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Ultrathin Bi2Se3 nanosheets/CdS nanoparticles were prepared, which display excellent photocatalytic H2 activity, ascribed to the synergistic mechanism of the unusual transfer process of high-energy electrons and the photothermal effect.

The oxygen evolution reaction (OER) is a critical electrochemical reaction in water splitting and rechargeable metal–air batteries. It plays a pivotal role in achieving high-efficiency clean-energy production and energy storage in these devices. Transition metal-based bimetallic MOFs (TMB MOFs) with two different metal ions possess specific synergistic effects, which could exhibit OER performance and stability superior to those of the corresponding monometallic MOFs for water oxidation. Benefiting from the diversity of chemical composition and structural type, TMB MOFs can also serve as precursors and templates to obtain alloy-particle-decorated carbon materials with high surface area, or metal compounds such as bimetallic sulfides, phosphides, and hydroxides with atomic-level mixing of heterometallic elements. These materials with high-density active sites exhibit much improved catalytic activity in the water oxidation reaction. This article aims to review the recent progress with TMB MOFs and their derivatives in relation to applications as electrocatalysts in OER, including analysis of the mechanism of the OER process with the assistance of DFT calculations and in situ or operando techniques.

Photocatalytic hydrogen (H2) evolution via water spilling over semiconductors has been considered to be one of the most promising strategies for sustainable energy supply in the future to provide non-pollution and renewable energy. The key to efficient conversion of solar-chemical energy is the design of an efficient structure for high charge separation and transportation. Therefore, cocatalysts are necessary in boosting photocatalytic H2 evolution. To date, semiconductor photocatalysts have been modified by various cocatalysts due to the extended light harvest, enhanced charge carrier separation efficiency and improved stability. This review focuses on recent developments of cocatalysts in photocatalytic H2 evolution, the roles and mechanism of the cocatalysts are discussed in detail. The cocatalysts can be divided into the following categories: metal/alloy cocatalysts, metal phosphides cocatalysts, metal oxide/hydroxide cocatalysts, carbon-based cocatalysts, dual cocatalysts, Z-scheme cocatalysts and MOFs cocatalysts. The future research and forecast for photocatalytic hydrogen generation are also suggested.

The surface plasmonic resonance (SPR) effect of Bi can effectively improve the light absorption abilities and photogenerated charge carrier separation rate. In this study, a novel ternary heterojunction of g-C3N4/Bi2MoO6/Bi (CN/BMO/Bi) hollow microsphere was successfully fabricated through solvothermal and in situ reduction methods. The results revealed that the optimal ternary 0.4CN/BMO/9Bi photocatalyst exhibited the highest photocatalytic efficiency toward rhodamine B (RhB) degradation with nine times that of pure BMO. The DRS and valence band of the X-ray photoelectron spectroscopy spectrum demonstrate that the band structure of 0.4CN/BMO/9Bi is a z-scheme structure. Quenching experiments also provided solid evidence that the •O2− (at −0.33 eV) is the main species during dye degradation, and the conduction band of g-C3N4 is only the reaction site, demonstrating that the transfer of photogenerated charge carriers of g-C3N4/Bi2MoO6/Bi is through an indirect z-scheme structure. Thus, the enhanced photocatalytic performance was mainly ascribed to the synergetic effect of heterojunction structures between g-C3N4 and Bi2MoO6 and the SPR effect of Bi doping, resulting in better optical absorption ability and a lower combination rate of photogenerated charge carriers. The findings in this work provide insight into the synergism of heterostructures and the SPR absorption ability in wastewater treatment.

