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Two-dimensional (2D) Sn-based perovskites exhibit significant potential in diverse optoelectronic applications, such as on-chip lasers and photodetectors. Yet, the underlying mechanism behind the frequently observed dual-peak emission in 2D Sn-based perovskites remains a subject of intense debate, and there is a lack of research on the carrier dynamics in these materials. In this study, we investigate these issues in a representative 2D Sn-based perovskite, namely, PEA2SnI4, through temperature-, excitation intensity-, angle-, and time-dependent photoluminescence studies. The results indicate that the high- and low-energy peaks originate from in-face and out-of-face dipole transitions, respectively. In addition, we observe an anomalous increase in the non-radiative recombination rate as temperature decreases. After ruling out enhanced electron–phonon coupling and Auger recombination as potential causes of the anomalous carrier dynamics, we propose that the significantly increased exciton binding energy (Eb) plays a decisive role. The increased Eb arises from enhanced electronic localization, a consequence of weakened lattice distortion at low temperatures, as confirmed by first-principles calculations and temperature-dependent x-ray diffraction measurements. These findings offer valuable insights into the electronic processes in the unique 2D Sn-based perovskites. [ABSTRACT FROM AUTHOR]

In this work, nitrogen vacancy (NV) centers of high nitrogen diamond implanted with arsenic ions were investigated by photoluminescence spectroscopy. The transition of the NV center charge state was discussed by the regularly changing laser excitation power and measurement temperature following high-temperature annealing. After high-temperature annealing, the amorphous layer generated by arsenic ion implantation is transformed into a graphitization layer, resulting in a decrease in the NV yield. The electric neutral NV (NV0) center and negatively charged NV (NV−) center are affected by both radiation recombination and Auger recombination with increasing laser power. Accompanied by the increasing measurement temperature, the intensities of NV centers gradually decreased and eventually quenched. In addition, the charge states of NV− and NV0 centers were undergoing a transition. The zero phonon line positions of NV centers were also red shift, it was attributed to the dominant role of electron–phonon interaction in the temperature-dependent displacement of diamond energy gaps. The full width at half maxima of NV center were broadened significantly at higher temperatures. [ABSTRACT FROM AUTHOR]

In this study, we investigate the tradespace between the improvement of mid-infrared light-emitting diode efficiency through microcavity enhancement vs reduction of Auger recombination for different W-superlattice thicknesses. Several sample designs are modeled and then grown and fabricated to test the tradespace at different W-superlattice thicknesses down to the quantum well limit. In a half-cavity, with a single reflector from the top metal contact, intermediate thickness W-superlattices gave the highest efficiencies, outperforming those in the W-quantum well limit across the entire measured current range. Experimentally, we report wallplug efficiencies of 0.4% for a room temperature 3.2 μm device. W-superlattices of intermediate thickness were also found to be optimal for a full-cavity device with a bottom distributed Bragg reflector added. The resonant full cavity did strongly improve the peak spectral radiance, with a measured increase of four to five times for a 3.6 μm device, and a value that is >250 times larger than previously reported. [ABSTRACT FROM AUTHOR]

Determining the correlation between the size of a single quantum dot (QD) and its photoluminescence (PL) properties is a challenging task. In the study, we determine the size of each QD by measuring its absorption cross section, which allows for accurate investigation of size-dependent PL blinking mechanisms and volume scaling of the biexciton Auger recombination at the single-particle level. A significant correlation between the blinking mechanism and QD size is observed under low excitation conditions. When the QD size is smaller than their Bohr diameter, single CsPbI3 perovskite QDs tend to exhibit BC-blinking, whereas they tend to exhibit Auger-blinking when the QD size exceeds their Bohr diameter. In addition, by extracting bright-state photons from the PL intensity trajectories, the effects of QD charging and surface defects on the biexcitons are effectively reduced. This allows for a more accurate measurement of the volume scaling of biexciton Auger recombination in weakly confined CsPbI3 perovskite QDs at the single-dot level, revealing a superlinear volume scaling (τXX,Auger ∝ σ1.96). [ABSTRACT FROM AUTHOR]

In order to develop an efficient metal-free solar energy harvester, we herein performed the electronic structure calculation, followed by the hot carrier relaxation dynamics of two dimensional (2D) aza-covalent organic framework by time domain density functional calculations in conjunction with non-adiabatic molecular dynamics (NAMD) simulation. The electronic structure calculation shows that the aza-covalent organic framework (COF) is a direct bandgap semiconductor with acute charge separation and effective optical absorption in the UV-visible region. Our study of non-adiabatic molecular dynamics simulation predicts the sufficiently prolonged electron–hole recombination process (6.8 nanoseconds) and the comparatively faster electron (22.48 ps) and hole relaxation (0.51 ps) dynamics in this two-dimensional aza-COF. According to our theoretical analysis, strong electron–phonon coupling is responsible for the rapid charge relaxation, whereas the electron–hole recombination process is slowed down by relatively weak electron–phonon coupling, relatively lower non-adiabatic coupling, and quick decoherence time. We do hope that our results of NAMD simulation on exciton relaxation dynamics will be helpful for designing photovoltaic devices based on this two dimensional aza-COF. [ABSTRACT FROM AUTHOR]

Epitaxial growth of wurtzite AlN films on Si {111} results in 19% lattice misfit, which gives rise to a large density of threading dislocations with different recombination rates of electron–hole pairs. Here, we investigate types and distributions of threading dislocations of the MOVPE-grown 200 nm AlN/Si {111} film, whereby the dislocations are visualized using the technique of wet chemical etching. Atomic force microscopy suggests the existence of four different types of etch pits without any topological differences. Cross-sectional transmission electron microscope studies on etched samples are employed to associate the types of dislocations with the shapes of their etch pits. The recombination activity of individual dislocations was quantified by measuring the electron beam induced current and by correlative measurement of topography, secondary electron imaging, and the electron beam absorbed current. The strongest recombination activity was obtained for the m + c-type (mixed), c-type (screw), and a + c-type (mixed) threading dislocations, whereas the a-type (edge) threading dislocations were nearly recombination-inactive. [ABSTRACT FROM AUTHOR]

