A first-principles study of electronic structure and photocatalytic performance of two-dimensional van der Waals MTe2–As (M = Mo,W) heterostructures

To efficiently produce green energy and to overcome energy crises and environmental issues, photocatalytic water splitting has become the core heart of recent research. Fabricating heterostructures with type-II band alignment can enhance the photocatalytic activity. By first-principles computations, we study Mo(W)Te₂–As van der Waals (vdW) heterostructures as promising photocatalysts for overall water splitting. The bandgap, band edge position and optical properties can be modified by biaxial strain. With appropriate compressive strain of 2% and 3%, the WTe₂–As heterostructures show transition from type-I to type-II band alignment, which could slow down electron-hole pair recombination. Compared with Mo(W)Te₂ and As monolayers, the band edge of Mo(W)Te₂–As heterostructures is on favorable positions for straddling the water redox potentials. Moreover, Mo(W)Te₂–As heterostructures fascinatingly show strong absorption peaks in both visible and near ultra-violet region, making them promising candidates for overall water splitting photocatalysts.     

Enhanced photocatalytic H2 production activity of CdZnS with stacking faults structure assisted by ethylenediamine and NiS

In order to enhance the visible light-driven photocatalytic H₂ production activity of CdZnS, an ethylenediamine-assisted hydrothermal pathway was used to synthesize CdxZn1-xS(en) with different Cd/Zn molar ratios. It was found out that the prepared Cd_0.5Zn_0.5S(en) possessed the highest photocatalytic H₂ production rate of 13539.0 μmol h^?1 g^?1 that was higher than that of CdZnS. The key to this achievement could be ascribed to the stacking faults formation, the optimum band gap with conduction band position and small crystallite size. Based on this, Cd_0.5Zn_0.5S(en) was modified by NiS for further improving the activity. The obtained Cd_0.5Zn_0.5S(en)NiS with NiS loading content of 0.25 wt% exhibited much higher photocatalytic H₂ production rate, reaching up to 38187.7 μmol h^?1 g^?1 that were among the highest efficiencies for semiconductor photocatalysts ever reported. It was confirmed that the nanosized NiS anchored on Cd_0.5Zn_0.5S(en) interface, acting as electron trapping sites, attributed to the spatial suppressions of electron-hole recombination. Meanwhile, the NiS loaded on the surface optimized the photogenerated electron transfer pathway between the semiconductor materials that gives rise to significantly enhanced photocatalytic activity. This study would put forward a facile method for developing high photocatalytic activity and low-cost catalytic material for H₂ production, which provide a new thought to address the global energy crisis and the environmental contamination.     

Direct Z-scheme photocatalytic overall water splitting on two dimensional MoSe2/SnS2 heterojunction

The direct Z-scheme photocatalysts for overall water decomposition have aroused much concern on account of their strong redox ability and efficient separation of photogenerated electron-hole pairs. In the present work, we have constructed the two dimensional (2D) van der Waals (vdW) MoSe₂/SnS₂ heterojunction and investigated its electronical and optical properties by applying hybrid functional calculations. The calculated band structures have implied that the MoSe₂/SnS₂ heterostructure as a direct Z-scheme photocatalyst can make the best of visible light. The induced built-in electric field can effectively improve the separation efficiency of the photoinduced carriers. Moreover, compared with the MoSe₂ and SnS₂ monolayers, the absorption intensity of MoSe₂/SnS₂ heterojunction is reinforced in the visible light range. Therefore, MoSe₂/SnS₂ nanocomposite shows a bright application prospect as a direct Z-scheme visible-light-driven photocatalyst for overall water splitting.     

