Z-scheme Heterojunction Photocatalyst Research Articles

Direct Z-scheme In2S3@BiYWO6 heterojunction photocatalysts for highly efficient environmental remediation

Novel In2S3@BiYWO6 heterojunction photocatalysts were designed and synthesized by a simple two-step hydrothermal method, which exhibit extremely excellent photocatalytic activity for degrading the residual antibiotics in wastewater. Especially, In2S3@BiYWO6 composite with mass ratio of 10:1 shows the highest photo-degradation efficiency towards Tetracycline Hydrochloride, which is about 2.46 and 7.55 times than that of pristine In2S3 and BiYWO6, respectively. A direct Z-scheme charge transfer mechanism was demonstrated in these heterojunctions through the XPS analysis, radical species trapping experiments and fluorescence detection. Within the framework of this mechanism, the critical built-in electric field (Ei) formed at the contact interface between In2S3 and BiYWO6 spatially separates reduction or oxidation sites and thus preserves the photogenerated carriers with stronger redox ability on reaction sites, which ultimately enhances the photocatalytic activity of the heterojunction catalysts. It is commendable that such Z-scheme heterostructures between In2S3 and BiYWO6 exist in a wide span of component ratios (from 5:1 to 30:1), which is beneficial for the environmental remediation applications. It is believed that this work provides new ideas for design and synthesis of novel Z-scheme heterojunction photocatalysts.

Facile synthesis of direct Z-scheme PPy/NH2-UiO-66 heterojunction for enhanced photocatalytic Cr(VI) reduction, industrial electroplating wastewater treatment, and tetracycline degradation

Z-scheme heterojunction photocatalysts generally have excellent redox ability and robust removal efficiency for contaminants in water. Herein, we combined p-type PPy and n-type NH2-UiO-66 by ball milling to prepare a direct Z-scheme PPy/NH2-UiO-66 photocatalyst with ultra-high redox potential. Notably, the optimized efficiency of PPy/NH2-UiO-66 (the mass ratio of PPy to NH2-UiO-66 is 1 wt%, named PPy/NU-1) rapidly reduced Cr(VI) (>95%, 60 min) and TC degradation (>90%, 180 min) at 100 W LED light. Moreover, the PPy/NU-1 has high stability and good anti-interference ability, which can effectively remove Cr(VI) from industrial electroplating wastewater, and the Cr(VI) removal rate is 99%, which meets the industrial wastewater standard and has the potential attraction of actual wastewater treatment. In addition, the techniques of UV-Vis diffuse reflection, electron spin resonance (ESR), photoluminescence (PL), and photoelectrochemical measurement showed that PPy/NH2-UiO-66 composites improved the light capture ability, thereby improving the photocatalytic efficiency. The PPy/NU-1 has a very high redox potential by constructing a Z-scheme heterojunction, enhances the interfacial charge transfer ability, and improves the separation efficiency of photogenerated carriers. Finally, the mechanism of the Z-scheme was systematically by nitroblue tetrazolium (NBT) and p-phthalic acid (TA) transformation, ESR experiments, and density functional theory (DFT) calculations. This work provides a strategy for the preparation of visible photocatalysts with excellent photocatalytic activity and provides new insights for interfacial charge transfer and molecular oxygen activation.

Engineering direct Z-scheme GCN/ bimetallic-MOF heterojunctions as efficient and recyclable photocatalysts for enhancing degradation of RR 195 under visible light

