Rapid synthesis of doped metal oxides via Joule heating for oxygen electrocatalysis regulation

Abstract

The development of low-cost, high-performance, and earth-rich electrocatalysts for the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is critical for Zn–air batteries (ZABs). Various doping and other modification methods lead to a large number of material systems, which require a rapid synthesis method for rapid screening. This study provides a simple and quick method for the synthesis of doped metal oxides as highly active catalysts in ZABs. Metal oxides with different structures, such as rock salt oxides, perovskite oxides, and so on, were synthesized by Joule heating, achieving rapid structural screening. Meanwhile, Fe, Mn, Ni, Zn, and Mg were also successfully doped in metal oxides, significantly improving the OER and ORR performance of CoO. Fe–CoO achieves an overpotential as low as 280 mV at a current density of 10 mA cm⁻² and exhibits excellent long-term stability. Fe–CoO + Mn–CoO ZABs show a high power density of 305 mW cm⁻² and significant durability, allowing stable cycling for more than 450 cycles at a current density of 5 mA cm⁻². The proposed design and synthesis strategy of highly active earth-rich catalysts paves the way for low-cost and rapid synthesis of electrochemical catalysts.