Bimetallic PtNi/g-C3N4 nanotubes with enhanced photocatalytic activity for H2 evolution under visible light irradiation

Bimetallic PtNi-decorated graphitic carbon nitride (g-C₃N₄) nanotubes were prepared through calcining the mixture of urea and thiourea in the presence of Pluronic F127, followed by deposition of bimetallic PtNi nanoparticles (NPs) via chemical reduction. It is found that the photocatalytic activity of PtNi/g-C₃N₄ nanotubes is strongly dependent on the molar ratio of Pt/Ni and the highest activity is observed for Pt₁Ni₁/g-C₃N₄. Under visible light (λ > 420 nm) irradiation, the H₂ generation rate over Pt₁Ni₁/g-C₃N₄ nanotubes is 104.7 μmol h^?1 from a triethanolamine (10 vol%) aqueous solution, which is higher than that of Pt/g-C₃N₄ nanotubes (98.6 μmol h^?1) and is about 47.6 times higher than that of pure g-C₃N₄ nanotubes. The cyclic photocatalytic reaction indicates that our Pt₁Ni₁/g-C₃N₄ nanotubes function as a stable photocatalyst for visible light-driven H₂ production. The effect of bimetallic PtNi NPs in the transfer and separation of photogenerated charge carriers occurring in the excited g-C₃N₄ nanotubes was investigated by performing photo-electrochemical and photoluminescence measurements. Our results reveal that bimetallic PtNi could replace Pt as a promising cocatalyst for photocatalytic H₂ evolution with better performance and lower cost.     

In situ fabrication of CDs/g-C3N4 hybrids with enhanced interface connection via calcination of the precursors for photocatalytic H2 evolution

Novel carbon dots (CDs)/graphitic carbon nitride (g-C₃N₄) hybrids were fabricated via an in situ thermal polymerization of the precursors, urea and glucose. This heterojunction catalyst exhibited enhanced photocatalytic H₂ evolution activity under visible-light (λ > 420). A sample of CDs/g-C₃N₄ hybrids, CN/G0.5, which was prepared from 0.5 mg of glucose in 6.0 g of urea (8.3 × 10^?3 wt% glucose), exhibited the best photocatalytic performance for hydrogen production from water under visible light irradiation, which is about 4.55 times of that of the bulk g-C₃N₄ (BCN). The improvement of photocatalytic activity was mainly attributed to the construction of built-in electric field at the interface of CDs and g-C₃N₄, which could improve the separation of photogenerated electron-hole pair. Moreover, the tight connection of CDs with g-C₃N₄ would serve as a well electron transport channel, which could promote the photocatalytic H₂ evolution ability.     

Improved photocatalytic H2 production assisted by aqueous glucose biomass by oxidized g-C3N4

Chemically modified g-C₃N₄ for the photocatalytic H₂ evolution from water was explored. Bulk g-C₃N₄ was treated in hot HNO₃ aqueous solution to obtain the oxidized material (o-g-C₃N₄), tested in water containing glucose as model water-soluble sacrificial biomass, using Pt as co-catalyst, under simulated solar light. The behaviour of o-g-C₃N₄ was studied in relation with catalyst amount, Pt loading, glucose concentration. Results showed that H₂ production is favoured by increasing glucose concentration up to 0.1 M and Pt loading up to 3 wt%, and it resulted strongly enhanced using small amount of o-g-C₃N₄ (0.25 g L^?1). o-g-C₃N₄ possesses superior photocatalytic activity (～26-fold higher) compared to pristine g-C₃N₄, with H₂ evolution further improved by ultrasound-assisted exfoliation and evolution rates up to ca. 1370 μmol h^?1 per gram of catalyst, with excellent reproducibility (RSD < 6%, n = 3). Significant production was observed also in river water and seawater, with results far better (up to ca. 2500 μmol g^?1 h^?1) compared to commercial AEROXIDE^® P25 TiO₂ under natural solar light.     

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.     

