Two-Dimensional Ni(OH)2@Pt Nanosheets: High Activity Fuel Cell Oxygen Reduction Reaction Electrocatalysts

Abstract

Oxygen reduction reaction (ORR) electrocatalysts with high activity, extended durability and lower cost are needed for proton exchange membrane fuel cells (PEMFCs). Compared with conventional nanoparticles, nanosheets composed of atomic-thin two-dimensional (2D) layers offer a higher relative concentration of catalytically active (111) surfaces. In contrast to many approaches that have investigated graphene-supported Pt ORR catalysts, we have explored Pt supported on Ni(OH)2 nanosheets (i.e. Ni(OH)2@Pt) for enabling high activity ORR electrocatalysts. Synthesis conditions were controlled to obtain Ni(OH)2 nanosheets with controlled sizes, phase, and aggregation. Temperature/atmosphere treatments were found to significantly affect the structure and morphology of the nanosheets. The effect of changing the Pt shell composition on the Ni(OH)2 nanosheets on the ORR activity was evaluated. The nanosheet structure and morphology with determined using x-ray diffraction and scanning electron microscopy, and the ORR activity was determined from rotating disc electrode experiments. Our initial results have shown that Ni(OH)2@Pt nanosheets provide significantly higher catalytic activities compared with Pt/C. The ability to control the structure and properties of 2D transition metal oxide nanosheets provides a route to develop electrocatalysts with high activity, extended durability, and lower cost.