Two dimensional MoSSe/BSe vdW heterostructures as potential photocatalysts for water splitting with high carrier mobilities

Production of hydrogen fuel from water splitting driven by solar energy is an effective technique to overcome the energy crisis and environmental problems in coming decades. To explore low cost and efficient photocatalysts is highly desired. In this work, we study the electronic, optical and photocatalytic properties of MoSSe/BSe (Model-1 and Model-2) vdW heterostructures by PBE and HSE06 functionals using first-principle calculations. The stabilities of these heterostructures are confirmed through phonon spectra and ab initio molecular dynamic simulations. The Model-1 and Model-2 heterostructures have indirect band gaps of 1.95 and 1.54 eV respectively by HSE06 hybrid functional. Interestingly, the transition from indirect to direct band gap occurs in Model-1 after including spin-orbit coupling effect. Remarkably, the high carrier mobilities are quantitatively explored by means of deformation potential theory. Furthermore, the transition from type-I to type-II band alignment happens at compressive strain in both Model-1 and Model-2, which effectively slows down the recombination of electron-hole pairs. Compared to the isolated monolayers, the MoSSe/BSe (Model-1 and Model-2) heterostructures harvest maximum portion of visible spectrum, revealing the outstanding paybacks of high efficiency utilization of solar spectrum. Most intriguingly, the band edges of MoSSe/BSe vdW heterostructures meet the redox potential requirements for water splitting. Our results will be valuable for easing the investigation and applications of MoSSe/BSe heterostructures for optoelectronics and photocatalytic water splitting.     

NiSe2/Cd0.5Zn0.5S as a type-II heterojunction photocatalyst for enhanced photocatalytic hydrogen evolution

A designed type-II heterojunction photocatalyst, NiSe₂/Cd_0.5Zn_0.5S (NiSe₂/CZS), was successfully synthesized and it exhibits outstanding photocatalytic hydrogen evolution performance. The optimal loading amount of NiSe₂ on Cd_0.5Zn_0.5S is 13 wt %, and the corresponding hydrogen production rate is approximately 121.01 mmol g^?1 h^?1 under visible light. The heterojunction structure between Cd_0.5Zn_0.5S and NiSe₂ promoted the separation of photogenerated electron-hole pairs, effectively suppressed the photogenerated carrier recombination and endowed the material with excellent interfacial charge transfer properties, thus improving the photocatalytic performance.     

Bamboo-charcoal-loaded graphitic carbon nitride for photocatalytic hydrogen evolution

Crystalline graphitic carbon nitride is an excellent photocatalyst for hydrogen production due to its non-toxicity, stability, elemental abundance, and visible-light response. Herein, we present a new type of composite photocatalysts, eco-friendly bamboo-charcoal-loaded graphitic carbon nitrides to accelerate the separation of electron-hole pairs. The suitable loading of bamboo charcoal on graphitic carbon nitrides shows an increased specific surface area from 85 to 120 m² g^?1, and excellent visible-light photocatalytic hydrogen production activity of 4.1 mmol g^?1 h^?1, which is 2.3 times higher than that of pristine carbon nitride (1.8 mmol g^?1 h^?1). Under irradiation, the photogenerated electrons fast migrate from graphitic carbon nitride to bamboo charcoal through an ohmic contact between them, reducing the recombination of electron-hole pairs. This study highlights the effect of carbonaceous material loading on photocatalytic activity of carbon nitrides and opens an avenue to design efficient loaded photocatalysts with natural abundant materials.     

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.     

Giant enhancement of photocatalytic H2 production over KNbO3 photocatalyst obtained via carbon doping and MoS2 decoration

This paper was designed for the first time to improve the photocatalytic activity of KNbO₃ via carbon doping and MoS₂ decoration simultaneously. The efficient photocatalytic hydrogen production was realized on the MoS₂/C-KNbO₃ composite under simulated sunlight irradiation in the present of methanol and chloroplatinic acid. The optimal composite presents a H₂ production rate of 1300  μmol·g^?1·h^?1, which reaches 260 times that of pure KNbO₃. Characterization results of the synthesized composite indicates that the introduction of a small amount of carbon into the KNbO₃ lattice greatly hinders the recombination of electron-hole pairs. The decoration of MoS₂ further induces the separation of charge carriers via trapping the electron in the conduction band of C-KNbO₃, which is proven by the EIS and transient photocurrent response analyses. The remarkably enhanced separation efficiency of electron-hole pairs is believed to be the origin of the excellent photocatalytic performance, though other changes in surface area and optical property may also contribute the photocatalytic process. This study provides a feasible way for the design and preparation of novel photocatalysts with high efficiency.     