The development and utilization of low-cost and efficient electrocatalysts for overall water splitting is of great significance for future energy supplies. Herein, a Co-doped NiCu mixed oxide film on Ni foam as a bifunctional electrocatalyst for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is synthesized by a facile solvothermal method using methanol as a reactant followed by annealing in air and it exhibits remarkably enhanced HER and OER activities. The well-constructed surface and porous skeleton structure with a large volume provide a large number of catalytically active sites during the electrochemical reaction. Notably, CuO plays an important role in improving the catalytic activity of the electrode; meanwhile, Co doping is beneficial for increasing the conductivity and activating the Ni sites at lower overpotentials via the charge transfer effect. Accordingly, the optimized CuO-NiO/Ni foam electrode exhibits a comparatively low overpotential of 38 mV and 172 mV at 10 mA cm-2 for the HER and OER in 1.0 M KOH, respectively. Moreover, the electrode shows excellent long-term stability for 1000 cyclic voltammetric cycles in both the HER and OER. A self-assembled overall water splitting device using this electrode as both the anode and cathode achieves a current density of 10 mA cm-2 at a low cell voltage of 1.51 V. This study is promising and provides a simple method for depositing a multimetal mixed oxide on a metal substrate resulting in an efficient bifunctional electrocatalyst, holding great significance for future energy applications.

Designing durable and highly active photocatalysts for hydrogen evolution via water splitting is still very challenging. Novel NiCo-LDH/P-CdS hybrid photocatalysts are fabricated by combining strategies of P-doping and in-situ loading of NiCo-LDH. P-doping creates a mid-gap at the bottom of the conduction band of CdS, which facilitates to prolong the life-time of the photo-induced electrons. Subsequently, the in-situ loading of NiCo-LDH is able to form heterojunctions between NiCo-LDH and P-CdS that not only promote the separation efficiency of carriers, but also effectively reduce the light corrosion phenomenon commonly observed in CdS. The as-prepared 2 mol% NiCo-LDH/40 wt% P-CdS sample shows a high visible-light catalytic H2 production rate of 8.665 mmol·h−1 g−1, which is 45 times higher than pure CdS. The apparent quantum yield is determined to be 14.0% at 420 nm monochromatic light. Based on the calculation of density function theory (DFT), the rational photocatalytic mechanism has been proposed and is well consistent with the experimental results. Our study not only demonstrates a facile, eco-friendly and scalable strategy to synthesize highly efficient photocatalysts, but also provides a new viewpoint of the rational design and synthesis of advanced photocatalysts by harnessing the strong synergistic effects through simultaneously tuning and optimizing the electronic structure and surface.

Novel PdAg bimetallic alloy nanoparticle modified graphitic carbon nitride (g-C3N4) nanosheet was designed and prepared by an in situ chemical reduction procedure. By optimizing the loading content of the PdAg alloy NPs, the PdAg/g-C3N4 composite photocatalyst showed a champion photocatalytic hydrogen generation rate of 3.43 mmol h−1 g−1, and the apparent quantum yield (AQY) was determined to be 8.43% at 420 nm. Moreover, the photoluminescence and photoelectrochemical experimental results suggest that a higher separation efficiency of photo-induced charge carriers (e- and h+) was obtained after loading PdAg alloy NPs on g-C3N4. The experimental outcomes indicate that there is a synergistic effect formed between PdAg and g-C3N4, which could significantly promote the charge transfer photo-induced charge carriers in the hybrid sample. A reasonable catalytic mechanism for the enhanced photocatalytic performance of the composite photocatalyst was proposed and verified by TRPL measurement, which could be taken as a guidance for the development of novel high performance catalytic system.

A novel plasmonic photocatalysts of Ag-AgI/Bi3O4Cl was successfully synthesized via a simple and mild wet-chemical process. The 30 wt% Ag-AgI/Bi3O4Cl photocatalyst showed the highest photocatalytic activity for degradation of methyl orange (MO) under visible light (5 W LED lamp), which represents a 3.2 and 7.4 times enhancement in the photocatalytic degradation efficiency as compared to pure Bi3O4Cl and Ag-AgI, respectively. The surface plasmon resonance (SPR) effect of Ag nanoparticles (NPs) was detected by the UV–vis diffusion reflectance spectroscopy (DRS) and surface photovoltage (SPV) measurement, finding that the SPR effect of Ag extends the absorption and photo-response range in the Ag-AgI/Bi3O4Cl composite photocatalyst. Based on the analysis of electron spin resonance (ESR), linear sweeping voltammetry (LSV) characterization results, three electron transfer processes were proposed: AgICB → Bi3O4ClCB, AgICB → Ag and methyl orange → Ag. Such electron transfer paths can not only effectively improve the separation efficiency of photo-generated carriers, but also ensure the stability of the catalyst. This study can provide a novel insight for modification of other desirable semiconductor materials to achieve high photocatalytic activity.

