In-situ interstitial zinc doping-mediated efficient charge separation for ZnIn₂S₄ nanosheets visible-light photocatalysts towards optimized overall water splitting

It is urgent to develop photocatalysts with high efficiency and simple preparation for overall water splitting. Herein, we successfully fabricate ultrathin ZnIn₂S₄ nanosheets with in-situ interstitial zinc doping and short-range disordered structure (d_Zni-ZIS) by one-step solvothermal method with magnetic stirring, which can realize overall water splitting without cocatalysts under visible light irradiation. In-situ interstitial Zn (Zn_i) doping can not only induce electrostatic potential difference to accelerate the separation efficiency of photogenerated carriers, but also broaden layer spacing and create short-range disordered structure in nanosheets. Moreover, the disordered regions possess abundant active sites and adjustable electronic configurations, which increase the surface carrier density and enable adequate charges for surface reaction. Consequently, the average photocatalytic H₂ and O₂ evolution rates of the resultant ultrathin d_Zni-ZIS nanosheets achieve 42.8 and 19.1 µmol g^-1h⁻¹ under visible-light irradiation, as well as an apparent quantum yield (AQE) of 1.51% at 420 nm without noble-metal cocatalysts.