Metal‐Free 2D/2D Phosphorene/g‐C3N4 Van der Waals Heterojunction for Highly Enhanced Visible‐Light Photocatalytic H2 Production

The generation of green hydrogen (H₂) energy using sunlight is of great significance to solve the worldwide energy and environmental issues. Particularly, photocatalytic H₂ production is a highly promising strategy for solar‐to‐H₂ conversion. Recently, various heterostructured photocatalysts with high efficiency and good stability have been fabricated. Among them, 2D/2D van der Waals (VDW) heterojunctions have received tremendous attention, since this architecture can promote the interfacial charge separation and transfer and provide massive reactive centers. On the other hand, currently, most photocatalysts are composed of metal elements with high cost, limited reserves, and hazardous environmental impact. Hence, the development of metal‐free photocatalysts is desirable. Here, a novel 2D/2D VDW heterostructure of metal‐free phosphorene/graphitic carbon nitride (g‐C₃N₄) is fabricated. The phosphorene/g‐C₃N₄ nanocomposite shows an enhanced visible‐light photocatalytic H₂ production activity of 571 µmol h^?1 g^?1 in 18 v% lactic acid aqueous solution. This improved performance arises from the intimate electronic coupling at the 2D/2D interface, corroborated by the advanced characterizations techniques, e.g., synchrotron‐based X‐ray absorption near‐edge structure, and theoretical calculations. This work not only reports a new metal‐free phosphorene/g‐C₃N₄ photocatalyst but also sheds lights on the design and fabrication of 2D/2D VDW heterojunction for applications in catalysis, electronics, and optoelectronics.     

Crafting Mussel‐Inspired Metal Nanoparticle‐Decorated Ultrathin Graphitic Carbon Nitride for the Degradation of Chemical Pollutants and Production of Chemical Resources

The development of efficient photocatalysts for the degradation of organic pollutants and production of hydrogen peroxide (H₂O₂) is an attractive two‐in‐one strategy to address environmental remediation concerns and chemical resource demands. Graphitic carbon nitride (g‐C₃N₄) possesses unique electronic and optical properties. However, bulk g‐C₃N₄ suffers from inefficient sunlight absorption and low carrier mobility. Once exfoliated, ultrathin nanosheets of g‐C₃N₄ attain much intriguing photocatalytic activity. Herein, a mussel‐inspired strategy is developed to yield silver‐decorated ultrathin g‐C₃N₄ nanosheets (Ag@U‐g‐C₃N₄‐NS). The optimum Ag@U‐g‐C₃N₄‐NS photocatalyst exhibits enhanced electrochemical properties and excellent performance for the degradation of organic pollutants. Due to the photoformed valence band holes and selective two‐electron reduction of O₂ by the conduction band electrons, it also renders an efficient, economic, and green route to light‐driven H₂O₂ production with an initial rate of 0.75 × 10^?6 m min^?1. The improved photocatalytic performance is primarily attributed to the large specific surface area of the U‐g‐C₃N₄‐NS layer, the surface plasmon resonance effect induced by Ag nanoparticles, and the cooperative electronic capture properties between Ag and U‐g‐C₃N₄‐NS. Consequently, this unique photocatalyst possesses the extended absorption region, which effectively suppresses the recombination of electron–hole pairs and facilitates the transfer of electrons to participate in photocatalytic reactions.     

A Full‐Spectrum Metal‐Free Porphyrin Supramolecular Photocatalyst for Dual Functions of Highly Efficient Hydrogen and Oxygen Evolution

A full‐spectrum (300–700 nm) responsive porphyrin supramolecular photocatalyst with a theoretical solar spectrum efficiency of 44.4% is successfully constructed. For the first time, hydrogen and oxygen evolution (40.8 and 36.1 µmol g^?1 h^?1) is demonstrated by a porphyrin photocatalyst without the addition of any cocatalysts. The strong oxidizing performance also presents an efficient photodegradation activity that is more than ten times higher than that of g‐C₃N₄ for the photodegradation of phenol. The high photocatalytic reduction and oxidation activity arises from a strong built‐in electric field due to molecular dipoles of electron‐trapping groups and the nanocrystalline structure of the supramolecular photocatalyst. The appropriate band structure of the supramolecular photocatalyst adjusted via the highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels of the porphyrin gives rise to thermodynamic driving potential for H₂ and O₂ evolution under visible light irradiation. Controlling the energy band structure of photocatalysts via the ordered assembly of structure‐designed organic molecules could provide a novel approach for the design of organic photocatalysts in energy and environmental applications.     

