Defective graphene aerogel-supported Bi–CoP nanoparticles as a high-potential air cathode for rechargeable Zn–air batteries

Constructing highly efficient, durable and bifunctional nanocatalysts for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is of great significance for the large-scale implementation of metal–air batteries. Herein, an electrocatalyst comprising Bi–CoP composite nanoparticles supported on an N, P co-doped defective graphene aerogel (Bi–CoP/NP-DG) was fabricated via a facile and scalable hydrothermal method, followed by a low temperature pyrolysis process. The graphene aerogel acting as a carbon matrix provided abundant channels and avoided the aggregation of catalyst nanoparticles. Moreover, the defects on graphene could not only enhance the catalytic performance but also anchor the catalyst nanoparticles to improve the stability of the designed electrocatalyst. Benefiting from the above merits, the as-prepared Bi–CoP/NP-DG catalyst presented excellent catalytic performances for ORR (half-wave potential, E1/2 = 0.81 V) and OER (overpotential, η10 mA cm−2 = 0.37 V) in an alkaline electrolyte. Moreover, the designed Bi–CoP/NP-DG catalyst with its bifunctional catalytic activities could endow the home-made zinc–air (Zn–air) battery with high power density (122 mW cm−2), specific capacity (752 mA h gZn−1) and cycling stability. Interestingly, the Zn–air battery can be utilized to drive the overall water-splitting reaction with the designed catalyst functioning as both anode and cathode. This study paves a new strategy to design non-precious electrocatalysts for highly efficient rechargeable metal–air battery setups.