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The simultaneous production of hydrogen and biomass-based chemicals from biomass-derived feedstock aqueous solutions via photocatalysis is appealing because no additional sacrificial agent is needed. However, limited success has been achieved. This paper reports efficient nori-shaped carbon nitride-based photocatalysts with potassium/oxygen co-doping and cyano group introduction for efficient conversion of biomass-derived monosaccharides to produce lactic acid and hydrogen simultaneously. The obtained photocatalyst has an adjustable bandgap, fast migration/separation rate of photo-generated carriers and displays excellent photocatalytic performance with respect to xylose conversion (∼95.0%), lactic acid selectivity (90.5%) and hydrogen generation (∼33 380 μmol g−1 h−1) in the presence of visible light. The h+, ˙OH, ˙O2− and 1O2 drive xylose conversion and lactic acid production. For biomass-derived pentoses and hexoses, the reaction system also exhibits excellent photocatalytic activity of lactic acid selectivity and hydrogen generation; the reported photocatalyst has excellent reusability. This paper provides a new perspective for hydrogen generation and biorefineries via a photocatalyst. [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]

Electrocatalytic hydrogen generation in alkaline medium has become widely used in a variety of sectors. However, the possibility for additional performance improvement is hampered by slow kinetics. Because of this restriction, careful control over processes such as water dissociation, hydroxyl desorption and hydrogen recombination is required. Covalent organic frameworks (COFs) based on porphyrin and polyoxometalates (POMs) show encouraging electrocatalytic performance, offering a viable route for effective and sustainable hydrogen generation. Their specific architectures lead to increased electrocatalytic activity, which makes them excellent choices for developing water electrolysis as a clean energy conversion method in the alkaline medium. In this regard, TTris@ZnPor and Lindqvist POM were coordinated to create a new eco-friendly and highly active covalent organic framework (TP@VL-COF). In order to describe TP@VL-COF, extensive structural and morphological investigations were carried out through FTIR, 1H NMR, elemental analysis, SEM, fluorescence, UV-visible, PXRD, CV, N2-adsorption isotherm, TGA and DSC analyses. In an alkaline medium, the electrocatalytic capability of 20%C/Pt, TTris@ZnPor, Lindqvist POM and TP@VL-COF was explored and compared for the hydrogen evolution reaction (HER). The TP@VL-COF showed the best catalytic efficiency for HER in an alkaline electrolyte, requiring just a 75 mV overpotential to drive 10 mA cm−2 and outperforming 20%C/Pt, TTris@ZnPor, Lindqvist POM and other reported catalysts. The Tafel slope value also indicates faster kinetics for TP@VL-COF (114 mV dec−1) than for 20%C/Pt (182 mV dec−1) TTris@ZnPor (116 mV dec−1) and Lindqvist POM (125 mV dec−1). [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]

This study developed an efficient photocatalyst for hydrogen production, consisting of CdS nanorods and the CoTPPBr4 co-catalyst. The synthesized photocatalyst was characterized using a suite of techniques including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), photoluminescence (PL) spectroscopy, and ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS). Additionally, transient photocurrent response and electrochemical impedance spectroscopy (EIS) were carried out to further probe the material's properties. Our findings demonstrate that the CoTPPBr4 co-catalyst significantly enhances the photocatalytic H2 evolution efficiency under visible light irradiation. Notably, among the tested photocatalysts, a 12.5% CoTPPBr4/CdS composite exhibited the most superior photocatalytic performance, achieving a hydrogen production rate of 41.3 mmol g−1 h−1, which is 4.1 times higher than that of pristine CdS. The introduction of CoTPPBr4 effectively facilitates charge transfer within CdS, enhances the separation efficiency of light-induced electron–hole pairs, and boosts the surface H2-evolution kinetics. This research not only introduces a promising photocatalyst for visible light-driven hydrogen production but also provides a way for the development of highly efficient and stable CdS-based hybrid semiconductor nanocomposites suitable for diverse photocatalytic applications. [ABSTRACT FROM AUTHOR]

