Cobalt single-atom catalyst as a multifunctional electrocatalyst for boosting radical generation

Electro-generated hydroxyl radicals (center dot OH) are of fundamental importance in electrochemical advanced oxidation processes (EAOPs). Herein, a cobalt single-atom (Co-1) dispersed on N-doped carbon black (NCB) was synthesized and used for the first time as a multifunctional electrocatalyst on both the anode and cathode to boost the generation of center dot OH. Specifically, the Co-1-NCB anode electrochemically generates center dot OH through water oxidation reaction (WOR), whereas the Co-1-NCB cathode generates hydrogen peroxide (H2O2) through oxygen reduction reaction (ORR), followed by its subsequent electrochemical/catalytic activation by Co-1-NCB, which synergistically promotes the formation of center dot OH. In an electrochemical system with the optimized coordination structure and operating conditions, the Co-1-NCB electrode-based EAOP exhibited high phenol-removal efficiency (>95%) over a wide pH range (pH = 3-9). This study provides a new strategy for maximizing radical production and suggests its application in the electrochemical oxidation of recalcitrant organic pollutants.