Composites of Ag-Doped ZnIn<sub>2</sub>S<sub>4</sub> Nanoplates with Graphitic Carbon Nitride and Reduced Graphene Oxide Nanosheets for Sunlight-Driven Hydrogen Production and Water Purification
Yanting Dou, Zhiman Liang, Zhenhe Xu, Yuanjin Wang, Jiqi Zheng, Dongling Ma, Yu Gao
Abstract
Photocatalysis is considered a promising technology to alleviate the energy crisis and environmental pollution; however, developing photocatalysts with improved light absorption efficiency is still a challenge. In this work, an effective strategy was proposed to synthesize a highly functional ternary nanocomposite (g-C 3 N 4 /RGO/AZIS) by coupling broader light-absorbing Ag-doped ZnIn 2 S 4 (AZIS) nanoplates with ultrathin g-C 3 N 4 and reduced graphene oxide (RGO) nanosheets. The 2D-on-2D stacking nanostructure of the composite provides a compact heterojunction, enlarged interfaces, and enriched active sites, resulting in the accelerated separation and relocation kinetics of charge carriers. Benefiting from these advantages, the g-C 3 N 4 /RGO/AZIS nanocomposite with systematically optimized contents of RGO and AZIS can serve as an efficient bifunctional photocatalyst for both H 2 production from water splitting and methyl orange (MO) photodegradation under the irradiation of visible light. The H 2 production rate of the ternary nanocomposite is 658.5 μmol h –1 g –1, which is 38 times higher than that of plain g-C 3 N 4 . The operation mechanism is proposed based on the results of scavenger tests and photoelectrochemical analysis. The formation of a type-II heterostructure between AZIS nanoplates and g-C 3 N 4 nanosheets along with RGO with lower potential can maximize the separation efficiency of photogenerated electron–hole pairs and decrease the charge recombination. This work provides a viable strategy to develop bifunctional photocatalysts with enhanced performance for both H 2 production and degradation of organic dyes.