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.     

Integrating optimal amount of carbon dots in g-C3N4 for enhanced visible light photocatalytic H2 evolution

Carbon dots (CDs) hold great promise for photocatalytic application owning to their low production cost, unique optical properties, as well as excellent stability and conductivity. Integrating CDs in graphite carbon nitride (g-C₃N₄) nanosheets helps to broaden visible light absorption, retard charge recombination and promote photoelectrons transport. Herein, we demonstrated a simple strategy to introduce CDs on g-C₃N₄ nanosheets by hydrothermal treatment of ginkgo leaves followed by thermal polymerization of urea. We found that there was were two volcano-trends in the photocatalytic H₂ evolution rate with the increase of CDs loading. As a result, the optimized CDs/g-C₃N₄ nanocomposites demonstrated a superior hydrogen evolution rate as high as 3.12 mmol g^?1·h^?1 and 14.4% apparent quantum efficiency (AQE) was achieved at 420 nm visible light irradiation. The contribution of CDs towards the photocatalytic hydrogen evolution enhancement was discussed in depth via experiment characterization and Density functional theory (DFT) calculation. This work may shed light on the rational design and bottom-up synthesis of eco-friendly energy conversion materials with high-performance and low cost.     

ZnCr LDH nanosheets modified graphitic carbon nitride for enhanced photocatalytic hydrogen production

ZnCr layered double hydroxides (ZnCr LDH) nanosheets modified graphitic carbon nitride (g-C₃N₄) nanohybrids were fabricated via a self-assembly procedure through electrostatic interaction between these two components. Such 2D-2D inorganic-organic hybrid material was employed for photocatalytic hydrogen production under visible light for the first time. The physical and photophysical properties of the hybrid nanocomposites were investigated to reveal the effect of ZnCr LDH nanosheets on the photocatalytic activities of g-C₃N₄. It was found that 1 wt% ZnCr LDH nanosheets modified g-C₃N₄ was optimal for the formation of intimate interfacial contact. The visible light photocatalytic H₂ production activity over g-C₃N₄ was enhanced about 2.8 times after ZnCr LDH nanosheets modification. The significant enhancement in photocatalytic performance for ZnCr LDH/g-C₃N₄ heterojunction should be attributed to the promoted charge transfer and separation efficiency, resulting from the intimate interfacial contact and Type II band alignment between ZnCr LDH and g-C₃N₄.     

Redox couple mediated charge carrier separation in g-C3N4/CuO photocatalyst for enhanced photocatalytic H2 production

Graphitic carbon nitride (g-C₃N₄) is one of the promising two-dimensional metal-free photocatalysts for solar water splitting. Regrettably, the fast electron-hole pair recombination of g-C₃N₄ reduces their photocatalytic water splitting efficiency. In this work, we have synthesized the CuO/g-C₃N₄ heterojunction via wet impregnation followed by a calcination method for photocatalytic H₂ production. The formation of CuO/g-C₃N₄ heterojunction was confirmed by XRD, UV–vis and PL studies. Notably, the formation of heterojunction not only improved the optical absorption towards visible region and also enhanced the carrier generation and separation as confirmed by PL and photocurrent studies. The photocatalytic H₂ production results revealed that CuO/g-C₃N₄ photocatalyst demonstrated the increased photocatalytic H₂ production rate than bare g-C₃N₄. The maximum H₂ production rate was obtained with 4 wt % CuO loaded g-C₃N₄ photocatalyst. Importantly, the rate of H₂ production was further improved by introducing simple redox couple Co²⁺/Co³⁺. Addition of Co²⁺ during photocatalytic H₂ production shuttled the photogenerated holes by a reversible conversion of Co²⁺ to Co³⁺ with accomplishing water oxidation. The effective shuttling of photogenerated holes decreased the election-hole pair recombination and thereby enhancing the photocatalytic H₂ production rate. It is worth to mention that the addition of Co²⁺ with 4 wt % CuO/g-C₃N₄ photocatalyst showed ∼7.5 and ∼2.0 folds enhanced photocatalytic H₂ production rate than bare g-C₃N₄/Co²⁺ and CuO/g-C₃N₄ photocatalysts. Thus, we strongly believe that the present simple redox couple mediated charge carrier separation without using noble metals may provide a new idea to reduce the recombination rate.     

