Eco-friendly and high-performance photoelectrochemical anode based on AgInS2 quantum dots embedded in 3D graphene nanowalls

Abstract

Photoelectrochemical (PEC) cells offer a promising approach for developing a solar energy conversion system to resolve the increasingly serious energy crisis and environmental issues. However, the lack of stable and eco-friendly electrodes hampers their practical applications. Herein, we prepare an eco-friendly photoanode with enhanced PEC performance embedding AgInS₂ quantum dots (QDs) into three-dimensional (3D) graphene nanowalls (GNWs). AgInS₂ QDs with tunable PL emissions are synthesized using a facile hydrothermal method and then deposited on GNWs directly grown on silica by a catalyst-free method. Benefitting from the interconnected 3D conductive network, GNWs act as an outstanding electron acceptor to transport the photogenerated carriers of AgInS₂ QDs. The experimental results demonstrate that the AgInS₂/GNWs photoanodes exhibit rapid photoresponse upon light excitation with comparable short rise-time (0.23 s) and decay-time (0.41 s). By optimizing the reaction temperature of the QDs, a photo-current density of 145 μA cm⁻² can be achieved due to the effective separation of the photogenerated carriers. Meanwhile, the as-prepared photoanodes exhibit excellent stability of the photoresponse for more than 4000 s of on–off switching and one-month duration. Our study provides a new strategy to construct an eco-friendly PEC system with high performance which shows potential applications for PEC-type devices.