In the photocatalytic processes of ferroelectric semiconductor materials, how to induce a depolarized electric field (Edp) by polarization to reduce the electron–hole recombination rate is still a big problem. Here, the ABO3-type K0.5Na0.5NbO3 (KNN) material is modified by Nd and Ni elements at A/B sites to narrow the band gap and maintain the room-temperature ferroelectric behavior. The 0.96KNN–0.04NdNiO3 sample shows the narrowed band gap (∼2.75 eV) and high residual polarization value (∼11.56 μC cm−2). After high-field poling, the hydrogen production rate of the sample in the full spectrum reaches 926.28 μmol g−1 h−1, indicating an increase of approximately 5 times compared to the 170.45 μmol g−1 h−1 of the unpoled sample. The improved performance of photocatalytic hydrogen production mainly results from the reduction of band gap and the formation of Edp after polarization. The change in the position of the top of the valence band after sample polarization reveals that high-field poling can improve charge transport efficiency by energy band bending. [ABSTRACT FROM AUTHOR]

Improving the separation efficiency of photo-generated electron–hole pair is a key issue in the field of photocatalytic hydrogen production. In this work, we successfully improved the efficiency of photo-generated carrier separation using the synergistic action of sulfur (S) vacancies and a Ni2P co-catalyst. Vs-Zn0.5Cd0.5S (Vs-ZCS) with S vacancies was designed and constructed, and Vs-ZCS/Ni2P photocatalysts were prepared with non-precious metal Ni2P as a co-catalyst. Among all the produced materials, Vs-ZCS/Ni2P-5% has a photocatalytic characteristic of 40.81 mmol g−1 h−1, which is 7.88, 3.08 and 3.75 times greater than those of ZCS (5.18 mmol g−1 h−1), Vs-ZCS (13.25 mmol g−1 h−1) and ZCS/Ni2P-5% (10.88 mmol g−1 h−1), respectively. The results of transient photo-current, electrochemical impedance spectroscopy, photoluminescence and time-resolved fluorescence show that the synergistic effect of S vacancies and Ni2P significantly promotes the separation and transfer efficiency of photo-generated carriers, as well as the photocatalytic hydrogen production reaction. Superoxide radicals and electrons are the active species for photocatalytic hydrogen generation, which is confirmed by active species capture tests and EPR. This study presents an innovative approach for developing photocatalysts with low cost and good catalytic performance. [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]

Natural photosynthetic biosystems, with elaborate spatial structures, possess substantial specific surface areas and strong light-scattering abilities and provide a blueprint for the fabrication of photocatalysts for efficiently capturing and utilizing solar energy. However, mimicking sophisticated natural structures by a rational design is a great challenge. Herein, we report a facile and universal symbiosis hydrothermal synthesis strategy for obtaining biomimetic volvox-like double-core nested hollow materials. The nested hollow materials possessed the special notched "mother–twin" core–shell structure and the core numbers could be well controlled by adjusting the amount of precursor. The notched double-core hollow ZnO/CdS (mother–twin HZC) was facilely constructed by the direct chemical deposition of CdS nanosheets on the double-core hollow ZnO (mother–twin HZ). The notched complex spatial heterostructure possessed a multiple light-reflection capability (improving the utilization of solar energy), tight interfacial contact (favoring charge migration), and a high surface-to-volume ratio (providing sufficient active sites for H2 production). Both the Z-scheme ZnO/CdS heterostructures and the special nested hollow structure could synergistically enable achieving a remarkable hydrogen generation rate (up to 18.70 mmol g−1 h−1) under visible-light irradiation, exceeding that of the reported similar ZnO/CdS heterostructure without co-catalysts. [ABSTRACT FROM AUTHOR]

