Search

The construction of a phase junction photocatalyst can significantly enhance the photocatalytic performance with high selectivity for CO2 reduction. In this study, an S-scheme junction Cd0.5Zn0.5S/CoWO4 semiconductor with the coupling of a twin crystal Cd0.5Zn0.5S homojunction and CoWO4 was designed through a hydrothermal method, which could convert CO2 to CO with high efficiency under visible-light illumination. Cd0.5Zn0.5S-10%CoWO4 exhibited the optimal performance and its CO yield and selectivity were up to 318.68 μmol·g-1 and 95.90%, respectively, which were 4.54 and 1.62 times higher than that of twin crystal Cd0.5Zn0.5S. Moreover, the Cd0.5Zn0.5S homojunction with a zinc-blende and wurtzite phase and the S-scheme phase junction of Cd0.5Zn0.5S/CoWO4 enhanced the property of CO2 adsorption and accelerated the detachment of photogenerated carriers. The combination of photogenerated holes in Cd0.5Zn0.5S and the electrons of CoWO4 can retain the reduction sites to improve photocatalytic performance. This study provides a neoteric concept and reference for the construction of the S-scheme phase junction.

The design of the photocatalytic materials has made a great of remarkable progress in the area of the enhancement photocatalytic activity, but there are still lots of problems such as wide band gap, low utilization of sunlight, low quantum efficiency and poor stability, which further limit the extensive practical applications. Thus, it is a hot research topic and key scientific problem to be solved that how to design and prepare the catalysts, which can respond to visible and near-infrared light in sunlight. Inspired by efficient nonlinear optical upconversion materials, upconversion-based nanocomposites can indirectly broaden the absorption ranges of semiconductors by converting the captured long-band visible and near-infrared incident light into high-energy short-band visible or ultraviolet light, which can be adopted as the promising candidate in wide-spectral-light-activating photocatalytic materials coupling with conventional semiconductors. According to our recent works and literature reports, recent review summarizes the research progress of photocatalytic materials with upconversion effect on photolysis of water for hydrogen production, degradation of organic and inorganic pollutants, reduction of CO2 and photodynamic therapy. The prepared nanocomposites can suppress the recombination of electrons and holes, and greatly improve the photocatalytic efficiency by the synergistic effect. It maybe stimulates a great interest in rational design and preparation of efficient full-spectrum photocatalytic systems and their wide application in solar energy conversion.

Using ion doping to engineer sulfur vacancies over metal sulfides is an effective method to improve photocatalytic properties, such vacancies form the center of the electron-captured state to promote the separation and transfer of photogenerated carriers. In this research, Yb/Er co-doped bulk Cd0.5Zn0.5S (CZS) was fabricated by a one-step simple hydrothermal process, and used for evaluating the catalytic activity for aquatic hydrogen production under visible light irradiation. The results showed that the Cd0.5Zn0.5S:Yb(15%), Er obtained exhibited a higher efficient photocatalytic activity of hydrogen evolution, in which the efficiency of Cd0.5Zn0.5S:Yb(15%), Er (422.0 μmol g−1 h−1) was 2.7 times higher than that of bare Cd0.5Zn0.5S (154.7 μmol g−1 h−1). This can be attributed to the augmented active surface area, the broadened spectral absorption of visible light and the facilitation of the separated efficiency of the photogenerated carriers. This finding provides a simple way to activate the metal-chalcogenides with S-vacancies for optimizing the photocatalytic performance.

