Ti3C2 MXene flakes assisted Mn0.5Cd0.5S/Ti3C2 MXene/g-C3N4 Z-scheme heterojunction for enhancing photocatalytic hydrogen evolution

Abstract

Efficient carrier separation and high electron migration efficiency are essential for sustainable H2 energy production via photocatalysis. In this work, a Mn0.5Cd0.5S/Ti3C2 MXene/g-C3N4 all-solid-state Z-scheme photocatalyst is constructed by a series of processes, including low temperature calcination, etching, ultrasonication and solvothermal process. The appropriate energy band structures of g-C3N4 and Mn0.5Cd0.5S enable the formation of the Z-scheme system, achieving efficient carrier separation. The Ti3C2 MXene flakes assembled between g-C3N4 nanosheets and Mn0.5Cd0.5S particles can accelerate the charge migration rate in the system. The optimized ternary composite exhibits the highest hydrogen evolution rate (HER) of 13.7 mmol g−1 h−1, which is much higher than that of the pure g-C3N4 and Mn0.5Cd0.5S. Meanwhile, the apparent quantum yield (AQY) value of the composite at 420 nm reaches up to 24.07 % and exhibits high stability. Based on the characterization, the photocatalytic mechanism of carrier transfer in the Z-scheme heterojunction is also revealed. The finding of this article provides insights into the high efficiency of carrier transfer and separation in the photocatalytic reactions.