Efficient composite semiconductor photocatalysts are highly desirable for the visible-light-driven degradation of organic pollutants. In this study, Bi24O31Cl10 photocatalyst was prepared via a hydrothermal method and modified with Pt nanoparticles (NPs) through a facile deposition procedure. The composite photocatalyst was characterized by X-ray diffraction, transmission electronic microscopy, X-ray photoelectron spectroscopy, UV-vis diffusion reflectance spectroscopy, photoluminescence spectroscopy, and electron spin resonance. The 1.0 wt% Pt/Bi24O31Cl10 photocatalyst showed the highest activity for the degradation of methyl orange under visible light (source: 300 W Xe lamp coupled with a UV-cutoff filter), and the photocatalytic degradation efficiency improved about 2.2 times compared to that of pure Bi24O31Cl10. The composite photocatalyst could maintain most of its activity after four runs of the photocatalytic experimental cycle. This study could provide a novel insight for the modification of other desirable semiconductor materials to achieve high photocatalytic activities.

Recently, MoS2 incorporates with Co2+ (or Ni2+) was found to increase the photocatalytic performance of semiconducting materials more effectively. In this study, novel CoxMo1-xS was effectively deposited on the surface of Zn0.5Cd0.5S semiconductors as an efficient promotor using in-situ hydrothermal process. The as-prepared CoxMo1-xS-Zn0.5Cd0.5S composites are examined by the following techniques: XRD, TEM, DRS, XPS, PL and TRPL. The photocatalytic hydrogen evolution performance under visible illumination over Zn0.5Cd0.5S is remarkably increased by adding cheap CoxMo1-xS as promotor. The CoxMo1-xS-Zn0.5Cd0.5S hybrid specimen with 10% molar amount illustrates the best catalytic performance with a homologous hydrogen generation rate of 188.65 μmol h−1, which is estimated to be 14.5 folds than that of unmodified Zn0.5Cd0.5S specimen in the presence of visible light. The apparent quantum yield of Co0.3Mo0.7 Zn0.5Cd0.5S sample is determined to be 16.72% at monochromatic light of 420 nm. The experimental outcomes indicate that the synergistic action between CoxMo1-xS and Zn0.5Cd0.5S obviously promotes transfer of photo-induced charge carriers in the hybrid sample. A reasonable catalytic mechanism for the increased photocatalytic performance of CoxMo1-xS promotor was presented and authenticated by TRPL measure, which would present a new notion for the design of ideal semiconductors with plummy photocatalytic capability.

PtPd bimetallic alloy nanoparticle (NP)-modified graphitic carbon nitride (g-C3N4) nanosheet photocatalysts were synthesized via chemical deposition precipitation. Characterization of the photocatalytic H2 evolution of the g-C3N4 nanosheets shows that it was significantly enhanced when PtPd alloy NPs were introduced as a co-catalyst. The 0.2 wt% PtPd/g-C3N4 composite photocatalyst gave a maximum H2 production rate of 1600.8 μmol g–1 h–1. Furthermore, when K2HPO4 was added to the reaction system, the H2 production rate increased to 2885.0 μmol g–1 h–1. The PtPd/g-C3N4 photocatalyst showed satisfactory photocatalytic stability and was able to maintain most of its photocatalytic activity after four experimental photocatalytic cycles. In addition, a possible mechanism for the enhanced photocatalytic activity was proposed and verified by various photoelectric techniques. These results demonstrate that the synergistic effect between PtPd and g-C3N4 helps to greatly improve the photocatalytic activity of the composite photocatalyst.