A series of unique 3D flower-like Bi2MoO6 (BMO)/reduced graphene oxide (rGO) heterostructured composites decorated with varying amounts of Ag nanoparticles (NPs) were fabricated. Their morphological characteristics, structural features, energy band structures and photoelectrochemical properties were systematically studied. All the Ag/BMO/rGO ternary composites (AgBG-y; y = 1%, 2% and 3%) demonstrated greater photocatalytic activity towards efficient removal of our selected organic models [methyl orange (MO), rhodamine B (RhB) and phenol], as compared with the BMO/rGO binary composites (BG-x; x = 0.25, 2, 4 and 5). Particularly, AgBG-2%, which was synthesized with the addition of 2 wt% rGO and 2 wt% Ag in BMO, possessed superior photocatalytic activity. The fitted rate constants (k) for the photocatalytic degradation of RhB, MO and phenol using AgBG-2% were estimated to be 0.0286, 0.0301 and 0.0165 min−1, respectively, which were over one order of magnitude greater than those obtained using pure BMO. Several factors may contribute to the observed enhancement, including greater specific surface area, enhanced light absorption, promoted spatial separation of electron–hole (e−–h+) pairs and their suppressed recombination, especially benefiting from the synergistic effects among BMO, rGO and Ag NPs. Our work suggests that the rational design of BMO/rGO/Ag ternary composite was an effective strategy to boost the photocatalytic activity of the resulting catalyst towards the highly efficient removal of organic pollutants from water. This work presents the construction of Ag NPs-decorated 3D flower-like Bi2MoO6 (BMO)/reduced graphene oxide (rGO) ternary composites as effective photocatalysts for efficient removal of organic pollutants under solar light irradiation. The separation efficiency of photogenerated charge carriers is significantly promoted by the synergistic effect of Ag NPs, BMO and rGO.

Wide spectral responsive photocatalysts are of great importance for making full use of solar energy and broad application in highly efficient photocatalytic wastewater treatment, production of H2O2, etc. Thereinto, it is significative to open an appropriate way to extend the absorption to the NIR region, in which it accounts for ~ 49% in the solar spectrum. In this work, we synthesized successfully the new-style NaYF4:Yb3+, Er3+/Ag2CrO4 photocatalyst via the hydrothermal and followed precipitation method, and it exhibited the more excellent photocatalytic performances than Ag2CrO4 for the photocatalytic H2O2 production and disposals of pollutants, such as methyl orange (MO), methylene blue (MB), rhodamine B (RhB) and tetracycline (TCs). The morphological, structural and optical behavior were investigated by XRD, SEM, N2 adsorption/desorption, TEM, XPS, UV–Vis DRS, UC luminescence and photoelectrochemical experiments. It revealed that NaYF4:Yb3+, Er3+/Ag2CrO4 photocatalyst presented stronger absorptive capacity in the visible–NIR region by the benign fluorescence resonance energy transfer (NaYF4:Yb3+, Er3+ can convert near-infrared light to visible light via upconversion process), and showed more efficient charge transfer and separation than that of pure Ag2CrO4. The primary reactive species of ·O2− and h+ by the trapping experiments played a considerable important role in the photocatalytic process. A promising potent system was suggested for the highly efficient utilization of sunlight in the enhancement of photocatalytic activities.

Photocatalysis has been regarded as a promising technology for degrading organic pollutants in wastewater and producing hydrogen. In this paper, TiO2 nanoparticles (NPs) were synthesized to improve the visible light absorption of TiO2, which were further combined with Bi2O3 nanosheets to synthesize a series of 0D/2D TiO2 NPs/Bi2O3 nanosheet heterojunctions. The visible light induced photocatalytic activities of the as-synthesized TiO2/Bi2O3 heterojunctions were studied. The optimized catalyst TB-3 with 15 wt% of Bi2O3/TiO2 exhibited the best photocatalytic degradation of tetracycline hydrochloride (TC). The degradation rate constant k of TC over TB-3 was approximately eight times and 39 times greater than that of P25 and Bi2O3, respectively. Additionally, TB-3 showed the highest amount of hydrogen evolution, while that of Bi2O3 was almost zero. The enhancement of photocatalytic performances was ascribed to the improved visible light absorption and the Z-scheme charge transfer path of the TiO2/Bi2O3 heterojunctions, which enhanced the separation efficiency and reduced recombination of photogenerated charge carries, as evidenced by UV–Visible diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), and electrochemistry measurements. The active species trapping experiments and the electron spin resonance (ESR) results revealed that ·O2− was the main active substance in the photocatalytic degradation. The possible degradation pathway and intermediate products of TC have been proposed. This work provides experimental evidence supporting the construction of Z-scheme heterojunctions to achieve excellent visible light induced photocatalytic activity.