The Zeeman-split spin states of a single quantum dot can be used together with its optical trion transitions to form a spin–photon interface between a stationary (the spin) and a flying (the photon) quantum bit. In addition to long coherence times of the spin state itself, the limiting decoherence mechanisms of the trion states are of central importance. Here, we investigate in time-resolved resonance fluorescence the electron spin and trion dynamics in a single self-assembled quantum dot in an applied magnetic field of up to B = 10 T. The quantum dot is only weakly coupled to an electron reservoir with tunneling rates of about 1 ms − 1 . Using this sample structure, we can measure, in addition to the spin-flip rate of the electron and the spin-flip Raman rate of the trion transition, the Auger recombination process that scatters an Auger electron into the conduction band. The Auger effect destroys the radiative trion transition and leaves the quantum dot empty until an electron tunnels from the reservoir into the dot. The combination of an Auger recombination event with subsequent electron tunneling from the reservoir can flip the electron spin and thus constitutes another mechanism that limits the spin lifetime. [ABSTRACT FROM AUTHOR]

To identify optimal monolayers for photocatalytic water splitting, we screened the lowest-energy structures of CdAl 2 Se 4 and HgAl 2 Se 4 monolayers with the P -3m1 space group from two pools of 675 allotropes. Unfortunately, the valence band maximum of these newfound monolayers did not meet the potential requirement for the oxygen evolution reaction. This led us to explore AAl 2 Se 4 /XSe 2 (A = Cd, Hg; X = Ti, Zr, Hf) heterostructures. Among these, we constructed several Z-schemes for overall water splitting, achieving a maximum solar-to-hydrogen efficiency (η ′ STH) of 38.28%. Non-adiabatic molecular dynamics simulations revealed that the electron transfer for hydrogen evolution reaction (HER) and hole transfer for oxygen evolution reaction (OER) in HgAl 2 Se 4 /ZrSe 2 and CdAl 2 Se 4 /HfSe 2 heterostructures are slower compared to the other five heterostructures, suggesting that their reduction and oxidation activities are well-protected. Notably, CdAl 2 Se 4 /TiSe 2 demonstrated the shortest electron-hole recombination time, indicating superior photocatalytic efficiency for the Z-scheme. Additionally, the Gibbs free energies for HERs and OERs in CdAl 2 Se 4 /TiSe 2 , CdAl 2 Se 4 /ZrSe 2 , and CdAl 2 Se 4 /HfSe 2 are lower than the energies provided by the overpotential, implying spontaneous HER and OER processes. Therefore, AAl 2 Se 4 /XSe 2 (A = Cd, Hg; X = Ti, Zr, Hf) heterostructures, particularly CdAl 2 Se 4 /TiSe 2 , show great promise as candidates for efficient photocatalytic water splitting to produce hydrogen. [Display omitted] • The stable structures of AAl 2 Se 4 (A = Cd, Hg) monolayers are screened. • The highest STH efficiency of the HgAl 2 Se 4 /TiSe 2 heterostructure can reach 38.28%. • Photocatalytic HER/OER with CdAl 2 Se 4 /XSe 2 heterostructures spontaneously proceed. • NAMD simulations reveal that CdAl 2 Se 4 /TiSe 2 has favorable carrier migrations. • CdAl 2 Se 4 /TiSe 2 heterostructure is the most optimal based on all evaluated criteria. [ABSTRACT FROM AUTHOR]

The carrier recombination behavior of GaN-based blue laser diodes (LDs) is studied and analyzed by experiments and simulation calculations before lasing, with a particular focus on the role of Auger recombination. It is found that Auger recombination plays a crucial role in the decrease in differential efficiency and threshold current of GaN-based blue LDs. The theoretical calculation results show that a large Auger recombination rate may lead to a dominant recombination channel before lasing, which could exceed the radiation recombination and result in an obvious decrease in the differential efficiency. Such a high Auger recombination will dissipate a large number of carriers in the quantum well, resulting in deterioration of device performance, a higher threshold current and a lower efficiency. This work presents a method to evaluate Auger recombination through differential efficiency and also provides evidence that suppressing the Auger recombination rate is beneficial to improve the performance of blue LDs. [ABSTRACT FROM AUTHOR]

g-C 3 N 4 is a promising metal-free photocatalyst for hydrogen production, whose application is difficult due to the low mobility of charge carriers and rapid electron-hole recombination. Here we propose a new route to improve its response to simulated sunlight and prevent electron-hole recombination by grafting mixed Ag–NiO (1:1 nominal Ag/NiO weight ratio) materials, as an alternative to platinum group metal co-catalysts. g-C 3 N 4 was prepared by urea pyrolysis, whereas Ag–NiO was prepared by a co-precipitation method, and then the composites were prepared by physical mixing using sonication-grinding. The presence of Ag–NiO on the surface plays a key role in accepting excited electrons and enhancing their lifetime for a subsequent reduction of protons to hydrogen. Hydrogen production was carried out from the photoreforming of ethanol under simulated sunlight. The results revealed that 2% (Ag–NiO)/g-C 3 N 4 is effective among others with 5.2 times higher H 2 production than unmodified g-C 3 N 4. The percentage of ethanol in the ethanol/water ratio is very important as we have found that with increasing its quantity, the evolution of hydrogen becomes significant. • New series of g-C 3 N 4 photocatalysts modified with mixed Ag–NiO. • Innovative synthesis of isolated Ag–NiO and (Ag–NiO)/g-C 3 N 4 composite. • Ag–NiO significantly reduces electron-hole recombination. • The optimal composite is 2% (Ag–NiO)/g-C 3 N 4. • Hydrogen evolution via ethanol photoreforming under simulated sunlight. [ABSTRACT FROM AUTHOR]

