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Construction of dual defect mediated Z-scheme photocatalysts for enhanced photocatalytic hydrogen evolution
摘要： The construction of Z-scheme system is a promising approach for photocatalytic hydrogen evolution (PHE). In this study, we fabricated a direct Z-scheme system consisting of defect-rich g-C3N4 nanosheets (DR-CNNS) crumpled nanosheets with defect-rich TiO2 (DR-TiO2) nanoparticles via a dual defective strategy. The optimized dual-defective rich TiO2/CNNS composite showed a superior PHE rate of ?651.79 μmol/h with a turnover frequency of ?419.3 h?1 as well as high stability and recyclability, which presented the highest value in single defective TiO2 or g-C3N4-based photocatalysts families reported previously. Furthermore, this protocol could also be extended to synthesize other dual defective g-C3N4/oxides (ZnO, SnO2, etc.) heterostructures. The improved photocatalytic performances could be ascribed to the following aspects: (1) rich dual defect, narrowing the band gap and providing more reactive sites for PHE; (2) intimate interface, facilitating interfacial migration and utilization of photogenerated charges; (3) Z-scheme structure, accelerating photogenerated electron-hole pair separation and thus leading to more e?cient PHE. Our work highlights the critical role of defects in construction of Z-scheme system and provides the possibility of utilizing dual defective g-C3N4-based systems for other photocatalytic applications including CO2 reduction and water puri?cation.
关键词： Photocatalytic hydrogen evolution,Dual defect,Oxides/g-C3N4,Heterojunction,Direct Z-scheme
更新于2025-11-14 15:27:09
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Review on metal sulphide-based Z-scheme photocatalysts
摘要： Semiconductor-based heterojunction photocatalysts have received considerable attention for solar energy conversion and environmental purification due to their spatially separated reduction and oxidation sites, effective separation and transportation of photo-excited charge carriers and strong redox ability. With their wide visible-light responsive range and high photocatalytic activity, metal sulphide is an important material in developing photocatalysts. This review summarizes and highlights recent research progress in sulphide-based direct Z-scheme photocatalysts, followed by analysis on the limitations over all-solid-state Z-scheme photocatalyst. Furthermore, the applications and characterization methods of sulphide-based direct Z-scheme photocatalyst are summarized. Finally, the challenges and perspectives of sulphide-based Z-scheme photocatalyst are discussed.
关键词： CdS,direct Z-scheme,All-solid-state Z-scheme,S-scheme,metal sulphide
更新于2025-09-23 15:23:52
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The superior photocatalytic activity of Nb doped TiO2/g-C3N4 direct Z-scheme system for efficient conversion of CO2 into valuable fuels
摘要： In this study, we firstly aimed to use Nb as dopant to dope into the TiO2 lattice in order to narrow band gap energy or enhance photocatalytic activity of the Nb-TiO2. Then, the prepared Nb-TiO2 was combined with g-C3N4 to establish Nb-TiO2/g-C3N4 direct Z-scheme system for superior reduction of CO2 into valuable fuels even under visible light. The obtained results indicated that the band gap energy of the Nb-TiO2 (2.91 eV) was lower than that of the TiO2 (3.2 eV). In the successfully established Nb-TiO2/g-C3N4 direct Z-scheme system, the photo-excited e- in the CB of the Nb-TiO2 combined with the photo-excited h+ in the VB of the g-C3N4 preserving the existence of e- in the CB of the g-C3N4 and h+ in the VB of Nb-TiO2, and thereby, the system produced numerous amount of available e-/h+ pairs for the reduction of CO2 into various valuable fuels. In addition, the produced e- of the Nb-TiO2/g-C3N4 existing in the CB of the g-C3N4, which the potential energy is approximately - 1.2 V, would be strong enough for the reduction of CO2 to generate not only CH4 and CO but also HCOOH. Among established Nb-TiO2/g-C3N4 materials, the 50Nb-TiO2/50g-C3N4 material was the best material for the CO2 reduction.