Abundant Ce3+ Ions in Au‐CeOx Nanosheets to Enhance CO2 Electroreduction Performance

The electroreduction of CO₂ to CO provides a potential way to solve the environmental problems caused by excess fossil fuel utilization. Loading transition metals on metal oxides is an efficient strategy for CO₂ electroreduction as well as for reducing metal usage. However, it needs a great potential to overcome the energy barrier to increase CO selectivity. This paper describes how 8.7 wt% gold nanoparticles (NPs) loaded on CeO_x nanosheets (NSs) with high Ce³⁺ concentration effectively decrease the overpotential for CO₂ electroreduction. The 3.6 nm gold NPs on CeO_x NSs containing 47.3% Ce³⁺ achieve CO faradaic efficiency of 90.1% at ?0.5 V in 0.1 m KHCO₃ solution. Furthermore, the CO₂ electroreduction activity shows a strong relationship with the fractions of Ce³⁺ on Au‐CeO_x NSs, which has never been reported. In situ surface‐enhanced infrared absorption spectroscopy shows that Au‐CeO_x NSs with high Ce³⁺ concentration promote CO₂ activation and *COOH formation. Theoretical calculations also indicate that the improved performance is attributed to the enhanced *COOH formation on Au‐CeO_x NSs with high Ce³⁺ fraction.     

Unraveling the Dynamic Nanoscale Reducibility (Ce4+ → Ce3+) of CeOx–Ru in Hydrogen Activation

The interaction of molecular hydrogen with ceria is of important relevance for heterogeneous catalysis related to green chemistry and renewable energy. Here, the complex structural transformations of a well‐defined cerium oxide model catalyst are followed in situ and in real time when exposed to a reactive H₂ environment. By using electron spectromicroscopy and diffraction with chemical and structural sensitivities, it is demonstrated that the transition from CeO₂ to crystalline Ce₂O₃ occurs through a mixture of transient, coexisting phases on the nanoscale. The findings establish a clear relationship between structure and functionality for hydrogen dissociation over ceria(111), bearing profound implications on the nature of the reduction (Ce⁴⁺ → Ce³⁺) and mechanism for H₂ scission.     

SnS2/Co3S4 Hollow Nanocubes Anchored on S‐Doped Graphene for Ultrafast and Stable Na‐Ion Storage

SnS₂ has been widely studied as an anode material for sodium‐ion batteries (SIBs) based on the high theoretical capacity and layered structure. Unfortunately, rapid capacity decay associated with volume variation during cycling limits practical application. Herein, SnS₂/Co₃S₄ hollow nanocubes anchored on S‐doped graphene are synthesized for the first time via coprecipitation and hydrothermal methods. When applied as the anode for SIBs, the sample delivers a distinguished charge specific capacity of 1141.8 mAh g^?1 and there is no significant capacity decay (0.1 A g^?1 for 50 cycles). When the rate is increased to 0.5 A g^?1, it presents 845.7 mAh g^?1 after cycling 100 times. Furthermore, the composite also exhibits an ultrafast sodium storage capability where 392.9 mAh g^?1 can be obtained at 10 A g^?1 and the charging time is less than 3 min. The outstanding electrochemical properties can be ascribed to the enhancement of conductivity for the addition of S‐doped graphene and the existence of p–n junctions in the SnS₂/Co₃S₄ heterostructure. Moreover, the presence of mesopores between nanosheets can alleviate volume expansion during cycling as well as being beneficial for the migration of Na⁺.     

Construction of 3D Electronic/Ionic Conduction Networks for All‐Solid‐State Lithium Batteries

