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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]

The activation capacity of molecular oxygen is an important indicator to evaluate the photocatalytic efficiency of photocatalysts. In this paper, WS2 nanosheet was deposited on hyper-crosslinked CTF-1-G (obtained by molecular expansion from covalent triazine framework CTF-1) to form a C-GW heterojunction, which promoted the photodegradation of pollutants and the activation of molecular oxygen. This novel C-GW heterojunction exhibited excellent degradation property for organic pollutants (tetracycline (TC), rhodamine B (RhB)) and activating molecular oxygen under visible light irradiation. Among them, C-GW15 could degrade 98% of 20 ppm TC in 60 min and 99% of 30 ppm RhB in 30 min, and it had the highest hydrogen generation rate and hydrogen production amount in 4 hours, which were 8.74 mmol h−1 g−1 and 34.94 mmol g−1, respectively. Meanwhile, C-GW15 had the strongest 3,3′,5,5′-tetramethylbenzidine oxidation capacity and could generate 1.83 μmol of ˙O2− in 60 min and the production of H2O2 was 20.8 μmol L−1 in 40 min. The results of this study clearly indicated that the combination of WS2 and CTF-1-G can enhance the visible light absorption capacity and photogenerated carrier separation efficiency, thus promoting the photocatalytic performance. Finally, a Z-type photocatalytic mechanism was proposed based on radical capture, molecular oxygen activation experiments and electron spin resonance analysis. These findings will extend the fundamental understanding of the Z-type photocatalytic mechanism and provide new opportunities for the rational design of CTF heterojunctions for the treatment of environmental pollution and clean energy conversion. [ABSTRACT FROM AUTHOR]

In this paper, NiCo2S4 was coated on the surface of WS2 of a 1T/2H mixed phase by a two-step hydrothermal method to form an in situ core–shell structure. The unique S-scheme heterojunction of the NiCo2S4@WS2 core–shell composite photocatalyst improved the easy recombination of carriers caused by the narrow band gap of NiCo2S4 and WS2, and improved the photocatalytic hydrogen production performance. The loading ratio of NiCo2S4@WS2, the addition of Eosin Y, and the pH value of TEOA were optimized. Under the optimal conditions, the hydrogen production rate reached 5.814 mmol g−1 h−1, which is about 8.55 times and 3.35 times the hydrogen evolution rates of NiCo2S4 and WS2, respectively. The composite catalyst exhibits excellent charge separation efficiency in photoelectrochemistry, PL and BET tests, carrier transport rate and large specific surface area that can provide more active sites, which are the main factors for the improvement of the hydrogen evolution performance. This paper demonstrates new design strategies to drive efficient photocatalytic hydrogen production by building in situ core–shell structures and optimizing the carrier transport paths, which will yield new insights. [ABSTRACT FROM AUTHOR]

Element doping and construction of heterojunction composites are the most common ways to enhance g-C3N4, which are very attractive in achieving high photocatalytic activity. In this study, 2D nanosheet structured BCN was obtained by doping B atoms with graphite carbon nitride. Subsequently, Ti MOFs were loaded on BCN to obtain a Z-scheme heterojunction composite TBCN through calcination. Under simulated sunlight, the photocatalytic hydrogen production rate of the TBCN heterostructure was 1242 μmol h−1 g−1, which was 2.2 times higher than that of BCN and 9.34 times higher than that of bulk graphite carbon nitride (GCN). Experimental results showed that the construction of a Z-scheme heterojunction composite (TBCN) could effectively adjust the material band gap position, expand the light absorption range, enhance electron transfer and inhibit electron–hole recombination, which are crucial for efficient photocatalysis. This study not only provides a strategy for constructing heterojunction composites in the field of g-C3N4 photocatalytic hydrogen evolution, but also deeply analyzes the electron migration direction and the reasons for enhancing carrier separation in the Z-type heterojunction scheme, thus providing potential guidance for future research. [ABSTRACT FROM AUTHOR]

