Photocatalytic H2 Production Activity Research Articles

Effective photocatalytic hydrogen generation and degradation for single cobalt and tungsten metal atom oxide anchored on titanium dioxide-bismuth molybdate-reduced graphene oxide

A simple hydrothermal method was used to prepare the single-metal atom oxide (SMAO) catalyst. The prepared dual Cobalt and tungsten (CoW) single metal atom oxide anchored on the TiO2-Bi2MoO6-reduced graphene oxide (rGO), an interstitial atomic line of tungsten and cobalt. The prepared photocatalyst showed good photocatalytic hydrogen (H2) evolution and organic contaminant degradation. As co-catalysts, surface-dispersed CoW sites were created using a Co mono-substituted hetero-polyacid (HPA-Co). A larger quantity of single atoms were uniformly decorated on the TiO2-Bi2MoO6-Ethylenediamine (ED)-rGO catalyst. The presence of the CoW species was verified employing extended X-ray absorption near edge structure (XANES), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), and extended X-ray absorption fine structure (EXAFS) analyses after a TiO2-Bi2MoO6-CoW-ED-rGO composite synthesized. The findings demonstrate that TiO2-Bi2MoO6-CoW-ED-rGO catalysts were more capable of producing hydrogen and degrading Ciprofloxacin (CIP) (21.46 mmol/g/h, 97.2%) than other bare and binary catalysts. Furthermore, it showed remarkable stability and reusability after five consecutive CIP photodegradation and H2 production cycles. Gas chromatography/mass spectroscopy (GC/MS) techniques were used to identify the intermediates in the photodegradation process. The prepared photocatalyst was significantly increased, and the separation of charge carriers was further boosted, thanks to the CoW material and the synergistic effect. A possible Z-scheme mechanism was proposed for the photocatalytic H2 production activity. More electrons can contribute to the reduction of H2 evolution because of the processability of the Z-scheme. This work created a recyclable, inexpensive, highly effective, and non-toxic catalytic material for H2 generation and CIP degradation.

General Synthesis of Single-Crystalline Ta2O5 Nanorods Towards Enhanced Photocatalytic H2 Production Activity.

As a potential candidate for photocatalytic H2 production from water splitting, Ta2O5 catalyst presents suitable conduction and valence band positions, but suffers from poor charge transfer ability, which seriously limits its photocatalytic performance enhancement. Here, a facile and eco-friendly hydrothermal method was developed for the fabrication of one-dimensional (1D) Ta2O5 nanorods using the freshly precipitated tantalic acids as the precursors. An oriented attachment mechanism was proposed for the growth of Ta2O5 nanorods. Moreover, the present synthetic approach was further extended to direct synthesis of nine kinds of alkaline tantalates and alkaline-earth tantalates nanostructures, suggesting its general applicability. A significant increase in activity in photocatalytic H2 production was revealed on 1D Ta2O5 nanorods. The improved photocatalytic H2 production activity of Ta2O5 nanorods was mainly attributed to its 1D nanorods structure with high crystallization and large specific surface areas as well as excellent charge transfer efficiency.

Boosted photothermal-assisted photocatalytic H2 production by dual heat source-based S-scheme heterojunction

With advances in catalytic research, improvement of catalytic efficiency by using photothermal synergies to strengthen the reaction mechanisms has been focused. In this work, a novel photothermal-assisted photocatalytic H2 production system was constructed by loading Co3O4 nanoparticles on surface of black carbon nitride (BCN) nanosheets, served as the dual thermal source to enhance photothermal effect for synergistically assisting in photocatalytic H2 evolution with optimal H2 production rate reached 3.7 mmol g−1 h−1, significantly higher than that of pure carbon nitride (CN) and BCN. Moreover, the S-scheme heterojunction is also formed between Co3O4 and BCN, leading to the optimization of the charge transfer path, which further promotes the improvement of photothermal-assisted photocatalytic H2 production activity. This study provides the design idea of coupling the multi-heat source effect with the heterojunction electron transport for constructing an efficient photothermal-assisted hydrogen production system.