Direct Z-scheme heterojunction photocatalyst GCN/M-FeBTC (M: Ni, Co, Cu, Zn, Mn; BTC: 1,3,5-benzenetricarboxylate, GCN: graphitic carbon nitrides) were synthesized by in-situ hydrothermal method assisted using microwave. GCN/M-FeBTC materials exhibit excellent photocatalytic performance with nearly 100 % of reactive red 195 (RR-195) being removed after 30 min under direct sunlight irradiation. Tests for reactive radicals have shown that holes (h+) and superoxide radicals (•O2–) close a major function in the removal of RR-195. Based on the band structure (BS) of the material, a direct Z-scheme heterojunction photocatalyst mechanism has been proposed. The effects of catalyst mass, pH and RY-145 concentration on the photocatalytic activity of GCN/Mn-FeBTC materials were also researched. The innovation of the photocatalytic activity of the GCN/Mn-FeBTC materials may be due to the synergistic combination of factors such as: (i) the high surface area; (ii) visible light absorption and efficient splitting of electron (e–) and h+; (iii) increased oxygen vacancies and defects; (iv) shortening of charge transport distances. The decomposition pathway of RR-195 was determined based on liquid chromatography mass spectrometry (LC-MS) analysis. Chemical oxygen demand (COD), biological oxygen demand (BOD) and total organic carbon (TOC) show high mineralization potential for the degradation of RR-195 on direct Z-scheme photocatalysts GCN/M-FeBTC.

Bi3O4Cl/g-C3N4/Cd0.5Zn0.5S Double Z-Scheme Heterojunction Photocatalyst for Highly Selective CO2 Reduction to Methane.

Solar-energy-driven CO2 hydrogenation is a promising strategy to alleviate the climate crisis. Methane is a desirable derivative of CO2 reduction. However, developing a photocatalyst for highly active and selective CH4 generation remains challenging. Herein, we report a double Z-scheme Bi3O4Cl/g-C3N4/Cd0.5Zn0.5S photocatalyst for efficient reduction of CO2 to CH4. In situ characterization techniques confirmed that the charge migration mechanism in Bi3O4Cl/g-C3N4/Cd0.5Zn0.5S promotes charge separation through double internal electric fields. As a result, the optimized C0.01B0.02C catalyst displayed a formation rate high up to 25.34 μmol g-1 h-1 and a selectivity of 96.52% of CH4. Moreover, the AQY of CO2 conversion on C0.01B0.02C (1.84%) was almost 41 times higher than that of the bare CN. This study provides a novel perspective to develop heterojunction photocatalysts for selective CO2 conversion to CH4.

Efficient photothermal catalytic CO2 reduction over in situ construction ZnIn2S4@Ni(OH)2/NiO Z-scheme heterojunction

Photocatalytic reduction of CO2 into valuable chemicals has been considered as a sustainable and environmentally friendly technology, which can simultaneously alleviate the energy crisis and environmental problems that have puzzled people for a long time. Herein, we successfully synthesize defective ZnIn2S4@Ni(OH)2/NiO (ZIS@NOH/NiO) Z-scheme heterojunction photocatalysts through solvothermal and low-temperature calcination strategies. The loading of Ni(OH)2 nanosheets can increase the specific surface area of photocatalyst, and form Z-scheme heterojunction with ZIS to improve the utilization of photogenerated electrons. It is worth noting that during the low-temperature calcination process, Ni(OH)2 is partially converted into NiO, and a large number of metal defects are formed, which reduces the bandgap of Ni(OH)2 and shows visible light response. In addition, the generated black defective NiO with full spectrum response and good photothermal effects can accelerate the migration of photogenerated carriers and reduce the catalytic reaction barrier of CO2. Consequently, the prepared ZIS@NOH/NiO exhibits a high yield (133.74 μmol g−1) and selectivity (86.2 %) for CO2 to CH4, which almost is 3.2 and 11.1 times than those of ZnIn2S4@Ni(OH)2 and ZnIn2S4, respectively. Furthermore, in-situ Fourier transform infrared spectroscopy (FTIR) analysis reveal the effective adsorption of CO2 on the ZnIn2S4@Ni(OH)2/NiO surface and the high selectivity of CH4. This work will provide meaningful prospects for designing a carbon dioxide reduction photocatalyst with high conversion and selective.

