Novel and noble-metal-free CdIn2S4/MoB Schottky heterojunction photocatalysts with efficient charge separation for boosting photocatalytic H2 production

Abstract

The construction of Schottky heterojunctions by selecting applicable metalloids and semiconductors is highly effective for improving the activity of semiconductors. Herein, we deposited CdIn2S4 on MoB by hydrothermal method to construct a noble metal-free and unreported CdIn2S4/MoB Schottky heterojunction for achieving high photocatalytic H2 production. In ultraviolet photoelectron tests, the Fermi level of the CdIn2S4/MoB composites exhibited a certain shift compared with CdIn2S4 and MoB, manifesting the rearrangement of the Fermi level and the formation of Schottky heterojunction. The formed Schottky heterojunction greatly promoted the electron migration from CdIn2S4 to MoB (proved by XPS tests) to obtain high charge separation efficiency (confirmed by PL and electrochemical tests). CdIn2S4/MoB composites possessed smaller H2 evolution overpotential and Tafel slope, which greatly promoted the release of H2 in the kinetics. Besides, CdIn2S4/MoB composites had higher light absorption capacity and larger specific surface area, which were for more conducive to H2 production. Ultimately, CdIn2S4/MoB composites had significantly improved H2 production activity. Among all composites, the activity of CdIn2S4/20MoB was the highest (463.53 μmol·g−1·h−1), which was 3.5 times that of CdIn2S4-1 %Pt. Besides, CdIn2S4/MoB composites possessed excellent stability in five experiments. Simultaneously, the formation of the Schottky heterojunction and its mechanism of promoting H2 production reaction were also thoroughly investigated. This work is the first to report that MoB could construct Schottky heterojunctions with sulfides for efficient photocatalytic H2 evolution, which is easily extended to sulfides other than CdIn2S4.