Developing novel catalysts with excellent photocatalytic hydrogen evolution activity is crucial for expediting current research on solar-chemical energy conversion. In the present study, unique Sn3O4/CdS composites were carefully designed and prepared using a facile hydrothermal method to achieve outstanding photocatalytic H2 production activity. Various techniques were employed to determine the crystalline structure, chemical composition, microstructure, and optical and electrochemical characteristics of the prepared samples. The experimental results indicate that zero-dimensional (0D) CdS quantum dots were tightly attached to the surface of three-dimensional (3D) Sn3O4 nanoflowers. Furthermore, enhanced light-absorbing capacity and accelerated electron–hole separation and transfer were achieved after incorporating CdS quantum dots into Sn3O4 nanoflowers. The generation rate of hydrogen using the optimal sample (Sn3O4/CdS QDs-2) was about 20.74 μmol g−1 h−1, which was 2.86 and 3.16 times those of pure Sn3O4 and CdS, respectively. In addition, the possible photocatalytic H2 production mechanism of Sn3O4/CdS nanocomposites was also revealed. This work is highly desirable to provide valuable inspiration for rational design and preparation of efficient photocatalysts for H2 evolution. [ABSTRACT FROM AUTHOR]

In the present work, a ternary composite MoS2/soluble g-C3N4/CdS was synthesized using a facile one-pot hydrothermal reaction and conventional reflux reaction method. The composition, morphology, and properties of the ternary composite were characterized. The photocatalytic performance of the ternary composite was evaluated for hydrogen generation under LED lamp irradiation (450 nm < λ < 465 nm) with lactic acid (LA) used as a sacrificial reagent. The results demonstrated that the maximum hydrogen production reached 4869.6 μmol under the optimal hydrogen production conditions, including a composition of 20% soluble g-C3N4, 9% MoS2, a solution pH of 1, and an irradiation time of 6 hours. The corresponding hydrogen production rate for the ternary composite was calculated to be 8116 μmol g−1 h−1. Furthermore, a possible electron transfer mechanism of the ternary composite system was briefly explored. The interaction and synergistic effects between MoS2, soluble g-C3N4, and CdS in the ternary composite likely facilitate efficient electron transfer, resulting in enhanced photocatalytic activity for hydrogen production. Mechanistic research showed that the electron transfer pathway represented either a double or single type II heterojunction photocatalytic system. [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]

The development of an efficient noble-metal-free cocatalyst is the key to photocatalytic hydrogen production technology. In this study, hierarchical Co(OH)2 nanosheet array-graphene (GR) composite cocatalysts are developed. With Eosin Y (EY) as a photosensitizer, the optimal Co(OH)2-10%GR hybrid cocatalyst presents excellent photocatalytic activity with an H2 production rate of 17 539 μmol g−1 h−1, and the apparent quantum yield for hydrogen production can reach 12.8% at 520 nm, which remarkably surpasses that of pure Co(OH)2 and most similar hybrid cocatalyst systems. Experimental investigations demonstrate that the excellent photocatalytic activity of Co(OH)2-GR arises from its unique nanosheet array architecture, which can collaboratively expose rich active sites for photocatalytic hydrogen evolution and facilitate the migration and separation of photogenerated charge carriers. It is desired that this study would supply a meaningful direction for the rational optimization of the constitute and structure of cocatalysts to achieve efficient photocatalytic hydrogen generation. [ABSTRACT FROM AUTHOR]

Piezocatalytic hydrogen evolution has emerged as a promising field for the collection and utilization of mechanical energy, as well as for generating sustainable energy throughout the day. Hexagonal CdS, an established semiconductor photocatalyst, has been widely investigated for its ability to split water into H2. However, its piezocatalytic performance has received less attention, and the relationship between its structure and piezocatalytic activity remains unclear. In this study, we prepared 3D ultrathin CdS nanoflowers with high voltage electrical response and low impedance. In pure water, without the use of any cocatalyst, CdS exhibited a piezoelectric catalytic hydrogen production rate of 1.46 mmol h−1 g−1, which was three times higher than that of CdS nanospheres (0.46 mmol h−1 g−1). Furthermore, the value-added oxidation product H2O2 was produced during the process of piezoelectric catalysis. These findings provide new insights for the design of high-efficiency piezoelectric catalytic hydrogen production. [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]