In this work, CoV-LDH/ZnIn2S4 (CoV-LDH/ZIS) nanocomposites were synthesized through a self-assembly process in order to investigate the influence of CoV-LDH addition on the rate of hydrogen production. XRD and TEM measurements confirmed the effective preparation of CoV-LDH/ZIS nanocomposites. Among all the nanocomposite photocatalysts, 2.0%-CoV-LDH/ZIS showed the best photocatalytic performance with a hydrogen production rate of 1397.3 μmol g−1 h−1, approximately 2.2 times that of pure ZnIn2S4 (ZIS). The X-ray photoelectron spectroscopy (XPS) measurement indicated that there is a strong interfacial interaction between ZIS and CoV-LDH, indicating that more than simple mechanical mixing had occurred. The steady-state fluorescence spectroscopy (PL) and time-resolved photoluminescence (TRPL) spectroscopy results showed that the electron and hole recombination in CoV-LDH/ZIS is significantly reduced and that efficient interface charge transfer and separation are achieved. This work sheds light on the interfacial electron transfer between two semiconductor materials, which promotes the separation of photogenerated carriers and thus enhances photocatalytic hydrogen production activity. [ABSTRACT FROM AUTHOR]

Finding efficient photocatalysts is the key to achieving sustainable hydrogen production. In this work, a rational design of Cd2+-doped Zn3In2S6 (ZIS) and a heterojunction structure with g-C3N4 (GCN) was carried out to form a GCN/Cd/ZIS composite. The synergistic effect of Cd2+ doping and heterojunction construction in the photocatalytic hydrogen production process was probed. The results showed that doping Cd2+ modified the bandgap structure of ZIS and improved the photocatalytic activity. The heterojunction construction between Cd/ZIS and GCN also effectively promoted the separation and migration of photogenerated carriers, which significantly improved the hydrogen production performance of the GCN/Cd/ZIS composite. The hydrogen production rate of 15% Cd/ZIS and 5% GCN/Cd/ZIS was 2.45 mmol g−1 h−1, 3.34 mmol g−1 h−1, which was 4.3 and 5.9 times higher than that of ZIS (0.57 mmol g−1 h−1), respectively. This study provides strong evidence that doping and heterojunction construction can synergistically improve photocatalytic activity. [ABSTRACT FROM AUTHOR]

Developing highly active and stable non-noble-metal cocatalyst-decorated semiconductors is desirable for the practical application of photocatalysis, which remains an open question. Herein, we report transition-metal nitride (Ni3FeN) loaded cadmium sulfide (CdS) nanorods prepared through a simple hydrothermal method and surface treatment with NH3. The as-prepared photocatalyst Ni3FeN (3 wt%)/CdS showed a hydrogen evolution rate of 4.6 mmol g−1 h−1, which was 23.8 and 6.8 fold higher than those of CdS and Pt (1 wt%)/CdS, respectively. The Ni3FeN/CdS sample exhibited remarkable stability for seven consecutive cycles of photocatalytic tests lasting 21 hours. It was confirmed through Kelvin probe measurements that a Schottky junction between Ni3FeN and CdS gave rise to the inhibited recombination of photogenerated carriers, which benefited the photocatalytic HER performance. [ABSTRACT FROM AUTHOR]

Designing cost-effective catalysts with the structural features and necessary functionality to drive ammonia borane hydrolysis for hydrogen generation remains a challenge. In this work, a close heterojunction of Fe3O4--Ni2P uniformly embedded in amorphous carbon material (Fe3O4--Ni2P@C) has been prepared via surface phosphorization. The catalyst displays superior activity with a turnover frequency (TOF) of 92.8 min-1 and favorable durability for ammonia borane hydrolysis, making it superior to most reported nickel-based catalysts. The theoretical studies show a high electron density on the Fe3O4--Ni2P heterojunction. Combining the theoretical and experimental results, the dual active sites at the heterojunction are beneficial to the adsorption of reactant molecules and the reduction of the reaction barrier. This strategy of constructing an appropriate heterojunction to maximize synergistic effects may open a new avenue for non-precious metal catalysis. [ABSTRACT FROM AUTHOR]

