Fabrication of core-shell Ag@CD oxygen reduction catalyst under ultraviolet irradiation using carbon dot as reducing agents

Abstract

The widespread applications of fuel cell depend on the reasonable designment of excellent catalysts that are easy to synthesize or abundant in reserves for oxygen reduction reaction (ORR). The application of precious metal catalysts (such as Pt, Pd etc.) is limited due to their scarcity of resources and high cost, while Ag/C catalysts have shown unique advantages in fuel cell and are expected to replace precious metal catalysts. In this paper, the fabrication of core–shell Ag@carbon dot (Ag@CD) with varying Ag loadings was achieved through a one-step method utilising CD as both a reducing agent and stabiliser, with the assistance of ultraviolet (UV) irradiation. Its suitable silver salt concentration and stable core–shell structure are the fundamental reasons for the excellent catalytic performance of ORR. The results show that the limiting current density (5.8 mA cm⁻²) of [email protected] catalyst is much greater than that of [email protected] and [email protected] catalysts. The Tafel slope of [email protected] catalyst is almost equivalent to those for Pt/C catalysts, suggesting the [email protected] exhibits an outstanding catalytic activity. The relative current density of [email protected] catalyst only decreased by 2.5 % after 50,000 s, suggesting that [email protected] exhibits more excellent stability for ORR, which is ascribing to the carbon layer coated outside the Ag nanoparticles (NPs).