High and balanced electronic and ionic transportation networks with nanoscale distribution in solid‐state cathodes are crucial to realize high‐performance all‐solid‐state lithium batteries. Using Cu₂SnS₃ as a model active material, such a kind of solid‐state Cu₂SnS₃@graphene‐Li₇P₃S₁₁ nanocomposite cathodes are synthesized, where 5–10 nm Cu₂SnS₃ nanoparticles homogenously anchor on the graphene nanosheets, while the Li₇P₃S₁₁ electrolytes uniformly coat on the surface of Cu₂SnS₃@graphene composite forming nanoscaled electron/ion transportation networks. The large amount of nanoscaled triple‐phase boundary in cathode ensures high power density due to high ionic/electronic conductions and long cycle life due to uniform and reduced volume change of nano‐Cu₂SnS_3. The Cu₂SnS₃@graphene‐Li₇P₃S₁₁ cathode layer with 2.0 mg cm^?2 loading in all‐solid‐state lithium batteries demonstrates a high reversible discharge specific capacity of 813.2 mAh g^?1 at 100 mA g^?1 and retains 732.0 mAh g^?1 after 60 cycles, corresponding to a high energy density of 410.4 Wh kg^?1 based on the total mass of Cu₂SnS₃@graphene‐Li₇P₃S₁₁ composite based cathode. Moreover, it exhibits excellent rate capability and high‐rate cycling stability, showing reversible capacity of 363.5 mAh g^?1 at 500 mA g^?1 after 200 cycles. The study provides a new insight into constructing both electronic and ionic conduction networks for all‐solid‐state lithium batteries.     

Oxygen‐Vacancy‐Introduced BaSnO3−δ Photoanodes with Tunable Band Structures for Efficient Solar‐Driven Water Splitting

To achieve excellent photoelectrochemical water‐splitting activity, photoanode materials with high light absorption and good charge‐separation efficiency are essential. One effective strategy for the production of materials satisfying these requirements is to adjust their band structure and corresponding bandgap energy by introducing oxygen vacancies. A simple chemical reduction method that can systematically generate oxygen vacancies in barium stannate (BaSnO₃ (BSO)) crystal is introduced, which thus allows for precise control of the bandgap energy. A BSO photoanode with optimum oxygen‐vacancy concentration (8.7%) exhibits high light‐absorption and good charge‐separation capabilities. After deposition of FeOOH/NiOOH oxygen evolution cocatalysts on its surface, this photoanode shows a remarkable photocurrent density of 7.32 mA cm^?2 at a potential of 1.23 V versus a reversible hydrogen electrode under AM1.5G simulated sunlight. Moreover, a tandem device constructed with a perovskite solar cell exhibits an operating photocurrent density of 6.84 mA cm^?2 and stable gas production with an average solar‐to‐hydrogen conversion efficiency of 7.92% for 100 h, thus functioning as an outstanding unbiased water‐splitting system.     

Oxygenated Triazine-Heptazine Heterostructure Creates an Enormous Ascension to the Visible Light Photocatalytic Hydrogen Evolution Performance of Porous C3N4 Nanosheets

A highly efficient g-C₃N₄ photocatalyst is developed by a novel one-pot thermal polymerization method under a salt fog environment generated by heating the aqueous solution of urea and mixed metal salts of NaCl/KCl, namely SF-CN. Thanks to the synergistic effect of the oxygenation and chemical etching of the salt fog, the obtained SF-CN is an oxygenated ultrathin porous carbon nitride with an intermolecular triazine-heptazine heterostructure, meanwhile, shows enlarged specific surface area, greatly enhanced absorption of visible light, narrowed band gap with a lower conduction band, and an increased photocurrent response due to the effective separation of photogenerated holes and electrons, comparing to those of pristine g-C₃N₄. The theoretical simulations further reveal that the triazine-heptazine heterostructure possesses better photocatalytic hydrogen evolution (PHE) capability than pure triazine and heptazine carbon nitrides. In turn, SF-CN demonstrates an excellent visible light PHE rate of 18.13 mmol h⁻¹ g⁻¹, up to 259.00 times of that of pristine g-C₃N₄.     

Ultrahigh‐Sensitive Broadband Photodetectors Based on Dielectric Shielded MoTe2/Graphene/SnS2 p–g–n Junctions

2D atomic sheets of transition metal dichalcogenides (TMDs) have a tremendous potential for next‐generation optoelectronics since they can be stacked layer‐by‐layer to form van der Waals (vdW) heterostructures. This allows not only bypassing difficulties in heteroepitaxy of lattice‐mismatched semiconductors of desired functionalities but also providing a scheme to design new optoelectronics that can surpass the fundamental limitations on their conventional semiconductor counterparts. Herein, a novel 2D h‐BN/p‐MoTe₂/graphene/n‐SnS₂/h‐BN p–g–n junction, fabricated by a layer‐by‐layer dry transfer, demonstrates high‐sensitivity, broadband photodetection at room temperature. The combination of the MoTe₂ and SnS₂ of complementary bandgaps, and the graphene interlayer provides a unique vdW heterostructure with a vertical built‐in electric field for high‐efficiency broadband light absorption, exciton dissociation, and carrier transfer. The graphene interlayer plays a critical role in enhancing sensitivity and broadening the spectral range. An optimized device containing 5?7‐layer graphene has been achieved and shows an extraordinary responsivity exceeding 2600 A W^?1 with fast photoresponse and specific detectivity up to ≈10¹³ Jones in the ultraviolet–visible–near‐infrared spectrum. This result suggests that the vdW p–g–n junctions containing multiple photoactive TMDs can provide a viable approach toward future ultrahigh‐sensitivity and broadband photonic detectors.     

