One-step fabrication of Cu₂O-Cu catalytic electrodes with regular porous array by ultra-fast laser scanning

Highly efficient oxygen evolution reaction (OER) electrocatalysts have been well developed over the past decades, but their large-scale preparation with good performance-to-cost ratio remains a critical challenge. Here we report a simple one-step fabrication method of catalytic electrode using ultra-fast laser scanning. SEM results demonstrate that the samples have a regular porous array microstructure; XRD shows that Cu₂O was formed on the surface of Cu substrate, which is in agreement with the large amount of Cu⁺ detected from XPS. The as-prepared Cu₂O-Cu catalyst exhibits excellent OER activity in 1 M NaOH with an over-potential of 384 mV at the current density of 10 mA cm⁻² (without iR compensation). During this process, thin Cu(OH)₂ passivation layer could be formed with weak crystallinity, which could be easily removed by reduction reactions using cyclic voltammetry and it has minimum side effect on the OER performance of the sample. This approach is ultra-fast, simple, and environmentally friendly, and thus holds great potential in large-scale practical applications of electrocatalysts.