To effectively enhance the utilization of clean sunlight energy, harvesting a large percentage of near infrared (NIR) light is significant. One of the commonly used effective methods for modifying semiconductors is by co-doping upconversion materials on semiconductors to heighten the photocatalytic efficiency. In this work, Yb3+/Tm3+ co-doped InVO4 nanosheets were synthesized by a facile hydrothermal path, and the crystal phases, morphologies, surface chemical compositions, as well as optical properties were characterized. Yb3+/Tm3+ co-doped InVO4 revealed significantly enhanced photoactivity towards chromium(VI) reduction and methyl orange oxidation under visible or NIR light irradiation. Furthermore, 5YT-IV presented the highest electrocatalytic performance and photocatalytic production of H2O2 under visible light irradiation, requiring low overpotential and low Tafel slope (390 mV dec−1) for hydrogen evolution reaction than that of the bare InVO4 (731 mV dec−1), and as well improved the yield of photocatalytic H2O2 production by about 3.5 times. This was primarily ascribed to intensive light absorption resulting from the benign upconversion energy transfer of Yb3+/Tm3+ and the boosted charge separation caused by the intermediate energy states. Moreover, the presence of h+ and ˙O2− as the main oxidative species played a significant role during the photocatalytic oxidation process of methyl orange and electrons played a decisive role in Cr(VI) reduction. This study provides a promising platform for efficiently utilizing the visible-NIR energy of sunlight in the field of photocatalytic H2O2 production and for alleviating environmental pollution in future.

The design and fabrication of heterojunctions has been proven to be a facile method for improving photocatalytic performance. Herein, in this work, a high performance photocatalyst based on AgVO3/LaVO4 was successfully synthesized via a one-step in situ hydrothermal method. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR) and photoluminescence (PL) spectra were used to characterize the structural and physicochemical characteristics. AgVO3/LaVO4 composites exhibited enhanced photocatalytic activity for the disposal of simulated pollutants (66% and 36% degradation rates for methyl orange and acid orange II) and superior photoelectrocatalytic oxidation of methanol compared with noble metal (Au, Ag and Pt) supported LaVO4 and bare LaVO4 photocatalysts (a lower Tafel slope of 24 mV dec−1 and a higher peak current density of 0.22 mA cm−2 over 2% β-AgVO3/LaVO4). This could be due to the introduction of β-AgVO3 in the form of phase junctions, leading to enhanced light harvesting and the promoted separation and transfer of photogenerated electrons/holes pairs, which was proved using ultraviolet-visible diffuse reflectance spectra (UV-Vis DRS), and photoelectrochemical and time-resolved PL measurements. Density functional theory (DFT) calculations revealed that the interaction of β-AgVO3 and LaVO4 would enhance the optical absorption and electron transfer.

The charge transfer between semiconductors and metals is greatly dependent on the crystal structure and properties of the interface. It is well known that Schottky junctions formed by depositing Pd nanoparticles on BiOBr nanosheets can accelerate the transfer and separation of carriers. However, the stability of the crystal structure and the exposed crystal surface with high performance both decrease in the process of photo-deposition. In the present work, Pd/BiOBr photocatalysts decorated with an La dopant were fabricated by a two-step synthesis with solvothermal and photo-deposition methods. Interestingly, Pd/BiOBr crystals could be reconstructed by doping with La ions, such as the regrowth of facets with UV light irradiation. The instability of the crystal structure and lower photocatalytic performance could be reversed by doping with La ions. La-Doping refined the crystal structure and strengthened the charge transfer and separation of carriers over Pd/BiOBr, exhibiting enhanced photocatalytic activity toward the degradation of acid orange II (AO II). Moreover, the reason for the effects of the La ions was investigated by density functional theory calculations.