The paper presents an investigation on the optoelectronic and photocatalytic properties of titanium-nitride (TiN) thin films, modified through the introduction of metal ions (Au, Ag, and Cu) during implantation, followed by thermal annealing. Employing high-resolution microscopic and spectroscopic techniques, we examined the microstructural and compositional features of the films in detail. The films exhibited a crystalline structure with distinct columnar patterns, attributed to defect release and recovery during annealing. Furthermore, metal nanoparticles were detected in samples implanted with gold and silver ions, indicating coalescence processes, while no such particles were observed in the case of Cu ions. Post-implantation annealing also led to surface oxidation and the formation of anatase TiO 2 , with a coexistence of TiO 2 , TiN, metallic Au and Ag, and CuO phases in subsurface regions. Comparative optical measurements revealed significant changes in photoluminescence efficiency and photocatalytic response of modified TiN. All implanted samples showed reduced photoluminescence intensity compared to pristine titanium-nitride, with the Au-implanted film exhibiting the most significant decrease, due to the presence of surface Au nanoparticles, thus resulting in the slower electron-hole recombination rates and enhanced photocatalytic activity. [ABSTRACT FROM AUTHOR]

[Display omitted] Selective oxidation of sulfur mustard gas (HD) to non-toxic sulfoxide by the visible-light-catalyzed generation of singlet oxygen (1O 2) is a promising degradation strategy. Although PCN-224 can absorb visible light, it suffers from rapid electron-hole recombination and low redox capacity, which limits the performance of HD degradation. Titanium dioxide (TiO 2) is an excellent photocatalyst but it lacks visible-light-activity in degrading HD. In this study, PCN-224@TiO 2 heterojunction with S-type core–shell structure was synthesized by in-situ growth method to prolong the visible light absorption capacity of TiO 2 and inhibit the rapid recombination of PCN-224. The interface formation and internal electric field were optimized by adjusting the Zr/Ti ratio to enhance the charge transfer, redox capacity, electron-hole separation, and visible light absorption. In this study, the formation of heterojunction composites based on Zr-O-Ti linkages is demonstrated by a series of characterization methods. It is demonstrated by experiments and theoretical calculations that PCN-224@TiO 2 can generate nearly 100 % 1O 2 under visible light conditions without a sacrificial agent, resulting in efficient and selective oxidation of 2-chloroethyl ethyl sulfide (CEES), a simulant of HD, to non-toxic sulfoxide form. [ABSTRACT FROM AUTHOR]

Covalent organic frameworks have emerged as a thriving family in the realm of photocatalysis recently, yet with concerns about their high exciton dissociation energy and sluggish charge transfer. Herein, a strategy to enhance the built-in electric field of series β-keto-enamine-based covalent organic frameworks by ionic polarization method is proposed. The ionic polarization is achieved through a distinctive post-synthetic quaternization reaction which can endow the covalent organic frameworks with separated charge centers comprising cationic skeleton and iodide counter-anions. The stronger built-in electric field generated between their cationic framework and iodide anions promotes charge transfer and exciton dissociation efficiency. Moreover, the introduced iodide anions not only serve as reaction centers with lowered H* formation energy barrier, but also act as electron extractant suppressing the recombination of electron-hole pairs. Therefore, the photocatalytic performance of the covalent organic frameworks shows notable improvement, among which the CH3I-TpPa-1 can deliver an high H2 production rate up to 9.21 mmol g−1 h−1 without any co-catalysts, representing a 42-fold increase compared to TpPa-1, being comparable to or possibly exceeding the current covalent organic framework photocatalysts with the addition of Pt co-catalysts. Covalent organic frameworks (COFs) show great promise in photocatalysis but are limited by slow charge transfer. Here, the authors report a strategy to enhance the built-in electric field of COFs via ionic polarization, resulting in a hydrogen evolution rate of 9.21 mmol g-¹ h-¹ without Pt co-catalysts. [ABSTRACT FROM AUTHOR]

ABSTRACT The existence of organic pollutants in aqueous media has become a vital issue and a critical threat to human health, where organic toxic dyes represent the major contaminants in wastewater. Over the past few years, photocatalytic techniques have garnered a lot of interest in dye removal from wastewater. In this study, a series of ErxTbxZn1 − 2xO nanophotocatalysts (where x = 0.00, 0.01, 0.03, and 0.05) were synthesized and coded as ZET0, ZET1, ZET2, and ZET3 NPs (nanoparticles). The chemical and physical characteristics of the NPs were investigated using Fourier‐transform infrared spectroscopy (FT‐IR), X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), energy‐dispersive X‐ray (EDX) spectroscopy, and ultraviolet–visible diffuse reflectance spectroscopy (UV–vis DRS) techniques. Further examination by performing photocatalytic experiments, ZET1 NPs demonstrated effective Rhodamine B (RhB) dye degradation within 60 min. It was found that the kinetic rate constant values were 0.008, 0.097, 0.050, and 0.040 min−1 for ZET0, ZET1, ZET2, and ZET3 NPs, respectively. Aside from their remarkable photocatalytic degradation efficiency, these ZET1 photocatalysts are highly stable even after five consecutive cycles. In addition, the active species test revealed that the primary oxidation species involved in the photocatalytic process are holes (h+) and hydroxyl radicals (•OH), and a possible photocatalytic mechanism for degrading RhB by ZET1 photocatalysts was tentatively proposed. The enhancement of the photocatalytic degradation efficiency is due to the low recombination rate of photogenerated charge carriers, as well as a strong synergistic impact of Tb, Er, and ZnO components. Thus, the current study could offer a versatile strategy for the design of new and effective nano photocatalysts for wastewater purification in the future. [ABSTRACT FROM AUTHOR]

The measurement and description of the charge-carrier lifetime ( τ c ) is crucial for the wide-ranging applications of lead-halide perovskites. We present time-resolved microwave-detected photoconductivity decay (TRMCD) measurements and a detailed analysis of the possible recombination mechanisms including trap-assisted, radiative, and Auger recombination. We prove that performing injection-dependent measurement is crucial in identifying the recombination mechanism. We present temperature and injection level dependent measurements in CsPbBr3, which is the most common inorganic lead-halide perovskite. In this material, we observe the dominance of charge-carrier trapping, which results in ultra-long charge-carrier lifetimes. Although charge trapping can limit the effectiveness of materials in photovoltaic applications, it also offers significant advantages for various alternative uses, including delayed and persistent photodetection, charge-trap memory, afterglow light-emitting diodes, quantum information storage, and photocatalytic activity. [ABSTRACT FROM AUTHOR]

