Te; X≠Y) monolayer. The results demonstrate exceptional structural stability and favorable characteristics for water splitting, including direct band gaps and optimal band edge alignment. Spatially separating band edge states and the intrinsic vertical electric field effectively suppress the recombination rate of photogenerated electron-hole pairs. Strain engineering enhances the monolayer's capacity for visible light absorption. Furthermore, All Janus monolayers exhibit an impressive electron mobility of 103 cm2/V/s, with Janus Zn 2 STe and Zn 2 SeTe monolayers reaching 16.28% and 16.34% Solar-to-hydrogen (STH) efficiencies, respectively. These findings showcase the superior performance of Janus Zn 2 XY in water splitting and guide future experimental endeavors. [Display omitted] • Janus Zn 2 XY (X = S, Se; Y Se, Te; X≠Y) shows promise for water splitting. • They exhibit suitable bandgaps and edge alignments for water splitting. • Exceptional stability and high electron mobility characterize these materials. • In-built electric fields effectively suppress electron-hole recombination. • Strain is an effective strategy to improve their light absorption. [ABSTRACT FROM AUTHOR]

The solution to the issue of energy scarcity lies in the search for an effective photocatalyst. In this study, the monolayers β-AsP and SiC are selected to build a heterostructure as an efficient photocatalyst and its geometric structure and stability, electronic properties, interfacial charge transfer, band edge alignment, optical absorption and solar-to-hydrogen energy conversion efficiency, biaxial strain engineering for band gap and optical adsorption, and the driving force for photocatalytic water splitting are explored systematically using first-principles calculations. The results show that the β-AsP/SiC heterostructure is a semiconductor with a direct band gap of 1.65 eV, and the charge transfer path conforms to a direct Z-scheme mechanism, which can effectively suppress the recombination of photogenerated electron–hole and improve the catalytic efficiency. The β-AsP/SiC heterostructure possesses fascinating band edge position to induce water splitting. Moreover, the optical absorption of the heterostructure is better than that of its monolayer materials, and the solar-to-hydrogen efficiency can reach 5.9%. The effect of biaxial strain on the electronic structure and optical absorption properties is discussed. Furthermore, the analysis of Gibbs free energy confirms that the β-AsP/SiC heterostructure can spontaneously carry out the redox reaction of water splitting in an alkaline environment. Therefore, we believe that the β-AsP/SiC heterostructure provides an effective reference value for the development of efficient photocatalysts. [ABSTRACT FROM AUTHOR]

The recalcitrant nature of emerging contaminants (ECs) in aquatic environments necessitates the development of effective strategies for their remediation, given the considerable impacts they pose on both human health and the delicate balance of the ecosystem. Semiconductor-based photocatalytic technology is recognized for its dual benefits in effectively addressing both ECs and energy-related challenges simultaneously. Among the plethora of photocatalysts, black phosphorus (BP) stands as a promising nonmetallic candidate, offering a host of advantages including its tunable direct band gap, broad-spectrum light absorption capabilities, and exceptional charge mobility. Nevertheless, pristine BP frequently underperforms, primarily due to issues related to its limited ambient stability and the rapid recombination of photogenerated electron–hole pairs. To overcome these challenges, substantial research efforts have been devoted to the creation of BP-based photocatalysts in recent years. However, there is a noticeable absence of reviews regarding the advancement of BP-based materials for the degradation of ECs in aqueous solutions. Therefore, to fill this gap, a comprehensive review is undertaken. In this review, we first present an in-depth examination of the fabrication processes for bulk BP and BP nanosheets (BPNS). The review conducts a thorough analysis and comparison of the merits and limitations inherent in each method, thereby delineating the most auspicious avenues for future research. Then, in line with the pathways followed by photogenerated electron–hole pairs at the interface, BP-based photocatalysts are systematically categorized into heterojunctions (Type I, Type II, Z-scheme, and S-scheme) and hybrids, and their photocatalytic performances against various ECs and the corresponding degradation mechanisms are comprehensively summarized. Finally, this review presents personal insights into the prospective avenues for advancing the field of BP-based photocatalysts for ECs remediation. [ABSTRACT FROM AUTHOR]

