Photocatalytic Hydrogen Evolution Reaction Research Articles

Mo(S,O)/(Ce,Mo)(S,O) sulfo-oxide with heterovalent metal states for efficient visible-light-driven hydrogen evolution and pollutant reduction via in-situ generated protons

The existence of the heterovalent metal states and S doping into Ce–Mo bimetallic oxide improve the photocatalytic activity by generating oxygen vacancy and narrowing the bandgap for suitable water splitting. Spherical and plate likes heterostructure Mo(S,O)/(Ce,Mo)(S,O) sulfo-oxide catalysts with heterovalent metal states and oxygen vacancy defects were synthesized by co-precipitation method for photocatalytic hydrogen evolution reaction. Catalyst labeled as 1-CeMoOS with more oxygen vacancies and high Ce3+/(Ce3++Ce4+) ratio evolved 405.18 μmol/h H2 and achieved AQE of 13.72%, whereas reduced 76.43% 4-NP and 91.52% RhB by in-situ generated protons. S doping, oxygen vacancy creation, Ce and Mo heterovalent states have narrowed the bandgap by substituting oxygen with sulfur, promoted the photogenerated charge carriers' effective separation, and prolonged the lifetime of electrons. The oxygen vacancy formation with a subsequently partial Ce4+-to-Ce3+ conversion achieves CeMoOS catalysts with excellent PHER and provides a promising way to improve photocatalysts' visible light PHER activity.

Amphiphilic Graphene Quantum Dots: Metal‐Free Photocatalyst for Hydrogen Evolution via Encapsulation of Organic Thermally Activated Delayed Fluorescence Photosensitizers

AbstractDesigning a metal‐free photocatalyst for the photocatalytic hydrogen evolution reaction (HER) is a very important research goal. Although graphene quantum dots (GQDs) have already been demonstrated as HER photocatalysts, it is necessary to address the poor visible light absorption of GQDs to achieve higher efficiency in the hydrogen evolution reaction (HER) rate. We have synthesized amphiphilic GQD by hexylamine (HA) functionalization through an amide bond formation reaction. We confirmed that HA functionalized GQD (GQD‐HA) is amphiphilic and can act as the photocatalyst and templating surfactant at the same time. GQD‐HA can form much more stable composite nanoparticles with thermally activated delayed fluorescence (TADF) photosensitizers than bare GQD. Importantly, the HER performance and the stability of the composite systems are remarkably enhanced after HA functionalization. Through electrochemical analyses, it was verified that composite photosensitizer nanoparticles with GQD‐HA have efficient charge separation and fast charge transfer properties.

Interfacial intimacy and internal electric field modulated S-scheme Sv-ZnS/ZnIn2S4 photocatalyst for efficient H2 evolution and CO2 reduction

The construction of S-scheme heterojunctions is an effective approach to realize artificial photocatalytic processes. For the higher solar energy conversion efficiency, current research focuses on improving the interfacial intimacy and precisely modulating the strength of the internal electric field (IEF). To address this issue, we propose a novel MOF-based synthesis and derivation strategy. The heterojunction obtained by this strategy tends to form an intimate interface and a tunable IEF, which facilitates the transfer and separation of photogenerated carriers. Herein, a ZnS/ZnIn2S4 (ZIS) S-Scheme heterojunction containing sulfur vacancies (Sv) was successfully synthesized, and its good photocatalytic hydrogen evolution reaction (HER) and CO2 reduction reaction (CO2RR) activity confirmed the feasibility of this strategy. The prepared Sv-ZnS/ZIS exhibits an apparent quantum yield of 19.8 ± 1.0 % at 420 nm and a hydrogen evolution rate of 2912.3 ± 185.9 μmol g−1h−1, which is 9.0 and 33.6 times higher than pure ZIS and Sv-ZnS, respectively. Furthermore, the yield of photoreduction CO2 to CO reaches 2075.7 ± 63.0 μmol g−1h−1 with a CO selectivity of 93.0 ± 0.8 %. This work provides new sights for the rational design and construction of S-scheme photocatalysts with sulfur vacancies for efficient photocatalysis.