The sustainability and feasibility of using visible irradiation in photocatalysis is a promising approach for water purification. In this study, photocatalytic degradation of a widely used analgesic and antipyretic drug, acetaminophen (ACM), with metal-loaded an efficient photocatalyst (TiO 2 NPs-Co/Polycalix (Christen et al., 2010) [4]resorcinarene (TCP)) was inv estigated using visible light. photocatalyst structural, surface, and morphological features were characterized using FTIR, XRD, TEM, EDX, PL, and DRS analyses. Considering various sites of Polycalix (Christen et al., 2010) [4]resorcinarene in the TCP, studied by trapping experiments. A novel charge transfer bridge for electron-hole recombination is made possible by using Co and TiO 2 as electron transfer mediators with electronic conductivity. This results in efficient process and energy optimization, which makes it easier for ACM to degrade throughout the absorption process. The ACM (15 and 40 mg/L) achieved complete degradation under visible light irradiation with 0.6 g/L of TCP at pH = 5.0 during 120 min reaction because of the good synergetic effect of the catalyst systems. Additionally, the intermediates generated by photo electrocatalytic activities were identified, and two potential paths for degradation were suggested. Some of these organic products were identified by High-Performance Liquid Chromatography (HPLC). [ABSTRACT FROM AUTHOR]

In this research work, synthesis, structural, and optical properties of activated carbon (AC) and AC/metal oxide nanocomposites (AC/ZnO and AC/Fe3O4) have been studied. Uniformly distributed metal oxide in AC (AC/ZnO and AC/Fe3O4) nanocomposites were obtained by a single-step impregnation-carbonization method, using bamboo as the biomass precursor, ZnCl2, and FeCl3 as chemical activating agents. The microstructural evolutions and optical characteristics of AC, and the composites have been investigated using X-ray diffraction (XRD), Raman, X-ray photoelectron spectroscopy (XPS), and photoluminescence spectroscopy. Both AC and composites exhibited broad photoluminescence (PL) emissions in the visible region. The PL emissions at 462 and 603 nm by AC were due to the radiative recombination of electron-hole pairs generated by sp2 sites embedded in the sp3 matrix. However, two new emission centers in addition to the above appeared at 520 and 560 nm, in both AC/ZnO and AC/Fe3O4 nanocomposites. The study suggests that metal oxide formation in composites led to a new sp2 cluster formation with a new energy band resulting in two additional emission centers in the green light region. This work provides a simple, cost-effective, and efficient way to develop broadband luminescent materials in visible regions with potential optical and sensing applications. [ABSTRACT FROM AUTHOR]

A novel organic-inorganic photocatalyst like layer structured graphitic carbon nitride (g-C3N4 or CN) hybrid with strontium titanate (SrTiO3 or STO) was prepared by a precipitation-sonication technique for photocatalytic activity. The crystal phases, morphologies, elemental composition, optical properties, and porous structure of the prepared pristine and STO/CN hybrid composite were measured using various physicochemical characterizations. It is indicated that STO nanospheres were effectively loaded on the g-C3N4 nanosheets, resulting in the STO/CN hybrid composite, high surface area, enhanced visible-light absorption, enhancing photoinduced charge separation and suppressing the recombination rate. Furthermore, the 3 wt% of g-C3N4 composited STO (STO/CN-3) catalyst demonstrated higher photocatalytic activity than pristine STO in 100 min under white light irradiation, reaching the degradation efficiency of 92.66 % and 93.31 % toward methylene blue (MB) and tetracycline (TC), respectively. The improved photocatalytic activity of STO/gCN hybrid composite could be ascribed to the synergistic effect between STO and CN with strong interfacial interaction facilitating efficient charge separation and inhibiting the charge recombination of photogenerated electron-hole pairs. Moreover, a possible photocatalytic mechanism has been proposed for the degradation of MB and TC. Besides, the excellent photocatalytic performance, STO/CN-3 nanocomposite also exhibits outstanding photostability under the current factors, suggesting that they are suitable for practical applications. [ABSTRACT FROM AUTHOR]

The cadmium manganese sulfide, despite being recognized as a highly efficient photocatalytic semiconductor for hydrogen evolution, faces significant challenges in terms of charge recombination when used solely as a catalyst for photocatalytic hydrogen production. The construction of heterojunction photocatalysts is regarded as one of the effective strategies to enhance the efficiency of photocatalytic hydrogen production. In this work, Zn-doped CdSe was adopted to enhance the photocatalytic active sites of the twinned Mn 0.65 Cd 0.35 S. As results, the photocatalytic hydrogen evolution of Zn–CdSe-1/T-MCS-40 can reach approximately 47447.15 μmol g−1 after 5 h, representing a 15 times increase compared to Mn 0.65 Cd 0.35 S. Besides, the hydrogen evolution rate shows almost no significant attenuation after four consecutive cycles (20 h). The significant achievement can be largely attributed to the successful construction of an S-scheme heterojunction of Zn – CdSe-1/T-MCS-40, which effectively minimized the charge transfer distance and suppressed the recombination of photo-generated electron-hole pairs. Additionally, the incorporation of Zn-doped CdSe significantly expands the response range to visible light, thereby providing a conceptual framework for advancing the design of solar-to-chemical energy conversion and effectively guiding the fabrication of metal sulfide-based photocatalytic heterojunctions. • Zn doping broadens the light absorption range of CdSe. • Zn–CdSe is coupled with T-MCS to form the S-scheme heterojunction. • The photocatalytic rate of Zn–CdSe-1/T-MCS-40 exhibits a 15 enhancement compared to Mn 0.65 Cd 0.35 S. • The separation of photogenerated carrier is accelerated by the construction of S-scheme heterojunction. [ABSTRACT FROM AUTHOR]