关键词： Nb dopant,CO2 reduction,Nb-TiO2,g-C3N4,direct Z-scheme
更新于2025-09-23 15:23:52
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<i>In situ</i> fabrication of a direct <i>Z</i> -scheme photocatalyst by immobilizing CdS quantum dots in the channels of graphene-hybridized and supported mesoporous titanium nanocrystals for high photocatalytic performance under visible light
摘要： We report the considerable advantages of direct Z-scheme photocatalysts by immobilizing high-quality CdS quantum dots (QDs) in the channels of graphene-hybridized and supported mesoporous titania (GMT) nanocrystals (CdS@GMT/GR) under facile hydrothermal conditions. The photocatalysts have been characterized by XRD, PL, XPS, SEM, DRS, TEM, EIS, and N2 adsorption. CdS QDs primarily serve as photosensitizers with a unique pore-embedded structure for the e?ective utilization of the light source. This direct Z-scheme CdS@GMT/GR exhibits higher photocatalytic activity than CdS/GR, GMT/GR, or CdS@MT. In addition, the rate constant of CdS@GMT/GR-2 is approximately twice the sum of those of CdS@MT and GMT/GR, because GR played the role of hole-transporting and collection layer as well as the hybridization level formation in terms of hybridizing MT and serving as a support. Therefore, the GR content tunes the energy band, a?ects the surface area, and controls the interfacial hole transfer and collection rate of the direct Z-scheme system. Furthermore, CdS@GMT/GR retains its high performance in repeated photocatalytic processes. This can be attributed to the fact that GR prevents QDs from photocorrosion by means of the hole-transporting and collection e?ect. A possible reaction mechanism is proposed. This work provides a promising strategy for the construction of highly e?cient visible-light-driven photocatalysts to reduce the growing menace of environmental pollution.
关键词： environmental pollution,visible-light-driven photocatalysts,graphene-hybridized mesoporous titania,direct Z-scheme photocatalysts,CdS quantum dots
更新于2025-09-11 14:15:04
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Rational construction of direct Z-scheme doped perovskite/palygorskite nanocatalyst for photo-SCR removal of NO: Insight into the effect of Ce incorporation
摘要： V-Ti oxide catalyst has been widely employed in selective catalytic reduction (SCR) of NOx in industry. However, considerable cost and high reaction temperatures are commonly required. Alternatively, photo-SCR working at low temperature has attracted widespread interest. In the present work, Pr1(cid:1)xCexFeO3/palygorskite (Pal) nanocomposite was synthesized by an in situ sol-gel method. Results indicate that Pr1(cid:1)xCexFeO3 remain as a perovskite solid solution uniformly immobilized on the surface of Pal when x is less than 0.05. CeO2 co-precipitates with Pr1(cid:1)xCexFeO3 when x is beyond 0.05, leading to an enhanced charge separation induced by the formation of intimate direct Z-scheme heterostructure of Pr1(cid:1)xCexFeO3/CeO2, which is unraveled by the photoluminescence spectroscopy and Mott-Schottky analysis and further verified by the DFT calculations. Under visible light irradiation, the influence of the doping amount of Ce (from 0.05 to 0.5) on the NO conversion and N2 selectivity was investigated. The Pr0.7Ce0.3FeO3/Pal was found to achieve the highest NO conversion rate of 92% and 99% N2 selectivity. In addition, the SO2 and H2O resistance experiment show that the doping of Ce could benefit the formation of cerium sulphate which prevents NH3 from being sulfated by SO2 while Pal prevents the catalysts from being corroded by H2O, respectively.
关键词： Direct Z-scheme,Photo-SCR,Palygorskite,Denitrification,CeO2,Perovskite
更新于2025-09-10 09:29:36
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Construction of direct Z-Scheme photocatalysts for overall water splitting using two-dimensional van der waals heterojunctions of metal dichalcogenides
摘要： The direct Z-scheme system constructed by two-dimensional (2D) materials is an efficient route for hydrogen production from photocatalytic water splitting. In the present work, the 2D van der Waals (vdW) heterojunctions of MoSe2/SnS2, MoSe2/SnSe2, MoSe2/CrS2, MoTe2/SnS2, MoTe2/SnSe2, and MoTe2/CrS2 are proposed to be promising candidates for direct Z-scheme photocatalysts and verified by first principles calculations. Perpendicular electric field is induced in these 2D vdW heterojunctions, which enhances the efficiency of solar energy utilization. Replacing MoSe2 with MoTe2 not only facilitates the interlayer carrier migration, but also improves the optical absorption properties for these heterojunctions. Excitingly, the 2D vdW MoTe2/CrS2 heterojunction is demonstrated, for the first time, to be 2D near-infrared-light driven photocatalyst for direct Z-scheme water splitting.
