Co–N Active Sites between Co Nanoparticles and N‑Doped Carbon toward Remarkably Enhanced Electrocatalytic Oxygen Evolution and Hydrogen Evolution Reactions

The rational design and synthesis of a non-noble-metal electrocatalyst for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) with good conductivity, high efficiency, and excellent stability are major challenges in the field of renewable energy. Therefore, we developed a simple and effective method to grow ZIF-67 in situ on graphitic carbon nitride (GCN) and then annealed it to generate nitrogen-doped carbon (NC) loaded with Co@C nanoparticles (Co@C/NC). Benefiting from this in situ growth method, after annealing, a large number of N atoms on the surface of NC nanosheets anchor more metal Co to form more catalytic Co–N active sites. At the same time, the Co@C/NC composites use NC nanosheets as the matrix, which can improve the electrochemical double-layer capacitance and conductivity of the composites. As demonstrated in electrochemical measurements, the OER and HER overpotentials of Co@C/NC composites at a current density of 10 mA cm^–2 were only 300 and 175.4 mV in 1.0 M KOH, respectively. The preparation method is suitable for synthesizing various metal and carbon composite electrocatalysts. It provides ideas for designing and manufacturing high-performance non-noble-metal dual-function OER/HER catalysts.