Aluminum and phosphorus codoped “superaerophobic” Co3O4 microspheres for highly efficient electrochemical water splitting and Zn-air batteries

Abstract

Abstract Multifunctional non-precious catalysts for hydrogen/oxygen evolution reaction (HER/OER) and oxygen reduction reaction (ORR) constitute the bottleneck in the applications in electrochemical overall water splitting (OWS) and Zn-air batteries. Herein, a trifunctional electrocatalyst of urchin-like Al,P-codoped Co3O4 microspheres supported on Ni foam (denoted as AP-CONPs/NF) was fabricated via a hydrothermal process and subsequent low-temperature annealing and phosphorization, exhibiting enhanced OER, HER and ORR activities compared with single-doped and undoped samples. Their surface self-organized microstructure and excellent “superaerophobic” feature make a high bubble repellency, which boost diffusion of reactants and electrolyte-electrode intimate contact. The codoping of Al and P elements into Co3O4 betters right the balance among surface chemical state, the increased oxygen vacancies and the promoted charge transfer. Encouraged by these synergistic advantages, the AP-CONPs/NF was further employed as excellent bifunctional electrodes for the OWS (low cell voltage of 1.57 V at 10 mA cm−2) and as air cathode for rechargeable Zn-air batteries (high power density of 89.1 mW cm−2), which demonstrates a great feasibility for practical applications.