Self-Limited Reconstruction Realized via Copper-Ligand Interaction for Stabilizing High-Selective CO2 Electromethanation

Highly dispersed metallic copper (Cu) nanomaterials are considered effective electrocatalysts for converting CO2 to methane. Nevertheless, they are susceptible to surface oxidization and electrochemical reconstruction, resulting in high oxidation states and severe agglomeration during storage and use. These issues inevitably lead to performance degradation. Here, we propose a self-limited reconstruction strategy to in situ construct highly dispersed Cu nanoparticles with robust structural stability during electrocatalysis. Choosing Cu-based complex precursors with flexible ligands and potent Cu-ligand interaction is crucial to realizing this strategy. As an exemplar precursor, Cu2+-polydopamine (PDA-Cu) undergoes reconstruction to in situ generate highly dispersed Cu nanoparticles under reduction potentials, while the dissociated PDA ligands self-assemble onto the Cu nanoparticles, induced by the strong Cu-PDA interaction, thereby impeding further reconstruction and effectively maintaining the superior dispersion of the Cu nanoparticles. As a result, the in situ reconstructed PDA-confined Cu nanoparticles demonstrate an impressive CH4 Faradaic efficiency of 83% and a remarkable long-term stability exceeding 100 h. We believe that this general strategy potentially enables in situ construction of metallic electrocatalysts in diverse morphologies for various applications by adjusting the metal–ligand interaction.