1T-phase MoS2/holey ultrathin g-C3N4 nanosheets based 2D/2D heterostructure for enhanced photocatalytic hydrogen production

Although graphitic carbon nitride (g-C₃N₄) is widely used for photocatalytic hydrogen production, its practical application is restricted by the high recombination rate of photoinduced electron-hole pairs and limited active sites. In this work, holey ultrathin g-C₃N₄ nanosheets (HCN NSs) with rich active sites are prepared, followed by the growth of 1T-MoS₂ NSs on their surfaces to construct 2D/2D 1T-MoS₂/HCN heterostructure. Due to the high surface area and abundant hydrogen active sites of the hybrid, large and intimate 2D nanointerface between MoS₂ and HCN, hydrogen ion adsorption and charge separation/transport ability are greatly enhanced. As a result, 1T-MoS₂/HCN-4 with the optimal 1T-MoS₂ content of 8 wt% displays the highest H₂ production rate of 2724.2 μmol^?1 h^?1 g^?1 under simulated solar light illumination with apparent quantum efficiency of 8.1% (λ = 370 nm). Moreover, the 1T-MoS₂/HCN-4 hybrid manifests improved stability after a long-time test. This study opens the door to design highly-efficient g-C₃N₄ based 2D/2D heterostructures for photocatalytic H₂ production.     

g-C3N4/CoAl-LDH 2D/2D hybrid heterojunction for boosting photocatalytic hydrogen evolution

In this work, a 2D/2D heterojunction composed of CoAl layered double hydroxide (LDH) and graphitic carbon nitride nanosheets (CNNS) was designed and fabricated for boosting photocatalytic hydrogen generation. The as-prepared 20 mol% CoAl-LDH/CNNS exhibited a remarkable photocatalytic hydrogen evolution rate of 680.13 μmol h⁻¹ g⁻¹, which was 21 times higher than that of pure CoAl-LDH (32.91 μmol h⁻¹ g⁻¹). The enhanced activity could be mainly attributed to its unique structure and high surface area. Distinct from ordinary heterojunction photocatalysts, two-dimensional (2D) heterojunctions with abundant 2D coupling interfaces and strong interfacial interaction could efficiently suppress the recombination of photo-induced charge carriers and shorten charge transmission distance. Particularly, compared with other concentrations, the increased surface area (138.70 m² g⁻¹) of 20 mol% CoAl-LDH/CNNS, which is 3.94 times of pure CNNS (35.48 m² g⁻¹), is more favorable for enhanced photocatalytic activity. Increasing the surface area of sheet-on-sheet heterostructure is an effective and novel strategy to facilitate the photocatalytic hydrogen evolution from water splitting.     

Boosting photocatalytic hydrogen evolution of g-C3N4 via enhancing its interfacial redox activity and charge separation with Mo-doped CoSx

To achieve low-cost photocatalytic hydrogen (H₂) production, it is necessary to develop low-priced transition metal co-catalysts to replace the roles of noble metals for photocatalytic H₂ evolution. Herein, a co-catalyst of Mo-doped CoS_x (Mo-CoS_x) was synthesized by using the hydrothermal procedure, then attached to g-C₃N₄ to construct a composite photocatalyst. As a co-catalyst, Mo-CoS_x can work as an electron acceptor, it is utilized to receive electrons generated by g-C₃N₄ photocatalyst on the surface of the catalyst, and inhibit the recombination of those electrons, thus showing enhanced charge transfer ability as well as reduction ability. The optimized Mo-CoS_x/g-C₃N₄ delivered a prominent photocatalytic H₂ evolution rate of 2062.4 μmol h^?1 g^?1, which was ～193 times higher than g-C₃N₄. Its AQE at 400 nm and 420 nm were 11.05% and 6.83%, respectively. This work provides a novel non-precious metal co-catalyst/g-C₃N₄ photocatalyst that is expected to be an acceptable cost route to solar energy conversion.     