Solar-driven photocatalytic hydrogen generation via splitting water requires an efficient visible light active photocatalyst. In this work, Ni cocatalysts on a TiO2 composite photocatalyst with different graphene oxide (GO) contents were prepared using a hydrothermal method and characterized by TEM, XRD, UV-vis, Raman and PL spectra. The results show that the synthesized TiO2/GO/Ni nanosheet composites have a large specific surface area and can provide a large number of active sites for a photocatalytic hydrogen production reaction. GO can broaden the optical absorption range of TiO2 and absorb more visible light, thus stimulating more photogenerated electron–hole pairs. At the same time, GO can collect electrons and promote the separation of photogenerated electron–hole pairs. Ni, as a cocatalyst, can be used as an active site for hydrogen ion adsorption, which is conducive to promoting the migration of photogenerated electrons in the system and prolonging the life of photogenerated electrons and holes, thus ensuring the high efficiency of the photocatalytic reaction. [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]

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]

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]

Na-doped g-C3N4/NiO 2D/2D laminated p–n heterojunction nanosheets are fabricated by facile calcination and hydrothermal methods. The average thickness of g-C3N4 nanosheets is ∼1.388 nm, and the ultrathin structure allows for a high specific surface area and enough surface active sites, increasing the surface reactivity. The flower ball like structure of NiO increases the light utilization rate. Na doping accelerates charge separation and transport by increasing the electrical conductivity. The g-C3N4 and NiO nanosheets form 2D/2D laminated structures, and the spherical structure can suppress the agglomeration of 2D nanosheets, which could realize adequate interface contact and form efficient p–n heterojunctions. The p–n heterostructure builds an internal electric field to accelerate spatial charge separation. Under visible light irradiation, the photocatalytic degradation efficiency for ciprofloxacin and the hydrogen production rate of Na-doped g-C3N4/NiO are up to 99.0%, and 2299.32 μmol h−1 g−1, respectively, which are several times higher than those of the pristine one. The fabrication strategy for 2D/2D laminated heterojunctions may provide new insights for the preparation of novel laminated photocatalysts with high performance. [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]

Electrochemical hydrogen production is greatly limited by the low efficiency, high cost, and poor stability of electrocatalysts. Here, we report a facile one-step method to synthesize nitrogen, phosphorus co-doped carbon encapsulated FeP/CoP derived from dual metal–organic frameworks (FeP/CoP@NPC). Thanks to the synergistic effect of its unique composition and structure, the resultant FeP/CoP@NPC shows excellent catalytic HER performance with low potentials of 198, 286, and 339 mV to achieve a current density of 10 mA cm−2 in acidic, neutral, and alkaline media along with remarkable long-time durability, respectively. More importantly, this work provides an efficient strategy for fabricating high-performance and stable pH-universal catalysts toward hydrogen generation. [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]

In this work, we successfully prepared composites of carbon-modified in-phase MoC–Mo2C (MoC–Mo2C@C, MMC) nanosheets with Cd0.5Zn0.5S (ZCS) nanorods. The loading of MMC nanosheets significantly improved the hydrogen production rate of ZCS nanorods. The results showed that the photocatalytic hydrogen production rate of ZCS is the highest when MMC nanosheets are 1 wt% of ZCS nanorods (1-MMC/ZCS), reaching 68.8 mmol h−1 g−1, which is 7.7 times that of pure ZCS nanorods. The 1-MMC/ZCS photocatalyst was measured with Na2S/Na2SO3 as a hole sacrifice reagent under irradiation with 420 nm monochromatic light, and the quantum efficiency of 1-MMC/ZCS was 32.9%. The carbon layer can promote the rapid transfer of photogenerated electrons, and in-phase Mo2C–MoC as the active site can synergistically improve the photocatalytic hydrogen production rate of ZCS. Most Mo2C-based materials are still used in the field of electrocatalysis. This study provides a new idea for exploring new molybdenum-based co-catalyst materials in the field of visible light catalytic hydrogen production. [ABSTRACT FROM AUTHOR]

