Selective deposition of cocatalyst NiS on a g-C3N4/ZnIn2S4 heterojunction for exceptional photocatalytic H2 evolution

Photocatalytic H-2 generation has long been supposed to be an intriguing approach for obtaining clean energy, but it is challenging to achieve a satisfactory efficiency mainly restricted by the high recombination rate of photoexcited carriers. The designing of a directional channel for the spatial separation of photogenerated electrons and holes to different components may be an ideal solution. To prove this point, a ternary hybrid g-C3N4/ZnIn2S4/NiS, in which NiS is directionally anchored onto ZnIn2S4, is successfully synthesized according to the Fajans rule. Compared with single g-C3N4, ZnIn2S4 and the counterpart in which NiS is randomly deposited onto g-C3N4/ZnIn2S4, the designed g-C3N4/ZnIn2S4/NiS exhibits the highest photocatalytic activity, with an H-2 evolution rate of 16310 mu mol g(-1). The mechanism research showed that the matched band structure and interfacial electric field oriented from ZnIn2S4 to g-C3N4 facilitate the photo-induced electron transfer from g-C3N4 to ZnIn2S4. NiS nanoparticles that attached to ZnIn2S4 can act as electron trappers, thus further promoting the electron-hole separation efficiency. This work sheds light on the rational design and synthesis of heterojunctions for photocatalytic applications.