In-situ growth of mesoporous Nb2O5 microspheres on g-C3N4 nanosheets for enhanced photocatalytic H2 evolution under visible light irradiation

Large-surface-area mesoporous Nb₂O₅ microspheres were successfully grown in-situ on the surface of g-C₃N₄ nanosheets via a facile solvothermal process with the aid of Pluronic P123 as a structure-directing agent. The resultant g-C₃N₄/Nb₂O₅ nanocomposites exhibited enhanced photocatalytic activity for H₂ evolution from water splitting under visible light irradiation as compared to pure g-C₃N₄. The optimal composite with 38.1 wt% Nb₂O₅ showed a hydrogen evolution rate of 1710.04 μmol h^?1 g^?1, which is 4.7 times higher than that of pure g-C₃N₄. The enhanced photocatalytic activity could be attributed to the sufficient contact interface in the heterostructure and large specific surface area, which leads to effective charge separation between g-C₃N₄ and Nb₂O₅.     

WO3/g-C3N4 two-dimensional composites for visible-light driven photocatalytic hydrogen production

WO₃/g-C₃N₄ two-dimensional (2D) composite photocatalysts were prepared through a simple hydrothermal method followed by a post thermal treatment. The H₂ generation activity of these photocatalysts in the visible light was evaluated. The photocatalysts were characterized by X-ray powder diffraction, Fourier transform infrared spectra, transmission electron microscopy and UV–vis diffuse reflectance spectroscopy et al. These results show that the orthorhombic-phase WO₃ nanoparticles with a grain size from 5 to 80 nm were successfully anchored on g-C₃N₄ nanosheets surface with intimate contact. Furthermore, the charge separation mechanisms of photo-generated charge carriers of the 2D WO₃/g-C₃N₄ photocatalysts were further studied by photoelectrochemical response and electrochemical impedance spectroscopy. The result shows that the 2D WO₃/g-C₃N₄ photocatalyst with 10 wt% WO₃ possesses the maximum photocatalytic performance for H₂ generation, as high as of 1853 μmol h^?1 g^?1, which is about 6.5 times higher than that of bare g-C₃N₄, indicating the fast injection of interface interaction between 2D g-C₃N₄ and WO₃. The increased photocatalytic performance of the composite photocatalyst can be attributed to the enhanced absorption of visible light, the higher photo-generated electrons and holes separation efficiency and low recombination rate of electrons and holes generated by photoexcitation.     

A facile dissolution strategy facilitated by H2SO4 to fabricate a 2D metal-free g-C3N4/rGO heterojunction for efficient photocatalytic H2 production

A 2D g-C₃N₄(pPCN)/rGO heterojunction for photocatalytic hydrogen production is fabricated by a facile dissolution strategy facilitated by H₂SO₄. The bulk g-C₃N₄ (CN) can be directly exfoliated into ultrathin protonated g-C₃N₄ (PCN) nanosheets under the assistance of H₂SO₄, and PCN can be further modified by rGO in a dissolved state under the electrostatic self-assembly process. The nanocomposite exhibits a large surface area (146.47 m²/g) and intimate contact interfaces between pPCN and rGO due to the specific synthesis method. Based on the DRS, PL and photoelectrochemical analyses, the introduction of rGO can greatly improve the light absorption and photogenerated charge carrier separation and transfer of g-C₃N₄. The optimal pPCN/2 wt% rGO nanocomposite shows an efficient photocatalytic H₂ evolution rate of 715 μmol g^?1 h^?1 under visible light irradiation, which is 2.6 and 13 times higher than those obtained on pPCN and CN. In addition, a photocatalytic mechanism over a 2D pPCN/rGO heterojunction is proposed. This work offers a new effective strategy for fascinating gC₃N₄based nanocomposites with promising hydrogen generation.     