Exfoliated and plicated g-C3N4 nanosheets for efficient photocatalytic organic degradation and hydrogen evolution

Exfoliated and plicated g-C₃N₄ nanosheets (CNsF) were prepared through a thermal-chemical exfoliation in which the bulk g-C₃N₄ was obtained first under thermal exfoliation, and then was exposed to an acidic etching using hydrofluoric acid under hydrothermal condition. The acidic etching not only exfoliated g-C₃N₄ nanosheets by disrupting weak van der Waals forces between layers, which led to formation of a monolayer or a few layers of g-C₃N₄ nanosheets, but also made disordered defects on its surface and created plicated g-C₃N₄ nanosheets. Under visible-light illumination, the optimized sample (CNsF-6%) showed a hydrogen evolution rate of 54.13 μmol h^?1g^?1 (without co-catalyst) and a specific surface area of 121.4 m² g^?1, which were about 4.7 and 2.5 times, respectively, higher than pristine g-C₃N₄. It also showed remarkably enhanced photocatalytic performance in removing various organic pollutants. This remarkable improvement probably arises from the porous nanosheets and an increased number of active sites resulting from the CNsF, which subsequently enhanced the charge separation efficiency. This work provided an alternative way to obtain highly active g-C₃N₄ photocatalysts.     

Bimetallic PtNi alloy modified 2D g-C3N4 nanosheets as an efficient cocatalyst for enhancing photocatalytic hydrogen evolution

Platinum-based alloy materials as effective cocatalysts in improving the performance of photocatalytic H₂ production have raised great interest. Herein, a facile strategy of chemical reduction is established to synthesize bimetallic PtNi nanoparticles on 2D g-C₃N₄ nanosheets with excellent photocatalytic activity. The addition of PtNi nanoparticles can provide new H⁺ reduction sites and increase more active sites of the material. The synergistic effect between PtNi alloy nanoparticles and 2D g-C₃N₄ nanosheets can regulate electronic structure, narrow the band, accelerate charge transfer efficiency and inhabit the recombination of photo-induced electron (e⁻) and hole pairs (h⁺), contributing to the improvement of hydrogen evolution activity. The optimal hydrogen evolution rate of Pt_0.6Ni_0.4/CN shows higher hydrogen evolution rate (9528 μmol·g⁻¹·h⁻¹), which is 13.1 times than that of pure g-C₃N₄ nanosheets. Besides, a possible mechanism of photocatalytic hydrogen generation has been brought up according to a series of physical and chemical characterization. This work also provides a potential idea of developing cocatalysts integrating metal alloys with 2D g-C₃N₄ nanosheets for promoting photocatalytic hydrogen evolution.     

An orderly assembled g-C3N4, rGO and Ni2P photocatalyst for efficient hydrogen evolution

On account of on the dominant performance of Ni₂P, rGO and g-C₃N₄ itself, with a view to conquer the disadvantages of Ni₂P, rGO and g-C₃N₄ its own, the g-C₃N₄/rGO/Ni₂P is successfully designed and prepared by a simple hydrothermal reaction, which is used in dye-sensitized system for high-efficient photocatalytic H₂ evolution. The rGO is adhered to the outside appearance of the g-C₃N₄ nanosheets and fish-scale shape Ni₂P is anchored on the surface of rGO and g-C₃N₄. The above three forms a synergistic effect. The maximum amount of H₂ evolution reaches about 266 μmol for 5 h over the g-C₃N₄/rGO/Ni₂P photocatalyst when the content of rGO is 8%, which is 10.6 times higher than g-C₃N₄. Synergy between the above three materials is certified by some characterizations and the results of which are consistent with each other. In addition, the possible mechanism of photocatalytic hydrogen production is proposed.     

Hybridization of g-C3N4 quantum dots with 1D branched TiO2 fiber for efficient visible light-driven photocatalytic hydrogen generation

The hybrid 1D branched TiO₂ loaded with g-C₃N₄ QDs was successfully fabricated that plays a significant role in photocatalysis. The 1D branched TiO₂ prepared by electrospinning followed by alkali-hydrothermal process, and g-C₃N₄ QDs were grafted over it by a chemical vapor deposition method. The composite display enhancement in photocatalytic hydrogen evolution is about 10.57 mmol. g⁻¹.h⁻¹ in comparison to the g-C₃N₄ sample that only produces 0.32 mmol. g⁻¹.h⁻¹ while the HBTiO₂ sample evolved a negligible amount of hydrogen under visible light. The composite sample shows quantum efficiency for HER at 420 nm light is 18.6% that is much higher than the other two samples. The specific surface area of the composite sample is 92.39 m²g^-1 that is about 13 times more than bulk g-C₃N_4. The bandgap of HBTiO₂/g-C₃N₄ QDs, g-C₃N₄, and HBTiO₂ samples calculated as 2.71 eV, 2.67eV, and 3.24eV, respectively. The TRPL spectra imply that the duration of the lifetime of composite becomes longer which effectually overwhelm the electron-hole recombination. The 1D branched TiO₂ fiber reduces the charge recombination by fast transfer of electron while g-C₃N₄ QDs facilitate the visible light absorption by improving the optical properties. The formation of the type II heterostructure system remarkably promotes the separation and transfer of electron holes and facilitates the photo-reduction reaction.     