Co-substituted LaFeO

Fe2TiO5 was synthesized via the solvothermal method and adopted as co-catalyst to improve the photoelectrochemical (PEC) water splitting performance of BiVO4 photoanode. After surface modification by Fe2TiO5, the BiVO4/Fe2TiO5 photoanode shows a 300 mV cathodic shift in onset potential and 3 times enhancement in photocurrent, which delivers a photocurrent density of 3.2 mA/cm2 at 1.23 V vs reverse hydrogen electrode. Systematic optical, electrochemical, and intensity-modulated photocurrent spectroscopy characterizations were performed to explore the role of Fe2TiO5 and reveal that the enhanced PEC performance is mainly caused by the surface passivation effect of Fe2TiO5.

Noble-metal-free photocatalyst Co2P-CdS was synthesized via a facile in situ hydrothermal method for the first time to boost the performance of photocatalytic H2 production. This synthesis process allows the Co2P nanoparticles to disperse evenly on the surface of CdS sub-microspheres and to form unique intimate contact interfaces. The physical and photophysical properties of as-prepared Co2P-CdS composite samples were characterized by X-ray diffractometry, transmission electron microscopy, UV–vis diffusion reflectance spectroscopy, X-ray photoelectron spectroscopy, photoluminescence, and surface photovoltage (SPV) spectroscopy. The results indicate that the photocatalytic H2 evolution activity of CdS sub-microspheres under visible-light irradiation is significantly enhanced by introducing inexpensive Co2P as co-catalyst. The Co2P-CdS sample with a loading of 1.2 mol% Co2P gives the highest H2 production rate of 0.303 mmol·h–1, which was about 3 times higher than that achieved with 0.5 wt% Pt-loaded CdS sa...

Semiconductor-based photocatalytic hydrogen evolution from water with earth-abundant and low cost co-catalysts has attracted much attention. Herein, novel Cu2(OH)2CO3 decorated 2D TiO2 nanosheets for photocatalytic water splitting were synthesized by a facile in situ synthetic method. The chemical and photophysical properties of Cu2(OH)2CO3/TiO2 nanosheets were investigated by X-ray diffractometry (XRD), transmission electron microscopy (TEM), UV-vis diffusion reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV) analysis. At an optimal Cu2(OH)2CO3 loading content of 1.5 mol%, the hybrid photocatalyst delivers a high photocatalytic H2 production rate of 1555.07 μmol g-1 h-1. Such enhanced photocatalytic activity is attributed to tight interfaces formed between Cu2(OH)2CO3 nanoparticles and TiO2 nanosheets, which play a vital role in the separation of photo-excited carriers, and the formation of active Cu1+ and Cu0 species can also benefit the charge separation process by reducing the over-potential of water reduction. Based on the above results, a possible mechanism is proposed and further verified using photoluminescence (PL) spectra. This work may provide more insight into the synthesis of novel Cu2(OH)2CO3/TiO2 nanosheets with high photocatalytic H2 evolution activity for solar-to-chemical conversion and utilization.

Rational design of low-cost and efficient electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is imperative for renewable energy conversion. Herein, for the first time, a facile strategy is developed to synthesize M (M = Fe, Cu, Zn, Mo) doped bimetallic sulfide heterostructure Ni3S2/Co3S4 electrocatalysts. The as-prepared bifunctional Cu-Ni3S2/Co3S4 electrode exhibits excellent electrocatalytic activity for HER and OER in 1 M KOH electrolyte, and it requires only an overpotential of 79 mV (150 mV) to deliver 10 mA cm−2 (20 mA cm-2) current density for HER process. Moreover, it shows a considerable low cell voltage of 1.49 V at the current density of 10 mA cm-2 in a two-electrode configuration which is far surpassing most of the reported bifunctional metal sulfides. Meanwhile, besides increasing the specific surface area of the electrocatalyst by optimizing the microstructure, the introduction of Cu cation could also stimulate the formation of high-valent Ni/Co sites, which can be verified by XPS technique. Density function theory calculations demonstrate that the Cu-doping boosts the formation of high valent Co sites and enhances the charge transfer performance of Ni and Co species, thus promotes intrinsic catalytic activity through modulating the d-band center of Co and reducing the adsorption energy of H and O-containing intermediates (H*, OH*, OOH*) on the surface of the catalyst. This work suggests the importance of exploitation of transition metal ion-doping for promoting the electrocatalytic activity of bimetallic sulfides.