Novel ternary carbon quantum dots (CDs)/Bi2MoO6 (BMO)/graphitic carbon nanofibers (GNFs) composites (CDs/BMO/GNFs) were prepared by a facile hydrothermal method and studied for use as photocatalysts. The morphological, structural and physicochemical properties of the as-prepared photocatalysts were examined in detail; that the CDs-decorated BMO particles anchored on the surfaces of modified GNFs to form heterojunctions. The photocatalytic activity of the resultant CDs/BMO/GNFs was superior for the degradation of three different organics, including Rhodamine B (RhB), methylene blue (MB) and phenol, as well as the reduction of a heavy metal ion Cr(VI), when compared with the corresponding binary composites (BMO/GNFs and CDs/BMO) and pure BMO. Our study revealed that the photocatalytic performance of ternary composite CDs/BMO/GNFs was significantly affected by the loadings of CDs or/and GNFs in BMO. Especially, the optimized sample C5/BMO/GNF-0.2, which was synthesized with a Bi/C molar ratio of 0.2 and the addition of 5 mL CDs, exhibited the best activity in the photocatalytic degradation of RhB. It was found that 99.4% of RhB was removed after 70-min exposure to the simulated solar light irradiation. This was attributed to the synergistic effects between components (CDs, BMO and GNFs) and heterojunctions, resulting in an efficient spatial separation of the photogenerated electrons and holes. A possible photocatalytic mechanism of C5/BMO/GNF-0.2 was proposed that the photogenerated holes, O2− and OH radicals contributed to the photocatalysis, which was supported by the radical quenching experiment and electron spin resonance analysis.

Semiconductor photocatalysts are extensively applied in environmental treatment and energy conversion. However, one of their major disadvantages is their relatively low photocatalytic performance owing to the recombination of generated electron-hole pairs. The presence of the phase junction is an effective way to promote the photocatalytic activity by increasing the separation efficiency of the electron-hole pairs. Accordingly, extensive research has been conducted on the design of phase junctions of photocatalysts to improve their charge transfer properties and efficiencies. Therefore, for the design of an appropriate phase junction and the understanding of the mechanism of electron-hole separation, the development of the photocatalytic phase junction, including the preparation methods of the heterogeneous materials, is tremendously important and helpful. Herein, the commonly used, externally induced phase transformation fabrication techniques and the primary components of the semiconductors are reviewed. Future directions will still focus on the design and optimization of the phase junction of photocatalytic materials according to the phase transition with higher efficiencies for broadband responses and solar energy utilization. Additionally, the most popular phase transformation fabrication techniques of phase junctions are briefly reviewed from the application viewpoint.

A series of binary-phase TiO2 modified Bi2MoO6 nanocrystals have been prepared via a solvothermal-calcination process. Trace TiO2 modification can effectively enhance the visible light catalytic activity of Bi2MoO6 to remove the antibiotics in aqueous solution. The obtained TiO2/Bi2MoO6 composites were investigated by some physicochemical techniques like XRD, N2 adsorption, SEM, TEM, UV–vis DRS, Raman, XPS, PL and Photo-electrochemical measurement. The presence of TiO2 nanoparticles (NPs) influenced the crystal growth of Bi2MoO6, decreasing the crystal size of Bi2MoO6 and effectively promoting its specific surface area. Moreover, the conduction band of TiO2 can serve as the electron transfer platform, which largely boosts the effective separation of photocarriers at TiO2/Bi2MoO6 heterojunction interface. With optimal TiO2 content (0.41 wt%), TiO2/Bi2MoO6 exhibited the best photocatalytic performance for different antibiotics degradation, e.g. ciprofloxacin, tetracycline and oxytetracyline hydrochloride under visible light irradiation. Moreover, the mechanism for enhanced photocatalytic performance in ciprofloxacin degradation was illuminated.

A series of four conjugated porous polymer CPPs (CPs1–4) with various geometries have all been readily synthesized via direct C–H arylation between bithiophene (BT) and 1,3,6,8-tetrabromopyrene (TBPy), 2,2′,7,7′-tetrabromo-9,9′-spirofluorene (TBSF), 1,3,5-tribromobenzene (TBB) and 1,4-dibromobenzene (DB) respectively. The photocatalytic hydrogen evolution from water splitting by these CPPs under visible light irradiation is studied in detail. An amazing hydrogen evolution rate (HER) of 95.85 μmol h−1 was successfully achieved by the four-directional Py-BT-based CPP (CP1, 6 mg), using ascorbic acid (AA) and N,N-dimethylformamide (DMF)/water as a sacrificial agent and co-solvents respectively. Such a HER value is 8-fold higher than that of applying commonly used MeOH/water as a co-solvent in the same photocatalytic system. Significantly, when a 0.5 wt% platinum (Pt) co-catalyst was added into the above photocatalytic system, an unprecedented HER of 184.86 μmol h−1 (6 mg) was further realized. The combination of atom-economically synthesized CPPs and accelerating the HER by means of simply tuning the composition of co-solvents provided herein represents a promising step toward accessing green energy by green chemistry.