Reductive Transformation of Layered‐Double‐Hydroxide Nanosheets to Fe‐Based Heterostructures for Efficient Visible‐Light Photocatalytic Hydrogenation of CO

Conversion of syngas (CO, H₂) to hydrocarbons, commonly known as the Fischer–Tropsch (FT) synthesis, represents a fundamental pillar in today's chemical industry and is typically carried out under technically demanding conditions (1–3 MPa, 300–400 °C). Photocatalysis using sunlight offers an alternative and potentially more sustainable approach for the transformation of small molecules (H₂O, CO, CO₂, N₂, etc.) to high‐valuable products, including hydrocarbons. Herein, a novel series of Fe‐based heterostructured photocatalysts (Fe‐x) is successfully fabricated via H₂ reduction of ZnFeAl‐layered double hydroxide (LDH) nanosheets at temperatures (x) in the range 300–650 °C. At a reduction temperature of 500 °C, the heterostructured photocatalyst formed (Fe‐500) consists of Fe⁰ and FeO_x nanoparticles supported by ZnO and amorphous Al₂O₃. Fe‐500 demonstrates remarkable CO hydrogenation performance with very high initial selectivities toward hydrocarbons (89%) and especially light olefins (42%), and a very low selectivity towards CO₂ (11%). The intimate and abundant interfacial contacts between metallic Fe⁰ and FeO_x in the Fe‐500 photocatalyst underpins its outstanding photocatalytic performance. The photocatalytic production of high‐value light olefins with suppressed CO₂ selectivity from CO hydrogenation is demonstrated here.     

Nanoconfined Nickel@Carbon Core–Shell Cocatalyst Promoting Highly Efficient Visible‐Light Photocatalytic H2 Production

The realization of large‐scale solar hydrogen (H₂) production relies on the development of high‐performance and low‐cost photocatalysts driven by sunlight. Recently, cocatalysts have demonstrated immense potential in enhancing the activity and stability of photocatalysts. Hence, the rational design of highly active and inexpensive cocatalysts is of great significance. Here, a facile method is reported to synthesize Ni@C core–shell nanoparticles as a highly active cocatalyst. After merging Ni@C cocatalyst with CdS nanorod (NR), a tremendously enhanced visible‐light photocatalytic H₂‐production performance of 76.1 mmol g^?1 h^?1 is achieved, accompanied with an outstanding quantum efficiency of 31.2% at 420 nm. The state‐of‐art characterizations (e.g., synchrotron‐based X‐ray absorption near edge structure) and theoretical calculations strongly support the presence of pronounced nanoconfinement effect in Ni@C core–shell nanoparticles, which leads to controlled Ni core size, intimate interfacial contact and rapid charge transfer, optimized electronic structure, and protection against chemical corrosion. Hence, the combination of nanoconfined Ni@C with CdS nanorod leads to significantly improved photocatalytic activity and stability. This work not only for the first time demonstrates the great potential of using highly active and inexpensive Ni@C core–shell structure to replace expensive Pt in photocatalysis but also opens new avenues for synthesizing cocatalyst/photocatalyst hybridized systems with excellent performance by introducing nanoconfinement effect.     

A Nonmetal Plasmonic Z‐Scheme Photocatalyst with UV‐ to NIR‐Driven Photocatalytic Protons Reduction

Ultrabroad‐spectrum absorption and highly efficient generation of available charge carriers are two essential requirements for promising semiconductor‐based photocatalysts, towards achieving the ultimate goal of solar‐to‐fuel conversion. Here, a fascinating nonmetal plasmonic Z‐scheme photocatalyst with the W₁₈O₄₉/g‐C₃N₄ heterostructure is reported, which can effectively harvest photon energies spanning from the UV to the nearinfrared region and simultaneously possesses improved charge‐carrier dynamics to boost the generation of long‐lived active electrons for the photocatalytic reduction of protons into H₂. By combining with theoretical simulations, a unique synergistic photocatalysis effect between the semiconductive Z‐scheme charge‐carrier separation and metal‐like localized‐surface‐plasmon‐resonance‐induced “hot electrons” injection process is demonstrated within this binary heterostructure.     