Ingenious regulation and activation of sites in the 2H-MoS2 basal planes by oxygen incorporation for enhanced photocatalytic hydrogen evolution of CdS

The 2H phase of MoS2 has the advantages of stable phase structure and tunable preparation approach, while the unfavorable H adsorption ability at the basal plane sites hinders the H2 evolution performance. Here, we developed an effective strategy for the regulation of the basal plane properties of MoS2 via oxygen doping. It is demonstrated that the Gibbs free energy of hydrogen adsorption (ΔGH*) at the sites in the basal plane can be effectively optimized. Using oxygen-doped MoS2 (OMoS) as a cocatalyst, the constructed OMoS/CdS heterojunction photocatalyst shows a stronger built-in electric field and improved photocatalytic H2 production activity. The optimized OMoS/CdS sample with only 0.3 wt% OMoS loading amount achieved an H2 evolution rate of 58.47 mmol g-1h−1 under AM 1.5 light irradiation, which is significantly superior to that of conventional MoS2 modified CdS and even higher than the 1 wt% Pt modified CdS. Our results not only highlighted the significant potential of OMoS as a photocatalyst for hydrogen production, but also proposed a superior to and effective conception for optimizing the H2 evolution activity at the basal plane sites of 2H-MoS2.

Strong Electron Coupling Effect of Prussian Blue Analogs Derived Ultrathin Nitrogen‐Doped Carbon Wrapped Fe‐CoP for Enhanced Wide Spectrum Photocatalytic H2 Evolution

AbstractWith the advantages of large specific surface area and high porosity of general metal‐organic frame materials, russian blue analogs have broad application prospects in catalysis. In this work, a series of ultra‐thin N‐doped carbon coated Fe‐CoP (Fe‐CoP@NC) are prepared by phosphating Fe‐Co‐Co Prussian blue analogs (Fe‐Co‐Co PBA) in different degrees for the broad‐spectrum photocatalytic hydrogen evolution. The results show that Fe‐CoP@NC‐3 has the highest photocatalytic hydrogen production rate of 16.6 mmol h−1 g−1, which is 83 times greater than that of Fe‐Co‐Co PBA. The excellent stability of Fe‐CoP@NC‐3 is proved by cyclic experiments. The outstanding photocatalytic H2 production activity of Fe‐CoP@NC‐3 can be ascribed to the strong electron coupling effect between Fe‐CoP and N‐doped carbon layer. The photogenerated electrons of Fe‐CoP are transferred to the N‐doped carbon layer, which is electron transport mediator accelerating the electron transfer and synergetic improving the hydrogen evolution efficiency. This work provides an effective strategy for designing an ultra‐thin N‐doped carbon layer coated phosphide photocatalyst with strong electron coupling effect.

Plasmonic tandem heterojunctions enable high-efficiency charge transfer for broad spectrum photocatalytic hydrogen production

Rational engineering of semiconductor photocatalysts for efficient hydrogen production is of great significance but still challenging, primarily due to the limitations in charge transfer kinetics. Herein, a fascinating plasmonic tandem heterojunction with the hc-CdS/Mo2C@C heterostructure is aimfully prepared for effectively promoting the charge separation kinetics of the CdS photocatalyst via the synergistic strategy of phase junction, Schottky junction, and photothermal effect. The difference in atomic configuration between cubic-CdS (c-CdS) and hexagonal-CdS (h-CdS) leads to effective charge separation through a typical II charge transfer mechanism, and plasmonic Schottky junction further extracts the electrons in the hc-CdS phase junction to realize gradient charge transfer. Besides, the photothermal effect of Mo2C@C helps to expand the light absorption, accelerate charge transfer kinetics, and reduce the hydrogen evolution energy barrier. The carbon layer provides a fast channel for charge transfer and protects the photocatalyst from photocorrosion. As a result, the optimized hc-CMC photocatalyst exhibits a significantly high photocatalytic H2 production activity of 28.63 mmol/g/h and apparent quantum efficiency of 61.8%, surpassing most of the reported photocatalysts. This study provides a feasible strategy to enhance the charge transfer kinetics and photocatalytic activity of CdS by constructing plasmonic tandem heterogeneous junctions.