Active-center-enriched Ni0.85Se/g-C3N4 S-scheme heterojunction for efficient photocatalytic H2 generation

Photocatalysts with abundant active sites are essential for photocatalytic H₂ evolution from water. Herein, Ni_0.85Se-deposited g-C₃N₄ was obtained by a physical solvent evaporation method. The investigation shows that Ni_0.85Se with unsaturated active Se atoms can significantly improve the photocatalytic activity of g-C₃N₄, and the H₂ production rate of Ni_0.85Se/g-C₃N₄ can reach 8780.3 μmol g^?1 h^?1, which is 3.5 and 92.9 times higher than that of Ni_0.85+xSe/g-C₃N₄ (2497.9 μmol g^?1 h^?1) and pure g-C₃N₄ (94.5 μmol g^?1 h^?1), respectively. This improvement can be attributed to the quick charge transfer between Ni_0.85Se and g-C₃N₄ with S-scheme heterojunction feature based on a series of trapping experiments and photoelectrochemical analysis. Moreover, abundant unsaturated Se atoms could provide more H₂ evolution active sites. This work sheds light on the construction of heterojunctions with abundant active sites for H₂ production.     

Construction of ternary hybrid layered reduced graphene oxide supported g-C3N4-TiO2 nanocomposite and its photocatalytic hydrogen production activity

Reduced graphene oxide (rGO) supported g-C₃N₄-TiO₂ ternary hybrid layered photocatalyst was prepared via ultrasound assisted simple wet impregnation method with different mass ratios of g-C₃N₄ to TiO₂. The synthesized composite was investigated by various characterization techniques, such as XRD, FTIR, Raman Spectra, FE-SEM, HR-TEM, UV vis DRS Spectra, XPS Spectra and PL Spectra. The optical band gap of g-C₃N₄-TiO₂/rGO nanocomposite was found to be red shifted to 2.56 eV from 2.70 eV for bare g-C₃N₄. It was found that g-C₃N₄ and TiO₂ in a mass ratio of 70:30 in the g-C₃N₄-TiO₂/rGO nanocomposite, exhibits the highest hydrogen production activity of 23,143 μmol g^?1h^?1 through photocatalytic water splitting. The observed hydrogen production rate from glycerol-water mixture using g-C₃N₄-TiO₂/rGO was found to be 78 and 2.5 times higher than g-C₃N₄ (296 μmol g^?1 h^?1) and TiO₂ (11,954 μmol g^?1 h^?1), respectively. A direct contact between TiO₂ and rGO in the g-C₃N₄-TiO₂/rGO nanocomposite produces an additional 10,500 μmol g^?1h^?1 of hydrogen in 4 h of photocatalytic reaction than the direct contact between g-C₃N₄ and rGO. The enhanced photocatalytic hydrogen production activity of the resultant nanocomposite can be ascribed to the increased visible light absorption and an effective separation of photogenerated electron-hole pairs at the interface of g-C₃N₄-TiO₂/rGO nanocomposite. The effective separation and transportation of photogenerated charge carriers in the presence of rGO sheet was further confirmed by a significant quenching of photoluminescence intensity of the g-C₃N₄-TiO₂/rGO nanocomposite. The photocatalytic hydrogen production rate reported in this work is significantly higher than the previously reported work on g-C₃N₄ and TiO₂ based photocatalysts.     

Ternary Ni2P/reduced graphene oxide/g-C3N4 nanotubes for visible light-driven photocatalytic H2 production

Developing low cost co-catalysts is crucial for both fundamental research and practical application of g-C₃N₄. In this work, we prepared ternary Ni₂P/rGO/g-C₃N₄ nanotubes with different Ni₂P contents for visible-light-driven photocatalytic H₂ generation from triethanolamine aqueous solution. The optimal Ni₂P/rGO/g-C₃N₄ produced H₂ at a rate of 2921.9 μmol h⁻¹ g⁻¹, which is about 35, 16 and 9 times as large as that of g-C₃N₄, binary rGO/g-C₃N₄ and Ni₂P/g-C₃N₄, respectively. The apparent quantum efficiency of optimal Ni₂P/rGO/g-C₃N₄ was 5.6% at λ = 420 nm. We believe that the improved photocatalytic performance of Ni₂P/rGO/g-C₃N₄ originates from the synergistic effect of rGO as electron transfer medium and Ni₂P as reaction site, which is supported by photoelectrochemical and photoluminescence measurements. Cyclic experiment demonstrated an excellent stability of Ni₂P/rGO/g-C₃N₄. Moreover, we further studied the effect of other nickel-based compounds by replacing Ni₂P with NiS, Ni₃C, and Ni₃N, respectively. The order of the H₂-generation rate is Ni₂P/rGO/CNNT > NiS/rGO/CNNT > Ni₃C/rGO/CNNT > Ni₃N/rGO/CNNT, which could be reasonably explained based on Mott–Schottky plots. Our work reveals that Ni₂P can be used as a promising cocatalyst for photocatalytic H₂ evolution.     