Developing economic and high-performance noble metal-free photocatalysts is the key to realize efficient photocatalysis. In this work, NiS nanoparticles and hierarchical Sn3O4 nanostructures are tightly bonded by a two-step method combining hydrothermal and ion precipitation to construct a 0D/3D nanocomposite structure, which accelerates the interface electron transfer rate and photogenerated electron–hole separation efficiency. Compared with the pure Sn3O4, the loaded samples obviously have stronger light absorption capacity and effectively improve the utilization of visible light, thus showing enhanced photocatalytic hydrogen generation performance. NiS provides more active sites on the surface and facilitates electron transit as an electron acceptor, resulting in increased photocatalytic activity. As a result, when the loading of NiS reaches 1.0%, the photocatalyst shows an excellent hydrogen production performance, with an average hydrogen generation rate of 17.43 μmol g−1 h−1, which is 2.4 times than that of the pristine Sn3O4. This research offers a new idea to develop noble metal-free photocatalysts with high activity. [ABSTRACT FROM AUTHOR]

A dual-phase transition metal nitride (TMN) based Co4N- WNx system has been fabricated using nitridation of CoWO4. The interface between centrosymmetric Co4N and non-centrosymmetric WNx promotes charge carrier separation. This system also shows piezoelectric behavior. The piezoelectric property has been proved using piezoelectric force microscopy (PFM) measurements. In addition, modulating the noncentrosymmetric structure of Co4N- WNx allows a hydrogen production rate of about 262.7 μmol g-1 h-1 in pure water. We also show that the piezocatalytic hydrogen evolution efficiency is satisfactory. Co4N- WNx can also help achieve simultaneous piezocatalytic hydrogen production and RhB degradation. This work provides a novel strategy for designing efficient piezocatalytic materials. [ABSTRACT FROM AUTHOR]

Developing efficient, low-cost, and environment-friendly electrocatalysts for hydrogen generation is critical for lowering energy usage in electrochemical water splitting. Moreover, for commercialization, fabricating cost-efficient, earth-abundant electrocatalysts with superior characteristics is of urgent need. Towards this endeavor, we report the synthesis of PANI--MnMoO4 nanocomposites using a hydrothermal approach and an in situ polymerization method with various concentrations of MnMoO4. The fabricated nanocomposite electrocatalyst exhibits bifunctional electrocatalytic activity towards the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER) at a lower overpotential of 410 mV at 30 mA cm-2 and 155 mV at 10 mA cm-2, respectively in an alkaline electrolyte. Furthermore, while showing overall water splitting (OWS) performance, the optimized PM-10 (PANI--MnMoO4) electrode reveals the most outstanding OWS performance with a lower cell voltage of 1.65 V (vs. RHE) at a current density of 50 mA cm-2 with an excellent long-term cell resilience of 24 h. [ABSTRACT FROM AUTHOR]

The development of organic–inorganic hybrid materials for redox catalysis is key to access new energy conversion schemes and the sustainable production of dihydrogen. Here, bare and P-doped graphene arising from the pyrolysis of biomass (alginate from marine algae) has been used as a support for the growth and stabilization of ultra-small Ru/RuO2 NPs through organometallic synthesis. P-doped graphene allows obtaining smaller and better dispersed NPs in hybrid electrodes of lower roughness and electroactive surface area. Electrochemical activation of the as-synthesised supported nanoparticles by reduction of the passivating RuO2 layer generates excellent HER electrocatalysts under acidic conditions (η10 of 29 mV and 15 mV for the bare and P-doped electrodes, respectively). P doping, identified as surface phosphates by 31P solid state NMR, induces improvement of all HER benchmarking parameters studied, including overpotential and exchange and specific current densities. All studied materials show excellent long-term stability and selectivity for hydrogen generation with no sign of deactivation after 12 h under turnover conditions and almost quantitative faradaic efficiencies. [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]

