A 3D multidirectional covalent hexaphenylbenzene‐based porphyrin polymer with precasting Co‐(Pyrrolic N) 4 moieties was thermally transformed into carbon microspheres with surface‐exposed Co‐(Pyrrolic N) 4 sites. The resulting material demonstrated efficient electrocatalytic performance for the two‐electron oxygen reduction reaction (2e ‐ ORR) to hydrogen peroxide (H 2 O 2 ) in 0.1 M perchloric acid (HClO 4 , pH = 1), 0.1 M phosphate‐buffered saline (pH = 7), and 0.1 M potassium hydroxide (KOH, pH = 13). In H‐type electrolytic cells, it achieved an H 2 O 2 production rate of about 512–850 mmol g cat. −1 h −1 in three electrolytes, exhibiting better durability. Moreover, the H 2 O 2 production rate was further elevated to 3.12 mol g cat. −1 h −1 in an alkaline flow cell with about 95% Faradaic efficiency. Experimental and theoretical studies revealed that a 3D multidirectional porphyrin polymer facilitated the formation of abundant Co‐(Pyrrolic N) 4 sites on the carbon surface, which can effectively adsorb *O 2 and *OOH intermediates, thereby promoting a four‐step 2e ‐ ORR mechanism with a low energy barrier. This work presents a multidirectional porphyrin polymer‐derivation strategy for precisely engineering Co‐(Pyrrolic N) 4 sites on a carbon surface, enabling efficient and durable electrochemical H 2 O 2 synthesis in different pH solutions.
Chen et al. (Mon,) studied this question.