Employing upconversion hosts (which convert lower-energy light into higher-energy light) and plasmonic Au nanoparticles, this work deals with the synthesis of a novel Au/NaYF4:Yb,Er/WO3·0.33H2O-W18O49 {denoted as A/NYYE/WW} heterojunction via a hydrothermal method followed by a photo-reduction method. Also, A/NYYE/WW exhibited the optimum photocatalytic activity and stronger photocatalytic stability for the degradation of nitrobenzene aqueous solution in comparison with a single WO3·0.33H2O or NYYE/WW component. Based on the results of X-ray diffraction patterns, field emission electron microscopy, X-ray photoelectron spectra, UV–Vis diffuse reflectance spectra, upconversion luminescence spectra, luminescence decay and photoelectrochemical measurements, it could be considered that a Z-scheme heterojunction was generated over A/NYYE/WW, in which a highly efficient Forster resonant energy transfer from NYYE to WO3·0.33H2O-W18O49 was observed and the localized surface plasmon resonance (LSPR) effects of Au NPs and W18O49 could induce the utilization of near infrared light to achieve broadband light absorption. On the other hand, Au NPs also played the role of an electron sink for enhanced charge carrier separation and utilization. Thus, the heterojunction showed the synergetic effects of both upconversion and LSPR features, which could broaden the absorption spectrum to the near infrared region and give rise to a higher yield. It provides a pathway to develop broadband absorption materials in photocatalytic systems.

Harvesting abundant and environmentally friendly near infrared (NIR) light in the solar spectrum is particularly significant to improve the utilization of the cleanest energy on the earth. One of the most effective methods to improve the photocatalytic efficiency of semiconductors in the full-solar spectrum is combining upconversion luminescence materials with semiconductors. In this work, a novel ZnS@YF3:Yb3+,Er3+ heterojunction as a full spectrum photocatalyst via a hydrothermal synthesis method is reported, which was applied in hydrogen production and pollutants disposal. Under metal halide lamp irradiation with UV-Vis-NIR light, ZnS@YF3:Yb3+,Er3+ exhibited higher photocatalytic performance compared to pure ZnS. In addition, the 20% YF3:Yb3+,Er3+/ZnS sample showed the highest chemical stability and strongest reduction ability. This was mainly attributed to the effective fluorescence resonance energy transfer of YF3:Yb3+,Er3+/ZnS, the broader light absorption and the efficient transfer of photoinduced electrons. Moreover, the ˙O2− and ˙OH free radicals were the main reactive species. This study suggests a promising system to efficiently utilize the visible-NIR solar energy of sunlight for processing industrial waste water and alleviating the energy crisis in the future.

ZnS-MoS2 solid solution anchored on reduced graphene oxide sheet (rGO/ZnS-MoS2) was explored as novel visible-light-driven photocatalysts, and synthesized by solvent thermal method. The light absorption intensity of rGO/ZnS-MoS2 was greatly strengthened, and rGO/ZnS-MoS2 possess modulated continuous band gaps from 3.47 to 3.56 eV by changing the Zn/Mo ratios and rGO content. Their photocatalytic activities for 2-nitrophenol degradation are dependent on the chemical composition, and the optimal 11% rGO/ZnS-MoS2 possessed the highest photocatalytic performance, which could be attributed to the most efficient charge separation, the largest specific area, and its optimized band structure. Moreover, 11% rGO/ZnS-MoS2 can effectively treat real industrial effluent with 74.05% COD removal, and maintain long-term stability without obvious decline after five use cycle.

