One-step synthesis of configurational-entropy In-doped Zn(O,S)/Zn-doped In(OH)3-xSx composite for visible-light photocatalytic hydrogen evolution reaction

Configurational entropy composites of In-doped Zn(O,S)/Zn-doped In(OH) 3-x S x has been synthesized with a one-step hydrothermal method and carefully characterized with XRD , XPS , SEM, TEM, DRS , PL , EIS , TPC , CV , and MS analyses. The composites were prepared with different sulfur amounts to obtain the optimum performance of visible-light photocatalytic HER . The primary phases of ZnS and In(OH) 3 were formed after the hydrothermal process. However, the results indicated In and O were doped into ZnS lattice and induced lower bandgap values (~2.71–2.84 eV) which are active in visible-light illumination. Simultaneously, the excess Zn and S were also doped to In(OH) 3 with lower bandgap values (~3.38–4.63 eV). The variation of bandgap values is due to the hybridization of In 5s5p to Zn 4s4p and O 2p to S 3p orbitals. As a result, In-doped Zn(O,S) and Zn-doped In(OH) 3-x S x will be a visible-light active material for photoreaction and a favorable phase for electron transfer , respectively. Furthermore, it is also related to a possible antisite-defect formation with I n Z n + to help the electron trapping and enhance the photocarrier separation, leading to an efficient photocatalytic activity . ZI-S1 with additional 5-mmol thioacetamide was found as the catalyst with the highest HER performance which achieved 730 μmol/g·h under visible-light illumination. A plausible photocatalytic HER mechanism is discussed and proposed in this work.