Recent research progresses in sustainable carbon-based electrocatalysts of oxygen reduction reaction

Among rechargeable batteries, metal-air batteries have attracted considerable attention because of their high theoretical specific energy, environmentally friendly, and low-cost. Oxygen reduction reaction (ORR) of electrocatalyst is considered to be a key reaction during discharge process of cathode, determining metal-air batteries performance. However, ORR electrocatalysts still face the key challenges of unsatisfactory electrocatalytic kinetics and complex preparation process that limits their wide applications. Herein, the research progresses of sustainable carbon-based ORR electrocatalysts are reviewed. We introduce the functional design approaches for performance improvement of carbon-based ORR electrocatalysts, including construction of pore structure, activation, and heteroatom doping. Abundant and inexpensive animal metabolites, plant, and microorganism are reviewed as raw material for obtaining high-performance ORR electrocatalysts. Furthermore, research directions of sustainable carbon-based ORR electrocatalysts are proposed.