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Semiconductor photocatalysis is a potential solution to meet energy needs with green and inexhaustible solar energy. However, designing efficient and stable photocatalysts is a challenging task due to the limited ability to effectively separate electrons and holes. In this paper, by using a straightforward ethanol dispersion technique, we were able to combine ultrathin layered Cu-TCPP MOFs with g-C3N4 nanosheets, resulting in the creation of an extremely effective nano-composite photocatalyst with exceptional UV-vis activity. CT/CN heterojunctions displayed remarkable photocatalytic efficacy for the production of H2, with 3CT/CN showcasing a five-fold enhancement in photoactivity as compared to the unadorned g-C3N4. Based on the results of photoluminescence spectroscopy, electrochemical impedance spectroscopy, and electrochemical reduction, the considerably improved charge transfer and separation, together with the possible catalytic capability of uniformly distributed metal nodes in Cu-TCPP, are believed to be the underlying reason for the observed exceptional photoactivity. After thorough analysis, a potential process for charge transfer and segregation between g-C3N4 and Cu-TCPP has been suggested. [ABSTRACT FROM AUTHOR]

Metal halide perovskites, such as iodine methylamine lead (MAPbI3), have received extensive attention in the field of photocatalytic decomposition of HI for hydrogen evolution, due to their excellent photoelectric properties. In this paper, a new MAPbI3-based composite, MoC/MAPbI3, was synthesized. The results show that 15 wt% MoC/MAPbI3 has the best hydrogen production performance (38.4 μmol h−1), which is approximately 24-times that of pure MAPbI3 (1.61 μmol h−1). With the extension of the catalytic time, the hydrogen production rate of MoC/MAPbI3 reached 165.3 μmol h−1 after 16 h due to the effective separation and transfer of charge carriers between MoC and MAPbI3, showing excellent hydrogen evolution rate performance under visible light. In addition, the cycling stability of MoC/MAPbI3 did not decrease in multiple 4 h cycle tests. This study used the non-precious metal promoter MoC to modify MAPbI3, and provides a new idea for the synthesis of efficient MAPbI3-based composite catalysts. [ABSTRACT FROM AUTHOR]

NiFe-LDH/g-C3N4 (LDH/CN) heterostructures with different amounts of NiFe-LDH (LDH) were prepared by a hydrothermal method and characterized using different experimental techniques. Their photocatalytic properties were investigated using the degradation of tetracycline hydrochloride (TC) and the production of hydrogen from water splitting. Experimental results showed that the hydrogen production rate (780.5 μmol g−1 h−1) was 2.29 times that of pristine CN, and the TC removal rate (76.3%) of 1.8LDH/CN was 3.71 times that of CN. According to the detailed study of the structural, optical, and photoelectrochemical properties, a type II charge transfer mechanism was proposed to explain the improved photocatalytic performance of LDH/CN. [ABSTRACT FROM AUTHOR]

C/Ti3C2/g-C3N4 hollow microspheres (HM) were prepared by the template method to construct Ti3C2/g-C3N4 Schottky junctions on the spherical surface. The C/Ti3C2/g-C3N4 HM Schottky junctions presented excellent photocatalytic properties for producing hydrogen and decomposing organic pollutants simultaneously from wastewater without the addition of a sacrifice agent. The research revealed that the built-in electric field between g-C3N4 and Ti3C2 MXene could decrease the charge transfer resistance, leading to efficient photo charge separation, and the organic pollutant tetracycline (TC) could act as a sacrifice agent for splitting water. The H2 evolution rate of the CN-TCM-3 sample in deionized water with a sacrifice agent reached 105.4 μmol g−1 h−1, and the TC removal rate reached 100% within 120 min. The hydrogen production efficiency of CN-TCM-3 in the natural water of Slender West Lake without or with TC as a sacrifice agent was 2.3 μmol g−1 h−1 and 3.2 μmol g−1 h−1, respectively. The addition of TC improved the hydrogen production efficiency by 39%. This research indicated that the C/Ti3C2/g-C3N4 HM Schottky junctions could be a potential photocatalyst for producing hydrogen and decomposing organic pollutants in sewage simultaneously. [ABSTRACT FROM AUTHOR]

