Assembling Ti3C2 MXene into ZnIn2S4-NiSe2 S-scheme heterojunction with multiple charge transfer channels for accelerated photocatalytic H2 generation

Exploring effective photocatalysts to promote water splitting into solar fuels remains a great challenge due to the fast charge recombination. Herein, the ZnIn2S4(ZIS)-NiSe2 S-scheme heterojunctions anchored on Ti3C2 MXene (MX) with multiple internal electric fields were rationally fabricated for effective photocatalytic H2 generation. Indeed, under the intense synergy between Schottky barrier and S-scheme heterojunctions, the optimized photocatalyst exhibits the highest hydrogen evolution rate of 23.51 mmol/g/h with an apparent quantum yield of 10.9% at 450 nm monochromatic light, which is about 23.51-fold of the pure ZnIn2S4. The formation of Schottky barrier between ZnIn2S4 and MX could achieve the transfer of the electrons from ZIS to MX via the Schottky-junction interface, while an internal electric field in S-scheme heterojunctions allows the migration of electrons from NiSe2 to ZIS. In this regard, multiple internal electric fields with vibrant kinetics are constructed between the ZnIn2S4, NiSe2 and MX, which facilitates the favorable charge separation, thus leading to the isolated construction of electron-enriched H2-evolution sites (MX) and hole-accumulated oxidation sites (NiSe2), respectively. It is expected that the coupling of S-scheme heterojunctions and Schottky barrier in this work could provide a better understanding of the rational design of highly-efficient ternary hybrid photocatalysts for promoted H2 evolution.