Zinc sulfide/molybdenum disulfide (ZnS@MoS 2) nanorods composites were synthesized by straightforward hydrothermal method. Experimental investigations revealed that the kinetic coefficient (k) of ZnS@MoS 2 was 0.0667 min−1 within 30 min, with a degradation efficiency of 88.6 % toward methylene blue dye in presence of both stirring and light. These performances were notably higher compared to conditions with either light or stirring irradiation alone. Moreover, ZnS@MoS 2 composites not only had excellent catalytic activity but also good cyclic stability. The catalytic mechanism of ZnS@MoS 2 for degradation of MB organic pollutant was further discussed based on relevant characterization. Under both stirring and light conditions, the strong piezoelectric field effectively promoted charge carriers separation and reduced the electron-hole recombination rate, thus enhancing catalytic degradation efficiency for ZnS@MoS 2. This research holds significant importance for the development of high-performance catalysts in wastewater treatments field. [Display omitted] • A novel ZnS@MoS 2 nanorods composites catalyst was rationally designed. • ZnS@MoS 2 exhibited superior catalytic activity and stability toward degradation of methylene blue dye. • Excellent catalytic performance was mainly ascribed to the efficient charge carriers separation. • A possible catalytic mechanism of ZnS@MoS 2 was clarified. [ABSTRACT FROM AUTHOR]

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]

Highly efficient interconversion of different types of energy plays a crucial role in both science and technology. Among them, electrochemiluminescence, an emission of light excited by electrochemical reactions, has drawn attention as a powerful tool for bioassays. Nonetheless, the large differences in timescale among diverse charge-transfer pathways from picoseconds to seconds significantly limit the electrochemiluminescence efficiency and hamper their broad applications. Here, we report a timescale coordination strategy to improve the electrochemiluminescence efficiency of carbon nitrides by engineering shallow electron trap states via Au-N bond functionalization. Quantitative electrochemiluminescence kinetics measurements and theoretic calculations jointly disclose that Au-N bonds endow shallow electron trap states, which coordinate the timescale of the fast electron transfer in the bulk emitter and the slow redox reaction of co-reagent at diffusion layers. The shallow electron trap states ultimately accelerate the rate and kinetics of emissive electron-hole recombination, setting a new cathodic electrochemiluminescence efficiency record of carbon nitrides, and empowering a visual electrochemiluminescence sensor for nitrite ion, a typical environmental contaminant, with superior detection range and limit. Differences in timescales of electron transfer reactions limit the efficiency of electrochemiluminescence. Here, the authors coordinate the timescales using shallow trap states in carbon nitride to achieve high efficiencies applied in nitrite sensing. [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]

In this research, we present a novel facile, scalable, and template-free technique of synthesizing graphitic carbon nitride (g-C 3 N 4) nanotubes for generating hydrogen through photocatalysis. The hybrid technique involves a two-fold mixing of the precursor materials melamine (M) and cyanuric acid (CA), involving ball milling followed by solution mixing. By varying the M:CA molar ratios, different compositions of g-C 3 N 4 nanotubes were fabricated. The study focused on examining the surface characteristics and the photocatalytic hydrogen evolution performance of these nanotubes. Nanotubes with high specific surface area of 206 m2 g−1 for M:CA molar ratio of 1:3 and 178 m2 g−1 for M:CA molar ratio of 1:5 were produced, with H 2 evolution rates of 543 μmol h−1 g−1 and 740 μmol h−1 g−1 respectively, which were an increase of 4 and 5-fold, respectively, in comparison to the pristine sample. The enhanced efficiency of hydrogen production through photocatalysis by nanotubes, when contrasted with pristine material, can be ascribed to their high crystallinity, superior specific surface areas, decreased recombination rates of electron-hole pairs generated during light exposure, and improved dynamics of charge carriers. This hybrid technique provides a new pathway for cost-effective fabrication of g-C 3 N 4 nanotubes with substantial surface areas and high yield photocatalysts on an industrial scale, without the use of templates and hydrothermal processes for efficient hydrogen generation. [Display omitted] • Graphitic carbon nitride (g-C 3 N 4) nanotubes were synthesized using a novel hybrid synthesis technique involving dual precursor mixing. • High specific surface area g-C 3 N 4 nanotubes of ∼206 m2 g−1 and 178 m2 g−1 were achieved. • A g-C 3 N 4 nanotube with a 1:3 melamine-cyanuric acid molar ratio achieved enhanced H 2 evolution performance (740 µmol h⁻¹ g⁻¹). • The stability of g-C 3 N 4 nanotubes was shown by the consistent H 2 evolution rate during extended irradiation. [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]

This research involved synthesizing In 2 S 3 –In(OH) 3 nanosheets through a simple hydrothermal method at a low reaction temperature. The impact of different indium chloride concentrations on the morphology and crystal structure of In 2 S 3 –In(OH) 3 nanostructures was investigated. The discussion extended to the photocatalytic hydrogen evolution of both In 2 S 3 –In(OH) 3 nanosheets and nanofibers. These findings indicated that In 2 S 3 –In(OH) 3 nanofibers exhibited optimal photocatalytic hydrogen production at various indium chloride concentrations. Furthermore, In 2 S 3 –In(OH) 3 –ZnS heterostructures were created by reacting In 2 S 3 –In(OH) 3 nanosheets with varying concentrations of ZnS precursors. The study delved into the morphology and crystal structure, emphasizing photocatalytic hydrogen production in In 2 S 3 –In(OH) 3 –ZnS nanofibers under different concentrations of ZnS precursors. Remarkably, the In 2 S 3 –In(OH) 3 –ZnS nanofibers demonstrated exceptional hydrogen production efficiency, attributed to their larger specific surface area, improved blue light absorption, and reduced electron-hole pair recombination. Additionally, a comprehensive analysis explored the photocatalytic reaction mechanism, pH values, sacrificial reagents, sacrificial reagent concentrations, light source types, and intensities. These results highlighted the exceptional reusability of In 2 S 3 –In(OH) 3 –ZnS nanofibers in photocatalytic hydrogen production, showcasing their potential for cost-effective and highly efficient applications in diverse fields. [Display omitted] • Synthesized In 2 S 3 –In(OH) 3 nanosheets using a simple hydrothermal method. • Explored photocatalytic hydrogen evolution in nanosheets and nanofibers. • In 2 S 3 –In(OH) 3 –ZnS nanofibers demonstrated exceptional hydrogen production efficiency. • Analyzed photocatalytic reaction mechanism, pH values, sacrificial reagents, and light sources. • Demonstrated high reusability and efficiency potential for various applications. [ABSTRACT FROM AUTHOR]