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.     

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.     

Composite of g-C3N4 and poly(3-hexylthiophene) prepared by polymerizing thiophene-3-acetic acid treated g-C3N4 and 3-hexylthiophene for enhanced photocatalytic hydrogen production

Composite of g-C₃N₄ and poly(3-hexylthiophene) (P3HT) with enhanced photocatalytic H₂ production activity was prepared by polymerizing 3-hexylthiophene and g-C₃N₄, which was treated with thiophene-3-acetic acid (T3A). The morphology, chemical structure, and light absorption properties of samples were characterized by SEM, TEM, BET, XRD, FT-IR, XPS, UV–visible diffuse reflectance spectra (UV–vis). The migration and separation efficiency of charge carriers were characterized by photoluminescence (PL) emission spectra, Time resolved photoluminescence spectra, transient photocurrent responses, and electrochemical impedance spectroscopy (EIS). The photocatalytic activity of the catalysts were tested as the H₂ evolution rate from water under visible light irradiation in the presence of triethanolamine as sacrifice agent. The results indicated that g-C₃N₄-P3HT composite shows significant enhanced migration and separation efficiency of charge carriers, and photocatalytic H₂ production activity from water. The intrinsic nature causing the significance enhanced photocatalytic performance was discussed. Our findings here may provide a new strategy to design composite photocatalyst with high photocatalytic activity.     

Facile one-step synthesis of porous graphene-like g-C3N4 rich in nitrogen vacancies for enhanced H2 production from photocatalytic aqueous-phase reforming of methanol

Exfoliation of bulk graphitic carbon nitride (g-C₃N₄) to single- or few-layered structures is an effective way to improve the photocatalytic performance. However, the synthesis methods for few-layer g-C₃N₄ are relatively complicated and time-consuming, with the bandgap of g-C₃N₄ increasing through quantum size effects, thus hampering effective utilization of visible light. To effectively exfoliate the bulk g-C₃N₄ to single or few-layered structures in a facile way without losing its visible light absorption ability is still a challenge. Herein, porous graphene-like g-C₃N₄ nanosheets with abundant nitrogen vacancies were prepared by facile thermal polymerization of melamine using graphene oxide (GO) as a sacrificial template. The two-dimensional (2D) layer morphology and nitrogen defect structure were proved using AFM, SEM, TEM, EA, XPS and EPR techniques. Compared with the bulk g-C₃N₄, the as-prepared g-C₃N₄ nanosheet possesses a high specific surface area, enhanced absorption ability of visible light, and elevated charge carrier generation and separation efficiency because of the unique structural features. The in situ DRIFT spectrum indicates that the surface nitrogen vacancies also serve as excellent locations for methanol adsorption and activation. Consequently, an excellent photocatalytic activity of hydrogen production from methanol aqueous-phase reforming is obtained, which is about 14 times more productive than the bulk g-C₃N₄.     

Influence of Rh nanoparticle size and composition on the photocatalytic water splitting performance of Rh/graphitic carbon nitride

The effect of Rh co-catalyst nanoparticle size for photocatalytic water splitting using graphitic carbon nitride (g-C₃N₄) as light absorber was investigated. Rh nanoparticles with sizes in the 4–9 nm range were synthesized and deposited on g-C₃N₄. The light-absorption properties of the g-C₃N₄ and the particle size of Rh supported on g-C₃N₄ were also not influenced by the catalyst synthesis procedures. Rh/C₃N₄ is active in the photocatalytic splitting of water using visible light. The activity for H₂ generation does not depend on Rh particle size. The results obtained point to two important design criteria for a successful photocatalyst: firstly, the surface of the semiconductor should support a sufficient number of Rh nanoparticles to remove the photogenerated electrons before their recombination with holes; secondly, the nanoparticles should be metallic in nature to catalyze the proton-electron transfer reaction to generate adsorbed H atoms. Surface oxidation of the Rh nanoparticles substantially lowers their photocatalytic activity.     

