Ag-Doped ZnIn₂S₄ Nanosheets on Hollow Co₉S₈ Polyhedral Nanocages as Photocatalysts for Enhanced Hydrogen Production and Pollutant Reduction

Abstract

The effective combination of two metallic sulfides to form a heterojunction and regulate semiconductor structure can significantly improve the response of photocatalysts under visible light. In this study, we have successfully grown Ag-doped ZnIn 2 S 4 nanosheets randomly on carefully designed hollow Co 9 S 8 polyhedral nanocages to construct the Co 9 S 8 /Ag:ZnIn 2 S 4 heterojunction. The optimized 1.0 wt % Co 9 S 8 /Ag:ZnIn 2 S 4 heterostructure shows excellent activity with the H 2 generation rate of 1947.7 μmol g −1 h −1 , which is 1.58 times greater than the Ag:ZnIn 2 S 4 (1232.0 μmol g −1 h −1 ). However, pure Co 9 S 8 has a narrow band gap but almost no response in visible light due to the fast photogenerated carrier recombination rate. The degradation trend of methyl orange (MO) in all as-prepared samples is the same as that of hydrogen production. The compound with the Co 9 S 8 mass fraction of 1.0 wt % has the fastest degradation rate and can completely degrade MO within 16 min. In addition, the Co 9 S 8 / Ag:ZnIn 2 S 4 heterostructure has also shown long-term stability after 20 photocatalytic hydrogen evolution and MO degradation cycle experiments, respectively. This work highlights the significance of improving the photocatalytic performance by modulating the morphology of metallic semiconductors and constructing heterostructures.

Enhanced photocatalytic hydrogen activities of CoV-LDH/ZnIn2S4 nanocomposites

“…6–8 Since Lei et al first discovered in 2003 that the ZnIn 2 S 4 photocatalyst synthesized by a hydrothermal method has an excellent photocatalytic ability of water splitting to produce hydrogen under visible light, the majority of scientific researchers have turned their research attention toward ZnIn 2 S 4 -based photocatalysts. 9–12 As a typical transition chalcogenide semiconductor, ZnIn 2 S 4 is widely used in photocatalytic water splitting due to its unique crystal structure, suitable band gap and excellent visible light response. 13 However, due to the easy recombination of photogenerated electron and hole pairs, the carrier transfer efficiency is low and the photocatalytic activity is limited.…”