Synthesis of Carbon Nitride Polymorphs by Sacrificial Template Method: Correlation between Physicochemical Properties and Photocatalytic Performance.

Carbon nitride compounds (CNCs) in the form of graphitic carbon nitride (g-C3N4) and poly(heptazine imide) were synthesized using different metal chloride salts (MClx), i.e., NaCl, KCl and CaCl2, as sacrificial templates and by varying the MClx to melamine molar ratios. A systematic study of their photocatalytic activity for H2 production in relation to the physicochemical, morphological, and optical properties was carried out. Each sample was tested achieving the highest hydrogen evolution rates of about 7660 µmol g-1 h-1, 5380 µmol g-1 h-1 and 3140 µmol g-1 h-1 using CaCl2, KCl, and NaCl, respectively. This work demonstrates how the synthesis of CNCs with different MClx leads to the production of high-performance photocatalysts due to a combination of factors as the formation of vacancies or cyano groups, a shift in the optical threshold and tuning of micro(nano)structure. The results demonstrate that, when CaCl2 is used as a sacrificial template, porous and exfoliated g-C3N4 nanosheets are formed leading to hydrogen productions which outperform most of the previously reported g-C3N4 prepared using a single synthetic step.

Pd-CQDs/CdS ternary composite for highly efficient visible light driven H2 evolution under combined action of type I heterojunctions and Schottky junctions

Visible light driven catalytic hydrogen production over CdS based catalysts could be a good candidate strategy to help solve the global energy crisis. To improve the photocatalytic H2 production activity of CdS, the series of Pd nanoparticles and carbon quantum dots (CQDs) co-modified CdS nanorods (NRs) composites were designed to simultaneously build the type I heterojunctions and Schottky junctions. The photocatalytic H2 evolution activities of the samples were assessed under visible light (λ > 420 nm) irradiation and the reaction mechanism was proposed. The Pd-0.35CQDs/CdS catalyst exhibited excellent activity with the average hydrogen evolution rate (HER) of 47.1 mmol h−1 g−1, which is 36.2 times higher than that of the pure CdS. Its apparent quantum efficiency is 17.1% (450 nm light). The combined action of Schottky junctions and type I heterojunctions in the composite Pd-0.35CQDs/CdS greatly promoted charge transfer and separation, resulting in enhancement of the photocatalytic activity. Additionally, the synergistic effect of the Pd nanoparticles and CQDs resulted in enhanced visible light absorption and optimized band structure, helpful to enhancement of the photocatalytic activity. This study provides a simple and cost-effective strategy for improving visible light catalytic H2 production performance of catalysts.

Strain-Driven Phase Transitions in Delafossite Cu1-xAxAlO2: A Key to Enhanced Photo(electro)catalytic Performance.

This study investigates the impact of intrinsic strain and phase transitions on the thermodynamic stability and electronic properties of Cu1-xAxAlO2 solid solutions, which are key to their photocatalytic performance. It is demonstrated that Cu1-xAxAlO2 with A = Ag, Au, Pt can form continuous isostructural solid solutions due to relatively small compressive strain, while a substantial increase strain restricts Cu1-xPdxAlO2 to forming only limited solutions. For A = Li, Na, the formation of heterostructural solid solutions is facilitated by structural motif alterations, accommodating significant differences in ionic radii and A-O bond characteristics. Specifically, Cu1-xLixAlO2 exhibits a phase transition at x ≈ 0.333, whereas Cu1-xNaxAlO2 undergoes three distinct phase transitions. Electronic structure analysis indicates that in Cu1-xAxAlO2 (A = Ag, Au), d10-d10 closed-shell interactions dominate, enabling tunable band gaps with varying solubility. Nevertheless, increased intrinsic strain in metal sublattices, as seen in A = Pd and Pt, shifts antibonding states to the Fermi level, inducing a semiconductor-to-metal transition. Experimental evidence confirms that Ag+ ions modulate the band gaps and carrier dynamics in Cu1-xAgxAlO2, with Cu0.75Ag0.25AlO2 exhibiting heightened photoelectrochemical activity and a 38.5-fold enhancement in H2 production rate over CuAlO2. Additionally, the coordination environment changes between alkali metals and O, induced by phase transitions, effectively tune the band edge positions and carrier dynamics of Cu1-xAxAlO2 (A = Li, Na) heterostructural solid solutions. Therefore, 3R-Cu0.97Li0.03AlO2 with asymmetric nonlinear dumbbell O-Cu-O demonstrates the highest photocatalytic H2 production activity, 72.9 times greater than CuAlO2. In contrast, α-Cu1-xAxAlO2 with a smaller CuO6 octahedral splitting energy exhibits increased band gaps, resulting in diminished photocatalytic activity. This research underscores that strain-driven phase transition provides an additional control factor and new mechanism for regulating the photo(electro)catalytic activity of Cu1-xAxAlO2 solid solutions.

