All‐Solid‐State Synthesis of High‐Performance Electrocatalysts for Oxygen Reduction Reaction Derived From g‐C3N4 and Cobalt Phthalocyanine

Abstract Herein, a combined method for planetary ball milling and pyrolysis of g‐C 3 N 4 /cobalt phthalocyanine mixture to synthesize Co nanoparticles loaded on CN nanosheets ( g ‐C 3 N 4 @CoPc‐ x with different mass ratios x of g‐C 3 N 4 :CoPc) is proposed. The synthesized catalysts exhibit a unique 3D open sheet‐like structure, and the average size of Co particles is 4.45 nm while encouragingly, a small amount of quasi single‐atom cobalt (mean particle size 0.5 nm) is also found in the samples. In addition, the mass ratio of g‐C 3 N 4 to CoPc presents a significant effect on ORR activity of the samples. Among the samples, g‐C 3 N 4 @CoPc‐3 shows excellent ORR performance with the onset potential of 0.94 V in neutral condition and the half‐wave potential of 1.00 V in alkaline condition, both better than Pt/C. Its onset potentials in acidic (0.83 V) and alkaline (1.07 V) conditions are also comparable to Pt/C. In a full pH range (acidic, alkaline, and neutral) electrolyte, the prepared samples catalyze ORR via a direct four‐electron reaction pathway, and the C 3 N 4 @CoPc‐3 reveals high catalytic stability and high anti‐alcohol tolerance. Results provide wide feasibility for the synthesis and application of g‐C 3 N 4 @CoPc‐3 in fuel cells.