Facile synthesis of a 2D/3D Z-scheme Cu-g-C3N4/BiOBr heterojunction for enhanced photocatalytic degradation of ciprofloxacin under visible light irradiation

A 2D/3D Z-scheme Cu-doped-g-C3N4/BiOBr (CuCNB) heterojunction was fabricated using a facile solvothermal technique for enhanced photocatalytic degradation of ciprofloxacin (CIP). It is believed that a Z-scheme heterojunction is formed between BiOBr and Cu-doped g-C3N4 (Cu-g-C3N4) based on Mott-Schottky analysis. Hence, the as-prepared nanocomposite exhibits an excellent charge carrier separation ability, a broadband and intense visible-light absorption potential, and a strong redox capacity. Under optimum conditions (pH 6.2 and catalyst dose of 0.75 g L−1), a degradation efficiency of approximately 91.5 % is achieved after 240 min of visible-light irradiation by using the CuCNB photocatalyst, which is nearly 1.22, 2.55, and 1.31 times higher than pristine BiOBr, Cu-g-C3N4, and BiOBr-Cu-g-C3N4 mixture, respectively. Radical quenching experiments and electron paramagnetic resonance measurements confirm that the net contribution of various oxidative species decreases in the order of hydroxyl radicals < superoxide anions < holes. A toxicity assessment of CuCNB, as well as the end products of CIP degradation, revealed that both the photocatalyst as well as the photocatalysis by-products were unlikely to inflict any negative impact on the environment. Additionally, the CuCNB photocatalyst showed good stability and acceptable photocatalytic activity over multiple cycles. Further, the practical utility of CuCNB was assessed in different actual water samples. It was observed that the degradation efficiency was lower in wastewater in comparison to surface water and tap water. Overall, the findings of this research offer new foresights into constructing a Z-scheme heterojunction photocatalysts with excellent stability and performance for removing emerging pollutants from aqueous matrices.

Electron bridge rGO synergized with Z-scheme ZnTe/WO3 heterojunction for simultaneous and efficient tetracycline degradation and Cu (II) reduction

Z-scheme heterojunction photocatalysts can restrain carriers’ recombination while retaining high redox capacity. Herein, a novel ZnTe/rGO/WO3 (ZRW) Z-scheme heterojunction was constructed for simultaneous removal of TC and Cu (II) from wastewater. The highly conductive rGO served as a bridge connecting the ZnTe and WO3 whereby forming a tight interaction interface, beneficial to carriers transfer and separation. The removals of TC and Cu (II) using the optimized ZRW-10% achieved 90.6% and 89.5% within 150 min of light exposure, which were much higher than those from the ZnTe and WO3. Results of free radical trapping experiments and electron spin resonance analysis suggested that·O2- and·OH were the key active species for TC oxidation while e- dominated Cu (II) reduction. Based on the identified TC degradation intermediates, two possible degradation pathways for TC were proposed, and the ecotoxicity of most intermediates were less than TC. This study can advance research development of designing efficient Z-scheme photocatalyst and elimination of complex pollutants.

Construction of BiOCl/Bi2WO6 Z-scheme heterojunction with close interfacial contact using CNT as electron medium

Enhancing carrier separation capabilities and extending the visible light absorption range are essential for overcoming the low photocatalytic performance of single semiconductors. In this study, by using hydrothermal and ion-exchange methods, a series of Z-scheme heterojunction BiOCl/CNT/Bi2WO6 photocatalysts with visible light response were successfully constructed by using carbon nanotubes (CNT) as an electronic medium. Under visible light irradiation, the photocatalytic performances of the samples were evaluated by the degradation of tetracycline and ciprofloxacin. The results shown that the BiOCl/CNT/Bi2WO6 heterojunction photocatalysts possessed excellent photocatalytic activity, and the kinetics reaction models of the photocatalysts followed pseudo-first-order kinetics. This excellent photocatalytic performance may be due to the acceleration of photogenerated carrier separation due to the formation of heterojunction and the CNT as an electronic medium, as well as the close contact interface between the BiOCl/Bi2WO6 heterojunction, which shortened the carrier migration path. The charge transfer mechanism in the BiOCl/CNT/Bi2WO6 Z-scheme heterojunction composites was proposed based on the results of trapping experiments, in-situ XPS and SPV. Furthermore, three degradation pathways were discussed, and toxicity assessments of intermediates showed that the toxicity after photocatalytic degradation decreased. This study could bring light on the development of promising and novel CNT-mediated Z-scheme heterojunction photocatalysts for pollutant degradation.