Biomimetic Catalysts Based on Au@TiO2-MoS2-CeO2 Composites for the Production of Hydrogen by Water Splitting.

The photocatalytic hydrogen evolution reaction (HER) by water splitting has been studied, using catalysts based on crystalline TiO2 nanowires (TiO2NWs), which were synthesized by a hydrothermal procedure. This nanomaterial was subsequently modified by incorporating different loadings (1%, 3% and 5%) of gold nanoparticles (AuNPs) on the surface, previously exfoliated MoS2 nanosheets, and CeO2 nanoparticles (CeO2NPs). These nanomaterials, as well as the different synthesized catalysts, were characterized by electron microscopy (HR-SEM and HR-TEM), XPS, XRD, Raman, Reflectance and BET surface area. HER studies were performed in aqueous solution, under irradiation at different wavelengths (UV-visible), which were selected through the appropriate use of optical filters. The results obtained show that there is a synergistic effect between the different nanomaterials of the catalysts. The specific area of the catalyst, and especially the increased loading of MoS2 and CeO2NPs in the catalyst substantially improved the H2 production, with values of ca. 1114 μm/hg for the catalyst that had the best efficiency. Recyclability studies showed only a decrease in activity of approx. 7% after 15 cycles of use, possibly due to partial leaching of gold nanoparticles during catalyst use cycles. The results obtained in this research are certainly relevant and open many possibilities regarding the potential use and scaling of these heterostructures in the photocatalytic production of H2 from water.

ALD-Deposited NiO Approaches the Performance of Platinum as a Hydrogen Evolution Cocatalyst on Carbon Nitride

The photocatalytic hydrogen evolution reaction is one of the most promising approaches to utilize solar energy and produce hydrogen as an alternative energy source to traditional fossil fuels. In this work, we focused on further exploring the cocatalyst potential of the transition metal nickel and prepared nickel oxide/carbon nitride (NiO/CNx) heterojunctions through thermal polymerization as well as plasma-enhanced atomic layer deposition (PEALD). The optimal NiO loading thickness on the surface of the CNx was found to be 6.5 nm, prepared from 65 cycles of ALD. This NiO(65)/CNx had a photocatalytic hydrogen evolution rate of 3.9 μmol h–1 in a 2 mg mL–1 aqueous photocatalyst solution (195 μmol h–1 g–1), corresponding to an AQY of 3.1% and exhibiting 54% of the activity of 3 wt % Pt/CNx under 405 nm light illumination with a sacrificial reagent. A 3 wt % Ni/CNx prepared through a photodeposition process from a dispersion of CNx and simple NiCl2 had a photocatalytic hydrogen evolution rate of 2.8 μmol h–1 (140 μmol h g–1) and an AQY of 2.2% with 2 mg mL–1 photocatalyst in the reactant solution, corresponding to 39% of the activity of 3 wt % Pt/CNx. An induction period at the beginning of the hydrogen evolution process was found in all Ni-based photocatalysts, which we related to a Ni in situ photoreduction from NiII to Ni0 and the reverse reaction. In addition, the reproducibility of the induction period even in an oxygen-free environment suggests that electrons flow back from reduced Ni species to CNx under dark conditions. Furthermore, a large population of trap states was detected in the bulk CNx materials via photoinduced absorption spectroscopy, and the trapping severely hinders cocatalysts (even the benchmark Pt cocatalyst) from extracting charges from CNx for subsequent interfacial redox reactions. We conclude that not only does the surface/interface engineering of the photocatalyst/catalyst heterojunctions need to be considered but also trap states in CNx that severely limit the transfer of photogenerated charges to cocatalysts.