The low-usage of solar energy and the sluggish separation efficiency of the photogenerated electrons/holes pairs are the obstacles in the practical application of photocatalysts. The integration of upconversion and Z-scheme heterojunction is expected to break the barriers to achieve the efficient charge separation and broaden near-infrared light absorption. Herein, an effective indirect Z scheme AgInS2/In2S3 heterostructure with carbon quantum dots (CQDs, as the electron conduction medium) and Lu3NbO7:Yb, Ho (as upconversion function) has been successfully synthesized. Consequently, the Lu3NbO7: Yb, Ho/CQDs/AgInS2/In2S3 heterostructure exhibited superior photocatalytic activities for Cr(VI) reduction and H2O2 production, reducing 99.9% of Cr(VI)(20 ppm, 15 min) and 78.5% of Cr(VI) (40 ppm, 30 min) with visible light irradiation as well as 94.0% of Cr(VI) (20 ppm, 39 min) under NIR light irradiation. Simultaneously, the heterostructure could generate 902.9 μM H2O2 for 5 h under visible light irradiation. The intensive photocatalytic properties could primarily be attributed to the boosted light absorption capacity, the improved solar-to-energy conversion by the remarkable upconversion capacity of Lu3NbO7: Yb, Ho/CQDs and the faster charge transfer through a Z-schematic pathway. This work is anticipated to open a novel “window” for designing the efficient photocatalysts by coupling of Lu3NbO7: Yb, Ho and CQDs.

Constructing organic-inorganic semiconductor heterojunctions is an efficient way to inhibit the recombination of photogenerated charge carriers and enhance photocatalytic performance of semiconductor. Herein, a novel heterojunction antimony sulfide-perylene diimides (Sb2S3-PDI) heterojunction has been fabricated through a facile hydrothermal method. Compared with bare Sb2S3 and PDI, the Sb2S3-PDI hybrid has showed significantly superior activity in photocatalytic reduction of Cr (VI). The superior photocatalytic performance of Sb2S3-PDI hybrid is due to the formation of type-I heterojunction, which leads to a more efficient separation and migration of photogenerated electron-hole pairs. This work is expected to promote continued interest in the construction of organic-inorganic semiconductor composites with enhanced photocatalytic performance.

A series of carbon quantum dots (CQDs)-decorated BiOCl/carbonized eggshell membrane (CEM) composites were synthesized with CEMs as bio-templates. The obtained composites, especially BiC-0.05, exhibited superior removal efficiencies of several organic pollutants, i.e. tetracycline hydrochloride (TC), Rhodamine B (RhB), and o-nitrophenol (NP). Approximately, 98% of TC was removed after 30 min dark adsorption and subsequent 30 min visible-light-initiated photocatalytic degradation. BiC-0.05 was also utilized to treat actual industrial wastewater and could reduce 73.1% COD, in comparison to 49.9% with the use of BiOCl. The boosted removal efficiencies were achieved by synergistic effect of adsorption and photocatalysis, where cooperative contribution of oxygen vacancies (OVs), CEMs and CQDs enabled faster charge migration and more effective separation of photogenerated charge carriers. Electron spin resonance (ESR) and trapping experimental results showed that superoxide radical ( O2−), along with holes (h+) and hydroxyl radical ( OH) would take part in photocatalytic degradation process. The intermediates of TC and its possible degradation pathway during the photocatalytic reaction were also studied. Our work developed a novel strategy by integrating carbon nanomaterials derived from bio-waste to design efficient photocatalysts for remediation of organic contaminants via adsorption – photocatalysis synergism and OVs – CQDs cooperation.

CaMg(CO3)2 microspheres were prepared and used as hard templates to fabricate a series of CaMg(CO3)2@Ag2CO3 composite microspheres via a fast and low-cost ion exchange process. The effects of ion exchange time and temperature on the physicochemical properties and photocatalytic activities of the composite microspheres were studied through photocatalytic degradation of Acid Orange II under xenon lamp irradiation. The obtained samples were analyzed by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, UV-vis diffuse reflectance spectroscopy, N2 physical adsorption, and photocurrent tests. The CaMg(CO3)2@Ag2CO3 sample with the highest activity was obtained with an ion exchange time of 4 h and temperature of 40 °C. The degradation rate of Acid Orange II by this sample reached 83.3% after 15 min of light irradiation, and the sample also performed well in phenol degradation. The CaMg(CO3)2@Ag2CO3 produced under these ion exchange conditions showed a well-ordered hierarchical morphology with small particle sizes, which was beneficial to light absorption and the transfer of photoelectrons (e−) and holes (h+) to the catalyst surface. Moreover, the separation of photogenerated·carriers over the composites was greatly improved relative to bare CaMg(CO3)2. Despite the very low content of Ag2CO3 (2.56%), excellent photocatalytic performance was obtained over the CaMg(CO3)2@Ag2CO3 microspheres.