In-situ Construction of Oxygen Vacancies-Rich Direct Z-Scheme δ-Bi2O3/Bi2WO6 Heterojunction for Enhanced Photocatalytic N2 Fixation

The recombination of interface charges hindered photocatalytic nitrogen fixation (NRR), but the introduction of surface oxygen defects (OV) and the construction of heterojunctions were found to effectively separate charges at the interface and enhance NRR efficiency. Here we successfully constructed the δ-Bi2O3/Bi2WO6 (BBWO-3) heterojunction with a core-shell similar structures and OV-rich via a solvothermal method, where the δ-Bi2O3 nanosheets were grown in-situ on the surface of Bi2WO6 (BWO) hollow microspheres. The optimized BBWO-3 achieved a nitrogen fixation yield of 65.6 μmol-1·g-1Cat under simulated sunlight, which was 6 times that of δ-Bi2O3 and 2.8 times that of Bi2WO6, without needing sacrificial agents. The enhanced photocatalysis activity was attributed to OV and the formation of direct Z-Scheme heterojunction with core-shell similar structures, achieving effective spatial separation of photogenerated charges and providing a dedicated pathway for charge migration. At the meanwhile, since the bending of the band, an internal electric field (IEF) was formed from δ-Bi2O3 to BWO at the interface, which accelerate the dynamics of charge transfer. Moreover, the mechanism of the NRR was elucidated based on density functional theory (DFT) and in-situ XPS. This study provides a new idea for the construction of OV-rich core-shell similar structures direct Z-Scheme heterojunction photocatalysts.

Bi2S3/NH2-MIL-53(Fe) composite photocatalysts for enhanced catalytic degradation of contaminants driven by UV light

The Z-scheme heterojunction photocatalyst Bi2S3/NH2-MIL-53 (Fe) was successfully constructed by in situ growth. The larger specific surface area and porosity of the composite provided more active sites for the photocatalytic reaction, which remarkably improved the photo-Fenton performance. The charge transfer mechanism effectively inhibits the recombination of electrons and holes, thereby significantly reducing the occurrence of photocorrosion. The degradation rates for CIP, TC-H, and SMX were 91 %, 87 %, and 86 % respectively. Additionally, the degradation rates for dyes all exceeded 98 % within 60 min, demonstrating their universal effectiveness in degrading pollutants. In addition, the materials showed good resistance to interference by natural organic matter. The good degradation rate remained after several cycles, indicating the high stability of the composite material. In conclusion, this study proposed a new method to design and fabricate composite photocatalysts using metal-organic skeletons, which provides a new way and feasible solution for the development of highly efficient photocatalytic materials and their application in the field of environmental purification.

In situ co-crystallization synthesis of the direct Z-scheme Bi5O7I/Bi2SiO5 heterojunction for enhanced photocatalytic rhodamine B and ciprofloxacin degradation

Semiconductor photocatalysis has driven considerable interests for its desirable potential to tackle the worldwide energy shortage and environmental pollution. In this paper, a novel Bi5O7I/Bi2SiO5 Z-scheme heterojunction photocatalyst was in situ synthesized via a co-crystallization process and partial anion exchange strategy. The XRD and FT-IR pattern validated the successful preparation of the heterojunction. The optimal Bi5O7I/Bi2SiO5 heterojunction displayed an excellent photocatalytic activity towards the ciprofloxacin under the simulated solar light, and the rate constant (0.46021 h−1) was 2 and 7.8 times higher than that of pure BiOI (0.22967 h−1) and Bi2SiO5 (0.05877 h−1). Similarly, the degradation efficiency on rhodamine B (RhB) reached 94%, which was much higher than that of the single photocatalysis. The enhanced photocatalytic performance of the heterojunction photocatalyst could be attributed to the formation of the direct Z-scheme heterojunction between the Bi5O7I and Bi2SiO5, which was favorable for retarding the recombination of photoinduced electron-hole pairs. Moreover, the bacteriostatic activity testing illustrated the toxicity of drug solutions decreased sharply after the photocatalytic degradation with the Bi5O7I/Bi2SiO5-3. The ESR characterization analysis and the free radical trapping experiments synergistically determined the Z-scheme electron transfer path of the heterojunction. The possible photocatalytic mechanism of Bi5O7I/Bi2SiO5 heterojunction was proposed. Overall, the well-designed Bi5O7I/Bi2SiO5 heterojunction depicted great practical promise in efficient treatment of organic pollutants.