Boosting Photocatalytic Hydrogen Evolution Reaction by the Improved Mass Flow and Energy Flow Process Based on Ultrasound Waves

Boosting Photocatalytic Hydrogen Evolution Reaction by the Improved Mass Flow and Energy Flow Process Based on Ultrasound Waves

Surface engineering of phase controlled defective 1 T-MoS2 QDs@g-C3Nx material for significantly enhanced hydrogen evolution under visible-light irradiation

Design and construction of non-precious metal photocatalysts are necessary to achieve excellent hydrogen evolution reaction (HER) performance and good stability in photocatalytic water splitting systems. Herein, the phase control and defect engineering are applied to fabricate metallic 1 T-phase molybdenum disulfide quantum dots (1 T-MoS2 QDs) decorated 2D g-C3Nx nanosheets with the feature of nitrogen vacancies (denoted as 1 T-MoS2 QDs@g-C3Nx) for photocatalytic HER. The introduction of N defects facilitates to design electronic and energy band structures of g-C3N4. MoS2 QDs is beneficial to improve the charge carrier transport performances in the composite system. And the synergistic effect of phase control and defect engineering can optimize the reaction dynamics of photocatalytic HER. The resultant 1 T-MoS2 QDs@g-C3Nx (15 wt%) shows excellent properties for photocatalytic H2 evolution, with highest H2 generation rate reaching 4.08 mmol g-1h−1. Significantly, the superior H2 production performance of 1 T-MoS2 QDs@g-C3Nx (15 wt%) are achieved, outperforming the benchmark photocatalyst Pt-loading g-C3Nx (2.69 mmol g-1h−1). In addition, 1 T-MoS2 QDs@g-C3Nx (15 wt%) also exhibits high and stable cycling and durability with no significant decay of photocatalytic H2 evolution under continuous 25 h of visible light irradiation (λ > 420 nm). Meanwhile, the possible HER mechanism is explained based on the electronic and energy band structures effects of the g-C3Nx and the 1 T-MoS2 QDs cocatalyst. This work presents an efficient strategy for tuning the optical properties of nitrogen-based photocatalyst to enhance solar energy capture and conversion.

L-cysteine capped CoNiSx combined with Mn-Cd-S solid solution form S-scheme heterojunction for efficient and stable H2-releasing photocatalysis

With the reduction of traditional energy sources, photocatalytic hydrogen production technology provides a practical way to solve the energy crisis. The construction of photocatalysts with high performance and excellent stability is the core of water splitting for hydrogen production. Here, L-cysteine capped CoNiSx (L-CNSx) nanoplates are used to generate Mn-Cd-S solid solution (MCS) nanomaterials in situ for the construction of efficient and robust L-CNSx/MCS S-scheme heterojunction for photocatalytic hydrogen evolution reaction (HER). As a result, the optimized L-CNSx/MCS-2 heterojunction exhibited an enhanced HER rate of 91.2 mmol∙g−1∙h−1, which was 4.8 times of the pure MCS and 690.9 times of pure CNSx. This work not only suppressed the photo-corrosion of MCS nanomaterials, but also greatly improved the charge transfer efficiency by generating a strong internal electric field. This study highlights the role of CNSx in photocatalytic HER, which provides a new method to inhibit the photocorrosion of MCS-based composites.

ZIF-L-derived C-doped ZnO via a two-step calcination for enhanced photocatalytic hydrogen evolution

Metal organic frameworks (MOFs) are considered as desirable precursors for the preparation of photocatalyst to improve photocatalytic hydrogen evolution efficiency due to the maintained special morphology. Herein, C-doped rod-like ZnO with porous structure has been successfully prepared by using ZIF-L as precursor via an optimized two-step calcination strategy, which is applied for photocatalytic hydrogen evolution reaction from water splitting. The results show that ZnO-350-450 exhibits the best photocatalytic activity with a hydrogen production rate of 0.35 mmol·g−1·h−1, which is 1.9 times higher than that of ZnO-400 (0.184 mmol·g−1·h−1) under simulated sunlight illumination. The enhanced photocatalytic performance is attributed to the fact that the two-step calcination provides the regular porous rod-like structure (ZIF-L) and the inclusion of carbon in ZnO photocatalyst. C-doped ZnO with regular morphology offers faster charge transfer rate and higher charge separation efficiency, and the C-doped expands a wider range of light absorption. Overall, the presented work could provide a new idea for designing and preparing of photocatalysts with high efficiency for photocatalytic hydrogen production.

