Bimetallic Two-dimensional Nanoframes: High Activity Acidic Bifunctional Oxygen Reduction and Evolution Electrocatalysts

Obtaining acidic bifunctional oxygen electrocatalysts that simultaneously provide high activity and high stability for both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) remains a significant challenge and need for unitized regenerative fuel cells and metal-air batteries. We report bimetallic nickel-platinum/cobalt-iridium two-dimensional (2D) nanoframes provide significantly higher ORR and OER activities compared with platinum-iridium oxide (Pt-IrO2). The metallic alloy 2D nanoframes (NiPt and CoIr) were synthesized by thermal reduction of noble metal-decorated transition metal hydroxide nanosheets followed by chemical leaching. The 2D nanoframes utilize noble metal (Pt, Ir)-non-noble metal (Ni, Co) interactions to alter the atomic structure, and the unsupported nanostructure provides a carbon-free matrix with three-dimensional (3D) accessibility to the catalytically active sites. Within the cyclic voltammograms, hydrogen adsorption/desorption features on Pt were suppressed with...