Ultrafast Two-Color X-Ray Emission Spectroscopy Reveals Excited State Landscape in a Base Metal Dyad.

Effective photoinduced charge transfer makes molecular bimetallic assemblies attractive for applications as active light-induced proton reduction systems. Developing competitive base metal dyads is mandatory for a more sustainable future. However, the electron transfer mechanisms from the photosensitizer to the proton reduction catalyst in base metal dyads remain so far unexplored. A Fe─Co dyad that exhibits photocatalytic H2 production activity is studied using femtosecond X-ray emission spectroscopy, complemented by ultrafast optical spectroscopy and theoretical time-dependent DFT calculations, to understand the electronic and structural dynamics after photoexcitation and during the subsequent charge transfer process from the FeII photosensitizer to the cobaloxime catalyst. This novel approach enables the simultaneous measurement of the transient X-ray emission at the iron and cobalt K-edges in a two-color experiment. With this methodology, the excited state dynamics are correlated to the electron transfer processes, and evidence of the Fe→Co electron transfer as an initial step of proton reduction activity is unraveled.

Z-scheme promoted interfacial charge transfer on Cu/In-porphyrin MOFs/CdIn2S4 heterostructure for efficient photocatalytic H2 evolution

The rational modulation of charge transfer pathway within heterojunction is essential toward boosting photocatalytic activity for H2 production from water splitting Herein, the bimetallic-modified porphyrin MOFs (CuIn-PMOFs) crystals have been developed as a substrate for the epitaxial wrapping of CdIn2S4 (CIS) nanosheets via a facile solvothermal process to fabricate novel hierarchical CuIn-PMOFs@CdIn2S4 (CuIn-PMOFs@CIS) heterojunctions. The experimental results, combined with density-functional theory calculations, demonstrated that the CuIn-PMOFs have a more negative conduction band position and the electrons transfer pathway is inclined from CIS to CuIn-PMOFs, which leads to the formation of unique Z-scheme heterojunctions. Profiting from the special “O-In” charge transfer channel, extensive highly active photoinduced electrons areaggregated and depleted in the conduction band of CuIn-PMOFs, contributing to the improvement of H2 generation activity. Moreover, the heterojunction model also revealed the minimum Gibbs free energy for H* intermediate adsorption (ΔGH*). Concretely, the optimized composite displayed a maximum H2 evolution rate of 7527.54 μmol g–1h−1, which is around 13.12 and 6.63 times higher than that of pure CdIn2S4 and CuIn-PMOFs, respectively. This work aims to suggest that constructing distinctive Z-scheme modulated charge transfer mechanism is an advanced strategy for acquiring highly efficient photocatalysts.

