Abstract: Copper-based nanomaterials have received much attention in electrocatalysis, but they suffer from low catalytic activity, unstable structures, and poor stability, and it is of great practical importance to explore simple and efficient strategies to solve these problems. In this study, a Co-MOF material was used to successfully construct cobalt-doped Cu₂Cl(OH)₃/CuCl composite materials on a nickel foam substrate through a hydrolysis-etching strategy in a CuCl₂ solution at room temperature. By varying the hydrolysis-etching time of Co-MOF in the CuCl₂ solution, the morphology and structure of the species and composites were controlled. The optimized catalyst only requires an overpotential of 238 mV to drive a current density of 100 mA·cm⁻². After 50 h of stability testing, the current density hardly decreases, indicating excellent stability. The excellent electrocatalytic oxygen evolution reaction (OER) performance can be attributed to the cobalt atom doping, which optimizes the electronic environment around the copper atoms, activating the catalytic activity of Cu₂Cl(OH)₃ and CuCl, as well as the CuCl₂ etching of the nickel foam, which increases the active sites. This study provides new ideas and strategies for the preparation of copper-based electrocatalytic materials and enhancing their electrocatalytic OER activity.