TiO 2 is a routinely used catalyst due to its photocatalytic activity. The main problem of TiO 2 is its large band gap. Doping metal and non-metal atoms in TiO 2 crystals reduce the band gap. In this work, first-principle calculations by the full-potential numeric atom-center orbital theory were used to investigate detailed electronic properties of N-doped one monolayer (1 ML) and two monolayers (2 ML) (4,4), (8,8) and (16,16) TiO 2 (001) nanotubes. The proposed model first validated by comparing its data with the experimental available data for rutile and anatase bulk phases, and then was used to predict the electronic properties of proposed nanotubes. PBE0 hybrid method was used to align the valence and conduction bands and to predict their standard reduction potential. In addition, different routine generalized gradient approximation (GGA) and meta -GGA exchange-correlation functionals were used to show how much their errors are in predicting the band gaps of nanotubes. Hybrid data showed that a 2 ML (8,8) nanotube is a proper candidate for photocatalyst not only for its band gap but also from its formation energy point of view. Contrary to the N-doped rutile and anatase phases, there is no electron-hole recombination center for the N-doped 2 ML (8,8) TiO 2 nanotube. • Hybrid method was used to align the bands, and to predict the standard reduction potential of VB and CB of TiO2 nanotubes. • Hybrid data show that the 2 ML (8,8) fluorite-like nanotube is a proper catalyst for solar water splitting. • Contrary to the bulk phases, there is no any electron-hole recombination center in N-doped 2 ML (8,8) TiO2 nanotubes. [ABSTRACT FROM AUTHOR]

[Display omitted] Addressing the energy crisis and environmental pollution necessitates efficient photocatalysts for hydrogen production via water hydrolysis. This study uncovers the potential of a novel photocatalyst - two-dimensional transition metal dichalcogenides (TMDs) heterojunction. Using density functional theory (DFT), we examined the photocatalytic performance of the two-dimensional WS2/MoSe2 heterojunctions for water splitting. Our findings reveal a direct band gap of 1.65 eV and a type II band structure in the heterojunction. This structure facilitates the separation of electrons and holes in the WS2 and MoSe2 monolayers, thereby significantly inhibiting electron-hole recombination. Furthermore, high optical absorption coefficient (105 cm − 1), small effective mass of electron(hole), low interlayer barrier, and adjustable band-edge stress in the heterostructure collectively enhance photocatalytic efficiency. [ABSTRACT FROM AUTHOR]

The present study examines the third order NLO and electrochemical properties of spray deposited lanthanum doped PbS (PbS:La) thin films. FCC crystallization was confirmed by XRD patterns along the plane (2 0 0). PbS crystallites vary in size between 27 and 36 nm with La doping concentration. Surface morphology improved with La doping. La doping increases the band gap from 1.97 to 2.18 eV. Near band edge (NBE) emissions in PL spectra originates from electron-hole recombination. A low resistivity of 0.23 x10−3 Ω-m was realized for PbS film doped with 4 wt% La concentration. Figure of merit of pure PbS improves from 1.32 x 10−3 Ω−1 to 1.607 x 10−2 Ω−1 with La doping. La doping modifies the energy states and band gap of PbS favouring strong nonlinear optical absorption. PbS:La thin films demonstrate self-defocusing due to temperature effects caused by absorption of single photons or free carriers. As a result of the low cationic field strength and high polarizability of La3+ ions, PbS exhibits a higher nonlinear refractive index. The nonlinear susceptibility and refractive index were found to be in the range 3.23–5.33 x 10−6 esu and 2.74 to 3.64 x 10−9 cm2/W, respectively. From the electrochemical studies, increased specific capacitance (256.46 F/g) and decreased charge transfer resistance (12 x 103 Ω) was observed for the 4 wt% La doped film. [ABSTRACT FROM AUTHOR]