A direct one-step synthesis of ultrathin g-C3N4 nanosheets from thiourea for boosting solar photocatalytic H2 evolution

Two-dimensional (2D) graphitic carbon nitride (g-C₃N₄) nanosheets, as the promising photocatalyst with fascinating properties, have become a “rising star” in the field of photocatalysis. Although g-C₃N₄ nanosheets exfoliated from the bulk g-C₃N₄ powders are extensively emerged, developing a simple synthetic approach is still full of challenge. To this end, here we report a direct polymerization strategy to fabricate the ultrathin g-C₃N₄ nanosheets, that is only heating treatment of thiourea in air without addition of any template. The photocatalytic activities of as-prepared samples were evaluated by photoreduction of water to hydrogen (H₂) using triethanolamine as sacrificial agent and Pt as co-catalyst under visible-light irradiation (λ > 420 nm). As a result, our few-layered g-C₃N₄ nanosheets with an average thickness of 3.5 nm exhibit a superior visible-light photocatalytic H₂ evolution rate (HER) of 1391 μmol g⁻¹ h⁻¹ and a remarkable apparent quantum efficiency of 6.6% at 420 nm. Eventually, the HER of as-fabricated ultrathin g-C₃N₄ nanosheets is not only much higher than the dicyandiamide-derived g-C₃N₄ or melamine-derived g-C₃N₄, but also greater than the thermal-oxidation etched g-C₃N₄ nanosheets under the same condition.     

Construction of 1D/0D/2D Zn0.5Cd0.5S/PdAg/g-C3N4 ternary heterojunction composites for efficient photocatalytic hydrogen evolution

A high-efficiency and easy-available approach was developed to obtain a ternary heterojunction composites with advanced hydrogen evolution reaction (HER) performance under visible light by water split. PdAg bimetallic nanoparticles make a close contact interface between g-C₃N₄(CN) and Zn_0.5Cd_0.5S(ZCS). Under visible light irradiation, CN and ZCS are both excited to generate electron-hole pairs, PdAg bimetallic nanoparticles act as a bridge between CN and ZCS. Not only can the photogenerated electrons from CN be captured, but they can also be quickly transferred to the surface of ZCS and participate in the photocatalytic reaction to release H₂, and the recombination of charge carriers between the contact interface of ZCS and CN can be significantly inhibited. In addition, the thin CN layer reduces the photocorrosion of the ZCS and enhances the specific surface area of the composite material. After testing, the composite material with 30 wt% ZCS and 4 wt% PdAg demonstrates hydrogen evolution performance, up to 6250.7 μmol g^?1h^?1, which is 753 times the hydrogen evolution rate of single-component CN and 12.6 times of ZCS/CN. Compared with single-component and two-component photocatalysts, the ternary ZCS/PdAg/CN photocatalyst achieves significantly enhanced photocatalytic activity.     

In situ oxidation of ultrathin Ti3C2Tx MXene modified with crystalline g-C3N4 nanosheets for photocatalytic H2 evolution

With photoconductor being transferred and separated, interface contact plays a crucial role in developing composites photocatalyst. In the present work, 2D crystalline g-C₃N₄ (called as CCN) with 2D TiO₂ nanosheets (called as TO) obtained in situ oxidized single-layered Ti₃C₂T_x MXene is designed by an electrostatic self-assembly technology. This CCN/TO nanosheets system with a few TiO₂ nanosheets distributed to the surface is not only prolonging lifetime of photoelectron but also stimulating photogenerated carriers transferred in contact interface. The electron transfer mechanism of CCN/TO is further proved by Pt photo-deposition method. Therein, the optimal CCN-TO-0.6 exhibits excellent performance of H₂ generation compared with single photocatalyst of CCN. The result shows that the crystalline g-C₃N₄ photocatalysts introduced TiO₂ with interfacial effect favorably reduce H⁺ to H₂ and enhance photocatalytic activity.     