The generation of hydrogen (H 2 ) through photocatalytic water splitting with the employment of various co-catalysts has attracted much attention. In this study, the CoP was successfully decorated on Zn 0.5 Cd 0.5 S as a highly efficient co-catalyst via a two-step in-situ chemical deposition method. The chemical as well as photophysical properties of the as-obtained CoP/Zn 0.5 Cd 0.5 S samples were characterized by X-ray diffractometry (XRD), Transmission electron microscope (TEM), UV–vis diffusion reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS) and surface photovoltage spectroscopy (SPV). The CoP/Zn 0.5 Cd 0.5 S composite sample with 5% molar content showed the highest photocatalytic H 2 evolution activity with a corresponding H 2 evolution rate of 734 umol h −1 , which was about 20 times higher than that of pure Zn 0.5 Cd 0.5 S sample and 2 times higher than Pt loaded Zn 0.5 Cd 0.5 S sample under visible light irradiation. The photocatalytic activity of the CoP/Zn 0.5 Cd 0.5 S composite sample was stable even after 4 cycling photocatalytic experiments. A possible mechanism on the photocatalytic enhancement of CoP was systematically investigated, which can provide a novel concept for the synthesis of other desirable photocatalytic materials with high photocatalytic performance.

Efficient separation of photo-generated electrons and holes is a crucial aspect for photocatalytic hydrogen evolution. Herein, novel plate-like Co(OH) 2 decorated TiO 2 nanosheets for photocatalytic water splitting were synthesized by a facile in-situ synthetic method. The results of X-ray diffractometry (XRD), transmission electron microscope (TEM), UV–Vis diffusion reflectance spectroscopy (DRS) and X-ray photoelectron spectroscopy (XPS) indicate the successfully incorporation of Co(OH) 2 co-catalysts onto the surface of TiO 2 nanosheet photocatalysts. Further photocatalytic hydrogen evolution experiments illustrate that all Co(OH) 2 decorated TiO 2 samples show higher rate of hydrogen production performance than pure TiO 2 sample and the composite sample with Co(OH) 2 loading amount of 0.5mol% presents the highest photocatalytic hydrogen production activity of 746.93 μmol g −1 ·h −1 . It is indicated that plate-like Co(OH) 2 particle act as an electron collector, which leads to photo-generated electrons transfer from TiO 2 to Co(OH) 2 , and therefore enhance the photocatalytic activity. Based on above results, a possible mechanism is proposed and further verified by surface photovoltage spectra (SPV).

Novel AuPd bimetallic alloy nanoparticles (NPs) decorated two-dimensional (2D) BiVO4 nanosheet photocatalysts were successfully synthesized via mild wet-chemical process and facile deposition procedure. The composite photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electronic microscope (TEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflection spectroscopy (DRS), electron spin resonance (ESR) and surface photovoltage spectroscopy (SPV). The 1.0 wt% AuPd/BiVO4 nanosheets showed highest photocatalytic activity for the degradation of Rhodamine B (RhB) under visible light (300 W Xe lamp coupled with a UV-cutoff filter (λ ≥ 400 nm)), and the photocatalytic efficiency was improved for about 21.9 and 6.1 times as compared to that of pure BiVO4 and 1.0 wt% Au/BiVO4, respectively. The novel AuPd/BiVO4 composites may make a way to synthesize 2D semiconductor composites with potential applications for solar energy conversion and environmental purifications.

