Electrochemical Reconstruction of Cu-LDH Catalysts via Cyclic Voltammetry for Tunable CO2 Reduction Selectivity.

Electrochemical CO2 reduction reaction (CO2RR) enables sustainable conversion of CO2 into high-value fuels and chemicals, yet precise selectivity control toward methane (CH4) and multicarbon (C2+) products remains difficult. Herein, we develop a cyclic voltammetry (CV)-triggered electrochemical reconstruction strategy to modulate the CO2RR selectivity of Cu-LDH-derived catalysts. Tailoring the CV potential window and cycle number effectively tunes the catalyst microstructure and copper (Cu) valence state: narrow potential windows with limited cycles produce grain-boundary-rich Cu particles with low-valence sites, which promote *CO accumulation and C-C coupling to yield a high C2+ Faradaic efficiency (FE) of 83.3% at 400 mA cm-2. In comparison, expanded potential windows with prolonged cycling induce the formation of nanoclusters with abundant high-valence Cu sites, which suppress C-C coupling and favor the sequential deep hydrogenation of adsorbed *CO intermediates, achieving a CH4 FE of 64.7% at 300 mA cm-2. Ex situ characterizations and in situ spectroscopic analyses reveal that CV-driven dissolution-redeposition dominates the evolution of particle size, grain boundaries, and Cu valence, thereby governing the CO2RR reaction pathways. This work establishes a facile electrochemical reconstruction strategy for programmable modulation of CO2RR product selectivity.