CoCO3 hierarchical structure embedded on g-C3N4 nanosheets to assemble 3D/2D Z-scheme heterojunction towards efficiently and stably photocatalytic hydrogen production

Structure and interface control of heterojunction is usually a challenging issue to improve the photocatalytic performance. Herein, a new 3D/2D CoCO₃/g-C₃N₄ heterojunction is assembled by embedding hexahedral CoCO₃ on g-C₃N₄ nanosheets. The unique step-like hierarchical structure of CoCO₃, the formed built-in electric field and Z-scheme charge transfer behavior at the interface jointly drive the high-efficient separation of photogenerated carriers to boost the photocatalytic H₂ production. It achieves the optimal H₂ production rate that is almost 2.6 times than g-C₃N₄, apparent quantum efficiency (AQE) of 10.1% at 400 nm and continuous running of 60 h over the 3D/2D CoCO₃/g-C₃N₄ heterojunction. This work endows a fresh structural control strategy for the fabrication of 3D/2D Z-scheme heterojunction to improve the photocatalytic H₂ production performance.     

Ag2CO3-derived Ag/g-C3N4 composite with enhanced visible-light photocatalytic activity for hydrogen production from water splitting

In this paper, Ag-based g-C₃N₄ composites have been successfully fabricated through two deferent synthetic methods: (i) a facile and efficient precipitation-calcination strategy (denoted as D–CN–xAg, x represents the dosage of Ag₂CO₃, the same below), (ii) a calcination method (denoted as Z–CN–xAg). All Ag-based g-C₃N₄ composites exhibit the enhanced photocatalytic activities under visible-light irradiation. Moreover, the optimal dosage of Ag₂CO₃ in the D–CN–xAg composite is found to be 5%, the corresponding hydrogen production capacity is 153.33 μmol g⁻¹ h⁻¹, which is 4.6 times higher than that of Z–CN–5%Ag composite. This might be attributed to appropriate content of metallic Ag and more active sites exposed on the surface of D–CN–5%Ag composite. Meanwhile, combining with photoelectrochemical results, it could be inferred that LSPR effect and the intimate interfacial between metallic Ag and g-C₃N₄ in the system play also important role for the improvement of photocatalytic activity. These results demonstrate that the appropriate loading of metallic Ag originated from Ag₂CO₃ into g-C₃N₄ could accelerate the separation and transfer of photogenerated electron-hole pairs, leading to the improvement of photocatalytic activity for hydrogen production from water splitting. Finally, a possible photocatalytic mechanism is proposed.     

0D/2D heterojunction constructed by high-dispersity Mo-doped Ni2P nanodots supported on g-C3N4 nanosheets towards enhanced photocatalytic H2 evolution activity

Development of low cost and efficient non-noble-metal cocatalyst is still a hot topic to improve the activity of g-C₃N₄ in photocatalytic water splitting to produce H₂. As a potential cocatalyst in photocatalytic application, transition metal phosphides (TMPs) have been proved to greatly enhance the photocatalytic H₂ evolution performance comparable to noble metal Pt. Modifying TMPs by incorporation of hetero-metal has also been reported as an effective strategy for their electronic structure regulation and optimizing the intermediates absorption energy, however, which is rarely reported in the field of photocatalysis. Herein, the 0D/2D heterojunction is constructed by high-dispersity Mo-doped Ni₂P nanodots supported on g-C₃N₄ nanosheets, which exhibits the significantly improved photocatalytic H₂ evolution performance compared with that of Ni₂P/g-C₃N₄ and Pt/g-C₃N₄. Specifically, the optimal H₂ evolution rate reaches 67.6 μmol h⁻¹ over Mo–Ni₂P/g-C₃N₄ sample, which is 6.0 and 2.4 times higher than those of Pt/g-C₃N₄ and Ni₂P/g-C₃N₄, respectively. The fascinating result mainly stems from the improved separation efficiency of charge carriers and more effective electron donating reaction sites resulted from the electronic structure adjustment through doping Mo element into Ni₂P as cocatalyst. This work provides a valid evidence for the modification of cocatalyst to realize high H₂ evolution performance, opening up new opportunities and possibilities for the application of TMPs in the photocatalytic field.     

