Mo₂C MXene Nanosheets Made in Different Etching Solutions as Co-catalysts for Hydrogen Production

Mo2C MXene is a two-dimensional material,which canbe applied as a co-catalyst to significantly enhance the photocatalyticperformance of CdS for H-2 production. To understand theeffect of the synthesis process of Mo2C MXene nanosheetson the catalytic performance, in this paper, Mo2C MXenewas made from Mo2Ga2C by hydrothermal etchingin different etchants. Diverse cations (Li+, Na+, K+, or NH4 (+)) in etchants residedon the surface of Mo2C MXene nanosheets. Then, the sampleswere used to construct CdS/Mo2C-MXene composites for photocatalyticH(2) evolution. Among them, Mo2C MXene with Li+ shows the best photocatalytic H-2 production rateof 22,048 mu mol g(-1) h(-1) undervisible light. The remarkable performance arises from the modificationat the nanoscale of Mo2C MXene with Li+, therebyresulting in better photoabsorption behavior, high separation efficiencyof photogenerated carriers, and fast charge transfer at the heterointerface.Moreover, the energy band structures explain that the changes of bandgap and the position of the conductive band in the photocatalyst tunedby cations are also key to affect photocatalytic activities.