The alkaline etching strategy enhances the methane production performance of LDH in electrocatalytic CO₂ reduction

Currently, electrocatalysts for CO₂ reduction to methane (CH₄) are mainly based on single-atom copper-based materials, but they tend to aggregate during the catalytic process, resulting in poor stability. Layered double hydroxide (LDH) materials are considered promising electrocatalysts due to their tunable layered elements, good stability, and simple synthesis methods. However, their low conductivity and limited active sites hinder their application in CO₂ reduction. Based on this, Cu-based hydrotalcite materials (CuMgAl-LDH) were controllably synthesized using a hydrothermal method, and partial Al sites were removed through alkaline etching, generating vacancy defects in the LDH structure. These Al defects not only modulate the electronic structure of the material but also expose more active sites, enhancing its performance in electrocatalytic CO₂ reduction to CH₄. The effects of the defects on the catalytic activity, selectivity, and stability of CuMgAl-LDH were systematically studied. A series of characterization techniques were used to analyze the morphology and electronic structure of the LDH materials in detail. The results show that alkaline etching can improve the conductivity of the material, and the etched CuMgAl-LDH achieves a methane selectivity of up to 57 % at a current density of 200 mA·cm⁻², maintaining stable performance for over 8 hours of testing. This provides insights for the application of LDH materials in the field of CO₂ reduction.