Hierarchical Porous Carbon Spheres Loaded CoO_X (CoO_x/HPCS) for Efficient Oxygen Reduction Reaction in Alkaline Media

Abstract The development of efficient non‐noble metal catalysts for oxygen reduction reaction (ORR) in alkaline media is vital for wide application of numerous energy conversion devices. In this work, the CoO_x/HPCS catalysts are demonstrated to show excellent activity toward ORR with more positive peak potential, initial potential, and half‐wave potential than pure HPCS. Moreover, the CoO_x/HPCS exhibits a long‐term stability and a stronger methanol resistance compared to 20% Pt/C. The outstanding ORR activity for CoO_x/HPCS is owing to its excellent characteristics, like: 1) a good conductivity of the carbon matrix to improve the electron transfer ability; 2) the rich hierarchical hollow carbon matrix and high surface area conducive to providing more accessible active sites and improving mass transportation; 3) the defect caused by oxygen vacancy beneficial for enhancing catalytic activity; 4) the synergistic effect between CoO_x and HPCS support being crucial for ORR, thence enhancing the electrochemical performance of CoO_x/HPCS.