Adapting two-dimensional (2D) van der Walls bilayer heterostructure is an efficient technique for realizing fascinating properties and playing a key role in solar energy-driven water decomposition schemes. By means of first-principles calculations, this study reveals the intriguing potential of a novel 2D van der Walls hetero-bilayer consisting of GeC and AlN layer in the photocatalytic water splitting method to generate hydrogen. The GeC/AlN heterostructure has an appropriate band gap of 2.05 eV, wherein the band edges are in proper energetic positions to provoke the water redox reaction to generate hydrogen and oxygen. The type-II band alignment of the bilayer facilitates the real-space spontaneous separation of the photogenerated electrons and holes in the different layers, improving the photocatalytic activity significantly. Analysis of the electrostatic potential and the charge density difference unravels the build-up of an inherent electric field at the interface, preventing electron–hole recombination. The ample absorption spectrum of the bilayer from the ultra-violet to the near-infrared region, reaching up to 8.71 × 105/cm, combined with the resiliency to the biaxial strain, points out the excellent photocatalytic performance of the bilayer heterostructure. On top of rendering useful information on the key features of the GeC/AlN hetero-bilayer, the study offers informative details on the experimental design of the van der Walls bilayer heterostructure for solar-to-hydrogen conversion applications. [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride (g-C 3 N 4) is a semiconductor polymeric photocatalyst with an attractive electronic band structure, a moderate band gap energy, facile synthesis, and functionalization which can be applied as a photocatalyst in the visible light of the spectrum. The main problem of the g-C 3 N 4 photocatalyst is the recombination of the photogenerated electron-hole pairs. The photogenerated electrons in the conduction band (CB) tend to return to the valence band (VB) with subsequent recombination which is unfavored for photocatalysis. It is difficult for a single-component photocatalyst to harvest a large portion of the sunlight spectrum, and simultaneously, possess a suitable spatial charge separation and efficient redox ability. Constructing a heterojunction aims to satisfy the above three factors in a photocatalyst heterojunction system. Constructing g–C 3 N 4 –based heterostructures can promote electron-hole pair separation through the charge transfer across the interface of the g-C 3 N 4 /semiconductor. In this review, the photocatalysis mechanism is discussed and several types of g-C 3 N 4 /semiconductor heterostructures including type II, Z-scheme, and S-scheme heterostructures are explained. Recent advances in different types of g–C 3 N 4 –based heterostructures have been addressed. The synthesis methods for mesoporous, 0D, 1D, and 3D g–C 3 N 4 and different modifications on this photocatalyst are reviewed. [Display omitted] • g-C 3 N 4 heterostructures are designed to improve charge carrier separation. • g-C 3 N 4 heterostructures increase the life time of electron and hole. • Type II, Z-scheme, and S-scheme heterostructures show different charge carrier path. • S-scheme heterojunctions are able to preserve the powerful photogenerated electrons and holes. • g-C 3 N 4 heterostructures improve the photocatalytic performance in pollutant degradation or H 2 production. [ABSTRACT FROM AUTHOR]