The combustion of fossil fuels has brought about serious energy shortages and environmental pollution issues. This study involves the development of green and environment-friendly nonprecious metal photocatalysts with high hydrogen production performance. Hence, a series of CoxSy/Mn0.5Cd0.5S composites was prepared through a simple hydrothermal process. When the loading amount of amorphous CoxSy was 3 wt%, the CoxSy/Mn0.5Cd0.5S composite catalyst showed the best photocatalytic activity under visible light irradiation (λ > 420 nm), giving a hydrogen production rate of 5677.6 µmol g−1 h−1, which is 121.6 times that of pure CdS and 4.8 times that of Mn0.5Cd0.5S. Moreover, the 3 wt%-CoxSy/Mn0.5Cd0.5S catalyst exhibited good photostability. The experimental results demonstrate that the construction of the CoxSy/Mn0.5Cd0.5S heterojunction effectively facilitates the separation of charge carriers, resulting in an enhanced photocatalytic activity. [ABSTRACT FROM AUTHOR]

Photocatalytic splitting of water for hydrogen generation is a green and renewable solution for converting solar energy to chemical energy; thus, the development of high-performance and stable photocatalytic materials has emerged as a research hotspot recently. Herein, a heterostructure composite photocatalyst of octahedral CoO uniformly modified with novel nitrogen-doped MXene quantum dots (N-MQDs) is successfully designed using a typical solvothermal approach. The optimum photocatalytic hydrogen evolution efficiency of the prepared N-MQDs@CoO heterojunction composite is 82.54 μmol g−1 h−1 with visible light, which is 16.57 times higher compared to the pure CoO. A series of photoelectrochemical tests were further performed to elucidate the photocatalytic hydrogen evolution mechanism. The remarkable improvement of activity is primarily attributed to the synergistic interaction between the closely spaced interface contacts and energy level matching among high conductivity Ti3C2 MXene quantum dots with CoO octahedra, dramatically hastening the segregation and transfer of photo-generated carriers. This study provides new ideas for the construction of MXene quantum dot-based co-photocatalysts with highly efficient photocatalytic performance and stability toward solar energy conversion applications. [ABSTRACT FROM AUTHOR]

Among carbon allotropes, 2D graphdiyne (GDY) possesses the merits of good ductility, strong conductivity and an adjustable energy band structure. In this study, a GDY/ZnCo-ZIF S-scheme heterojunction photocatalyst has been successfully prepared by a low-temperature mixing method. Using eosin as a photosensitizer and triethanolamine as a solvent, the hydrogen production of the GDY/ZnCo-ZIF-0.9 composite reaches 171.79 μmol, which is 6.67 and 13.5 times that of the GDY and ZnCo-ZIF materials, respectively. The apparent quantum efficiency of the GDY/ZnCo-ZIF-0.9 composite at 470 nm is 2.8%. The improved photocatalytic efficiency may be attributed to the creation of an S-scheme heterojunction structure that enables efficient separation of space charges. In addition, the EY-sensitized GDY/ZnCo-ZIF catalyst endows the GDY with a special structure to provide an abundance of electrons for the ZnCo-ZIF material, thus facilitating the photocatalytic reduction reaction to produce hydrogen. A novel perspective is presented in this study regarding the construction of an S-scheme heterojunction based on graphdiyne for efficient photocatalytic hydrogen generation. [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]

Hydrogen fuel plays a ubiquitous role in empowering the sustainable green energy economy. As an eco-friendly production method for hydrogen, photo-assisted water splitting is accepted to be the most reliable. However, the fabrication of stable and efficient photocatalysts is challenging. To overcome this difficulty, here we present a novel and inexpensive oxidant-promoted ultrasonic-assisted liquid phase layer exfoliation technique to fabricate a CdS/H-MoS2 nano hybrid. The newly fabricated CdS/H-MoS2 shows a hydrogen evolution rate of 162.4 mmol g−1h−1, which is 16 times higher compared to that of CdS/Pt and 67 times higher compared to that of bare CdS. Theoretical results clearly demonstrate a built-in electrostatic potential in the heterostructure junction, and that a shift in water reduction potential plays a key role in the enhancement of hydrogen production rate. We believe that the proposed experimental strategies and theoretical studies will open up a new avenue to develop new photocatalysts with high hydrogen evolution efficiency. [ABSTRACT FROM AUTHOR]