Achieving high-performance perovskite solar cells with satisfactory efficiency requires a decrease of charge carrier recombination and intrinsic density of defects in organic and inorganic halide perovskite absorber materials. In this study, the effect of vanadium copper sulfide (VCuS) nanoparticles (NPs) used to accelerate CH3NH3PbI3 perovskite crystallization in a single phase is investigated. The results indicate that the employed VCuS NPs influence the purity, formation of a single phase, and crystallinity of CH3NH3PbI3 perovskite with favorable crystal growth in the (110) direction. The morphological analysis indicates the existence of a dense, compact, and homogeneous structure, which is associated with a large grain size that extends the lifetime and reduces recombination by increasing the electron-hole diffusion length. According to its optical characteristics, perovskite has an energy gap between 1.62 and 1.6 eV for visible light and an absorption coefficient in excess of 105 cm− 1. Photoluminescence (PL) measurements revealed that when VCuS NPs were added to perovskite thin films, the PL intensity decreased, indicating a decrease in charge recombination. For sample 8 mg/mL-VCuS, the bulk heterojunction solar cells demonstrated a power conversion efficiency (PCE) of 15.11%, a short-circuit current density (Jsc) of 20.93 mA/cm2, an open-circuit voltage (Voc) of 1.043 V, and a fill factor (FF) of 69.23%. In addition to enhancing light harvesting efficiency, this superior doped perovskite film eliminates pinholes, which reduces charge recombination in solar cells. Highlights: Treatment of CH3NH3PbI3 perovskite layers with VCuS NPs to improve PSCs. VCuS NPs doping treatment deeply enhances the purity, formation of a single phase, morphology, and crystallinity of CH3NH3PbI3 perovskite. JSC, VOC, and FF changed depending on the concentration of VCuS NPs used. A sample of an 8 mg/mL-VCuS -based solar cell device exhibited PCEs of 15.11%. [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]

This research examines the incorporation of CuO and TiO2 nanoparticles into polypropylene or cotton fabrics to develop reusable personal protective equipment. Different preparation methods are applied to anchor the nanoparticles and avoid leaching. The composition and preparation of fabrics are verified by scanning electron microscopy and X-ray diffraction. Optical properties are assessed by diffuse reflectance spectroscopy and photoluminescence. The results show that for a low ratio of CuO to TiO2, the optical properties improve, reducing bandgap energy and the electron-hole pair recombination rate. Photodegradation of methylene blue increases by 22.8% in polypropylene fabrics and up to 350% in cotton fabrics. In conclusion, photoactivity in polypropylene fabrics is 23.7 times higher than in cotton fabrics, since the preparation method controls the loading of active species [ABSTRACT FROM AUTHOR]

Spherical quantum wells (SQWs) have proven to be excellent materials for suppressing Auger recombination due to their expanded confinement volume. However, research on the factors and mechanisms of their high-intensity optical properties, such as multiexciton properties and third-order optical nonlinearities, remains incomplete, limiting further optimization of these properties. Here, a series of CdS/CdSe (xML)/CdS SQWs with varying CdSe layer thicknesses were prepared. The modulation effects of CdSe shell variations on the PL properties, defect distribution, biexciton binding energy, and third-order optical nonlinearities of the SQWs were investigated, and their impact on the material's multiexciton properties was further analyzed. Results showed that the typical CdS/CdSe(3ML)/CdS sample exhibited a large volume-normalized two-photon absorption cross-section (18.17 × 102 GM/nm3) and favorable biexciton characteristics. Optical amplification was observed at 12.4 μJ/cm2 and 1.02 mJ/cm2 under one-photon (400 nm) and two-photon (800 nm) excitation, respectively. Furthermore, different amplified spontaneous emission spectra were observed for the first time under one/two-photon excitation. This phenomenon was attributed to thermal effects overcoming the biexciton binding energy. This study provides valuable insights for further optimizing multiexciton gain characteristics in SQWs and developing optical gain applications. [ABSTRACT FROM AUTHOR]

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In this work, low-temperature photoluminescence spectroscopy was employed to investigate the N3 optical color center in natural type Ia diamond. The optical properties of the N3 center with regular changes in testing temperature and laser power were studied, and the energy level transition was also discussed. The results showed that the PL intensity of the N3 center enhanced sub-linearly with laser power increased, indicating that the electron transition of the N3 center was mainly radiative recombination with weak Auger recombination participation. In addition, the physical model was employed to analyze the change in the zero phonon line with the increase in the test temperature; it obtained thermal quenching activation energy (25.2 meV), bond softening, and strong interaction with acoustical phonons of the N3 center. The theoretical analysis of the broadening parameters revealed that the longitudinal optical phonon energy was 55.1 meV, and the electron–optic phonon coupling strength was 2.3 meV. [ABSTRACT FROM AUTHOR]

We studied photoinduced charge transfer (CT) states and their dissociation processes at the donor/acceptor (D/A) interface of PTB7/BTAx (x = 1 and 3) nonfullerene organic thin-film solar cells using density functional theory (DFT) and time-dependent DFT calculations. We focused on the CT distances and electron coupling in the CT state generated by photoexcitation and the Huang–Rhys (HR) factors that describe the nonadiabatic processes associated with vibronic interactions. The PTB7/BTA3 system with a large short-circuit current density (JSC) exhibited a large charge CT distance and electronic coupling. Contrastingly, the PTB7/BTA1 system with a low JSC has a large HR factor because of the low-wavenumber vibrational modes in the CT state of the D/A complex and is prone to nonadiabatic relaxation to the ground state. Systematic theoretical analysis of the excitonic states in the D/A complex has provided insight into the control of CT exciton dynamics, namely JSC and electron–hole recombination. [ABSTRACT FROM AUTHOR]