Carbon vacancies improved photocatalytic hydrogen generation of g-C3N4 photocatalyst via magnesium vapor etching

Vacancies engineering was widely reported as the promising strategy for the improvement of the photocatalytic performance of semiconductor photocatalysts. In current work, carbon vacancies are constructed successfully in graphitic carbon nitride (g-C₃N₄) photocatalyst via magnesium vapor etching. Experimental results show that the formed carbon vacancies in g-C₃N₄ photocatalyst can significantly improve the photocatalytic H₂ generation performance. XRD, FTIR, SEM/TEM, XPS and PL characterization data are employed to evidence the construction of carbon vacancies, which are revealed to be the reason for the enhancement of photocatalytic H₂ evolution. This work develops an alternative route to construct carbon vacancies in g-C₃N₄ materials and gives an insight into the influence of vacancies on the photocatalytic performance of photocatalysts.     

An efficient exfoliation method to obtain graphitic carbon nitride nanosheets with superior visible-light photocatalytic activity

Graphitic carbon nitride (g-C₃N₄) has a promising application in the photocatalytic field due to its large aspect ratio and the favorable band gap energy. Herein, g-C₃N₄ nanosheets (g-C₃N₄ NS) with high photoactivity are obtained with the aid of isopropanol (IPA) in the synthesis process. The introduced IPA causes a more intense oxidation in the exfoliation process and the obtained g-C₃N₄ NS owns its unique properties of a broaden absorption range of visible light, an enlarged surface area and the irregular surface. As a result, the g-C₃N₄ NS has good photocatalytic activity in the degradation of organic pollutant. Moreover, the photocatalytic hydrogen evolution rate of g-C₃N₄ NS is three times as that of g-C₃N₄ NS* synthesized without IPA using the same method.     

Synthesis and characterization of composite visible light active photocatalysts MoS2–g-C3N4 with enhanced hydrogen evolution activity

Molybdenum disulfide (MoS₂) and graphitic carbon nitride (g-C₃N₄) composite photocatalysts were prepared via a facile impregnation method. The physical and photophysical properties of the MoS₂–g-C₃N₄ composite photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microcopy (HRTEM), ultraviolet–visible diffuse reflection spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) spectroscopy. The photoelectrochemical (PEC) measurements were tested via several on–off cycles under visible light irradiation. The photocatalytic hydrogen evolution experiments indicate that the MoS₂ co-catalysts can efficiently promote the separation of photogenerated charge carriers in g-C₃N₄, and consequently enhance the H₂ evolution activity. The 0.5wt% MoS₂–g-C₃N₄ sample shows the highest catalytic activity, and the corresponding H₂ evolution rate is 23.10 μmol h⁻¹, which is enhanced by 11.3 times compared to the unmodified g-C₃N₄. A possible photocatalytic mechanism of MoS₂ co-catalysts on the improvement of visible light photocatalytic performance of g-C₃N₄ is proposed and supported by PL and PEC results.     

AQ-coupled few-layered g-C3N4 nanoplates obtained by one-step mechanochemical treatment for efficient visible-light photocatalytic H2O2 production

Solar-driven photocatalytic H₂O₂ production is a sustainable and clean technique with respect to the traditional route. Here, the efficient H₂O₂ generation was accomplished by π?π coupling of AQ onto the few-layered graphitic carbon nitride (g-C₃N₄) nanoplates through one-step mechanochemical treatment. A H₂O₂ generation rate of 231 μM h^?1 was obtained using AQ-coupled g-C₃N₄ nanoplates under visible light illumination, exceeding that of the g-C₃N₄ nanoplates and bulk g-C₃N₄ by 7-time and 14-time, respectively. Experimental results showed that the high oxygen reduction efficiency could be ascribed to the enhanced surface area, more exposed active sites and the distinct AQ roles of the electrons storage and restraining the charge recombination. This work inspired future work in synthesizing H₂O₂ through a sustainable and green route.     