The rapid recombination of photogenerated carriers and strong photocorrosion have considerably limited the practical application of CdS in the field of photocatalysis. Loading a cocatalyst has been widely utilized to largely enhance photocatalytic activity. In the present work, a WC@C cocatalyst was prepared by a novel molten salt method and explored as an efficient noble-metal-free cocatalyst to significantly enhance the photocatalytic hydrogen evolution rate of CdS nanorods. The WC@C/CdS composite photocatalyst with a 7 wt% content of WC@C showed the highest photocatalytic hydrogen evolution rate of 8.84 mmol g−1 h−1, which was about 21 and 31 times higher than those of CdS and 7 wt% Pt/CdS under visible light irradiation. A high apparent quantum efficiency (AQY) of 55.28% could be achieved under 420 nm monochromatic light. Furthermore, the photocatalytic activity of the 7 wt% WC@C/CdS photocatalyst exhibited good stability for 12 consecutive cycles of the photocatalytic experiment with a total reaction time of 42 h. The excellent photocatalytic performance of the photocatalyst was attributed to the formation of a Schottky junction and the loading cocatalyst, which not only accelerated the separation of the photogenerated carrier but also provided a reactive site for hydrogen evolution. This work revealed that WC@C could act as an excellent cocatalyst for enhancing the photocatalytic activity of CdS nanorods. [ABSTRACT FROM AUTHOR]

Photocatalysis is one of the most promising methods to solve the problems of solar energy conversion and sustainable fuel production. Among them, the semiconductor electronic transition to produce hydrogen is the most critical research topic in the field of photocatalysis. ZnS and Ag2Mo2O7 monomers were prepared by the hydrothermal method. The S-scheme heterojunction was formed by electrostatic adsorption of the two materials. The S-scheme heterojunction can improve the separation rate of photogenerated carriers through the built-in electric field so that the hydrogen production rate of the system can reach a maximum of 871.9 μmol g−1 h−1. The system showed a good photoelectric response according to UV-Vis DRS and electrochemistry studies and excellent hydrogen evolution performance. In this study a DFT simulation of the heterojunction interface formed by the system was also carried out, and the relative size of the surface work function indicated the transfer direction and path of electrons. [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]

Due to the serious energy and environmental issues, hydrogen generation via water splitting has been regarded as a green and promising alternative strategy to the use of fossil fuels. Developing highly efficient and non-noble metal based dual-functional electrocatalysts for overall water splitting to generate hydrogen and oxygen has become more critical. In order to fulfill the requirements of efficient hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), herein, we report novel hierarchical Co(OH)F@CoFe-LDH heterostructured nanorod arrays fabricated via a facile two-step approach. The resultant Co(OH)F@CoFe-LDH displays exceptional electrocatalytic OER and HER activity with a small overpotential of 240 mV and 130 mV at 10 mA cm−2, respectively. Further, the electrocatalyst revealed excellent long-term stability during a recyclability test for 37 h. The superior performance of Co(OH)F@CoFe-LDH can be attributed to the synergistic effect at the interface of the Co(OH)F nanorods and the covered CoFe-LDH nanosheets. Meanwhile, Co(OH)F@CoFe-LDH as a water electrolyzer to produce a current density of 10 mA cm−2 requires a small voltage of 1.58 V. This work paves the way for the design and construction of low cost and highly efficient 3D hierarchical electrodes for practical applications in electrocatalysis. [ABSTRACT FROM AUTHOR]

Photocatalytic hydrogen production using renewable energy sources is promising as a new method of energy supply. Research on photocatalytic materials has received increasing attention. In this work, efficient photocatalytic hydrogen production was achieved by using ZnIn2S4@CoS2 heterostructures as photocatalysts. The heterostructures were prepared by a simple hydrothermal method using ZIF-67 derived Co3O4 as a precursor. ZIF-67 derived Co3O4 inherits the dodecahedral structure of ZIF-67. ZnIn2S4 nanosheets uniformly grew on the surface of CoS2, which is prepared from Co3O4. The heterostructures achieved a high hydrogen production rate, about 3.2 times higher than that of pristine ZnIn2S4 under simulated sunlight. The enhanced photocatalytic activity can be attributed to the faster electron transfer and more efficient electron–hole pair separation, which are formed in the heterostructure at the interface between CoS2 and ZnIn2S4. This study provides a strategy for noble metal-free photocatalytic hydrogen production using heterostructures. [ABSTRACT FROM AUTHOR]