The motivation of this work is to identify structural, optical, magnetic properties of ZnFe2O4/CeO2 nanocomposites and their potential use in removal of water-polluting dye. The cost-effective hydrothermal technique was used to synthesize ZnFe2O4/CeO2 nanocomposites of different weight ratio (1:1, 1:2, 1:3, and 1:4). XRD pattern of synthesized samples show two different phases corresponding to ZnFe2O4 and CeO2, respectively. FTIR spectra enlightened Zn–O, Fe–O, and O–Ce–O bonds in synthesized nanocomposites. Further UV–Vis spectroscopy demonstrated that band gap varies from 2.17 to 3.12 eV. This change may be attributed to creation of new sub-band gap energy levels upon addition of wide band gap semiconductor (CeO2). Magnetic investigations showed that pure ZnFe2O4 has greater magnetic character than other synthesized materials, with a maximum magnetization of 1.42 emu/g. HRTEM analysis showed spherical morphology of synthesized samples. In comparison to single metal oxides (ZnFe2O4 and CeO2), maximum photodegradation efficiency of ZnFe2O4/CeO2 (1:4) nanocomposites for Rose Bengal dye was observed to be 95% in 75 min. Furthermore, photocatalytic activity remains unchanged after four runs for this photocatalyst, allowing the reusability of catalysts. In nanocomposites, Ce4+/Ce3+ redox couple and heterojunction interfaces have encouraged electron transport and photo-excited electron–hole recombination which ultimately affects photodegradation efficiency of nanocomposites. [ABSTRACT FROM AUTHOR]

In this study, a synergetic structural design is developed to improve the photocatalytic performance of the sub‐micro core–shell hollow sphere (TiO2@H‐CeO2). TiO2@H‐CeO2 with maximum surface/interface effect is chosen as the substrate and then reacts with different concentrations of Ce(NO3)3·6H2O solutions. Optical properties analysis shows that after the reaction, the band gap of the composite structure and the electron–hole recombination efficiency both decrease while the photodegradation ability is effectively improved. Spectroscopic and microscopic observations reveal two changes in the structure after the reaction. The first is the deposition of CeO2 nanoparticles that can be observed inside and on the surface of the shell; the second is the doping of Ce3+ in the TiO2 nanoparticles of this shell. The deposition of CeO2 particles increases the interfacial area between the CeO2 and TiO2 and facilitates the corresponding charge transfer. The Ce3+ doping in the TiO2 shell changes the optical properties of TiO2. Therefore, the improved performance of the composite structure can be attributed to the synergy of different surfaces and interfacial effects caused by the reactions. [ABSTRACT FROM AUTHOR]

We have conducted first-principles calculations to reveal type-II vdW heterostructures WSi2N4/MoSi2N4 with high catalytic performance, focusing on the excellent optoelectronic properties of the MA2Z4 family of 2D materials. Initially, we investigated the performance of photocatalytic water splitting of MA2Z4 family monolayers, which exhibit higher carrier mobility than traditional two-dimensional materials. Moreover, we built vdW heterostructures based on the MA2Z4 family to promote carrier spatial separation and suppress electron–hole interlayer recombination. The results show that the WSi2N4/MoSi2N4 heterostructure has negative binding energy (−33.47 meV Å−2) and forms a built-in electric field with an average charge transfer of 0.03e. Interestingly, we found that strain tuning can enhance the solar-to-hydrogen efficiencies to 18.01% at 3% biaxial strain, and the heterostructure exhibits a high light absorption coefficient with a band gap of 2.007 eV. In conclusion, the WSi2N4/MoSi2N4 heterostructure with high performance in photocatalytic hydrogen production represents a new impetus for achieving carbon neutrality. [ABSTRACT FROM AUTHOR]

Photocatalytic degradation of pharmaceutical residues through natural solar radiation represents a green and economical treatment process. In this work, ultrasonically assisted hydrothermal synthesis of WO3-TiO2 nanocomposite was carried out at 140–150 °C for 5 h and calcinated at 600 °C. The structural and optical properties of the synthesized material were investigated using techniques like XRD, FESEM/EDX, HRTEM, BET surface area, UV-DRS optical analysis, and photocurrent response. The band gap of TiO2 was successfully reduced from 3.0 to 2.54 eV and thus making it effective under solar light. Complete degradation of paracetamol (50 ppm and natural pH of 6.5) was achieved in 3.5 h under natural sunlight at catalyst dose of 0.5 g/l. The extent of mineralization was evaluated by measuring the COD reduction. Based on the degradation products identified by GC–MS/LC-TOF–MS, the degradation process under natural solar-light could be interpreted to initiate through OH. radical species. The toxicity removal of the treated paracetamol solution under natural solar-light was evaluated by the seed germination test using Spinacia oleracea seeds and exhibited 66.70% seed germination, confirming the reduction in toxicity. The enhanced photocatalytic efficiency of the nanocomposite is attributed to the higher surface area, low rutile content, lower band gap, and incorporation of WO3, which led to an extended absorption range and a slower rate of electron–hole recombination. The technical insights presented in this research offer a feasible approach for utilizing natural solar light driven photocatalysis for wastewater treatment in an efficient and sustainable way. The proposed degradation pathway, and seed germination test (toxicity removal) of the treated paracetamol solution under natural sunlight, has not been previously evaluated. [ABSTRACT FROM AUTHOR]

