Pulsed Strategy Steers the Structural Evolution of Cu Metal-Organic Framework for CO₂ Reduction to Methane

The electrochemical CO₂ reduction reaction (CO₂RR) to produce hydrocarbon fuels, such as methane (CH₄), offers a promising pathway to address the dual challenges of climate change and energy shortage. Although copper-based metal-organic frameworks (Cu-MOFs) have proven to be promising CO₂RR catalysts for hydrocarbon production, their uncontrollable structural reconstruction under operating conditions leads to elusive active sites. Herein, we demonstrate that a pulsed potential electrolysis strategy with well-designed pulse parameters can steer the dynamic reconstruction of Cu-MOFs to customize the active sites to enable the CH₄ formation pathway. Mechanistic studies using electron microscopic and spectroscopic methods indicated that constant-potential electrolysis caused the rapid reduction of Cu-MOF to metallic Cu nanoparticles, whereas pulsed electrolysis enabled the controlled generation of active Cu₂O/CuO nanoclusters. Benefiting from this, the pulsed system delivers an exceptional Faradaic efficiency (FE) of 82.9% in CH₄ production from the CO₂RR. This selectivity markedly surpasses that of the constant-potential counterpart, representing the state-of-the-art. In addition, this approach facilitates stable CH₄ production for over 12 hours while maintaining an FE above 60%.