A hybrid Co NPs@CNT nanocomposite as highly efficient electrocatalyst for oxygen evolution reaction

Low-cost, environmentally friendly, and efficient electrocatalysts are required for large-scale and commercial generation of O₂ and H₂ by the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Herein, composites composed of Co and carbon nanotubes (Co NPs@CNT) are fabricated by one-step chemical vapor deposition (CVD) using commercial Co nanoparticles and benzene as precursors. In the alkaline medium, Co NPs@CNT exhibits a small overpotential of 380 mV at a current density of 10 mA cm⁻², small Tafel slope of 82.2 mV dec⁻¹, and excellent structural and electrochemical durability and the properties are better than those of most previously reported Co-based electrocatalysts and commercial Co nanoparticles. The CNTs not only provide high conductivity, but also decrease the adsorption energy of OH* on the surface of Co NPs@CNT. The small energy barrier is responsible for the enhanced OER performance of Co NPs@CNT. In addition to the revelation of the synergistic effects between Co and CNTs, our results provide insights into the development of metal-carbon electrocatalysts and the simple and effective strategy described here has large commercial potential.