Lead halide perovskite nanocrystals (LHPs) are emerging with enormous potential for high‐performance optoelectronics. Regrettably, most of the reported lead halide nanocrystal‐based photodetectors (LHP‐PDs) focus on six‐faceted hexahedron (cube/platelet) shapes and encounter issues of interface recombination of the photogenerated electron‐hole pairs and low carrier migration efficiency. Herein, a vertical heterojunction photodetector with type‐I band alignment based on high‐quality polyhedral orthorhombic CsPbBr3 nanocrystals (NCs) is designed and realized. The results show that utilizing these rhombic dodecahedron CsPbBr3 as photosensitive layers, the p‐Si/CsPbBr3 device presents high responsivity (R) and detectability (D*) values of 8.36 A W−1 and 9.33 × 1013 Jones, a powerful weak light detection capability with an ultralow noise equivalent power (NEP) of 2.14 × 10−15 W Hz−1/2, and a fast response time of 90/162 µs. Meanwhile, based on theoretical density functional theory (DFT) and energy band analysis, it is shown that the recombination of photogenerated electron‐hole pairs can be significantly suppressed, and the spectral response of the PDs is almost contributed by photogenerated carriers in CsPbBr3. The work provides a new avenue for improving the performance of PDs based on large‐size orthorhombic polyhedral CsPbBr3 NCs by morphological structure modulation and optimized band alignment engineering. [ABSTRACT FROM AUTHOR]

Cuprous oxide (Cu2O) has a narrow band gap of 2.1–2.3 eV, which facilitates the absorption of visible light and the photocatalytic removal of pollutants from water. However, the catalytic efficiency of Cu2O has been affected by the rapidly compounding carriers in the photocatalytic process. In order to achieve adequate separation of the photogenerated carriers, a straightforward liquid‐phase reduction technique was used in this study to successfully obtain praseodymium‐doped cuprous oxide Pr : Cu2O (0, 1, 3, and 5 mol %). Praseodymium ions were successfully doped into the Cu2O lattice interstitial, as demonstrated by XRD and SEM studies, and the doped praseodymium ions decreased the crystallite size. The FT‐IR peak also confirmed the existence of Cu2O at 631 cm−1. With the increase of Pr doping to 3 %, the band gap gradually decreased to 2.12 eV. Experiments on the degradation of methyl orange (MO) under visible light irradiation showed that 3 % Pr : Cu2O photocatalyst showed the best photocatalytic performance. The Pr doping reduced the recombination of photogenerated electron‐hole pairs and enhanced the photocatalytic activity of Cu2O, according to the analysis results of PL, EIS and transient photocurrent response. Combining these results with active radical capture experiments, the functioning mechanism of the Pr : Cu2O photocatalyst was examined. [ABSTRACT FROM AUTHOR]