Synthesis and photocatalytic performance of MoS2/Polycrystalline black phosphorus heterojunction composite

As a promising catalyst for solar hydrogen production, black phosphorus (BP) has received widespread attention due to variable band gaps, high carrier mobility, and strong light absorption performance. Herein, we use MoS₂ as a cocatalyst to synthesize BP/MoS₂ catalyst with polycrystalline BP to improve photocatalytic performance under visible light irradiation. A small amount of MoS₂ can reduce the recombination of electron-hole pairs in the composite, increase carrier transport efficiency, and then improve photocatalytic performance. As expected, the 10/0.5 ratio of BP/MoS₂ catalyst exhibits the highest photocatalytic hydrogen evolution performance with a hydrogen evolution rate of 575.4 μmol h^?1 g^?1, which is 2.5 times of pure BP. Based on the results above, a simple method is provided to synthesize low-cost black phosphorus-based photocatalysts.     

Vertically-heterostructured TiO2-Ag-rGO ternary nanocomposite constructed with {001} facetted TiO2 nanosheets for enhanced Pt-free hydrogen production

TiO₂ nanosheets with high ratio of {001} facets were coupled with reduced graphene oxide (rGO) nanosheets through the link of silver (Ag) nanoparticles, forming a novel ternary nanocomposite photocatalyst with a vertical heterostructure, TiO₂-Ag-rGO. The vertical anchoring of TiO₂-Ag nanosheets between rGO sheets was confirmed by transmission electron microscopy (TEM), Raman spectroscopy, energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). Due to excellent separation of electron-hole pairs in the TiO₂ nanosheets, enhanced electron transfer to rGO via Ag nanoparticles, the TiO₂-Ag-rGO nanocomposite exhibited an outstanding performance in photocatalytic hydrogen production, with a hydrogen production rate of 593.56 μmol g^?1 h^?1. This study provides new insights to the development of Pt-free photocatalysts for hydrogen production.     

Two dimensional Janus SGaInSe(SeGaInS)/PtSe2 van der Waals heterostructures for optoelectronic and photocatalytic water splitting applications

Hydrogen generation by photocatalytic water splitting is considered as a viable and clean energy source for dealing with energy shortages and environmental pollution challenges. By means of first-principles calculations, the SGaInSe(SeGaInS)/PtSe₂ van der Waals (vdWs) heterostructures are confirmed to be energetically, dynamically, and thermally stable, indicating that they have a lot of potential for experimental implementation. The Model-I of SGaInSe/PtSe₂ heterostructures possesses type-II indirect band alignment, while the other three heterostructures retain type-I band alignment, which is further tuned to type-II with the application of strain. The charge transfer to SGaInSe/SeGaInS layer from PtSe₂ layer generates built-in electric field that effectively resists the recombination of photo-generated electron-hole pairs. At pH = 0, the band edge positions of both heterostructures completely straddle the redox potentials. The Model-I of SeGaInS/PtSe₂ heterostructures with biaxial ?2% compressive strain makes the band edges to do complete water splitting in natural environment (pH = 7). In the visible range of the irradiating spectrum, our designed heterostructures have enhanced imaginary part of the dielectric function and absorption coefficient up to 10⁵ cm^?1. Moreover, with the biaxial compressive (tensile) strains, the blue-shift (red-shift) in absorption spectra is examined. Our study extends the applications of Janus monochalcogenides/PtSe₂ vdWs heterostructures and supports to design of more heterostructures-based photocatalysts and optoelectronic devices.     

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.     