Facile synthesis of AuPd/g-C3N4 nanocomposite: An effective strategy to enhance photocatalytic hydrogen evolution activity

AuPd bimetallic nanoparticle (NP) modified ultra-thin graphitic carbon nitride nanosheet photocatalysts were synthesized via photochemical deposition-precipitation followed by hydrogen reduction. The crystal structure, chemical properties, and charge carrier behavior of these photocatalysts were characterized by X-ray diffraction (XRD), surface photovoltage spectroscopy (SPS), transient photovoltage spectroscopy (TPV), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM), and UV-Vis diffuse-reflectance spectroscopy (DRS). Photocatalytic H₂ evolution experiments indicate that the hydrogen treated AuPd nanoparticles can effectively promote the separation efficiency of electron-hole pairs photo-excited in the g-C₃N₄ photocatalyst, which consequently promotes photocatalytic H₂ evolution. The 1.0 wt% AuPd/g-C₃N₄ (H₂) composite photocatalyst showed the best performance with a corresponding photocatalytic H₂ evolution rate of 107 μmol h^?1. The photocatalyst can maintain most of its photocatalytic activity after four photocatalytic experiment cycles. These results demonstrate that the synergistic effect of light reduction and hydrogen reduction of AuPd and g-C₃N₄ help to greatly improve the photocatalytic activity of the composite photocatalyst.     

In-situ fabrication of CuS/g-C3N4 nanocomposites with enhanced photocatalytic H2-production activity via photoinduced interfacial charge transfer

In this work, novel CuS/g-C₃N₄ composite photocatalysts were successfully prepared via a simple in-situ growth method. CuS nanoparticles, with an average diameter of ca.10 nm, were well dispersed on the surface of g-C₃N₄, revealing that g-C₃N₄ nanosheets were promising support for in-situ growth of nanosize materials. The CuS/g-C₃N₄ composites exhibited highly enhanced visible light photocatalytic H₂ evolution from water-splitting compared to pure g-C₃N₄. The optimum photocatalytic activity of 2 wt% CuS/g-C₃N₄ composite photocatalytic H₂ evolution was about 13.76 times higher than pure g-C₃N₄. The enhanced photocatalytic activity is attributed to the interfacial charge transfer (IFCT). In this system, electrons in the valence band (VB) of g-C₃N₄ can transfer directly to CuS clusters, causing the reduction of partial CuS to Cu₂S, which can act as an electron sink and co-catalyst to promote the separation and transfer of photo-generated electrons. The accumulated photoinduced electrons in CuS/Cu₂S clusters could effectively reduce H⁺ to produce H₂. This work provides a possibility for constructing low-cost CuS as a substitute for noble metals in the photocatalytic production of H₂ via a facile method based on g-C₃N₄.     

Highly efficient visible-light-assisted photocatalytic hydrogen generation from water splitting catalyzed by Zn0.5Cd0.5S/Ni2P heterostructures