Effectively extending visible light absorption with a broad spectrum sensitizer for improving the H2 evolution of in-situ Cu/g-C3N4 nanocomponents

Photocatalysts with broad spectrum absorption have been desired for a long time due to their ability to absorb more visible light. Herein, we developed an in-situ approach to specifically fabricate Cu nanoparticles onto the exterior surface of g-C₃N₄, followed by sensitization with Erythrosin B, to improve the photocatalytic H₂ evolution of g-C₃N₄ and extend the spectrum absorption. The photocatalytic H₂ evolution rate was significantly promoted, to more than 26 times that of pure g-C₃N₄, and the photocatalytic ability was maintained until reaching a wavelength of 700 nm. The origin of the improved activity was attributed to an in-situ Cu nanoparticle modification, which acts as an electron reservoir, and dye sensitization, which could extend the range of the visible light absorption, preventing charge recombination and enhancing the visible light utilization efficiency. In addition, the photocatalytic stability was investigated, and no significant attenuation was detected after six recycles.     

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.     

Vanadium (V) and Niobium (Nb) as the most promising co-catalysts for hydrogen sulfide splitting screened out from 3d and 4d transition metal single atoms

The options of transition metals as co-catalysts for photocatalytic H₂S splitting are restricted to some noble metals and related compounds which have noticeable achievements despite their high prices. Substituting with cheap transition metals and downsizing the size to single atom level are economic ways to lower the cost. Herein, the s-triazine graphite-like carbon nitride sheet g-C₃N₄ (001) is chosen as the model to study the performances of 3d and 4d transition metal single atoms (TMSA = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd) in H₂S splitting based on density functional theory (DFT) calculations. It is found that low-cost transition metals with industrial relevance (Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Tc, Cd) are completely comparable with noble metals (Ru, Rh, Pd, Ag). Among them, V and Nb are the most promising co-catalysts with good thermodynamic stabilities, favorable responses to visible light, high photoinduced electron-hole separation efficiencies, sufficient potentials for H₂S splitting, and low energy barriers for H₂S dissociation into H₂ and S. The noticeable improved activities of V/g-C₃N₄ and Nb/g-C₃N₄ are attributed to the formation of strong interfacial chemical bonds which could promote electrons transferring to H₂S derivates. In addition, the introduction of photoinduced electrons could further improve the activities of V/g-C₃N₄ and Nb/g-C₃N₄ with more electrons transferring to H₂S derivates. It is expected that this work could provide a helpful guidance to choose appropriate TMSA co-catalysts as references for H₂S splitting.     

Recent progress in g–C3N4–Based materials for remarkable photocatalytic sustainable energy

In recent years, the most appealing way to harvest solar energy via cost-effective, renewable, clean and sustainable technology is the artificial photocatalysis which has drawn multidisciplinary attention to mitigate the upcoming energy disaster and environmental issues in the arena of sustainable development of society. For this purpose, significant progress has been made, regarding the selectivity of photocatalytic energy sources for potential productivity using solar energy pathway, nonetheless it has still become a difficult task for scientists in order to make and resolve the noteworthy problem of increasing global deterioration. According to a recent literature survey, the non-metal based graphitic carbon nitride (g-C₃N₄) as a fascinating conjugated polymer based photocatalyst has emerged as a new research hotspot in the form of viable option related to its earth abundant elements, good stability, and ease in fabrication. Still, there are many disadvantages associated with g-C₃N₄, such as rapid recombination of photoexcited electron-hole pairs, which ultimately affect the photocatalytic hydrogen (H₂) and carbon dioxide (CO₂) conversion under solar illumination. Previously published several reviews only emphasize the proficient use of g-C₃N₄ photocatalyst for overall sustainable energy production as an effective treatment strategy. But the literature has never been addressed the use of g-C₃N₄ with different morphological and structural characteristics for simultaneous H₂ production and carbon dioxide reduction. Therefore, the proper designing and development of novel photocatalysts with proper surface tuning and intrinsic properties towards efficient energy harvesting is of utmost interest. This review article is basically designed to properly address the existing issues and the recent progress of g-C₃N₄ through various strategies with the aim of obtaining a robust and resourceful photocatalyst towards sustainable energy production. In this context, we had a clear debate regarding the proper tuning of g-C₃N₄ based photocatalysts through various fabrication strategies, such as electronic structure via metals/non-metals doping, defects engineering, carbon dots, etc. along with Z-scheme heterojunctions, bimetallic cocatalyst, and organic metal-organic framework. At the end, this review is devoted to sufficiently summarizing the recent advancements and the possible future recommendation of the fundamental contribution of g-C₃N₄ in a wide variety of sustainable energy production fields.     