Efficient photoelectrochemical water splitting of CaBi6O10 decorated with Cu2O and NiOOH for improved photogenerated carriers

Broadening the light absorption and accelerating the separation of photogenerated electron-hole pairs is of crucial importance for strongly enhancing the photoelectrochemical (PEC) water splitting performances of photoelectrode. In this paper, a novel CaBi₆O₁₀/Cu₂O/NiOOH photoanode for photoelectrochemical water splitting is prepared, where, the NiOOH acts as water oxidation catalyst to accelerate water oxidation taking place in the interfaces between electrode and electrolyte, Cu₂O is chosen to extend the absorption range of the light absorber, enhancing an efficient separation and transfer of the electron-hole pairs. This triple CaBi₆O₁₀/Cu₂O/NiOOH photoanode negatively shifts the onset potential and exhibits an improved photocurrent density 1.89 mA·cm^?2 at 1.23 V vs RHE, which is 1.4 and 4.8 times higher compared to CaBi₆O₁₀/Cu₂O and CaBi₆O₁₀, respectively. More importantly, the CaBi₆O₁₀/Cu₂O/NiOOH electrode shows excellent photoelectrochemical stability in comparison with CaBi₆O₁₀/Cu₂O after 2 h irradiation. The amazing photoelectrochemical performance is due to the broader light absorption spectrum, the improved photogenerated carriers separation, transfer and consumption. The research results demonstrate a promising ternary semiconductor structure, which can improve photoelectrochemical performance effectively. Moreover, these results also imply that the CaBi₆O₁₀/Cu₂O/NiOOH heterojunction structure has a great potential application for photoelectrochemical water splitting systems.     

Promoted interfacial charge transfer by coral-like nickel diselenide for enhanced photocatalytic hydrogen evolution over carbon nitride nanosheet

Seeking an efficient and non-precious co-catalyst for g-C₃N₄ (CN) remains a great demanding to achieve high photocatalytic hydrogen generation performance. Herein, a composite photocatalyst with high efficiency was prepared by modifying CN with coral-like NiSe₂. The optimal hydrogen evolution rate of 643.16 μmol g^?1 h^?1 is from NiSe₂/CN-5 under visible light. Superior light absorption and interfacial charge transfer properties including suppressed photogenerated carrier recombination and efficient separation of photogenerated electron-hole pairs have been observed, which account for the enhanced photocatalytic performance of CN.     

Photocatalytic hydrogen production by flower-like graphene supported ZnS composite photocatalysts

Flower-like graphene (FG) prepared by a transformer coupled plasma enhanced chemical vapor deposition method was used as support for the preparation of composite photocatalysts. Small ZnS particles were formed on the surface of FG by a hydrothermal process with ZnCl₂ and Na₂S precursors. The surface morphology, surface area, surface chemistry, crystalline property, optical properties, photogenerated current and photocatalytic hydrogen production activity of the FG-ZnS photocatalysts were investigated by using the X-ray diffraction, scanning electron microscope, transmission electron microscopy, X-ray photoelectron spectroscopy, ultraviolet-visible diffuse reflectance spectra, photocurrent response, photoluminescence spectra, electrochemical impedance spectra and photocatalytic hydrogen production tests. The maximum hydrogen production rate of FG-ZnS composite photocatalyst ZS-G0.02 was 11600 μmol g^?1h^?1 under UV light irradiation at a graphene/ZnCl₂ precursor weight ratio of 0.02. The flower-like structure of FG may help the light absorption, adsorption of sacrificing agents in the solution, and separation of photogenerated carriers. In comparison with pristine ZnS photocatalyst, the FG-ZnS nanocomposites exhibits enhanced photocatalytic hydrogen production activity.     