Development of heterostructured photocatalysts which can facilitate spatial separation of photo-generated charge carriers is crucial for achieving improved photocatalytic H₂ production. Consequently, herein, we report the synthesis of Zn_0.5Cd_0.5S/Ni₂P heterojunction photocatalysts with varying amount of Ni₂P, 0.5 (S1), 1 (S2), 3 (S3), 5 (S4) and 10wt% (S5) for the efficient visible-light-assisted H₂ generation by water splitting. The heterostructures were characterized thoroughly by PXRD, FE-SEM, EDS, HR-TEM and XPS studies. FE-SEM and HR-TEM analyses of the samples unveiled the presence of Zn_0.5Cd_0.5S microspheres composed of smaller nanocrystals with the surface of the microspheres covered with Ni₂P nanosheets and the intimate contact between the Zn_0.5Cd_0.5S and the Ni₂P. Further, visible-light-assisted photocatalytic investigation of the samples showed excellent water splitting activity of the heterostructure, Zn_0.5Cd_0.5S/1wt%Ni₂P (S2) with very high H₂ generation rate of 21.19 mmol h^?1g^?1 and the AQY of 21.16% at 450 nm with turnover number (TON) and turnover frequency (TOF) of 251,516 and 62,879 h^?1 respectively. Interestingly, H₂ generation activity of S2 was found to be about four times higher than that of pure Zn_0.5Cd_0.5S (5.0 mmol h^?1g^?1) and about 240 times higher than that of CdS/1wt%Ni₂P. The enhanced H₂ generation activity of S2 has been attributed to efficient spatial separation of photogenerated charge carriers and the presence of highly reactive Ni₂P sites on the surface of Zn_0.5Cd_0.5S microspheres. A possible mechanism for the enhanced photocatalytic H₂ generation activity of Zn_0.5Cd_0.5S/1wt%Ni₂P (S2) has been proposed and is further supported by photoluminescence and photocurrent measurements. Furthermore, the catalyst, S2 can be recycled for several cycles without significant loss of catalytic activity and photostability. Remarkably, the H₂ generation activity of S2 was found to be even higher than the reported examples of Zn_xCd_1-xS doped with noble metal cocatalysts. Hence, the present study highlights the importance of Zn_0.5Cd_0.5S/Ni₂P heterostructures based on non-noble metal co-catalyst for efficient visible-light-driven H₂ production from water splitting.     

Facile synthesis of anatase/rutile TiO2/g-C3N4 multi-heterostructure for efficient photocatalytic overall water splitting

Rational design of high-efficiency heterostructure photocatalyst is an effective strategy to realize photocatalytic H₂ evolution from pure water, but remains still a considerable challenge. Herein, an anatase/rutile TiO₂/g-C₃N₄ (A/R/CN) multi-heterostructure photocatalyst was prepared by a facile thermoset hybrid method. The combination of two type-II semiconductor heterostructures (i.e., A/R and R/CN) significantly improve the separation and transfer efficiency of photogenerated carriers of anatase TiO₂, rutile TiO₂ and g-C₃N₄, and A/R/CN photocatalyst with high activity is obtained. The optimal A/R/CN photocatalyst exhibits significantly increased photocatalytic overall water splitting activity with a rate of H₂ evolution of 374.2 μmol g⁻¹h⁻¹, which is about 8 and 4 times that of pure g-C₃N₄ and P25. Moreover, it is demonstrated to be stable and retained a high activity (ca. 91.2%) after the fourth recycling experiment. This work comes up with an innovative perspective on the construction of multi-heterostructure interfaces to improve the overall photocatalytic water splitting performance.     

Facile construction of phosphate incorporated graphitic carbon nitride with mesoporous structure and superior performance for H2 production

Novel mesoporous phosphate incorporated g-C₃N₄ (CNM-Px) polymeric material was synthesized via a facile hydrothermal-calcination method, using melamine as precursor and phosphoric acid as dopant. The successful incorporation of phosphate into the framework of g-C₃N₄ nanosheets was verified by XRD, FT-IR and XPS characterizations and the possible formation mechanism was put forward. The as-fabricated CNM-Px samples were applied to photocatalytic hydrogen evolution reaction and exhibited remarkably improved photocatalytic performance both under simulated sunlight and visible light irradiation. The concentration of phosphoric acid was also well tuned and the optimal concentration was 2.5 mol L^?1. The hydrogen evolution rate of the optimized sample CNM-P2.5 (the concentration of treating phosphoric acid was 2.5 mol L^?1) reached 8163 μmol g^?1 h^?1 under simulated sunlight irradiation, which is 3.7 times higher than that of pristine g-C₃N₄ (CNM). It also showed dramatically improved hydrogen evolution rate under visible light irradiation, which was 2105 μmol g^?1 h^?1, about 6.7 times higher than that of CNM. The excellent photocatalytic activity of CNM-Px samples is due to the synergic advantages of larger surface area and reduced recombination of photo-generated electrons and holes. This study paves the way for tailoring design and synthesis of highly active metal-free carbon nitride materials for photocatalytic hydrogen evolution.     