g-C3N4/B doped g-C3N4 quantum dots heterojunction photocatalysts for hydrogen evolution under visible light

Developing high activity and eco-friendly photocatalysts for water splitting is still a challenge in solar energy conversion. In this paper, B doped g-C₃N₄ quantum dots (BCNQDs) were prepared via a facile molten salt method using melamine and boron oxide as precursors. By introducing BCNQDs onto the surface of g-C₃N₄, g-C₃N₄/BCNQDs heterojunction was constructed via hydrothermal treatment. The resulting g-C₃N₄/BCNQDs heterojunction exhibits enhanced hydrogen evolution performance for water splitting under visible light irradiation. The mechanism underlying the improved photocatalytic activity was explored and discussed based on the formation of heterojunction between g-C₃N₄ and BCNQDs with well-matched band structure.     

Properly aligned band structures in B-TiO2/MIL53(Fe)/g-C3N4 ternary nanocomposite can drastically improve its photocatalytic activity for H2 evolution: Investigations based on the experimental results

The development of new tools that could meet the demand of sustainable energy production has attracted worldwide scientific attention. Over the past few decades, significant research efforts have been carried out to efficiently reduce water to H₂ (green fuel) over semiconductor photocatalysts. Numerous semiconductor photocatalysts have been employed in photocatalysis for optimum H₂ production. All the techniques were chosen based on their flexibility, cost-effectiveness, and ease of availability. Recently, polymeric carbon nitride (g-C₃N₄) received worldwide attention in visible light photocatalysis for energy and environmental applications due to its low price, robust nature, and superior thermal stability. Nevertheless, g-C₃N₄ (CN) exhibits shortfalls such as high charge carrier's recombination rate and weak reduction ability. To overcome these drawbacks, herein, for the first time we have fabricated B-TiO₂/MIL-53(Fe)/CN ternary composite via hydrothermal and wet-chemical methods. The resultant B-TiO₂/MIL53(Fe)/CN ternary composite shows drastically improved photocatalytic activity for hydrogen evolution compared to the bare CN, B-TiO_2, and MIL53(Fe) components. The B-TiO₂/MIL53(Fe)/CN ternary composite produced approximately 166.3 and 581.2 μmol h^?1 g^?1 of hydrogen under visible light and UV–visible light irradiations, respectively, with the assistance of co-catalyst Pt. Photo-luminescence (PL) and the fluorescence (FL) spectroscopy measurements reveal that the enhanced photoactivity is due to the greatly promoted charge carrier's separation and transfer at the interfacial contact of the well-aligned three-component systems. This work will promote the design and development of efficient photocatalyst based on CN for clean energy production and environmental purification.     

A novel CoSeO3 photocatalyst assisting g-C3N4 in enhancing hydrogen evolution through Z scheme mode

A novel CoSeO₃/g-C₃N₄ composite photocatalyst with Z-scheme heterostructure is constructed through electrostatic self-assembly to be utilized in photocatalytic hydrogen evolution. The optimal photocatalytic H₂ evolution rate of CoSeO₃/g-C₃N₄ hybrids and apparent quantum yield (AQY) have raised about 65.4 times under full light irradiation with no noble metal cocatalyst loading than that of pure g-C₃N₄. The CoSeO₃ semiconductor is firstly prepared for assisting to elevate the photocatalytic hydrogen evolution activity. After combining with g-C₃N₄, CoSeO₃/g-C₃N₄ hybrids with a sheet-sheet structure enhance the contact area with water and broaden the light absorption region as well as reduce transfer resistance of carriers. Moreover, the photo generated carriers possess a typical direct Z scheme transmission, which decreases the recombination of electrons and holes. This work offers a new choice for constructing a Z scheme heterostructure to apply in photocatalytic water reduction, and offers a deep view to explain the elevated photocatalytic activity.