This work presents the synthesis of MoO3 and zirconium doped MoO3 nanoparticles by hydrothermal method and their characterizations by several analytical techniques. The XRD patterns of all the undoped and doped samples could be indexed to the hexagonal phase with rod shaped morphologies which were obtained from SEM images. The EDX patterns show the respective elemental composition in the samples thus revealing the effective doping of zirconium into the host lattice of MoO3 without any impurities. The structural features were substantiated by FTIR and Raman spectral studies. The band-gap energies tend to decrease on increasing the dopant concentration. The decrease in PL intensities after doping reveals the lower electron–hole recombination rate which is an important characteristic of photocatalytic studies. The XPS spectra of the NPs were studied to confirm the oxidation state of Zr ions. The doping of zirconium with MoO3 nanoparticles enhanced the photodegradation of Alizarin red S (ARS) in visible region which were studied by varying certain parameters such as catalytic dosage, dye concentration and so on. [ABSTRACT FROM AUTHOR]

The direct or indirect discharge of organic pollutants causes serious environmental problems and endangers human health. The high electron–hole recombination rate greatly limits the catalytic efficiency of traditional TiO2-based catalysts. Therefore, starting from low-cost activated carbon (AC), a photocatalyst (F-Si-TiO2/AC) comprising fluorine (F)- and silicon (Si)-doped TiO2 loaded on AC has been developed. F-Si-TiO2/AC has a porous structure. TiO2 nanoparticles were uniformly fixed on the surface or pores of AC, producing many catalytic sites. The band gap of F-Si-TiO2/AC is only 2.7 eV. In addition, F-Si-TiO2/AC exhibits an excellent adsorption capacity toward methyl orange (MO) (57%) in the dark after 60 min. Under the optimal preparation conditions, F-Si-TiO2/AC showed a significant photodegradation performance toward MO, reaching 97.7% after irradiation with visible light for 70 min. Even under the action of different anions and cations, its degradation efficiency is the lowest, at 64.0%, which has good prospects for practical application. At the same time, F-Si-TiO2/AC has long-term, stable, practical application potential and can be easily recovered from the solution. Therefore, this work provides new insights for the fabrication of low-cost, porous, activated, carbon-based photocatalysts, which can be used as high-performance photocatalysts for the degradation of organic pollutants. [ABSTRACT FROM AUTHOR]

In this study the three natural dyes of madder, curcumin and gardenia blue were used as sensitizers to treat the nano-TiO2 which was prepared with the sol-gel method improved by plant honeysuckle extract, and then oxalic acid (OA) and citric acid (CA) were compounded as crosslinkers to modify the cotton fabric, The carboxyl groups on the modified cotton fabric can anchor the dye-sensitized nano-TiO2 to give it self-cleaning performance. Fourier Transform Infrared (FTIR), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) showed that the dye-sensitized nano-TiO2 was successfully loaded on the surface of the cotton fabrics, and basically did not change their crystalline structure. UV-Visible diffuse reflectance spectra (UV-Vis-DRS) and Photoluminescence Spectroscopy (PL) spectra showed that, compared with nano-TiO2 photocatalytic cotton fabrics, the photocatalytic cotton fabric prepared from our dye-sensitized nano-TiO2 had a narrower band gap energy and a decrease in the recombination rate of electron-hole pairs. The cross-linked cotton fabric treated with dye-sensitized nano-TiO2 had excellent photocatalytic performance and washing resistance. In addition, the cross-linking treatment greatly improved the wrinkle recovery of the cotton fabrics, and the load of dye-sensitized nano-TiO2 endowed the fabric with excellent hydrophilic properties. but it also led to a certain degree of decrease in its breaking strength. [ABSTRACT FROM AUTHOR]