Site- and polarity-controlled core–shell InGaN/GaN nanorod LED structures were grown by metal organic vapor phase epitaxy on Si(111). Scanning transmission electron microscope images reveal uniform multiple quantum wells on polarization-free sidewalls. Spatially resolved photoluminescence mapping on a single nanorod demonstrates that the emission at 3.0 eV stems from the polarization-free m-plane, which is supported by a fast recombination lifetime of ∼490 ps at low temperatures. Quasi-resonant laser excitation demonstrates predominant radiative recombination at low excitation densities, whereas at high excitation densities, the efficiency is lowered by Auger recombination and/or carrier leakage. [ABSTRACT FROM AUTHOR]

A coupling model is established on piezoelectric semiconductor bipolar junction transistors (PS-BJT) subjected to mechanical loadings by abandoning depletion layer approximation and low injection assumption. Effect of base region on device performance and interaction between emitter/base junction (E/B) and base/collector junction (B/C) are investigated. It is found that too small a base width will cause B/C to extract electrons directly from emitter region, implying that an electron passageway will be excited to link from collector- to emitter-region by striding over base-region (abbreviated as "EP-CE" hereafter). We particularly clarify that the current produced by electrons flowing across EP-CE is independent of electron-hole recombination in E/B, which means that this current has not yet been bestowed on the information of base current. "Information of base current" refers to dispatching information of base current on the electrons in emitter region. Thus, a current from EP-EC cannot be reckoned in the amplification effect of base current. Our investigations show that base width should not be designed too small to avoid EP-CE, which has not been revealed before. As regards to tuning PS-BJT performance by mechanical loadings, we revealed the mechanism as follows: 1) raising electron-hole recombination rate inside E/B to reduce resistivity such that more electrons can be driven from emitter- to base-region; 2) elevating electron conductivity in base-region for easier pass of electrons; 3) promoting attractive ability of B/C on electrons such that more electrons cross the interface. Numerical results show that transmission characteristics can be greatly increased as expected by mechanical tuning. [ABSTRACT FROM AUTHOR]

Piezocatalysts have shown great promise for effcient hydrogen generation. However, their application is limited by the rapid charge recombination and sluggish charge transfer rate of piezo‐induced charge carriers. This work aims to address the preceding limitations by controlled synthesis of a representative piezocatalyst, BiFeO3 doped with Mo atoms and decorated with Bi4MoO9 (BMO) heteroatoms using sol‐gel method. The substitutional doping of Mo on BFO (BFMO) was shown to induce a shallow energy level near the conduction band that acted as a trapping state, to suppress recombination of charge carriers, enhance charge mobility for transport to the surface, modulate band alignment, and lower the energy barrier for surface reaction. The formation of BFMO/BMO heterostructures induced electrical band bending, leading to the electric potential gradient, hence promoting charge carrier separation and transfer. The BFMO/BMO with 0.5 mol % Mo (Mo‐5) demonstrated four times faster piezocatalytic Rhodamine B (RhB) dye degradation rate (k of 0.032 min−1) compared to pristine BFO (0.009 min−1). Further, the Mo‐5 exhibited a 45% higher piezocatalytic H2 production rate (14.4 µmol/g/h) compared to pristine BFO (9.8 µmol/g/h) while being cocatalyst‐free. Coupling piezocatalysis with photocatalysis was found to reduceperformance relative to the individual processes, which is attributed to Auger recombination which impedes any potential synergistic effect. [ABSTRACT FROM AUTHOR]

Extending the emission wavelength of III‐V nanowire (NW) lasers grown on silicon into the mid‐infrared (MIR) spectral range has strong potential for applications. Examples include optical sensing and metrology, as well as integrated silicon photonics for information technologies. NW‐lasers with continuous wave (CW) operation, have remained, however, scarce in the MIR due to significant material physics challenges, and intrinsic effects such as Auger recombination that limit the radiative efficiency. Here, the CW operation of single InAs NW‐lasers site‐selectively grown on Si with emission in the range of 2.4–2.7 µm is reported. The cavity design is optimized via simulations of the threshold material gain and the parameters for selective area growth to minimize the modal gain for the TE01 optical mode. For NW diameters exceeding 700 nm, lasing under CW optical pumping with low thresholds of 1.4–27 kW cm−2 are obtained from 10 to 90 K for NW lengths ranging from 9–30 µm. The observed lasing behavior is quantified by the observation of clear positive net modal gain (630 cm−1) obtained using Hakki‐Paoli analysis. These findings mark an important advancement in the development of nanolasers for integrated MIR photonics. [ABSTRACT FROM AUTHOR]

The production of solar hydrogen presents a compelling opportunity to harness solar energy, playing a crucial role in addressing climate change and reducing reliance on fossil fuels. The progress of the hydrogen economy largely depends on establishing hydrogen production as a key foundational element. Moreover, selecting appropriate materials to support the main catalyst is vital for enhancing hydrogen production. This article furnishes a simple, affordable approach to existing water-splitting technologies that harness solar energy as the primary source for hydrogen production. To achieve this, the impact of GO content on ZnO nanoparticles/GO compositions' photoelectrochemical efficiency is studied. While all the presented samples show sensitivity to light, the sample with 0.35% GO performs the best, demonstrating the highest photocurrent density, the lowest rate of electron-hole recombination, and the greatest photoelectrochemical efficiency. • The PEC behavior of ZnO/GO nano composite was studied with varying GO amount. • Efficient separation of e & h decreases recombination and charge transfer resistance. • The 0.35-%G sample shows the most enhanced PEC and best photo stability properties. • The 0.35-%G sample has the narrowest band-gap and the lowest-intensity PL spectrum. • The 0.35%G sample provides the most optimal conditions for water splitting. [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]

On the basis of first-principles calculations and non-adiabatic molecular dynamics (NAMD) simulations, we explore the photocatalytic water splitting properties of PtSSe/ζ-Phosphorene heterostructure. This heterostructure possess semiconducting nature with high carrier mobility (≈ 103 cm2V− 1s− 1). The calculated high value of electron-hole recombination rate as compared to electron transfer rate and hole transfer rate, establish the Type-II mechanism more favorable for PtSSe/ζ-Phosphorene heterostructure. Further, the calculated value of solar-to-hydrogen (STH) conversion efficiency of PtSSe/ζ-Phosphorene exceeds to 10%, which makes it the potential candidate for commercial production of hydrogen for industrial use. STH conversion efficiency is further tunable on rotating one monolayer over other with specific angles in the heterostructure. Our study demonstrates PtSSe/ζ-Phosphorene heterostructure to be efficient Type II-scheme photocatalyst for water splitting. [ABSTRACT FROM AUTHOR]

