Embedding CdS@Au into Ultrathin Ti3–xC2Ty to Build Dual Schottky Barriers for Photocatalytic H2 Production

One of the research hotspots in solar energy conversion is developing photocatalysts for visible-light-driven H2 production. In this study, a ternary CdS@Au/MXene composite was elaborately constructed by a facile in situ self-assembly strategy, where the ultrathin Ti3–xC2Ty nanosheets with characteristic Ti vacancies were employed as a support for core–shell structured CdS@Au nanojunctions. In the presence of 1.0 wt % MXene, merely 0.1 wt % Au helped the composites achieve a high H2-production rate of 5371 μmol·g–1·h–1 under visible-light irradiation, more than 26.6 times higher than that of bare CdS. Such an enhancement was predominantly attributed to the "dual Schottky barriers" formed at the interface of CdS@Au/MXene, which was evidenced by systematic characterizations including X-ray photoelectron spectroscopy and Kelvin probe measurements, in conjunction with density functional theory (DFT) calculations. This work not only highlights the significant role of MXene in reducing the dosage of noble metal cocatalysts for photocatalysis, but also opens avenues to fabricate more MXene-based composites for solar energy conversion and beyond.