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

The electrochemical CO reduction reaction (CORR) to produce hydrocarbon fuels, such as methane (CH), 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 CORR 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 CH 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 CuO/CuO nanoclusters. Benefiting from this, the pulsed system delivers an exceptional Faradaic efficiency (FE) of 82.9% in CH production from the CORR. This selectivity markedly surpasses that of the constant-potential counterpart, representing the state-of-the-art. In addition, this approach facilitates stable CH production for over 12 hours while maintaining an FE above 60%.