The Construction of an α-F2O3/Tubular g-C3N4 Z-Scheme Heterojunction Catalyst for the Efficient Photocatalytic Degradation of Tetracycline

Morphological engineering and semiconductor coupling show significant potential to increase the photocatalytic performance of graphite carbon nitride (g-C3N4). In this work, a unique Z-scheme heterojunction photocatalyst composed of tubular g-C3N4 (TCN) and α-F2O3 was successfully synthesized. Combining the experimental results and characterization, we extensively investigated the charge transfer mechanism of the α-F2O3/tubular g-C3N4 (FO-TCN) heterojunctions and processes in the photocatalytic degradation of tetracycline (TC). The tubular morphology provided a larger specific surface area, enhancing the light absorption area and thus improving the exposure of the active sites. Not only was the light absorption range expanded through the coupling with α-F2O3, but the charge transfer properties of the sample were also strengthened. The synergism between photocatalysis and the Fenton reaction enhanced the photocatalytic performance of the FO-TCN. Due to the previously mentioned beneficial factors, the performance of the FO-TCN photocatalyst was significantly increased; its reaction rate k value in the degradation of TC (0.0482 min−1) was 4.05 times faster than that of single g-C3N4 and it exhibited the best photocatalytic performance (95.02%) for the degradation of TC in 60 min, with an enhancement of 38.41%. Quenching experiments showed that h+ and ·O2− were the major active substances in the photocatalytic degradation process.

Construction of a Z-scheme heterojunction photocatalyst with oxygen vacancies using cobalt–alumina-layered double hydroxide dispersed between bismuth oxybromide layers for efficient photocatalytic reduction of carbon dioxide

Under the context of energy shortages and global warming, the photocatalytic reduction of carbon dioxide (CO2) to carbon monoxide (CO) using simulated sunlight has attracted considerable research attention. Herein, three-dimensional (3D) Z-scheme cobalt–alumina-layered double hydroxide/bismuth oxybromide (CoAl-layered double hydroxide (LDH)/BiOBr) heterojunction photocatalysts with oxygen vacancies were constructed by intercalating two-dimensional CoAl-LDH between BiOBr layers in the mechanical mixing. The conversion of CO2 in the water phase was greatly improved compared to CoAl-LDH/BiOBr under 300-W xenon light. The transformation efficiency of 23.62 μmol⋅g−1⋅h−1 for CoAl-LDH/BiOBr-10 (CBO-10) is 2.96 and 8.34 times that of pure BiOBr and CoAl-LDH, respectively, with CO selectivity in the obtained products reaching as high as 95 %. Furthermore, CBO-10 catalysts exhibited outstanding stability in terms of structure and catalytic performance. The construction of Z-scheme heterojunctions and oxygen vacancies enlarges the photoresponse range of the BiOBr catalyst while reducing the photoelectron–hole recombination efficiency. The unique 3D structure offers more Z-scheme heterojunction interfaces for the separation and transfer of electrons between CoAl-LDH and BiOBr during photoreaction. This study is expected to guide the development of new high-performance photocatalysts and the selective regulation of reduction products.

