Efficient electrocatalytic chlorine evolution under neutral seawater conditions enabled by highly dispersed Co3O4 catalysts on porous carbon

Chlorine evolution reaction (CER) is fundamental and critical for the conversion of Cl- to Cl2 in a seawater environment. However, the selectivity and electrocatalytic activity of non-precious metal-based catalysts in CER remain unsatisfactory. It is still a challenge to develop cost-effective and efficient CER electrocatalysts that can be produced in large scale. Herein, we proposed a metal-organic framework (ZIF-67) as a precursor for the synthesis of Co3O4 with a high specific surface area (SSA) and porous nano-sized. We then demonstrated for the first time that the porous nano-sized Co3O4 has high chlorine precipitation activity and stability. The potential (vs. Ag/AgCl) increased slightly from 1.225 to 1.258 V within 24 h of electrocatalytic reaction, and the Faraday efficiencies were higher than 80% at different current densities, indicating significant stability and selectivity. CER mechanism of the Co3O4 material under neutral seawater conditions was verified to be the Krishtalik mechanism by theoretical calculations.