Spatially Separating Redox Centers on Z‐Scheme ZnIn2S4/BiVO4 Hierarchical Heterostructure for Highly Efficient Photocatalytic Hydrogen Evolution

Photocatalysis technology using solar energy for hydrogen (H₂) production still faces great challenges to design and synthesize highly efficient photocatalysts, which should realize the precise regulation of reactive sites, rapid migration of photoinduced carriers and strong visible light harvest. Here, a facile hierarchical Z‐scheme system with ZnIn₂S₄/BiVO₄ heterojunction is proposed, which can precisely regulate redox centers at the ZnIn₂S₄/BiVO₄ hetero‐interface by accelerating the separation and migration of photoinduced charges, and then enhance the oxidation and reduction ability of holes and electrons, respectively. Therefore, the ZnIn₂S₄/BiVO₄ heterojunction exhibits excellent photocatalytic performance with a much higher H₂‐evolution rate of 5.944 mmol g^?1 h^?1, which is about five times higher than that of pure ZnIn₂S₄. Moreover, this heterojunction shows good stability and recycle ability, providing a promising photocatalyst for efficient H₂ production and a new strategy for the manufacture of remarkable photocatalytic materials.     

Super-Hydrophilic Microporous Ni(OH)x/Ni3S2 Heterostructure Electrocatalyst for Large-Current-Density Hydrogen Evolution

Exploiting active and stable non-precious metal electrocatalysts for alkaline hydrogen evolution reaction (HER) at large current density plays a key role in realizing large-scale industrial hydrogen generation. Herein, a self-supported microporous Ni(OH)x/Ni₃S₂ heterostructure electrocatalyst on nickel foam (Ni(OH)x/Ni₃S₂/NF) that possesses super-hydrophilic property through an electrochemical process is rationally designed and fabricated. Benefiting from the super-hydrophilic property, microporous feature, and self-supported structure, the electrocatalyst exhibits an exceptional HER performance at large current density in 1.0 M KOH, only requiring low overpotential of 126, 193, and 238 mV to reach a current density of 100, 500, and 1000 mA cm⁻², respectively, and displaying a long-term durability up to 1000 h, which is among the state-of-the-art non-precious metal electrocatalysts. Combining hard X-rays absorption spectroscopy and first-principles calculation, it also reveals that the strong electronic coupling at the interface of the heterostructure facilitates the dissociation of H₂O molecular, accelerating the HER kinetics in alkaline electrolyte. This work sheds a light on developing advanced non-precious metal electrocatalysts for industrial hydrogen production by means of constructing a super-hydrophilic microporous heterostructure.     

A Brown Mesoporous TiO2‐x/MCF Composite with an Extremely High Quantum Yield of Solar Energy Photocatalysis for H2 Evolution

A brown mesoporous TiO_2‐x/MCF composite with a high fluorine dopant concentration (8.01 at%) is synthesized by a vacuum activation method. It exhibits an excellent solar absorption and a record‐breaking quantum yield (Φ = 46%) and a high photon–hydrogen energy conversion efficiency (η = 34%,) for solar photocatalytic H₂ production, which are all higher than that of the black hydrogen‐doped TiO₂ (Φ = 35%, η = 24%). The MCFs serve to improve the adsorption of F atoms onto the TiO₂/MCF composite surface, which after the formation of oxygen vacancies by vacuum activation, facilitate the abundant substitution of these vacancies with F atoms. The decrease of recombination sites induced by high‐concentration F doping and the synergistic effect between lattice Ti³⁺–F and surface Ti³⁺–F are responsible for the enhanced lifetime of electrons, the observed excellent absorption of solar light, and the photocatalytic production of H₂ for these catalysts. The as‐prepared F‐doped composite is an ideal solar light‐driven photocatalyst with great potential for applications ranging from the remediation of environmental pollution to the harnessing of solar energy for H₂ production.     