Water splitting to H2 by photocatalysis remains an effective strategy to alleviate the energy crisis. Unfortunately, single-component photocatalyst still suffers from sluggish reaction kinetics. In this work, a noble-metal free photocatalytic system of nitrogen-doped carbon@Co embedded in carbon nanotubes (NC@Co-NCT)/cadmium sulfide (CdS) is fabricated by coupling CdS nanorods with the metal-organic framework-derived Co encapsulated nitrogen-doped carbon (NC) material. The optimal photocatalytic activity of NC@Co-NCT/CdS is determined to be 3.8 mmol h-1 g-1 , which is ≈5.8 times of CdS. By combining the experimental evidences and density functional theory calculations, a novel photoelectron transfer channel in the heterojunction interfaces is revealed, expediting the migration and separation of photo-induced charge carriers of CdS. Moreover, the presence of Co nanoclusters can act as the active sites, boosting the H2 evolution reaction. This study can present a new avenue to design advanced photocatalysts with high-efficiency electrons and holes separation.

Cobalt oxide decorated octahedral ceria hollow structures (CoOx/CeO2) with various contents of CoOx nanoparticles were prepared via a simple chemical impregnation method. The obtained samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), UV-Vis diffuse-reflectance spectroscopy (DRS), surface photovoltage spectroscopy (SPV) and transient photovoltage spectroscopy (TPV). The photocatalytic oxygen evolution via water oxidation was investigated for the as-prepared CoOx/CeO2 nanocage composites. The photocatalytic results indicate that the CoOx/CeO2 nanocage composite with 1 mol% CoOx shows the highest photocatalytic activity. The excellent photocatalytic activity can be attributed to the improved visible-light absorption of CoOx/CeO2 composites and the efficient separation of excited electron-hole pairs between CoOx and CeO2, which can effectively enhance the lifetime of charge carriers in the CoOx-modified samples and then improve the oxygen evolution activity. Cobalt oxide is expected to be an excellent water oxidation co-catalyst for semiconductor photocatalysts.

Novel layer-like Ni(OH)2 co-catalyst-decorated ZnIn2S4 microsphere photocatalysts were synthesized for the first time via a facile in situ deposition method to boost the photocatalytic H2-production performance. The physical and optical properties of the as-prepared Ni(OH)2-ZnIn2S4 composite samples were characterized via X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-vis diffusion reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), and surface photovoltage spectroscopy (SPV). The results indicate that the photocatalytic H2 evolution activity of the ZnIn2S4 microspheres under visible light irradiation significantly enhances by introducing inexpensive Ni(OH)2 as a co-catalyst. The 5 mol% Ni(OH)2-ZnIn2S4 sample shows the highest H2-production rate of 8.35 mmol g-1 h-1, which is 18 times higher than that of pure ZnIn2S4. Moreover, photocatalytic activity of the Ni(OH)2-ZnIn2S4 sample remains stable even after 4 cycling photocatalytic experiments. In addition, a possible mechanism on the enhanced photocatalytic activity was proposed and verified by surface photovoltage spectroscopy.

High-voltage tandem and triple-junction polymer solar cells (PSCs) were demonstrated by using one of the highest- V OC, high-efficiency polymer donors in bulk heterojunction (BHJs) with fullerenes, namely poly(benzo[1,2- b :4,5- b'] dithiophene?thieno[3,4- c ]pyrrole-4,6-dione) (PBDTTPD). While the efficiency of PBDTTPD-based single-junction PSCs is limited by incomplete optical absorption, we show that homo-tandem PSCs with MoO3 /ultrathin Al/ZnO intermediate recombination layers can achieve higher PCE values. The PV performance of single-junction PBDTTPD:PC 71 BM PSCs were investigated with the standard device structure ITO/PEDOT:PSS/PBDTTPD:PC71 BM/Ca/Al. Next, the potential for further PCE increments were examined via a triple-junction PSC device approach, using the same ZnO/Al/MoO3 interconnection layer between the three subcells. PBDTTPD homo-tandem PSCs yield high operating voltages of 1.54 V at their maximum power point, providing sufficient potential for the dissociation of water and the evolution of hydrogen and oxygen in a standard electrochemical cell.