Reasonable design of heterojunction photocatalysts can effectively promote charge separation, thus improving their photocatalytic performance. Herein, a Bi2Fe4O9@ZnIn2S4 S-scheme laminated heterojunction photocatalyst with 2D/2D interface interaction is prepared via a hydrothermal–annealing–hydrothermal method. The photocatalytic hydrogen production rate of Bi2Fe4O9@ZnIn2S4 is up to 3964.26 μmol h−1 g−1, which is 12.1 times higher than that of pristine ZnIn2S4. In addition, its photocatalytic tetracycline degradation efficiency (99.9%) is also optimized. The enhanced photocatalytic performance can be attributed to the formation of S-scheme laminated heterojunctions that facilitate charge separation as well as strong 2D/2D laminated interface interactions favoring charge transfer. By combining in situ irradiation X-ray photoelectron spectroscopy with other characterization methods, the photoexcited charge transfer mechanism of S-scheme heterojunctions has been proved. Photoelectric chemical tests demonstrate the effectiveness of the S-scheme laminated heterojunction in improving the charge separation. This strategy provides a novel perspective for designing other high-efficient S-scheme laminated heterojunction photocatalysts. [ABSTRACT FROM AUTHOR]

A porous and highly dispersed Co3O4-modified ZnO@ZnS heterostructure (Co3O4–ZnO@ZnS) was developed by the simple calcination and sulfurization of the designed bimetallic ZnCo-ZIF@ZIF-8. The charge separation and transfer in this novel heterostructure were significantly improved owing to the highly dispersed Co3O4 and the porous structure. The hydrogen production rate of Co3O4–ZnO@ZnS was 1816.3 μmol g−1 h−1 with Na2S–Na2SO3 as the sacrificial agent under a Xe lamp, which was 1.5 times greater than that of ZnO@ZnS (1215.6 μmol g−1 h−1). Moreover, the photocatalytic performance of Co3O4–ZnO@ZnS was further improved by loading a Pt cocatalyst, with the hydrogen production rate reaching 3269.3 μmol g−1 h−1. This method can be used to design other effective photocatalytic heterostructures for water splitting. [ABSTRACT FROM AUTHOR]

Developing high-performance and low-cost self-supporting electrodes as pH-universal electrocatalysts for the hydrogen-evolution reaction (HER) and realizing high-quality hydrogen production at a high current density are highly desirable, but are hugely challenging. We created a self-supporting electrode with a coupled hierarchical heterostructure by simple electrodeposition followed by sulfurization. It comprised oxygen-deficient molybdenum oxide (MoO3−x) and cobalt phosphide (CoP) on nickel foam (NF), which represented a highly active pH-universal electrocatalyst for the HER at a high current density. Benefiting from a plethora of catalytic active sites, improved interfacial charge transfer, and strong electronic interaction, this type of MoO3−x@CoP/NF electrode delivered a superior catalytic performance. Overpotentials of only 100 mV, 135 mV, and 400 mV were needed to realize a high current density of 1 A cm−2 in alkaline, acid and neutral media, respectively, which were superior to those of most other well-developed materials based on non-noble metals. Our experimental work demonstrates the synergistic advantages of a MoO3−x@CoP heterostructure for improving the intrinsic catalytic performance but also paves a new path for the rational design of advanced electrodes for hydrogen generation in a wide range of pH conditions. [ABSTRACT FROM AUTHOR]