Designing of a novel Mn0.2Cd0.8S@ZnO heterostructure with Type-II charge transfer path for efficient photocatalytic hydrogen evolution reaction

The development of photocatalysts with efficient hydrogen evolution activity has been the goal for sustainable hydrogen production. In this work, heterojunction composite photocatalyst is formed by hydrothermal coupling of ZnO and Mn0.2Cd0.8S. Compared with pure ZnO and Mn0.2Cd0.8S, the composite photocatalyst has the ability to provide more abundant active sites and better photogenerated carriers separation efficiency. The optimized composite photocatalyst shows a 9.36-fold increase in hydrogen evolution activity (4297.99 μmol g−1 h−1) compared to Mn0.2Cd0.8S (459.31 μmol g−1 h−1) and exhibits excellent cycling stability. Density functional theory calculations identifies Type-II charge transfer path in the composite photocatalyst, achieving effective separation in space of photogenerated electrons from holes and suppressing recombination within the semiconductor. The results show that the construction of Type-II heterojunction in this work achieves a significant enhancement of the hydrogen evolution activity of the photocatalyst by constructing carrier transport channels at the contact interface of the heterojunction.

Anisotropic phenanthroline-based ruthenium polymers grafted on a titanium metal-organic framework for efficient photocatalytic hydrogen evolution

Conjugated polymers and titanium-based metal-organic framework (Ti-MOF) photocatalysts have demonstrated promising features for visible-light-driven hydrogen production. We report herein a strategy of anisotropic phenanthroline-based ruthenium polymers (PPDARs) over Ti-MOF, a tunable platform for efficient visible-light-driven photocatalytic hydrogen evolution reaction (HER). Several analytical methods including X-ray absorption spectroscopy (XAS) revealed the judicious integration of the surface-active polymer over the Ti-MOF reinforcing the catalytic activity over the broad chemical space. PPDAR-4 polyacrylate achitecture led to a substantial increase in the H2 evolution rate of 2438 µmolg−1h−1 (AQY: 5.33%) compared to pristine Ti-MOF (238 µmol g−1 h−1). The separation of photogenerated charge carriers at the PPDAR-4/Ti-MOF interface was confirmed by the optical and electrochemical investigations. The experimental, as well as theoretical data, revealed their physical and chemical properties which are positively correlated with the H2 generation rate. This offers a new avenue in creating polymer-based MOF robust photocatalysts for sustainable energy.

Facile Synthesis of Amorphous NiO/Reduced Graphene Oxide as a Cocatalyst for Enhanced Dye-Sensitized Photocatalytic H2 Evolution

It is still a challenge to develop efficient catalysts for hydrogen evolution reaction (HER) via a low-cost and simple method. Herein, we report an amorphous NiO/reduced graphene oxide (A-NG) composite as a cocatalyst for enhanced photocatalytic H2 evolution via dye sensitization. The A-NG composite is facilely fabricated by calcinating the NiCl2/GO precursor at a low temperature of 250 °C. The detailed characterizations show that amorphous NiO presents as tiny nanoparticles highly dispersed on graphene sheets, and nickel carbide is formed at the NiO/graphene interface, which demonstrates the strong interaction between Ni and the defective carbon of graphene. Compared with crystalline NiO/rGO (C-NG), the A-NG cocatalyst shows much enhanced dye-sensitized photocatalytic HER activity because the amorphous NiO nanoparticles can effectively adsorb the dye. As a result, highly dispersed amorphous NiO accelerates the photoinduced electron transfer from the excited dye to the cocatalyst, namely, the amorphous nickel carbide formed between NiO and rGO. This work provides a low-cost and simple method to develop efficient cocatalysts for photocatalytic H2 evolution.

