The rational design of sustainable noble-metal-free heterojunctions remains a key challenge for highly efficient and durable photocatalytic H2 production. In this study, it was revealed that the robust copper phosphide (Cu3P) nanoparticles may serve as a cocatalyst and a p-type semiconductor at low (1.5 wt %) and high (10 wt %) loading contents, respectively. Both Cu3P cocatalyst and semiconductor could evidently boost visible-light-driven photocatalytic H2 production over graphitic carbon nitride (g-C3N4) nanosheets. Comparably speaking, the heterojunction effects between p-type Cu3P and n-type g-C3N4 are speculated to play a more prominent role in dramatically boosting photocatalytic H2 production than the electron-sink roles of surface Cu3P cocatalysts. Impressively, among all the as-fabricated photocatalysts, high quality 10 wt % g-C3N4–Cu3P could achieve the highest photocatalytic H2-production rate of 159.41 μmol g–1 h–1, which is approximately 1014 times higher than that of pristine g-C3N4. In cycling experiments, g-C3N4–10 wt % Cu3P exhibited an acceptable photostability. More importantly, it was further demonstrated that earth-abundant dual-functional Cu3P nanoparticles could markedly facilitate the separation of electron–hole pairs and H2-evolution kinetics, thus achieving distinctly boosted photocatalytic H2 generation. This work will provide new insights into the rational design of environmentally friendly g-C3N4-based hybrid nanoheterojunctions for visible-light-responsive photocatalytic H2 generation through loading noble-metal-free bifunctional cocatalysts on semiconductors.

Efficient H2O splitting for H2 evolution over the semiconductor photocatalyst is a crucial strategy in the field of energy and environment. Herein, cocatalyst‐free 2D–2D CdS/g‐C3N4 step‐scheme (S‐scheme) heterojunction photocatalysts are fabricated through in situ hydrothermal growth of 2D CdS nanosheets (NSs) on 2D g‐C3N4 NSs. The results clearly confirm that the binary CdS/0.7g‐C3N4 S‐scheme heterojunction shows the best H2 production rate (15.3 mmol g−1 h−1) without using any cocatalyst, which is 3.83 times and 3060 times higher than those of pure CdS and g‐C3N4, respectively. The apparent efficiency of CdS/0.7g‐C3N4 at 420 nm is 6.86%. Importantly, the as‐prepared CdS/0.7g‐C3N4 S‐scheme heterojunction has good stability when continuously irradiated for 21 h. The improved stability and activity are attributed to the formation of the S‐scheme heterojunction, which can markedly accelerate the interfacial charge separation for surface reaction. It is expected that the design of robust cocatalyst‐free CdS/g‐C3N4 2D–2D S‐scheme heterojunction can become a promising approach to develop the highly active H2 evolution systems based on various kinds of conventional semiconductor NSs.

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Photocatalytic hydrogen (H2) evolution is an appealing and promising means for productive solar-to-chemical energy conversion. g-C3N4(CN) is an exciting semiconductor, but its undesirable pristine activity seriously limited the potential for large-scale application. Herein, we, for the first time, demonstrated that the low-cost nickel boride (Ni3B)/nickel hydroxide (Ni­(OH)2) is an ecofriendly hybrid cocatalyst for remarkably boosting visible-light H2 evolution over CN. The maximum H2 evolution rate of CN–3%Ni3B–2%Ni­(OH)2 reaches 352.43 μmol g–1 h–1, with an apparent quantum efficiency of 0.70% at 405 nm, which is much higher than that of pure CN, only 0.1 μmol g–1 h–1. In the cycling experiment, the ternary CN–3%Ni3B–2%Ni­(OH)2 shows relatively high stability in the triethanolamine solution. More importantly, the promoted charge separation and reduced overpotential were demonstrated to be responsible for the significantly boosted visible-light H2 generation over CN nanosheet-based photocatalysts due to the loading of Ni3B/Ni­(OH)2 cocatalyst. It is believed that this study will provide a suitable strategy to rationally design a low-cost, facile-fabrication, and ecofriendly cocatalyst for efficient visible-light hydrogen evolution of CN nanosheet-based photocatalysts.