Hydrogen production with higher efficiency and lower cost is of great significance for the sustainable development of energy. Zinc cadmium sulfide (CZS) is gaining more attention owing to its excellent photocatalytic properties. However, its development is greatly limited due to photogenerated charge recombination. In this work, an innovative design with a unique 3D morphology was introduced by integrating 3DTiO2 into CZS to form a novel 3DTiO2/CZS heterojunction photocatalyst. As a result, the optimized composite achieved a very high hydrogen production rate of 75.38 mmol h−1 g−1 under visible light, which is 2.4 times higher than that of the original CZS. It can also be greatly demonstrated through photoelectrochemical tests that this unique 3D morphology contributes to the effective separation of electrons and holes, thus dramatically improving the photocatalytic activity of 3DTiO2/CZS composites. The 3DTiO2/CZS composite has a rational energy band structure, which makes it more favorable for the hydrogen precipitation reaction. It is believed that such a modification strategy based on 3DTiO2 can be applied to other similar photocatalysts as well for boosting hydrogen evolution. [ABSTRACT FROM AUTHOR]

The rapid separation and transport of photogenerated carriers are pivotal toward enhancing the photocatalytic performance. Herein, CdS nanoparticles are grown in situ on oxygen deficiency-rich WO3−x nanosheets, successfully providing a direct Z-scheme CdS/WO3−x heterojunction to enhance photocatalytic hydrogen production. We demonstrate an effective electron collection in the Z-scheme CdS/WO3−x heterojunction by regulating the relative content of WO3−x. The optimized CdS/20 wt% WO3−x (CW20) affords a high photocatalytic hydrogen production rate of 6545.3 μmol g−1 h−1 in lactic acid aqueous solution under visible light (400–800 nm), which is about 54.1 times that of pure CdS (121.0 μmol g−1 h−1). In addition, CW20 also provides a considerable external quantum efficiency (EQE) of 10.03% at λ = 420 nm. The best-performing CW20 sample is explored by cyclic stability experiment and XRD characterization after hydrogen production, which reveals the robust stability of CW20. The excellent photocatalytic activity can be attributed to the formation of a Z-scheme CdS/WO3−x heterojunction, resulting in an efficient spatial separation of photogenerated carriers. Electron and hole catalytic centers are maintained in two separate components to minimize the adverse products of photocatalytic hydrogen production. This study uncovers the role of oxygen deficiency based on the Z-scheme heterojunction in affecting electron transfer and reaction sites, opening new opportunities for achieving efficient hydrogen production. [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]

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]

The separation and transfer of photoelectrons is a crucial factor in the process of photocatalysis. Herein, we successfully designed and prepared WP as a cocatalyst, modified the g-C3N4(CN)/CdS heterojunction structure, achieved the effective separation and directional transfer of photoelectrons, and also efficient photocatalytic hydrogen evolution. In addition, the as-prepared WP–CN/CdS composite photocatalyst not only prominently improved the separation and pre-assigned transfer of photogenerated electrons, but also had abundant surface active sites, which greatly improved the photocatalytic performance of the catalyst; namely, the highest photocatalytic activity of WP–CN/CdS was achieved at 5% WP content and the highest hydrogen production rate could reach 18 238.89 μmol h−1 g−1, which is about 12.49 times that of pure CdS. The detailed characterization studies with SEM, TEM, XRD, XPS, DRS, UV–vis, BET, transient photocurrent, FT-IR etc. effectively supported the abovementioned results, and all the characterization results were in good agreement with each other. Moreover, a possible mechanism of the photocatalytic reaction in the WP–CN/CdS system is proposed. [ABSTRACT FROM AUTHOR]

