Ultra-thin hierarchical porous carbon coated metal phosphide self-assembled efficient tri-functional electrodes for overall water splitting and rechargeable zinc-air batteries

Abstract

Highly efficient and stable trifunctional electrocatalysts with controllable nanostructures toward hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR) are extraordinarily important for the sustainable energy development. Here we report a general and facile synthetic method for designing a hierarchically porous Ni-foam-based self-supported electrode (NPO/NixPy@NF-HPCs). Based on its unique design concept, the NPO/NixPy@NF-HPCs shows high tri-functional catalytic activities. As a result, the NPO/NixPy@NF-HPCs-based rechargeable zinc-air battery (ZAB) and water splitting device exhibit high power density up to 377 mW cm−2 and low cell voltage of 1.52 V@10 mA cm−2, respectively. Notably, the mapping between the stability and the quasi-in situ characterization demonstrates that it is a reliable method to improve electrode stability by establishing a stable outer carbon layer to avoid the oxidation of internally active sites. This work is promised to provide a viable new approach to developing efficient and low-cost carbon-supported phosphate tri-functional electrode.