Non-noble-metal Ni nanoparticles modified N-doped g-C3N4 for efficient photocatalytic hydrogen evolution

The use of non-noble-metal to replace precious metal as co-catalyst in solar-driven hydrogen evolution reaction (HER) is important for lowering hydrogen production cost. In this work, nickel metal nanoparticles loaded nitrogen-doped graphite carbon nitride (NiNCN3) was prepared, which significantly enhanced the HER activity of nitrogen-doped graphite carbon nitride. The hydrogen evolution rate of NiNCN3 can reach to 1507 μmol g⁻¹ h⁻¹, much higher than that of 3 wt % Pt/NCN (1055 μmol g⁻¹ h⁻¹). The distinguished photocatalytic performance is due to the accelerated electron transfer efficiency and inhibited photogenerated electron-hole recombination. Our study offers an alternative method to achieve the low-cost and effective noble-metal-free photocatalyst for HER.     

The charge transfer pathway of g-C3N4 decorated Au/Bi(VO4) composites for highly efficient photocatalytic hydrogen evolution

In this report, a novel g-C₃N₄/Au/BiVO₄ photocatalyst has been prepared successfully by assembling gold nanoparticles on the interface of super-thin porous g-C₃N₄ and BiVO₄, which exhibits outstanding photocatalytic performance toward hydrogen evolution and durable stability in the absence of cocatalyst. FESEM micrograph analysis suggested that the intimate contact between Au, BiVO₄, and g-C₃N₄ in the as-developed photocatalyst allows a smooth migration and separation of photogenerated charge carriers. In addition, the XRD, EDX and XPS analysis further confirmed the successful formation of the as-prepared g-C₃N₄/Au/BiVO₄ photocatalyst. The photocatalytic hydrogen production activity of the developed photocatalyst was evaluated under visible-light irradiation (λ > 420 nm) using methanol as a sacrificial reagent. By optimizing the 5-CN/Au/BiVO₄ composite shows the highest H₂ evolution rate (2986 μmolg⁻¹h⁻¹), which is 15 times higher than that of g-C₃N₄ (199 μmolg⁻¹h⁻¹) and 10 time better than bare BiVO₄ (297 μmolg⁻¹h⁻¹). The enhancement in photocatalytic activity is attributed to efficient separation of the photoexcited charges due to the anisotropic junction in the g-C₃N₄/Au/BiVO₄ system. The enhancement in photocatalytic activity is attributed to efficient separation of the photoexcited charges due to the anisotropic junction in the g-C₃N₄/Au/BiVO₄ system.     

Constructing g-C3N4 quantum dots modified g-C3N4/GO nanosheet aerogel for UV-Vis-NIR driven highly efficient photocatalytic H2 production

The development of ultraviolet to near-infrared (UV-Vis-NIR) responsive photocatalysts offers a unique opportunity for the full use of solar energy to solve the energy and the environmental problems. Here, successful preparation of a three-dimensional (3D) porous photocatalyst of graphitic carbon nitride quantum dot (CNQDs) modified g-C₃N₄/graphene oxide composite aerogel (CNGO/CNQDs) via hydrothermal and vacuum injection method was reported. In this unique ternary 3D photocatalyst, graphene oxide could improve the separation of photogenerated electrons and holes and promote the charge separation, while the aerogel's 3D network structure provided a rich active site. Simultaneously, due to the appropriate up-conversion performance of the nitrogen carbide quantum dots, CNGO/CNQDs achieved a light response from ultraviolet (UV) to near-infrared (NIR). These properties endow it with a good photocatalytic performance. The hydrogen production efficiency of CNGO/CNQDs reached 1231 μmol h⁻¹, which was 16 times more than that of matrix material. In addition, the apparent quantum yields (AQY) of CNGO/CNQDs at wavelengths of 420 nm and 700 nm were 13% and 0.116%, respectively.     