Constructing a Z-scheme heterojunction photocatalyst I-ABN-C3N4@CDs/BiOI by synergistically in situ modified g-C3N4 via carbon dots and copolymerization for BPA degradation

The rapid recombination of photogenerated carriers and the narrow absorption range of visible light greatly limit the photocatalytic activity of graphite carbon nitride (g-C3N4). Herein, g-C3N4 was jointly modified by carbon dots (CDs) and copolymerization via in situ co-calcining of three precursors (urea, glucose and 2-amino-5-iodo-benzonitrile (I-ABN)), and named as I-ABNx-C3N4@CDsy. Then, solid-state Z-scheme photocatalysts PC1–PC9 with CDs as the electron mediators were prepared via in situ growth of BiOI on the surface of I-ABNx-C3N4@CDsy through solvothermal method. The optimal proportion of each component was explored through orthogonal experiments. The existence of CDs act as an electron transport medium to accelerate the transportation rate of photogenerated carriers, improve the light absorption capacity. The copolymerization with I-ABN introduce benzene rings and I− to g-C3N4, which enhance the light absorption capacity and photoelectric efficiency. The Z-scheme heterojunction effectively suppresses the recombination of photogenerated electron–hole pairs. Therefore, PC1–PC9 presented excellent performance for the degradation of BPA due to the synergistic effects of the above three points. Among them, PC6 showed the best photocatalytic activity, which completely degraded BPA (15 mg/L) within 40 min, and whose rate constant (0.091 min−1) was 22.8 times that of bulk g-C3N4. The active radical trapping experiment determined •O2− and h+ were the main active radicals. Finally, the BPA degradation mechanism by PC6 was proposed. This study provides new insights for the combination of heterojunction, carbon dots, and copolymerization to rationally design efficient photocatalysts to restore the environment.

Facile construction of Z-scheme g-C3N4/BiOI heterojunction for improving degradation of tetracycline antibiotics

Tubular g-C3N4 derived from melamine and trithiocyanuric acid was coupled with flower-like BiOI microspheres to form Z-scheme heterojunction photocatalyst for efficient photocatalytic degradation of tetracycline (TC). The structure, morphology, and optical properties of the prepared g-C3N4/BiOI were characterized. When the mass fractions of g-C3N4 in the composites was 5 wt%, g-C3N4/BiOI exhibited the highest removal efficiency of 84.2 % within 60 min. The enhanced photocatalytic performance of g-C3N4/BiOI could be ascribed to stronger absorption in the visible region and faster charge transfer rate. Trapping experiments revealed that h+ and ·O2− radicals were the main active species. Based on the band structure and trapping experiments, the Z-scheme pathway was proposed to clarify the photocatalytic mechanism.

Synthesis of a Z-scheme photocatalyst (P-doped g-C3N4/Bi3+-doped Ag3PO4) and its photocatalytic performance

A Z-scheme heterojunction photocatalyst was prepared by combining P-doped carbon nitride (PCN) and Bi3+-doped silver phosphate (BPO). The prepared materials were systematically characterized by SEM, XRD, XPS, FT-IR and electrochemical tests. The photocatalytic performance was investigated under visible light irradiation with tetracycline as the model pollutant. The results revealed that doping phosphorus had a markedly impact on widening the light absorption of PCN by reducing its bandgap. Water and hydroxyl groups adsorbed on the BPO surface increased as a result of bismuth doping. Besides, the photocurrent responses of PCN and BOP were all higher than those of the un-doped ones. Especially, doping phosphorus made valence band of PCN move up, while conduction band of BPO went downwards due to bismuth doping. This facilitated formation of Z-scheme heterojunction between PCN and BPO. Consequently, the photocatalytic activity of BPO/PCN was further enhanced. The pseudo-first-order kinetics constant of tetracycline degradation for BPO/PCN was 62.7, 8.2, 1.9, and 1.3 times higher than that for g-C3N4, PCN, Ag3PO4, and BPO, respectively. Radical trapping experiments confirmed that ·O2− and h+ were major reactive species. Additionally, with BPO/PCN as the anode of photocatalytic fuel cell, the performance on decontamination and electricity generation was significantly enhanced.

Graphitic Carbon Nitride/Zinc Oxide-Based Z-Scheme and S-Scheme Heterojunction Photocatalysts for the Photodegradation of Organic Pollutants.