One step co-deposition of Ni0.96S and Ag2S on TiO2 nanosheets for enhanced photocatalytic H2 generation with superior stability

Introduction of co-catalysts to construct heterojunctions is one of the important strategies to improve the photocatalytic hydrogen production activity of semiconductor catalysts. Here, Ni0.96S and Ag2S co-decorated TiO2 composites were prepared by a simple one-step solvothermal method, whose photocatalytic H2 production activities were evaluated and related H2 evolution mechanism was explored. The 5%Ni0.96S-8%Ag2S/TiO2 ternary composite exhibited much enhanced photocatalytic activity with the photocatalytic hydrogen evolution rate (HER) of 23.67 mmol·h−1·g−1, which is 131.5 fold higher than that of the pure TiO2. Even higher HER, 29.45 mmol·h−1·g−1, was obtained in the presence of 40 mL glycerol. The photocatalytic HERs of the 5%Ni0.96S-8%Ag2S/TiO2 catalyst under visible light (λ > 420 nm) and simulated solar light (AM1.5) were 353.78 and 935.24 µmol·h−1·g−1, respectively. The apparent quantum efficiency (365 nm) is as high as 13.9%. Remarkably, the catalyst exhibited excellent photocatalytic cycling stability and durability, beneficial to practice applications. The improved photocatalytic activity of the composite can be attributed to much improved charge carrier transfer/separation, optimized energy band structure and enhanced visible light absorption caused by synergistic effect of Ni0.96S and Ag2S.

Interface engineering of Ti3C2 MXene assisted anatase/rutile TiO2 with hetero-phase junction for enhancing the photocatalytic activity of tetracycline hydrochloride removal and H2 production

The conventional heterojunction formed by combining two different semiconductors is associated with issues of low compatibility, restricted intimate contact, and limited charge anti-recombination process. To address these issues, a simple strategy was adopted to fabricate a hetero-phase junction flanked with two dissimilar crystal phases of a single semiconducting material. This study employed TiB2 as the initial material to fabricate an anatase/rutile TiO2 hetero-phase junction material (AR-TiO2), followed by its combination with highly conductive monolayer Ti3C2 nanosheets to develop an AR-TiO2/Ti3C2 composite photocatalyst. The photocatalyst displayed a wide range of light absorption and a remarkable capability for separating photogenerated carriers. The closely interconnected hetero-phase junction surface, formed by the rutile and anatase phases of AR-TiO2, combined with the incorporation of highly conductive Ti3C2 nanosheets, synergistically increased the availability of multi-dimensional active sites and increased the efficacy of separating photogenerated electron pairs. The optimized AR-TiO2/Ti3C2 achieved a degradation efficiency of 91.49 % for tetracycline hydrochloride (TCH) within 2 h and produced 1005.81 μmol of hydrogen in 6 h. The impacts of initial pH, co-existing anions, initial TCH concentration, initial temperature, and various pollutant species on the catalytic efficiency were also investigated. pH was shown to have the greatest impact on the photocatalytic performance of AR-TiO2/Ti3C2 for TCH degradation. •O2−, and h+ were identified as the primary reactive species that enabled the photocatalytic performance of AR-TiO2/Ti3C2 through trapping experiments. This study presents a novel method to synthesize hetero-phase junction photocatalysts and suggests that Ti3C2 has potential prospects for use in photocatalysis.

Electron-transfer dynamics and photocatalytic H2-production activity of PbS@Cu2S nanocomposites

BackgroundLead citrate is a precursor that can be prepared by recycling the spent lead paste of lead-acid batteries. Lead citrate is used to synthesize lead oxide, which can be repeatedly utilized for the lead-acid battery application. MethodsWe report a new application of lead citrate precursor to synthesize PbS@Cu2S nanomaterials for photocatalytic H2 production. PbS@Cu2S was prepared by microwave-assisted hydrothermal and ion-exchange processes. The electron-transfer dynamics and H2-production activity of PbS@Cu2S photocatalysts were studied. Significant findingsA S-scheme heterojunction is proposed based on the results of Tauc plots, ultraviolet photoelectron spectroscopy, the electron paramagnetic resonance scavenger test, and in situ near-edge X-ray absorption fine structure (NEXAFS) analysis. Results of in situ NEXAFS reveal the transfer of photoexcited electrons from PbS to Cu2S. By loading an optimized amount of Cu2S, the carrier separation and photocatalytic activity of PbS@Cu2S photocatalysts are improved. This technology can transform the lead citrate precursor to the PbS@Cu2S photocatalyst with excellent high H2 production activity (3824 μmol g−1 h−1).