Engineering Single-Atom Sites into Pore-Confined Nanospaces of Porphyrinic Metal-Organic Frameworks for the Highly Efficient Photocatalytic Hydrogen Evolution Reaction.

As a type of heterogeneous catalyst expected for the maximum atom efficiency, a series of single-atom catalysts (SACs) containing spatially isolated metal single atoms (M-SAs) have been successfully prepared by confining M-SAs in the pore-nanospaces of porphyrinic metal-organic frameworks (MOFs). The prepared MOF composites of M-SAs@Pd-PCN-222-NH2 (M = Pt, Ir, Au, and Ru) display exceptionally high and persistent efficiency in the photocatalytic hydrogen evolution reaction with a turnover number (TON) of up to 21713 in 32 h and a beginning/lasting turnover frequency (TOF) larger than 1200/600 h-1 based on M-SAs under visible light irradiation (λ ≥ 420 nm). The photo-/electrochemical property studies and density functional theory calculations disclose that the close proximity of the catalytically active Pt-SAs to the Pd-porphyrin photosensitizers with the confinement and stabilization effect by chemical binding could accelerate electron-hole separation and charge transfer in pore-nanospaces, thus promoting the catalytic H2 evolution reaction with lasting effectiveness.

Cobaltous selenide/g-C3N4 heterojunction photocatalyst based on double-electron migration mechanism promotes hydrogen production and tetracycline hydrochloride degradation

Regulating photogenerated charge carrier transfer kinetics in multi-component heterostructure by surface-interface design is of great significance for accelerating efficiently photocatalytic hydrogen evolution reaction. Herein, a novel binary CoSe2/CNNS composite is successfully fabricated by a successive high-temperature calcination method of g-C3N4 followed by in-situ hot injection process of CoSe2 for the first time. The optimal 7.5% CoSe2/CNNS heterostructure reaches moderate hydrogen production rate of 1386.8 μmol·g−1·h−1 and exhibits good mineralization efficiency for tetracycline hydrochloride (40.6%) within 120 min under light irradiation, respectively. The photogenerated charge migration behaviors, the generation process and function of various radical species (H2O2, ·OH and ·O2−) are detailedly analyzed. Moreover, photocatalytic hydrogen evolution reaction process and the intermediates and active species for tetracycline hydrochloride degradation can also be discussed. Such significantly enhanced photocatalytic activity can be resulting from good light trapping ability, rapid photocarriers transfer efficiency and accelerated H2O2 decomposition ability via a continuous two-electron/two-step reduction route. This work provides an effective strategy to control and understand the charge migration kinetics as well as to suppress H2O2 production during photocatalytic hydrogen evolution process.

Efficient and Stable Catalytic Hydrogen Evolution of ZrO2/CdSe-DETA Nanocomposites under Visible Light

Composite photocatalysts are crucial for photocatalytic hydrogen evolution. In this work, ZrO2/CdSe-diethylenetriamine (ZrO2/CdSe-DETA) heterojunction nanocomposites are synthesized, and efficiently and stably catalyzed hydrogen evolution under visible light. X-ray photoelectron spectroscopy (XPS) and high resolution transmission electron microscope (HRTEM) confirm the formation of heterojunctions between ZrO2 (ZO) and CdSe-DETA (CS). Ultraviolet–visible spectroscopy diffuse reflectance spectra (UV-vis DRS), Mott–Schottky, and theoretical calculations confirm that the mechanism at the heterojunction of the ZrO2/CdSe-DETA (ZO/CS) nanocomposites is Type-I. Among the ZO/CS nanocomposites (ZO/CS-0.4, ZO/CS-0.6, and ZO/CS-0.8; in the nanocomposites, the mass ratio of ZO to CS is 0.1:0.0765, 0.1:0.1148, and 0.1:0.1531, respectively). ZO/CS-0.6 nanocomposite has the best photocatalytic hydrogen evolution activity (4.27 mmol g−1 h−1), which is significantly higher than ZO (trace) and CS (1.75 mmol g−1 h−1). Within four cycles, the ZO/CS-0.6 nanocomposite maintains an efficient catalytic hydrogen evolution rate. Due to the existence of the heterojunction of the composites, the photogenerated electron-hole pairs can be effectively separated, which accelerates the photocatalytic hydrogen evolution reaction and reduces the progress of photocorrosion. This work reveals the feasibility of ZO/CS nanocomposite photocatalysts for hydrogen evolution.