Graphitic carbon nitride (g-C3N4), a metal-free polymer semiconductor, has been recognized as an attractive photocatalytic material for environmental remediation because of its low band gap, high thermal and photostability, chemical inertness, non-toxicity, low cost, biocompatibility, and optical and electrical efficiency. However, g-C3N4 has been reported to suffer from many difficulties in photocatalytic applications, such as a low specific surface area, inadequate visible-light utilization, and a high charge recombination rate. To overcome these difficulties, the formation of g-C3N4 heterojunctions by coupling with metal oxides has triggered tremendous interest in recent years. In this regard, zinc oxide (ZnO) is being largely explored as a self-driven semiconductor photocatalyst to form heterojunctions with g-C3N4, as ZnO possesses unique and fascinating properties, including high quantum efficiency, high electron mobility, cost-effectiveness, environmental friendliness, and a simple synthetic procedure. The synergistic effect of its properties, such as adsorption and photogenerated charge separation, was found to enhance the photocatalytic activity of heterojunctions. Hence, this review aims to compile the strategies for fabricating g-C3N4/ZnO-based Z-scheme and S-scheme heterojunction photocatalytic systems with enhanced performance and overall stability for the photodegradation of organic pollutants. Furthermore, with reference to the reported system, the photocatalytic mechanism of g-C3N4/ZnO-based heterojunction photocatalysts and their charge-transfer pathways on the interface surface are highlighted.

Dual Z-scheme TCN/ZnS/ ZnIn2S4 with efficient separation for photocatalytic nitrogen fixation

The development of an efficient catalyst that can use solar energy for NH3 production is of great significance in solving the environmental and energy crisis caused by the traditional ammonia synthesis process. In this work, a dual Z-scheme tubular carbon nitride/zinc sulfide/zinc indium sulfide ternary composited photocatalyst (TCN/ZnS/ZnIn2S4) with excellent nitrogen photofixation performance under visible light was prepared by self-assembly and hydrothermal methods. The crystal structure studies confirmed that tubular carbon nitride (TCN) had more active sites that could promote N2 adsorption. The photochemical studies proved that the double charge transfer channel provided by the dual Z-scheme heterojunction could improve the efficiency of electron-hole separation and achieve excellent photocatalytic nitrogen fixation. The ammonia production rate of the TCN/ZnS/ZnIn2S4 catalyst was up to 136.56 μmol/L, and it also has good stability and reusability. This work provides new insight into the development of Z-scheme heterojunction photocatalysts with green and efficient nitrogen fixation.

AlSb/ZrS2 heterojunction: A direct Z-scheme photocatalyst with high solar to hydrogen conversion efficiency and catalytic activity across entire PH range

Using the First principles method, the electrical, optical, and photocatalytic characteristics of AlSb/ZrS2 van der Waals heterojunctions (vdwH) with direct Z-scheme photogenerated electron transfer mechanism were calculated in this study. The inherent type-II band structure, the built-in electric field that facilitates photogenerated carrier separation, and the high mobility of electrons and holes along the x and y axes all contribute to the strong photocatalytic activity. Furthermore, the AlSb/ZrS2 van der Waals heterojunction has better light absorption performance than monolayers, with a light absorption coefficient of 4.7 × 105 cm−1 at 500 nm and a solar to hydrogen efficiency of 25.81%. Meanwhile, the breakdown reaction of heterojunctions for water can be spontaneously reacted under the light, according to the free energy calculations of the Hydrogen Evolution Reaction (HER) and Oxygen Evolution Reaction (OER) processes. Unexpectedly, adding biaxial strain to the heterojunction allows for effective band gap and light absorption coefficient adjustments. and the photolysis reaction of water can be realized in the whole PH range within a suitable strain range. The AlSb/ZrS2 van der Waals heterojunction is expected to be a promising candidate for Z-scheme heterojunction photocatalysts for the whole hydrolysis in the future.

ZIF-67/BiOCl Z-Scheme Heterojunction Photocatalyst for Photodegradation of Organic Dyes and Antibiotics

ZIF-67/BiOCl Z-Scheme Heterojunction Photocatalyst for Photodegradation of Organic Dyes and Antibiotics