A novel noble-metal-free FeS2/Mn0.5Cd0.5S heterojunction for enhancing photocatalytic H2 production activity: Carrier separation, light absorption, active sites

BackgroundThe development of efficient and noble-metal-free photocatalysts is greatly essential for photocatalytic hydrogen production. However, the photocatalytic activity of a single photocatalyst is usually limited for various reasons. MethodsHerein, FeS2/Mn0.5Cd0.5S (FSMCS) heterojunctions were constructed by a simple solvent evaporation method. The morphological characterizations revealed a raspberry-like hollow microsphere structure for FeS2 and irregular granularity for Mn0.5Cd0.5S. Photoluminescence (PL) and electrochemical experiments indicated that the FSMCS composite effectively facilitated the separation of photogenerated electron-hole pairs. The UV–vis diffuse reflectance spectrum (DRS) showed that, in FSMCS composite, the visible light absorption range was effectively expanded to the full visible light. Significant findingsExcellent photocatalytic activity in FSMCS heterojunctions without loading noble metals because FeS2 could serve an active site for hydrogen production. The optimum FSMCS composite had excellent photocatalytic hydrogen production activity (6.1 mmol·g−1·h−1), which was 5.6 and 2.3 times higher than that of the pristine Mn0.5Cd0.5S (1.1 mmol·g−1·h−1) and Mn0.5Cd0.5S-1 %Pt (2.7 mmol·g−1·h−1). Meanwhile, in four round-robin tests, the activity of the 5FSMCS photocatalyst did not significantly decrease. This work proved that combining Mn0.5Cd0.5S and non-precious metal cocatalysts to construct heterojunctions is a promising strategy for photocatalytic hydrogen production.

AgCo bimetallic cocatalyst modified g-C3N4 for improving photocatalytic hydrogen evolution

Bimetallic AgCo/g-C3N4 photocatalysts were successfully prepared by a facile chemical reduction method and used to investigate their photocatalytic H2 production performance. Bimetallic AgCo as a cocatalyst can be well matched with g-C3N4, which is beneficial for increasing the number of active reaction sites and narrowing the band gap. A possible photocatalytic mechanism was explored by XRD, FTIR, SEM, TEM, UV–vis DRS, BET, and PL characterization. The photocatalytic H2 production activity of the optimal 5%AgCo/g-C3N4 photocatalyst reached 12994.2 μmoL/g, which was 54.7 times higher than g-C3N4. Owing to the close interfacial contact between bimetallic AgCo and g-C3N4, the transfer distance was shortened, and the photogenerated electron and hole pairs were effectively separated. This study provides a new strategy for the synthesis of excellent H2 production photocatalysts using bimetallic nanoparticles.

Pd(II) coordination molecule modified g-C3N4 for boosting photocatalytic hydrogen production

The photocatalytic H2 production activity of polymer carbon nitride (g-C3N4) is limited by the rapid recombination of photoelectron-hole pairs and slow surface reduction dynamic process. Here, a supramolecular complex (named R-TAP-Pd(II)) was fabricated via self-assembly of (R)-N-(1-phenylethyl)-4-(4-(pyridin-2-yl)-1H-1,2,3-triazol-1-yl)benzamide (R-TAP) with Pd(II) and used to modify g-C3N4. In the R-TAP-Pd(II)@g-C3N4 composite photocatalyst, the spin polarization of R-TAP-Pd(II) can promote charge transfer and inhibit photogenerated carrier recombination, as confirmed by spectral tests and photoelectrochemical performance tests. Electrochemical tests and in situ X-ray photoelectron spectroscopy (XPS) tests proved that the Pd(II) ion in the R-TAP-Pd(II) molecule can serve as active sites to accelerate H2 production. The R-TAP-Pd(II)@g-C3N4 presented a photocatalytic H2 generation rate of 1085 μmol g−1 h−1 when exposed to visible light, which was a about 278-fold increase compared with g-C3N4. This work finds a new approach to boost the photocatalytic efficiency of g-C3N4 via supramolecular self-assembly.