Designing and fabricating efficient photocatalysts for photocatalytic hydrogen evolution has drawn abundant attention in recent years. In this work, Co9S8/Zn0.5Cd0.5S hybrids were successfully synthesized. The Zn0.5Cd0.5S nanospheres were in-situ grown on the surface of Co9S8 co-catalysts with polyhedral hollow structure so that self-aggregation is suppressed. Moreover, the photocatalytic activity of Zn0.5Cd0.5S was exaggeratedly improved after introducing Co9S8 species and 10 wt% Co9S8/Zn0.5Cd0.5S sample exhibited an optimal H2 evolution rate of 10.9 mmol h−1 g−1. The improved catalytic performance may be ascribed to the efficient charge separation, resulting from the formation of built-in electric field between Zn0.5Cd0.5S and Co9S8. The mechanism has been investigated by the techniques of surface photovoltage spectroscopy (SPV), electron spin resonance (ESR) and the surface work function. This work may deliver some new insights on designing efficient photocatalysts with hierarchical architectures.

Effective and suitable utilization of solar energy was achieved using a full-spectrum-response photocatalyst AgBr/CsxWO3, applied in the photocatalytic and photochromic field. Benefitting from near-infrared (NIR) absorption ability of CsxWO3, AgBr/CsxWO3 exhibits enhanced visible-near-infrared (Vis-NIR) driven photocatalytic activity. Based on X-ray photoelectron spectroscopy (XPS), photoluminescence spectra (PL), and the photoelectrochemical analysis, AgBr and CsxWO3 formed a Z-scheme system at the interface to efficiently separate and transfer photo-induced electrons at a fast rate. The quenching experiment and the electron spin resonance (ESR) tests indicated that the photocatalytic reaction is activated by the production of superoxide radicals. Furthermore, the photochromic analysis to different light exhibits the AgBr/CsxWO3 heterostructure is stable under visible light with negligible photodeposition of AgBr, and has excellent double photochromic activity with visible-shielding effect of AgBr to Ag0 and infrared-blocking effect of CsxWO3 under ultraviolet light. This research provides new insights into the manufacture of energy-efficient and environmentally friendly materials that provide excellent performance in both thermal insulation and decontamination.

Bi3O4Cl and Bi3O4Cl-OV nanosheets with oxygen vacancies were successfully synthesized and detected using UV–visible diffuse reflectance spectra (DRS), X-ray photoelectron spectrometry (XPS) and Kelvin probes to explore the impact of the oxygen vacancies on the energy band structure. It is suggested that the defect states will shorten the forbidden band, close the distance between the Fermi level and the conduction band, and reduce the work function. All of these effects were confirmed by density functional theory (DFT) calculations and provide a reasonable explanation for the improvement of the photocatalytic performance of Bi3O4Cl-OV nanosheets. At the same time, Bi3O4Cl-OV was further modified by loading with the metal halide AgBr and the photocatalytic degradation efficiency was significantly improved approximately 11.2-fold compared to that of pure Bi3O4Cl nanosheets. This work not only offers efficient guidance for ascertaining the energy band structure of a semiconducture but also provides tentative suggestions for improving photocatalytic performance via defect engineering.

We investigate hybrid tandem solar cells that rely on the combination of solution-processed depleted-heterojunction colloidal quantum dot (CQD) and bulk heterojunction polymer:fullerene subcells. The hybrid tandem solar cell is monolithically integrated and electrically connected in series with a suitable p–n recombination layer that includes metal oxides and a conjugated polyelectrolyte. We discuss the monolithic integration of the subcells, taking into account solvent interactions with underlayers and associated constraints on the tandem architecture, and show that an adequate device configuration consists of a low bandgap CQD bottom cell and a high bandgap polymer:fullerene top cell. Once we optimize the recombination layer and individual subcells, the hybrid tandem device reaches a VOC of 1.3 V, approaching the sum of the individual subcell voltages. An impressive fill factor of 70% is achieved, further confirming that the subcells are efficiently connected via an appropriate recombination layer.

Semiconductor-based photocatalytic hydrogen evolution from water with earth-abundant and low cost co-catalysts has attracted much attention. Herein, novel Cu