Enhanced photocatalytic hydrogen evolution by piezoelectric effects based on MoSe2/Se-decorated CdS nanowire edge-on heterostructure

The build-in electric field by the construction of heterojunction is one of the most promising strategies to suppress the recombination of photogenerated carriers. Here, we reported a piezo-photocatalytic system composed of Se-decorated CdS nanowires and few-layered edge-on MoSe2 nanosheets for efficient H2 generation by two-pot hydrothermal synthesis. The few-layered MoSe2 exposed abundant edge sites for hydrogen evolution reaction (HER). The activity of 20-MoSe2/CdS0.95Se0.05 (20-MS/CSS, with 20 mol% of MoSe2 loading) nanocomposite casted a remarkable photocatalytic HER performance, with a rate of 47.3 mmol h−1 g−1. Moreover, MoSe2 nanosheets deformed to generate the piezoelectric polarization field under magnetic stirring, which rendered efficient separation of photogenerated carriers, resulting in a piezo-photocatalytic synergistic effect. As a result, the HER of 20-MS/CSS at 900 rpm for piezo-photocatalysis was 59.1 mmol h−1 g−1, which was 1.25 times that of 20-MS/CSS for photocatalysis. Meanwhile, the photoelectrochemical measurements further visualized the piezo-photoelectric synergy. This study exposes a new way for utilizing mechanical energy to improve photocatalytic performance, and achieving high piezo-photocatalysis.

Halogen–Hydrogen Bonding for the Synthesis of Efficient Polymeric Carbon‐Nitride Photocatalysts

Carbon nitride (CN) materials demonstrate great promise as photocatalysts for various reactions. However, synthesizing a CN with high dispersibility in water, large specific surface area, ordered morphology, and high catalytic activity remains a challenge. Melem (2,5,8‐triamino‐tri‐s‐triazine) has emerged as a monomer for the synthesis of CN materials owing to its high thermal stability, which favors controlled condensation over sublimation and decomposition at high temperatures. Herein, the synthesis of porous CN materials is shown with high dispersibility in water and excellent photocatalytic activity for the hydrogen evolution reaction (HER). To this end, various supramolecular assemblies are designed which are composed of melem combined with different hydrohalogenic acids as precursors of CNs. The results show that the HX (HX (aq), where X = Cl, Br, I) type directs the morphology, optical, and electronic properties of the resulting CN materials, particularly their surface area and photophysical properties. Moreover, the presence of HX results in a CN with a larger amount of free NH2 groups, which allow good dispersibility in water and act as linking groups to a photodeposited Pt cocatalyst. The elucidation of the optimum acid concentration and type leads to the synthesis of a CN with high and stable photocatalytic HER activity.

Plate-on-plate structured MoS2/Cd0.6Zn0.4S Z-scheme heterostructure with enhanced photocatalytic hydrogen production activity via hole sacrificial agent synchronously strengthen half-reactions