One-pot sulfurized synthesis of ZnIn2S4/S,N-codoped carbon composites for solar light driven water splitting

To enhance the intrinsic active sites and to suppress the recombination of charge carriers, ZnIn₂S₄ modified with S,N-codoped carbon (ZIS/SN-C) composites were prepared for solar light driven water splitting via the one-pot sulfurized route. Compared with g-C₃N₄ and S-doped g-C₃N₄, the combined effect between S,N-codoped carbon and ZnIn₂S₄ can greatly enhance the photocatalytic activity of ZIS/SN-C. The optimal 4-ZIS/SN-C with the Zn(II) content of 13.78% and the calculated In/Zn molar ratio of 2.03:1 presents the H₂ evolution rate of 2937.1 μmol g^?1 h^?1, which is 2.98 and 23.42 times higher than that of one-pot sulfurized ZnIn₂S₄ and S-doped g-C₃N₄, respectively. However, long-term photo-corrosion induces to the declined durability of 4-ZIS/SN/C for water splitting after three cycles. S vacancies of ZnIn₂S₄ serve as the efficient active sites of H₂ evolution reaction, and S, N-codoped carbon acts as the photo-induced electrons trapper. The one-pot sulfurized approach is thus a potential strategy to fabricate metal sulfide-based photocatalysts.     

In situ metal–organic framework-derived c-doped Ni3S4/Ni2P hybrid co-catalysts for photocatalytic H2 production over g-C3N4 via dye sensitization

Controlled integration of metal-based sulfides with phosphides possessing strong coupling effects is a promising way to accelerate electron transfer by modulating the electronic structures of the host species. In this work, a c-doped Ni₃S₄/Ni₂P (C@Ni₃S₄/Ni₂P) hybrid co-catalyst produced by in situ sulfuration and phosphidation of Ni-MOF was decorated on g-C₃N₄ and subsequently used for photocatalytic H₂ evolution under visible-light irradiation. Among the prepared composites tested herein, the optimized g-C₃N₄/C@Ni₃S₄/Ni₂P-30 composite showed the highest H₂ evolution rate (14.49 mmol g⁻¹ h⁻¹) with 1.0 mmol L⁻¹ of Eosin Y (EY)-sensitization, which is 10 times higher than that of pristine g-C₃N₄ (1.33 mmol g⁻¹ h⁻¹). The enhanced photocatalytic activity of this composite can be attributed to: (i) electronic interactions between Ni₂P and Ni₃S₄ (which synergistically increased the electron transfer rate) and (ii) staggered band alignment of excited-stated EY, g-C₃N₄, Ni₃S₄, and Ni₂P. This work may provide some perspectives for utilization of MOF-derived hybrid co-catalysts as substitutes of noble metals for effective photocatalytic H₂ evolution.     

Hydrogen evolution from hydrolysis of ammonia borane catalyzed by Rh/g-C3N4 under mild conditions

Developing effective catalysts for hydrogen evolution from hydrolysis of ammonia borane (AB) is of great significance considering the useful applications of hydrogen. Herein, graphitic carbon nitride (g-C₃N₄) prepared through the simply pyrolysis of urea was employed as a support for Rh nanoparticles (NPs) stabilization. The in-situ generated Rh NPs supported on g-C₃N₄ with an average size of 3.1 nm were investigated as catalysts for hydrogen generation from the hydrolysis of AB under mild conditions. The Rh/g-C₃N₄ catalyst exhibits a high turnover frequency of 969 mol H₂· (min·mol_Rh)^?1 and a low activation energy of 24.2 kJ/mol. The results of the kinetic studies show that the catalytic hydrolysis of AB over the Rh/g-C₃N₄ catalyst is a zero-order reaction with the AB concentration and a first-order reaction with the Rh concentration. This work demonstrates that g-C₃N₄ is a useful support to design and synthesis of effective Rh-based catalyst for hydrogen-based applications.     

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.     

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.