A First-principles study was accomplish to examine the various characteristics of 2-D hetero-junction layer structure Molybdenum disulfide (MoS2) material such as structural, electronic, and optical properties through variation of external static pressure 0–100 GPa with a 4-steps escalations such as 0, 50, 75 100 GPa. Scheming bandgap tuning by the external static pressure engineering of 2-D layered MoS2 is a relatively new approach for tailoring different properties. The bandgap of MoS2 is found to be decreasing from 1.65 to 0.0 eV with increased external static pressure from 0 to 100 GPa. By increasing the external static pressure in MoS2 extra gamma states are produced into an energy band gap (Eg). The bandgap nature originated indirect moreover bandgap represented that material is an eminent semiconductor. MoS2 is a proficient photo-catalysis have a large surface area for light absorption and decreases the electron–hole pairs recombination rate and increases the charge transport. A significant decrement is found in the reflectivity due to the decrement in the bandgap. It is also examined that increment in energy adsorption peaks at 0 to 35 eV furthermore optical conductivity peaks shifts at larger energy band through increment the static pressure engineering. The optical properties significantly increased by the decrement of Eg. MoS2 has high energy absorption, optical conductivity, and refractive index and is an appropriate material for photocatalytic applications. [ABSTRACT FROM AUTHOR]

The aim of this study was to develop a new rotating photocatalytic reactor operating in recirculation mode with light sources placed outside the photoreactor vessel. The photoreactor with cylindrical geometry was equipped with four artificial lamps used to simulate solar irradiation (2.4% UVB and 12% UVA; 300–700 nm). The photocatalyst was immobilized on abrasive material used as a support and placed on the central (inner) photoreactor tube, which was connected to a power-driven shaft that allowed rotation at a desired speed. A suitable modification of the commercial TiO2 P25 photocatalyst was carried out to reduce its band gap energy and electron-hole recombination and to extend the visible light response range of TiO2. The main task of this research was to apply the basic principles of process intensification methodology, i.e. to explore the influence of rotational hydrodynamics, which allows good access of reactants to the photocatalyst surface, good irradiation of the photocatalytic surface and reduction of mass transfer resistance, leading to increased process efficiency. The homemade photoreactor was used for the photocatalytic degradation of one of the major types of neonicotinoid insecticides, acetamiprid. The influence of various working conditions, such as initial solution pH, rotation speed, recirculation flow rate and initial concentration of acetamiprid on the photocatalytic degradation process was investigated. The optimum degradation conditions were found at a recirculation flow rate of 200 cm3 min−1 and a rotation speed of 200 rpm, indicating that the mass transfer process strongly contributes to the photocatalytic degradation rate at the conditions used in this study. The results obtained during the photocatalytic degradation of acetamiprid in a rotating photoreactor were compared with those obtained under similar operating conditions in a flat-plate photoreactor, and the corresponding conclusions were drawn based on the performed kinetic analysis. [ABSTRACT FROM AUTHOR]

We developed here the efficient photocatalysts for the removal of high concentrations of tetracycline under visible light by immobilizing the AWO (A = Ag, Bi, Na) nanocrystals on the surface of siligraphene (g-SiC) nanosheets. The g-SiC/AWO composites was synthesized by magnesiothermic synthesis of g-SiC and sonochemical immobilization of tungstates. These new heterojunctions of g-SiC/tungstates show superior photocatalytic activities in the degradation of high concentrations of tetracycline and 97, 98, and 94% of tetracycline were removed by using low amounts of g-SiC/Ag2WO4, g-SiC/Bi2WO6, and g-SiC/Na2WO4 catalysts, respectively. Based on band structures, the band gaps reduce and the photocatalytic activities were extremely enhanced due to the shortening of electron transfer distance through the Z-scheme mechanism. Also, the graphenic structure of g-SiC is another parameter that was effective in improving photocatalytic performance by increasing the electron transfer and decreasing the rate of electron–hole recombination. Furthermore, the π back-bonding of g-SiC with metal atoms increases the electron–hole separation to enhance the photocatalytic activity. Interestingly, g-SiC composites (g-SiC/AWO) showed much higher photocatalytic properties compared to graphene composites (gr/AWO) and can remove the tetracycline even at dark by producing the oxygenated radicals via adsorption of oxygen on the positive charge of Si atoms in siligraphene structure. [ABSTRACT FROM AUTHOR]