Low-coordinated sites protection of Pt nanoparticles for durable ORR catalyst using thiol derivatives

Abstract

For the commercialization of polymer electrolyte membrane fuel cell (PEMFC), studies on improvement of catalyst durability have recently gained interest as increasing importance of durability issues of PEMFC. Dissolution of Pt nanoparticles is the main catalyst degradation mechanism under PEMFC operation condition. Dissolution characteristics differ by facets of Pt. The low-coordinated sites of Pt have high oxygen binding energy, which result to low oxygen reduction reaction (ORR) activity and vulnerability to dissolution. In this work, we were focused on characteristics of thiol functional groups that have adsorption selectivity to the low-coordinated sites of Pt, then introduced selective protection layer on the low-coordinated Pt sites of conventional Pt catalyst using (3-Mercaptopropyl) triethoxysilane (MPTES), the thiol derivatives which have silane functional groups. We demonstrated that the adsorbed MPTES affected to the electronic structure of Pt and it had adsorption selectivity on the low-coordinated sites. By these characteristics, the ORR catalyst with higher activity and improved durability compared to the conventional catalyst were achieved.