Structural tailoring of Ag/AgCl core/shell nanowires for enhanced oxygen reduction

Abstract

As the need for eco-friendly and clean energy increases, green energy production is receiving a lot of attention. Anion exchange membrane fuel cells (AEMFCs) operate in an alkaline environment and can use several materials as electrocatalysts. Among them, silver (Ag)-based compounds are promising for oxygen reduction reaction (ORR) because of high catalytic activity and low cost. Although silver chloride (AgCl) has good catalytic activity because of the charge transfer effect according to the difference in electronegativity between Ag and Cl, it has a disadvantage in that the high conductivity, which was the advantage of Ag, is lost. In this paper, we made Ag/AgCl core/shell nanowires decorated with AgCl particles using precipitation method (PD-Ag@AgCl NWs). This catalyst maintains long Ag NWs as a core, has good Ag conductivity, and has high catalytic activity due to silver chloride (AgCl). In addition, since the AgCl shell is decorated with AgCl particles, it has a large surface area, which has a roughness factor larger than that of Ag/AgCl core/shell NWs, and can be confirmed through double layer capacitance (DLC) analysis. In the electrochemical characterization evaluation, PD-Ag@AgCl NWs have a more positive half-wave potential and a large limiting current density, resulting in increased catalytic properties. Stability was confirmed through accelerated durability tests (ADTs) comparing the polarization curve before and after the potential sweep of 4000 cycles, and the efficiency was confirmed through rotating ring disk electrode (RRDE). This catalyst has an electron transfer number close to 4, so it was confirmed that the most reaction pathways were 4-electron pathway, showing that it has a good efficiency.