In the present investigation, we report the formation of a metal–metal oxide (Zn/ZnO) nanoscale heterointerfac with concomitant hydrogen generation. The synthesis process is simple and involves the optical illumination of Zn nanoparticles (Zn(NP)) suspended in water. The concomitant hydrogen (H2) evolution during synthesis was found to be linear, and it is dependent on the growth of the Zn/ZnO nano interface. The progressively increasing amount of ZnO relative to Zn(NP) was a limiting factor in H2 evolution. Two different Zn/ZnO nanoscale heterointerfaces were created and samples were extracted at two different stages of the illumination process. The first sample, extracted from the most reactive illumination phase and named Zn(NP)/ZnO-R, had the highest hydrogen evolution reaction (HER) rate. The second sample, extracted from a less reactive illumination phase and named Zn(NP)/ZnO-S, had a lower HER rate. These in situ (solar light-induced) samples were characterized by XRD, HRTEM, and other methods. The optoelectronic features and the photoelectrochemical (PEC) investigations showed the optimal light-harvesting ability of Zn(NP)/ZnO-R and the effective separation of photoexcited charge carriers, leading to remarkable HER performance. During the visible-light-induced (in situ) conversion of Zn(NP) to Zn(NP)/ZnO-R, a concurrent HER rate of 1115 μmol h−1 was observed. Indeed, the photocurrent density value of the Zn(NP)/ZnO-R catalyst is significantly higher than that of Zn(NP)/ZnO-S, pristine Zn(NP), and ZnO. Thus, this study provides new insights into the optimal fabrication of the Zn(NP)/ZnO interface for PEC application with concomitant solar hydrogen generation. [ABSTRACT FROM AUTHOR]

Hydrogen evolution and dye degradation catalyzed by environmentally benign and inexpensive photocatalyst in aqueous solution is regarded as a promising avenue to effectively address the global energy and environmental crisis. It is difficult for traditional photocatalysts to perform efficient light harvesting, with conducive recycling and promoted charge separation and transport, which limit practical applications in photocatalytic conversion. In this study, a facile template-assisted coaxial electrospinning approach was explored to successfully build close contacted heterojunctions within the interface of g-C3N4 nanosheets and hollow porous TiO2 nanofibers, which significantly increased the separation efficiency of photo-induced electron–hole pairs in the visible-light region. A hollow and porous structure with abundant surface-active sites assisted in inducing multiple light reflection for more efficient light harvesting. Moreover, one dimensional TiO2/g-C3N4 composite nanofibers with a large length-to-diameter ratio would be more attractive for recovery. At the optimal g-C3N4 loading, hollow porous TiO2/g-C3N4-50% nanofibers exhibited the highest rate of hydrogen evolution and RhB degradation. The enhanced photocatalytic performance of hollow porous TiO2/g-C3N4 composite photocatalysts was mainly attributed to the synergistic effect of the hollow porous architecture and heterojunction. This work might make a significant contribution to insight into preparing hollow structure heterogenous nanofiber photocatalysts with improved activities in hydrogen generation and pollutant degradation. [ABSTRACT FROM AUTHOR]

The development of low-cost and high-efficiency photocatalysts is an important way to realize photocatalytic hydrogen production. In this work, polyvinylpyrrolidone (PVP) is used as a morphological modifier to prepare a three-dimensional (3D) sea-urchin-structure NiCo2O4. Mn0.05Cd0.95S and NiCo2O4 spontaneously assemble into a spatial structure of the NiCo2O4–Mn0.05Cd0.95S p–n heterojunction under the action of the Coulomb force. The 3D sea-urchin-structure NiCo2O4 provides support for the Mn0.05Cd0.95S particles in the space, which improves the dispersion of Mn0.05Cd0.95S and exposes more reaction sites. Furthermore, the NiCo2O4–Mn0.05Cd0.95S composite catalyst with a spatial structure has good light absorption capacity. Mn0.05Cd0.95S is tightly bound on the surface of NiCo2O4, forming a built-in electric field at the contact interface to induce the directional migration of photogenerated carriers and effectively inhibit the recombination of electrons and holes. Photoelectrochemical and fluorescence tests show that the appropriate conduction band and valence band positions of NiCo2O4 and Mn0.05Cd0.95S, and the built-in electric field of the p–n heterojunction are more conducive to thermodynamic charge transfer. Because the composite catalyst has a large number of reaction sites, and shows faster charge transfer speed and effective inhibition of the recombination of electrons and holes, the hydrogen production rate of 3%NiCo2O4–Mn0.05Cd0.95S is as high as 17 008 μmol g−1 h−1, which is 4.45 times that of pure MCS. This work will provide new ideas for the design of 3D metal oxides and trigger the synthesis of other p–n heterojunction catalysts with a spatial structure. [ABSTRACT FROM AUTHOR]