1D/2D carbon-doped nanowire/ultra-thin nanosheet g-C3N4 isotype heterojunction for effective and durable photocatalytic H2 evolution

It is still challenging to design effective g-C₃N₄ photocatalysts with high separation efficiency of photo-generated charges and strong visible light absorption. Herein, a simple, template-free and “bottom-up” strategy has been developed to prepare 1D/2D g-C₃N₄ isotype heterojunction composed of carbon-doped nanowires and ultra-thin nanosheets. The ethanediamine (EE) grafted on melamine ensures the growth of 1D g-C₃N₄ nanowires with high carbon doping, and the ultra-thin g-C₃N₄ nanosheets were produced through HCl-assisted hydrothermal strategy. The apparent grain boundary between 2D nanosheets and 1D carbon-doped nanowires manifested the formation of the isotype heterojunction. The built-in electric field provide strong driving force for photogenerated carriers separation. Meanwhile, the doping carbon in g-C₃N₄ nanowires promotes visible light absorption. As a result, the photocatalytic H₂ evolution activity of 1D/2D g-C₃N₄ isotype heterojunction is 8.2 time that of the pristine g-C₃N₄, and an excellent stability is also obtained. This work provides a promising strategy to construct isotype heterojunction with different morphologies for effective photocatalytic H₂ evolution.     

Two dimensional N-doped ZnO-graphitic carbon nitride nanosheets heterojunctions with enhanced photocatalytic hydrogen evolution

The effective separation of photogenerated charge carriers, their transport and interfacial contact is of great significance for excellent performance of semiconductor based photocatalysts. Herein, we report the fabrication of two dimensional (2D) nanosheets heterojunction comprising of N-doped ZnO nanosheets loaded over graphitic carbon nitride (g-C₃N₄) nanosheets for enhanced photocatalytic hydrogen evolution. The prepared 2D-2D heterojunctions with varying amount of g-C₃N₄ nanosheets have been characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and x-ray photoelectron spectroscopy (XPS) techniques. The optimized heterojunction photocatalyst with 30 wt% of g-C₃N₄ nanosheets (NZCN30) exhibit hydrogen evolution rate of 18836 μmol h^?1 g_cat^?1 in presence of Na₂S and Na₂SO₃ as sacrificial agents under simulated solar light irradiation. The enhanced photocatalytic performance of NZCN30 heterojunction has been supported well by photoluminescence and photoelectrochemical investigations, which shows the minimum recombination rate and high photoinduced current density, respectively. In addition, the existence of 2D-2D interfacial contact plays a major role in enhanced H₂ evolution by high face-to-face contact surface area for separation of photogenerated charge carriers in space which facilitate their transfer for H₂ generation. This work paves way for the development of 2D-2D heterojunctions for diverse applications.     

Recent advances in g-C3N4-based photocatalysts for hydrogen evolution reactions

Graphitic carbon nitride (g-C₃N₄), having unique properties, like suitable electronic band structure, ease of functionalization, easy synthesis, and high stability is a polymeric semiconductor. These properties make it suitable to act as a photocatalyst and have attracted researchers to use it for hydrogen evolution reactions (HER). This review provides the recent advances (2019 onwards) in the development of g-C₃N_4-based photocatalysts to be employed for HER, starting with the fundamentals of g-C₃N₄, designing and engineering g–C₃N₄–based photocatalysts categorized as doped-g-C₃N_4, composites of g-C₃N₄, and engineered-g-C₃N₄ are discussed. Analysis of characteristics and advantages of g-C₃N_4-based heterojunctions is also provided, followed by current challenges and future perspectives, leading to the conclusion. It is expected to offer valuable information for rational design of novel and efficient g-C₃N_4-based photocatalysts for visible-light-driven HER.     

Z-scheme MoO3-2D SnS nanosheets heterojunction assisted g-C3N4 composite for enhanced photocatalytic hydrogen evolutions

In this work, the 2D SnS/g-C₃N₄ nanosheets have been successfully prepared by a facile ultrasonic and microwave heating approach, which formed intimate interfacial contact and suitable energy band structure. The optimized sample displayed enhanced photocatalytic hydrogen evolution from water assisted with Pt co-catalyst, which is much higher than that of pure g-C₃N₄. After loaded with MoO₃ particles, the stability of photocatalysts displayed significate improvement due to the formed Z-scheme heterojunction. With the characterization, the enhanced hydrogen evolution reaction (HER) performance might be ascribed to the improved light-harvesting capability of the composite, lowered charge-transfer resistance, increased electrical conductivity and the co-catalyst effect of SnS. This study provides insights about SnS assisted HER photocatalysts and a new strategy to improve the stability of metal sulfides photocatalysts.