The practicable technology for producing hydrogen energy was mainly photocatalytic water splitting. Recently, heterostructural photocatalysts have attracted much attention due to its unique band structures and interfacial interactions. Herein, plate-on-plate MoS2/Cd0.6Zn0.4S heterostructure was rationally designed and fabricated by a simple strategy. It was revealed that Zn-doping content in the Cd0.6Zn0.4S solid solution as well as the mass ratio of MoS2 in the MoS2/Cd0.6Zn0.4S heterostructure can significantly affect the photocatalytic hydrogen evolution reaction (HER) activity. Especially, when Zn doping content is 40 % and the mass ratio of MoS2 is approximately 0.8 % (0.8 % MoS2/Cd0.6Zn0.4S), it exhibits the highest hydrogen production (47.68 µmol·g−1 at 2.5 h) without sacrificial agents. When Na2S/Na2SO3 is employed as sacrificial agent, its HER activity reaches 13466.50 µmol·g−1·h−1, 1.3 folds higher than Cd0.6Zn0.4S. The boosted HER activity of the Z-scheme MoS2/Cd0.6Zn0.4S heterostructure was ascribed to the greatly improved separation efficiency of photogenerated carriers. Most importantly, studies have revealed that the existence of sacrificial agents (Na2S/Na2SO3) can not only accelerate the kinetics of oxidation half reaction, but also synchronously strengthen HER half-reactions. The present work reveals a facile strategy for construction of Z-scheme heterostructures for efficient hydrogen evolution via hole sacrificial agent synchronously strengthen half-reactions.

Engineered charge transfer and reactive site over hierarchical Ti3C2T x MXene@In2S3-NiS toward enhanced photocatalytic H2 evolution

Steering photogenerated electron flow to the effective reactive sites is ideal for photocatalytic H2 evolution. Herein, as a proof-of-concept, NiS is coupled with a typical Schottky heterojunction of Ti3C2T x MXene@In2S3 through the photodepotition method towards improving the photocatalytic H2 evolution performance. In addition to the Schottky effect-mediated electron transfer in Ti3C2T x MXene@In2S3 heterojunctions, p–n junctions form between In2S3 and NiS to extract photoinduced electrons, which is found to cooperate with the role of effective H2 evolution reactive sites. The synergistic dual functions of NiS cooperate with Ti3C2T x MXene promote multichannel electron transfer in Ti3C2T x MXene@In2S3-NiS hybrids to improve the photocatalytic hydrogen evolution reaction (HER) efficiency by 41 times compared to the bare In2S3. These results enlighten the engineering of the spatial transfer of photoinduced electrons to the reactive sites toward boosting the efficiency of photocatalytic HER.

TiO2/FePS3 S‐Scheme Heterojunction for Greatly Raised Photocatalytic Hydrogen Evolution

AbstractThe aggravating extreme climate changes and natural disasters stimulate the exploration of low‐carbon/zero‐carbon alternatives to traditional carbon‐based fossil fuels. Solar‐to‐hydrogen (STH) transformation is considered as appealing route to convert renewable solar energy into carbon‐free hydrogen. Restricted by the low efficiency and high cost of noble metal cocatalysts, high‐performance and cost‐effective photocatalysts are required to realize the realistic STH transformation. Herein, the 2D FePS3 (FPS) nanosheets anchored with TiO2 nanoparticles (TiO2/FePS3) are synthesized and tested for the photocatalytic hydrogen evolution reaction. With the integration of FPS, the photocatalytic H2‐evolution rate on TiO2/FePS3 is radically increased by ≈1686%, much faster than that of TiO2 alone. The origin of the greatly raised activity is revealed by theoretical calculations and various advanced characterizations, such as transient‐state photoluminescence spectroscopy/surface photovoltage spectroscopy, in situ atomic force microscopy combined with Kelvin probe force microscopy (AFM‐KPFM), in situ X‐ray photoelectron spectroscopy (XPS), and synchrotron‐based X‐ray absorption near edge structure. Especially, the in situ AFM‐KPFM and in situ XPS together confirm the electron transport pathway in TiO2/FePS3 with light illumination, unveiling the efficient separation/transfer of charge carrier in TiO2/FePS3 step‐scheme heterojunction. This work sheds light on designing and fabricating novel 2D material‐based S‐scheme heterojunctions in photocatalysis.