A series of La/Ce-codoped Bi2O3 composite photocatalysts were fabricated via hydrothermal–calcination process. The as-prepared products were intensively characterized by some physicochemical characterizations like N2 physical adsorption, X-ray powder diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), UV–Vis diffuse reflectance (UV–Vis DRS), Fourier transform infrared spectroscopy (FT-IR), photoelectrochemical measurements, and photoluminescence (PL) spectroscopy. The characterization results indicated that La and Ce doping induced obvious crystal phase transformation in Bi2O3, from monoclinic to tetragonal phase. La and Ce codoping also gave rise to the obvious synergetic effects, e.g., the lattice contraction of Bi2O3, the decrease of crystal size and the increase of surface area. The photocatalytic performance of the prepared catalysts was evaluated by removal of dye acid orange II with high concentration under visible light irradiation. Results showed that La/Ce-codoped Bi2O3 displayed much higher photocatalytic performance than that of bare Bi2O3, single La or Ce doped Bi2O3 samples. The superior photocatalytic activity was mainly attributed to the improved texture and surface properties and the synergistic effects of La and Ce codoping on suppressing the recombination of photo-generated electrons (e−) and holes (h+).

Novel N-doped Bi-BiOCl nanoplates with the diameter of 50–200 nm were successfully fabricated via calcination route under NH3 atmosphere. The obtained products were investigated by N2 physical adso...

In consideration of environmental protection and energy conversion, the development of semiconductor photocatalytic technology is as first choice. But the photocatalytic performance of typical ZrO2 catalyst is seriously inhibited since it can only been driven by ultraviolet light. Herein, constructing S-scheme g–C3N4–modified ZrO2 heterostructures can be conducive to enhance photocatalytic performance by separating rapidly the photogenerated carriers. In this work, a series of S-scheme g-C3N4/ZrO2 heterostructures were constructed via the simple calcination, and their photocatalytic performances were evaluated by degradating Rhodamine B (RhB), Methyl orange (MO) and Acid orange II (AO II) under visible light irradiation. Importantly, 15% g-C3N4/ZrO2 heterostructures exhibited superior photocatalytic activities (degradating 82% RhB, 50% MO and 98% AO II in 150 min) and electrocatalytic performance (possessing lower overpotential, Tafel slope as well as more exposed active sites). The enhanced performances were ascribed to the intensive light absorption, the larger specific surface area, more exposed active sites as well as the higher separation of photogenerated electrons/holes pairs, which were confirmed by UV–vis diffuse reflectance spectra (DRS), photoluminescence (PL) spectra, electrochemical and radicals trapping experiments. This research provides the platform for the application in environmental protection and energy conversion via constructing S-scheme heterostructures.

Graphitic carbon nitride with nitrogen vacancies was successfully synthesized by the three-step method for the calcination of melamine, following urea-assisted hydrothermal and jacjoin calcination approach. The structural, surface, optical and electric properties were characterized by XRD, FT-IR, SEM, TEM, UV–Vis DRS, PL, N2 physical adsorption/desorption and electrochemical methods, which proved that this strategy of modifying g-C3N4 by nitrogen vacancies not only increased the specific surface area, exposed more active sites, but also inhibited the recombination of photogenerated carriers on the surface of photocatalysts, resulting in the enhancement of photocatalytic and electrocatalytic performances. The photocatalytic activities were measured under visible light irradiation ([Formula: see text][Formula: see text]nm), and their degradation efficiencies could be achieved for 99.8%, 55%, 100% and 99.7% corresponding to that of rhodamine B, acid orange II, methyl orange and methylene blue, respectively. The trapping experiments demonstrated that [Formula: see text] played an important role in the degradation process. In addition, being an active electrocatalyst, nitrogen-deficient g-C3N4 showed a lower Tafel slope, smaller overpotential and the more effective electrochemical surface area compared with that of bare g-C3N4 in neutral media. This work underlines the importance of defect engineering to promote catalytic performance, which can provide a simple and efficient way for modifying g-C3N4 and other N-based catalysts.