Tunneling Diode Based on WSe2/SnS2 Heterostructure Incorporating High Detectivity and Responsivity

van der Waals (vdW) heterostructures based on atomically thin 2D materials have led to a new era in next‐generation optoelectronics due to their tailored energy band alignments and ultrathin morphological features, especially in photodetectors. However, these photodetectors often show an inevitable compromise between photodetectivity and photoresponsivity with one high and the other low. Herein, a highly sensitive WSe₂/SnS₂ photodiode is constructed on BN thin film by exfoliating each material and manually stacking them. The WSe₂/SnS₂ vdW heterostructure shows ultralow dark currents resulting from the depletion region at the junction and high direct tunneling current when illuminated, which is confirmed by the energy band structures and electrical characteristics fitted with direct tunneling. Thus, the distinctive WSe₂/SnS₂ vdW heterostructure exhibits both ultrahigh photodetectivity of 1.29 × 10¹³ Jones (I_ph/I_dark ratio of ≈10⁶) and photoresponsivity of 244 A W^?1 at a reverse bias under the illumination of 550 nm light (3.77 mW cm^?2).     

PtTe2‐Based Type‐II Dirac Semimetal and Its van der Waals Heterostructure for Sensitive Room Temperature Terahertz Photodetection

Recent years have witnessed rapid progresses made in the photoelectric performance of two‐dimensional materials represented by graphene, black phosphorus, and transition metal dichalcogenides. Despite significant efforts, a photodetection technique capable for longer wavelength, higher working temperature as well as fast responsivity, is still facing huge challenges due to a lack of best among bandgap, dark current, and absorption ability. Exploring topological materials with nontrivial band transport leads to peculiar properties of quantized phenomena such as chiral anomaly, and magnetic‐optical effect, which enables a novel feasibility for an advanced optoelectronic device working at longer wavelength. In this work, the direct generation of photocurrent at low energy terahertz (THz) band at room temperature is implemented in a planar metal–PtTe₂–metal structure. The results show that the THz photodetector based on PtTe₂ with bow‐tie‐type planar contacts possesses a high photoresponsivity (1.6 A W^?1 without bias voltage) with a response time less than 20 µs, while the PtTe₂–graphene heterostructure‐based detector can reach responsivity above 1.4 kV W^?1 and a response time shorter than 9 µs. Remarkably, it is already exploitable for large area imaging applications. These results suggest that topological semimetals such as PtTe₂ can be ideal materials for implementation in a high‐performing photodetection system at THz band.     

Preparation and doping modification of cerium oxide photosensitizers applied to photosensitive glass ceramics

CeO₂ nanoparticles doped with different types of Pr, Y, W and CaF₂ are prepared via a facile one-pot combustion method. Their crystallinity, particle size and absorption spectrum are investigated by X-ray diffraction (XRD), grading analysis and ultraviolet–visible spectroscopy (UV–Vis) absorption spectrum. Among the doped samples, W-doped CeO₂ (Ce_0.9W_0.1O₂) is selected out, which exhibits obvious red-shift of the absorption band as compared with the undoped CeO₂, achieving good match between the ceria absorption peak and the industrial 365 nm light source. Consequently, under the 365 nm exposure, the W-doped CeO₂ show more efficient reduction ability for Ag⁺ to Ag. The results indicate that W-doped CeO₂ is a very promising photosensitizer for photosensitive glass ceramics under industrial 365 nm light exposure, which can better absorb photons under UV light and then reduce Ag⁺ to elemental Ag.

     

2D‐GaS as a Photocatalyst for Water Splitting to Produce H2

Using first‐principles local and hybrid density functional theoretical calculations, a thickness‐dependent electronic structure of layered GaS is determined, and it is shown that 2D GaS has an electronic structure with valence and conduction bands that straddle the redox potentials of hydrogen evolution reaction and oxygen evolution reaction up to a critical thickness (<5.5 nm). Here, simulations of adsorption of H₂O on nanoscale GaS reveal that localized electronic states at its edges appear in the gap and strengthen the interaction with H₂O, further activating the surface atomic sites. It is thus predicted that GaS synthesized with a controlled thickness and preferred edges may be an efficient catalyst for photocatalytic splitting of water. Experiments that verify some of the predictions in this study are presented, and it is shown that GaS is effective in absorption of light and evolution of H₂ (887 μmol h⁻¹ g⁻¹) in the presence of aqueous solution of hydrazine (1% v/v). This study should open up the use of nanoscale GaS in conversion of solar energy into environment‐friendly chemical energy in the form of hydrogen.