关键词： photocatalysis,direct Z-scheme systems,water splitting,two-dimensional van der Waals heterojunctions
更新于2025-09-10 09:29:36
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In situ synthesis of Z-scheme BiPO4/BiOCl0.9I0.1 heterostructure with multiple vacancies and valence for efficient photocatalytic degradation of organic pollutant
摘要： Design and construction of Z-scheme photocatalyst has been attracted much attention, which is a great challenge to develop highly efficient photocatalyst without the external redox mediators. Herein, a novel efficient redox-mediator-free Z-scheme BiPO4/BiOCl0.9I0.1 heterojunction is synthesized in situ via a mild 90℃ water bath reaction. The as-synthesized BiPO4/BiOCl0.9I0.1 heterostructure exhibits outstanding photocatalytic performance for degradation of phenol and Rhodamine B, approximately 2.6 and 4.3 times higher than that of BiOCl0.9I0.1, respectively. The BiPO4/BiOCl0.9I0.1 heterostructure have multiple vacancies and valence, such as Bi5+, Bi3+, Bi(3-x)+, I-, I3-, and IO3-, which could facilitate the charge separation and transfer in the photocatalytic process. The higher photocatalytic activity of redox-mediator-free Z-scheme BiPO4/BiOCl0.9I0.1 heterostructure could be attributed to the strong redox ability, multiple charge transfer channels via the various defects, and tight contact due to in situ synthesis. The finding provides some new insights for the design of effective direct Z-scheme photocatalyst with multiple defects.
关键词： direct Z-scheme heterojunction,photocatalysis,BiOCl0.9I0.1/BiPO4,redox-mediator-free,multiple defects
更新于2025-09-04 15:30:14
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<i>In situ</i> topotactic fabrication of direct Z-scheme 2D/2D ZnO/Zn <sub/>x</sub> Cd <sub/>1?x</sub> S single crystal nanosheet heterojunction for efficient photocatalytic water splitting
摘要： Direct Z-scheme heterojunction can effectively enhance the photocatalytic activity due to its low carrier recombination rate and high redox ability. In this study, a 2D/2D ZnO/ZnxCd1?xS single crystal nanosheet heterojunction is synthesized in situ by topotactic sulfurization/oxidization pyrolysis of Zn/Cd/Al layer double hydroxides (LDHs). Its unique structure provides not only numerous intimate interfaces but also a direct Z-scheme junction. The in situ topotactic fabrication of ZnO by the oxidation process causes some Zn ions to dissolve out from the Zn0.67Cd0.33S solid solution nanosheets with increase in annealing temperature and time. The longer the time for oxidation, the more ZnO is obtained. The formation of ZnO yields 2D/2D ZnO/ZnxCd1?xS single crystal nanosheet heterojunction, which increases the visible light absorption and boosts the separation of photogenerated carriers. The ZnO/ZnxCd1?xS-4 single crystal nanosheet heterojunction presents the highest photocatalytic activity under visible light irradiation (38.93 mmol h?1 g?1), which is nearly 16.93 times higher than that of Zn0.67Cd0.33S-300, and an external quantum efficiency of 40.97% at λ = 420 nm. The proposed synthetic route for the construction of 2D/2D ZnO/ZnxCd1?xS single crystal nanosheet provides a direct Z-scheme structure with highly efficient photocatalytic hydrogen evolution activity.
关键词： 2D/2D ZnO/ZnxCd1?xS,photocatalytic water splitting,Zn/Cd/Al layer double hydroxides,Direct Z-scheme heterojunction,topotactic sulfurization/oxidization pyrolysis
更新于2025-09-04 15:30:14