Pyrolysis-free, facile mechanochemical strategy toward cobalt single-atom/nitrogen-doped carbon for highly efficient water splitting

Exploring new synthetic strategies for single-atom catalysts (SACs) is filled with promise for the production of SACs. Conventional pyrolysis of selected precursors for SACs requires well-controlled pyrolysis conditions, and currently, it is still a critical challenge to establish a versatile strategy for preparing well-defined SACs. Herein, we demonstrate a facile mechanochemical-induced self-sustaining reaction to fabricate Co SACs supported by nitrogen-doped carbon via direct milling of cobalt (II) 5,10,15,20-tetrakis-(4′-bromophenyl)porphyrin (Co-TPP-Br) with calcium carbide. The as-prepared ball-milling sample (BM) Co-BM-C can be directly obtained without the utilization of pre-prepared carbon support or further pyrolysis procedure. Furthermore, the obtained Co-BM-C shows both excellent performance for oxygen evolution (240 mV overpotential@10 mA cm⁻²) and hydrogen evolution (126 mV overpotential @10 mA cm⁻²) in 1 M KOH, exhibiting great potential as the water-splitting electrocatalyst (1.60 V@10 mA cm⁻²). Therefore, the present study not only proposes new insights on preparing SACs but also provides new opportunities for water-splitting devices.