The exploration of photoanode materials with high efficiency and stability is the
eternal pursuit for the realization of practically solar-driven photoelectrochemical
water splitting. Here we develop a novel deficient ternary metal sulfide (CdIn2S4)
as photoanode, and its PEC performance is significantly enhanced by introducing
surface S vacancies, achieving a photocurrent density of 5.73 mA cm-2 at 1.23 V vs.
RHE and 1 Sun and an applied bias photon-to-current efficiency of 2.49% at 0.477
V vs. RHE, which, to the best of our knowledge, are the record-high values for a
single sulfide photon absorber to date. The experimental characterizations and
theoretical calculations highlight the enhanced effect of surface S vacancies on the
interfacial charge separation and transfer kinetics, and also demonstrate the
restrained surface states distribution and the transformation of active sites after
introducing surface S vacancies. This work may inspire more excellent work on
developing sulfide-based photoanodes.