The study of environmentally friendly semiconductor photocatalysts has important practical significance for efficient photocatalytic hydrogen evolution. In this experiment, type II heterojunction NiCo-LDH/CeO2 was prepared by in situ loading, and the NiCo-LDH/CeO2 catalyst showed good activity under simulated sunlight irradiation. Under simulated visible light irradiation, its hydrogen production rate reached 2.7 mmol h−1 g−1, which was higher than that of NiCo-LDH (0.86 mmol h−1 g−1). Through a series of characterization data, it can be concluded that the heterojunction successfully constructed by the close contact between NiCo-LDH and CeO2 accelerates the separation of photogenerated electrons and holes and can effectively inhibit the recombination of the two so that more electrons are involved in the hydrogen evolution reaction. The material has good interfacial charge transfer performance, which improves the photocatalytic performance. This work can provide an effective method for the research and development of NiCo-LDH. [ABSTRACT FROM AUTHOR]

As a research hotspot, 2D-MoS2 has been regarded as a low-cost substitute for platinum, and has fascinated researchers worldwide. Two crystalline phases of MoS2, i.e. the metallic octahedral 1T phase and semiconducting trigonal prismatic 2H phase, have been extensively analysed. In comparison to 2H-MoS2, the 1T phase exhibits enhanced and unique physicochemical properties. Designing a structure with two-dimensional mixed-phase MoS2, i.e. 1T/2H-MoS2 nanosheets, via phase engineering for effective charge separation and migration has received growing interest in the field of photocatalytic hydrogen generation. In this study, by varying the wt% of ammonium bicarbonate via a facile hydrothermal technique, a series of 1T/2H-MoS2 nanosheets have been fabricated. The presence of the corresponding elements, the electronic environment, phase purity, morphology and phase distinction were confirmed by Raman, XPS, XRD and HRTEM analyses. Additionally, the impedance data and the photocurrent density of the photocatalysts verify the efficient charge separation and transfer phenomenon. In accordance with the electrochemical measurements, the developed mixed-phase MoS2 nanosheets exhibit a six times greater current density than 2H-MoS2. Furthermore, the highest response of photocatalytic hydrogen production is observed with the photocatalyst with 79% 1T phase, which is about 17 times greater than that of pristine 2H-MoS2 due to the enrichment of active sites on both the edges and basal plane as well as the enhanced electronic conductivity due to the 1T phase. This study indicates that with the construction of a heterophase, i.e. 1T/2H-MoS2 nanosheets, the photocatalytic hydrogen evolution capability can be boosted, providing new insights regarding these materials. [ABSTRACT FROM AUTHOR]

Catalysts with low cost, high efficiency, and no need for precious metal cocatalysts are the key to realizing the maximum utilization of solar energy-efficient hydrogen (H2) production. In this study, a series of graphitic carbon nitride-derived catalysts (g-C3N4/CoP@C) were successfully obtained by in situ phosphating of g-C3N4/Co-BDC. A CoP@C cocatalyst developed with Co-BDC nanosheets as precursors can accelerate the H2 generation of g-C3N4. The close interface between CoP@C and g-C3N4 increased the electron–hole separation efficiency. Moreover, the CoP@C surface carbon accelerated electron transfer and increased the light absorption range. The prepared g-C3N4/CoP@C composite material exhibited H2 production capability up to 1968 μmol g−1 (3 h), approximately 129.9 times that of g-C3N4. Therefore, the CoP@C cocatalyst is proposed as an alternative to non-precious metal cocatalysts based on the findings of the study. [ABSTRACT FROM AUTHOR]

Formic acid (FA) as a safe and promising hydrogen carrier has attracted widespread attention. The use of solid catalysts in the controllable and efficient dehydrogenation of FA is still a challenge. Here, a series of Au nanoclusters supported on rare earth metal doped ZrO2 catalysts (Au/ReZrO2 (Re = Nd, Ce and Sm)) was prepared. Doping rare earth metals in zirconia stabilizes the mixed-phase zirconia into the tetragonal phase. Meanwhile, the rare earth metal dopants can promote the formation of oxygen vacancies in zirconia, which promotes charge transfer from the support to Au and enhances the metal–support interaction on all the three catalysts. As a result, Au/ReZrO2 (Re = Nd3+, Ce3+ and Sm3+) catalysts exhibited better catalytic performance in the liberation of CO-free H2 from FA, outperforming Au supported on primary ZrO2. Structural and electronic characterization by XPS and H2-TPR further confirmed the contribution of doping rare earth metal cations in Au/ReZrO2, which can enhance the metal–support interaction and accelerate the decomposition of HCOOH into H2, thus resulting in the improvement in catalytic activity for hydrogen production from FA. [ABSTRACT FROM AUTHOR]