Low‐cost, room‐temperature operating light emitters in the 3–8 µm mid‐wave infrared wavelengths are desired for a broad range of applications such as chemical spectroscopy and infrared scene projection. The photoluminescence properties of PbSnSe ternary alloys grown by molecular beam epitaxy on (001) GaAs are studied in this work. Despite a large threading dislocation density, much greater than 109 cm−2, room temperature photoluminescence out to a peak wavelength of 8.4 µm is observed. In situ surface passivation with amorphous GeSe and an optimized thick PbSe buffer layer are shown to be necessary for enabling bright photoluminescence in PbSnSe heterostructures, stemming from Sn‐related defect complexes generated from ambient exposure and lying near the GaAs interface. Luminescence is found to be strongly blueshifted by unrelaxed tensile strains associated with thermal expansion and lattice constant mismatch, which makes emission wavelengths farther in the infrared more difficult to achieve. Carrier recombination analysis indicates room for further improvement as luminescence efficiencies are still limited by extrinsic mechanisms rather than intrinsic Auger recombination. Overall, this work demonstrates the exciting potential of PbSnSe for spontaneous emission in the mid‐wave infrared at room temperature, alongside more established material platforms like InAsSb. [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]

A colloidal synthesis protocol is demonstrated for InAs@InP core@shell quantum dots (QDs) with a tunable InP shell thickness (ranging from 3 to 8 monolayers), utilizing tris(diethylamino)‐arsine and ‐phosphine. Structural analysis reveals that the InP shell preferentially grows onto the tetrahedral InAs cores along the <‐1‐1‐1> directions, forming tetrapodal‐shaped InAs@InP QDs. Growth of the InP shell causes a red shift in the absorption spectrum of the QDs. This is explained by considering that electrons are delocalized throughout the whole core@shell QDs, while holes preferentially leak along the <‐1‐1‐1> directions, as indicated by the density functional theory calculations. This means such heterostructures cannot be described as type‐I or quasi type‐II, contrary to earlier assumptions. The overlap of carrier wavefunctions throughout the entire InAs@InP QD structure results in no significant reduction of the Auger recombination rate, which remains as fast as in InAs QDs. However, the InP shell enhances photoluminescence (PL) efficiency (up to ≈13%) by passivating surface trap states of the InAs QDs (mainly located close to the top of the valence band). The overgrowth of a ZnSe shell endows the QDs with a high PL efficiency (≈55%) and good stability upon air exposure (≈80% PL intensity retention after 14 days). [ABSTRACT FROM AUTHOR]

We investigate the photon statistics of the light emitted by single self-assembled hybrid gold-CdSe/CdS/CdZnS colloidal nanocrystal supraparticles through the detailed analysis of the intensity autocorrelation function g (2)(τ). We first reveal that, despite the large number of nanocrystals involved in the supraparticle emission, antibunching can be observed. We then present a model based on non-coherent Förster energy transfer and Auger recombination that well captures photon antibunching. Finally, we demonstrate that some supraparticles exhibit a bunching effect at short time scales corresponding to coherent collective emission. [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]

The hole accelerator is proven to benefit the hole injection for traditional light‐emitting diodes (LEDs) because the induced electric field provides the holes with more kinetic energy to pass through the electron‐blocking layer, enhancing the hole injection efficiency. Herein, the effect of the hole accelerator (HA) layer on the micro‐LEDs by modeling the characteristics of the devices with a current density of lower than 10 A cm−2 is investigated. The simulation results show that the appended HA layer brings a knot of the electric field in the HA layer, leading to higher internal quantum efficiency (IQE) than the device without HA under the low current density. The thickness and composition of HA, the quantum number, and the material of quantum barrier are also simulated and analyzed. The simulated radiative, Shockley–Read–Hall, and Auger recombination rates show that the IQE of the micro‐LED with the HA layer is higher than that without the HA layer under the current density of lower than 10 A cm−2. [ABSTRACT FROM AUTHOR]

g-C3N4 emerges as a promising metal-free semiconductor photocatalyst due to its cost-effectiveness, facile synthesis, suitable visible light response, and robust thermal stability. However, its practical application in photocatalytic hydrogen evolution reaction (HER) is impeded by rapid carrier recombination and limited light absorption capacity. In this study, we successfully develop a novel g-C3N4-based step-scheme (S-scheme) heterojunction comprising two-dimensional (2D) sulfur-doped g-C3N4 nanosheets (SCN) and one-dimensional (1D) FeCo2O4 nanorods (FeCo2O4), demonstrating enhanced photocatalytic HER activity. The engineered SCN/FeCo2O4 S-scheme heterojunction features a well-defined 2D/1D heterogeneous interface facilitating directed interfacial electron transfer from FeCo2O4 to SCN, driven by the lower Fermi level of SCN compared to FeCo2O4. This establishment of electron-interacting 2D/1D S-scheme heterojunction not only facilitates the separation and migration of photogenerated carriers, but also enhances visible-light absorption and mitigates electron-hole pair recombination. Band structure analysis and density functional theory calculations corroborate that the carrier migration in the SCN/FeCo2O4 photocatalyst adheres to a typical S-scheme heterojunction mechanism, effectively retaining highly reactive photogenerated electrons. Consequently, the optimized SCN/FeCo2O4 heterojunction exhibits a substantially high hydrogen production rate of 6303.5 µmol·g−1·h−1 under visible light excitation, which is 2.4 times higher than that of the SCN. Furthermore, the conjecture of the S-scheme mechanism is confirmed by in situ XPS measurement. The 2D/1D S-scheme heterojunction established in this study provides valuable insights into the development of high-efficiency carbon-based catalysts for diverse energy conversion and storage applications. [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]