Hydrogen storage in chemicals is regarded as one of the sustainable techniques for tackling the energy-related challenges. However, hydrogen production from ammonia borane (NH3BH3, AB) is restricted by the inherent activity of metallic catalysts, which may be boosted by light irradiation. Herein, Pd-doped Co nanoparticles (NPs) were incorporated into a Zr-MOF composite composed of MXene-derived Ti3C2 nanosheets and UiO-66-NH2 (denoted as TUNS) by a double-solvent approach, obtaining a CoPd@TUNS composite. The optimized Co30Pd@TUNS composite exhibited outstanding catalytic activity for the complete dehydrogenation of AB within 0.6 min under 300 W Xe lamp light, with a high turnover frequency of 130.37 molH2 (molmetal)−1 min−1 at 298 K. The activity of Co30Pd@TUNS increased 10-fold under light irradiation as compared to that in the dark. For photocatalytic dehydrogenation, Co30Pd@TUNS was more active than Co30Pd@UiO-66-NH2 and Co30Pd/Ti3C2. Its excellent performance might be attributed to multiple factors including the photo-harvesting MOF generating electron–hole pairs, Ti3C2 nanosheets promoting the charge separation, and the Schottky effect facilitating electron migration to metal NPs for activating the substrate via an electron-deficient BH3 moiety, along with the attack of photogenerated hydroxyl radicals and water molecules. Moreover, the kinetic study manifested that AB dehydrogenation is a zero-order reaction with regard to the substrate. The great stability and recyclability of Co30Pd@TUNS was also confirmed after 5 runs. This study would widen a pathway for the design of an efficient MOF-based catalyst for hydrogen generation in the energy-related field. [ABSTRACT FROM AUTHOR]

Hydrogen has received significant attention as a carbon-free energy carrier for power generation. Water is an environmentally-benign source for hydrogen production either through electrolysis or catalytic splitting, and the latter has a relatively low equilibrium constant. Coupling catalytic water splitting with a mixed ionic–electronic conducting (MIEC) membrane reactor has been demonstrated as a very promising approach to enhance the hydrogen production rate by extracting the oxygen produced. This review provides a comprehensive coverage of critical aspects included in this process, including membrane materials, structure, morphology, catalysts, and operating conditions for water splitting. Moreover, process intensification can be further achieved by integrating methane-related oxidation reactions to facilitate oxygen removal, so as to improve the hydrogen production rate. Some trends for future development have also been summarized. [ABSTRACT FROM AUTHOR]

Herein, we put forward a novel electrode by electrochemically integrating metal W species and Co2P nanosheets onto nickel foam (W@Co2P/NF), which delivers excellent bifunctional activity for both the HER and HzOR. The hydrazine assisted water electrolyzer provides a small cell potential of 0.18 V at 100 mA cm−2 and stability for hydrogen generation, which is superior to most of the other bifunctional materials. [ABSTRACT FROM AUTHOR]

In this communication, a PdMn bimetallene is synthesized using a template-free solvothermal method with the assistance of diamines. The PdMn bimetallene with rich defects and highly curved structures shows superior performance for the formate oxidation reaction (FOR) and the hydrogen evolution reaction (HER). For the two-electrode HER–FOR system, the PdMn bimetallene achieves a much lower voltage of 0.376 V at 10 mA cm−2, demonstrating an energy-effective path for hydrogen production. [ABSTRACT FROM AUTHOR]