A direct Z-scheme NiCoO/ZnInS heterojunction for highly efficient visible-light-driven H evolution.

Exploiting efficient and stable photocatalysts is the primary goal of photocatalytic water splitting for H production. In this work, a sea urchin-like bimetallic NiCoO-decorated ZnInS heterojunction was fabricated a solvent evaporation method. Investigation shows that the introduction NiCoO can expand the UV-vis absorption range, enhance the absorption intensity, promote the charge separation, decrease the charge transfer resistance, induce more active sites, and decrease the H evolution overpotential of the composite. Besides, the charge transfer between NiCoO and ZnInS follows a Z-scheme route based on the ˙OH radical capture experiments; this can preserve the strong oxidation-reduction reaction ability of photogenerated electrons and holes, leading to a faster H evolution rate, which reaches 17.28 mmol g h over the 4.8%-NiCoO/ZnInS composite under 300 W Xe lamp irradiation in 20 vol% triethanolamine (TEOA) solution and is 3.0 times higher than that of ZnInS. In addition, NiCoO/ZnInS also has excellent stability during 5 consecutive cycles. This work provides an effective method for constructing a highly effective Z-scheme heterojunction system for photocatalytic H production.