In-situ construction of CdS@ZIS Z-scheme heterojunction with core-shell structure: Defect engineering,enhance photocatalytic hydrogen evolution and inhibit photo-corrosion

Designing the core-shell structure and controlling defect engineering are desirable for improving the performance and stability of semiconductor photocatalysts. Herein, CdS nanorods covered with ultra-thin ZnIn₂S₄ nanosheets, named as CdS@ZnIn₂S₄-S_V (CdS@ZIS-S_V), was synthesized through the strategy of constructing core-shell structure and regulating vacancies. The core-shell structure can confine Cd²⁺ and S^2? locally around CdS instead of rapidly diffusing into the solution, thereby inhibiting photo-corrosion. The abundant S vacancies can capture photogenerated electrons and promote the separation of electron-hole pairs, thereby preventing the oxidation of S^2? by the holes. In addition, Z-Scheme heterojunction structure helps the effective separation of electron-hole pairs. Notably, the hydrogen production rate of CdS@ZIS-S_V reached 18.06 mmol g^?1 h^?1, which was 16.9 and 19.6 times than pristine CdS (1.16 mmol g^?1 h^?1) and ZIS (0.92 mmol g^?1 h^?1), respectively. Photoelectric Characterization (PEC), Scanning Kelvin Probe (SKP), UV–vis diffuse reflectance spectra (UV–Vis DRS), Finite-Difference Time-Domain (FDTD) explain the electron transfer mechanism and the reason for the enhanced photocatalytic activity. This work has guiding significance for the preparation of photo-catalysts with high activity and inhibiting photo-corrosion by adjusting S vacancies.     

Biomolecule-assisted hydrothermal synthesis of ZnxCd1−xS nanocrystals and their outstanding photocatalytic performance for hydrogen production

To achieve scalable applications in solar hydrogen production, it is necessary to develop visible-light-responsive photocatalysts that are highly efficient, cost-effective, stable and environmentally-benign. Here narrow bandgap Zn–Cd–S solid solution photocatalysts (E_g = 2.11–2.53 eV) were prepared via a facile and green hydrothermal strategy under mild conditions. Amazingly, over the naked Zn_0.5Cd_0.5S photocatalyst, an extraordinarily high H₂ production activity in Na₂S–Na₂SO₃ aqueous solution is achieved up to 18.3 mmol h^?1 g^?1 with an apparent quantum efficiency of 73.8% per 50 mg under 420 nm light irradiation, which, to our knowledge, outperforms cocatalyst-free metal sulfide photocatalysts previously reported to date. Such super high performance arises from the enhanced visible-light-absorption capacity, suitable conduction and valence band potential together with the facilitated charge transport in Zn–Cd–S solid solutions. This work may open an avenue for the green preparation of inexpensive photocatalysts for solar H₂ production.     

Z-scheme heterojunction ZnSnO3/rGO/MoS2 nanocomposite for excellent photocatalytic activity towards mixed dye degradation

In this work, a novel (ZnSnO₃/rGO/MoS₂) nanocomposite was prepared and its photocatalytic performances were investigated. The synthesised ZnSnO₃ spheres were well dispersed over the surface of rGO sheet and MoS₂ layers (ZSGM). The structural, morphological and elemental properties of the composites were examined by XRD, SEM, HRTEM and EDS. The surface chemical composition and functional groups of the elements interlinked in the composites were identified from XPS and FTIR analysis. BET and Raman analysis indicate the effective formation between MoS₂/rGO/ZnSnO₃ ternary heterostructure nanocomposite. The suppressed photogenic charge carrier's recombination rate was investigated by PL analysis. From UV analysis, the bandgap of ZSGM nanocomposite was successfully tuned from 3.13 eV to 2.70 eV, leading to high photocatalytic performance by mixed dye pollutant under UV-visible light illumination. The ZSGM photocatalyst achieved highest removal rate of 0.0131 min^?1 for Rh B degradation, and 0.0153 min^?1 for MB dye degradation and efficiency was 78% (Rh B) and 86% (MB), respectively in 100 min, which shows dramatically enhanced activity than other samples. In the presence of rGO/MoS₂ in ZS, ZSGM photocatalysts exhibit higher catalytic activity due to a lower bandgap, more absorption in the visible region, and suppressed recombination rate of photogenerated e^?/h⁺ pairs.     

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.     

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.