Enhanced photocatalytic H2 production activity by loading Ni complex on flower-like MoS2 nanomaterials

BackgroundExploring efficient H2-production photocatalysts is very important for converting solar energy to chemical energy. Some approaches were developed to prevent the recombination of photogenerated electron-hole pairs, ultimately enhancing the photocatalytic H2 production activity. Methods3D flower-like MoS2 nanomaterials were surface-modified by the Ni complex as the redox mediator to make the composite photocatalysts. This work investigated the effect of zeta potential on the Ni-complex loading, charge separation, and photocatalytic H2 production activity of MoS2. Significant findingsThe Ni-complex with central cation can be loaded on MoS2 with negative zeta potential due to the columb attraction force. The photogenerated carriers can transfer from MoS2 to the central Ni ion of the complex due to the ligands-stabilized multiple oxidation states of Ni, leading to suppressed charge recombination. The FE-TEM mapping and XPS confirm the loading of Ni complex. The photoluminescence, photocurrent response, and EIS tests confirm the improved photoinduced charge separation of the Ni complex-modified photocatalyst. The flower-like microstructure of MoS2 provides a large specific surface area and high light absorption. The H2 production activity of MoS2-Ni complex photocatalyst (3320 μmol g−1 h−1) is higher than that of the pristine MoS2 photocatalyst (2576 μmol g−1 h−1).

2D MoB MBene: An Efficient Co-Catalyst for Photocatalytic Hydrogen Production under Visible Light.

Highly active and low-cost co-catalysts have a positive effect on the enhancement of solar H2 production. Here, we employ two-dimensional (2D) MBene as a noble-metal-free co-catalyst to boost semiconductor for photocatalytic H2 production. MoB MBene is a 2D nanoboride, which is directly made from MoAlB by a facile hydrothermal etching and manual scraping off process. The as-synthesized MoB MBene with purity >95 wt % is treated by ultrasonic cell pulverization to obtain ultrathin 2D MoB MBene nanosheets (∼0.61 nm) and integrated with CdS via an electrostatic interaction strategy. The CdS/MoB composites exhibit an ultrahigh photocatalytic H2 production activity of 16,892 μmol g-1 h-1 under visible light, surpassing that of pure CdS by an exciting factor of ≈1135%. Theoretical calculations and various measurements account for the high performance in terms of Gibbs free energy, work functions, and photoelectrochemical properties. This work discovers the huge potential of these promising 2D MBene family materials as high-efficiency and low-cost co-catalysts for photocatalytic H2 production.

(Sr0.6Bi0.305)2Bi2O7/KNbO3 nanocomposites with significantly enhanced photocatalytic H2 generation driven by simulated sunlight

A novel (Sr0.6Bi0.305)2Bi2O7/KNbO3 Z-scheme heterojunction was synthesized by two-step hydrothermal method and its photocatalytic activity for splitting water was studied under simulated sunlight. Compared with KNbO3 and (Sr0.6Bi0.305)2Bi2O7, the as-prepared (Sr0.6Bi0.305)2Bi2O7/KNbO3 samples exhibited remarkably enhanced photocatalytic activity for H2 production. It was found that the H2 production efficiency of (Sr0.6Bi0.305)2Bi2O7/KNbO3 (1:800) composite was nearly 39.5 times as large as that of pure KNbO3. The potential fields at interfaces between KNbO3 and (Sr0.6Bi0.305)2Bi2O7 with different energy band potential can drive the secondary distribution of photogenerated carriers, thereby improving photocatalytic activity. The composite demonstrates good stability for photocatalytic activities and still has excellent H2 production performance after four cycle experiments. This work verifies that the addition of a small amount of (Sr0.6Bi0.305)2Bi2O7 into the photocatalytically H2-generating semiconducting materials is an efficient strategy for significantly boosting photocatalytic H2 evolution.