Composites of Ag-Doped ZnIn₂S₄ Nanoplates with Graphitic Carbon Nitride and Reduced Graphene Oxide Nanosheets for Sunlight-Driven Hydrogen Production and Water Purification

Photocatalysis is considered a promising technology toalleviatethe energy crisis and environmental pollution; however, developingphotocatalysts with improved light absorption efficiency is stilla challenge. In this work, an effective strategy was proposed to synthesizea highly functional ternary nanocomposite (g-C3N4/RGO/AZIS) by coupling broader light-absorbing Ag-doped ZnIn2S4 (AZIS) nanoplates with ultrathin g-C3N4 and reduced graphene oxide (RGO) nanosheets. The 2D-on-2Dstacking nanostructure of the composite provides a compact heterojunction,enlarged interfaces, and enriched active sites, resulting in the acceleratedseparation and relocation kinetics of charge carriers. Benefitingfrom these advantages, the g-C3N4/RGO/AZIS nanocompositewith systematically optimized contents of RGO and AZIS can serve asan efficient bifunctional photocatalyst for both H-2 productionfrom water splitting and methyl orange (MO) photodegradation underthe irradiation of visible light. The H-2 production rateof the ternary nanocomposite is 658.5 & mu;mol h(-1) g(-1), which is 38 times higher than that of plaing-C3N4. The operation mechanism is proposedbased on the results of scavenger tests and photoelectrochemical analysis.The formation of a type-II heterostructure between AZIS nanoplatesand g-C3N4 nanosheets along with RGO with lowerpotential can maximize the separation efficiency of photogeneratedelectron-hole pairs and decrease the charge recombination.This work provides a viable strategy to develop bifunctional photocatalystswith enhanced performance for both H-2 production and degradationof organic dyes.