A facile synthetic route, by using rhombic dodecahedral zeolitic imidazolate framework-8 (ZIF-8) as the structure template, is devoted to fabricating the ZnS/ZnIn2S4 hybrid heterojunction; the compact heterostructure was produced by combining the sulfurization of ZIF-8 and the in situ precipitation of ZnIn2S4 in one pot. The resulting ZnS nanoparticles of about 100 nm were uniformly dispersed in the folds of flower-like ZnIn2S4, whose structure is beneficial for charge transfer at the heterointerface. The additional quantities of ZIF-8 are varied to find an optimum ratio of the two components to obtain the best photocatalytic activity. In the photocatalytic hydrogen generation irradiated by simulated solar light, all the ZnS/ZnIn2S4 hybrid photocatalysts displayed improved hydrogen production rates compared to single ZnS or ZnIn2S4, and the best hydrogen production rate of 453.4 μmol h−1 g−1 is obtained by ZnS/ZIS-20, whose value is approximately 4 times higher than that of single ZnIn2S4. The electrochemical properties of the ZnS/ZnIn2S4 hybrid photocatalysts were measured to explore the charge transfer mode at the interface, and the band structure and enhanced photocatalytic hydrogen generation mechanism have been proposed. The excellent recycling properties of hydrogen production indicated the prospective applications of this kind of ZIF-derived metal sulfide in photocatalytic reactions. [ABSTRACT FROM AUTHOR]

This is the first report on the application of InWO4 nanospheres in the field of photocatalysis. Tungstates have excellent thermal and chemical stability; in this work, we have successfully prepared an InWO4/CdS composite catalyst. Since the CB of InWO4 is more negative than that of CdS, InWO4 can act as a cocatalyst to promote the separation and transfer of photogenerated charges, thereby suppressing the recombination of photogenerated electron–hole pairs and significantly improving the performance of the InWO4/CdS composite, and the hydrogen production rate of InWO4/CdS reached 6146.63 μmol g−1 h−1, which was about 4.21 times that of pure CdS. Especially, the InWO4/CdS composite exhibits high photocatalytic stability. In addition, these properties are well characterized by SEM, TEM, XRD, XPS, UV-vis, BET, transient photocurrent and FT-IR analyses etc., and all the results showed good consistency with the hydrogen production experiment. [ABSTRACT FROM AUTHOR]

Improving the efficiency of charge separation is an important aspect in photocatalysis. In this work, the hybrid nanostructure of α-Ni(OH)2/Zn0.5Cd0.5S has been prepared by a simple two-step method for the first time. Here, designed/constructed with α-Ni(OH)2 over Zn–Cd–S, the catalyst efficiently boosts hydrogen evolution in photocatalytic hydrogen production. With a 25% content of α-Ni(OH)2 in the ZSN25 composite under visible light (λ≥ 420 nm) irradiation, remarkable hydrogen production of 22.45 mmol g−1 h−1 has been achieved. In addition, we found that the activities could be improved by means of controlling the formation of α-Ni(OH)2 species. The reason is that the interface between α-Ni(OH)2 and Zn0.5Cd0.5S provides a fast charge transfer channel to reduce the recombination of photogenerated carrier. Also, the formation of this interface is largely related to the content of α-Ni(OH)2. The Tafel slope, EIS and PL spectra support enhanced photocatalytic energy in the α-Ni(OH)2/Zn0.5Cd0.5S charge transfer state and faster hydrogen evolution kinetics. These nanocomposites of Zn0.5Cd0.5S modified by α-Ni(OH)2 are of great significance for renewable hydrogen generation technology. [ABSTRACT FROM AUTHOR]