Stabilizing Reticular Frameworks and Modulating Interfacial Water via Conductive Polymer Encapsulation in Metal-Organic Frameworks Electrocatalysts for Efficient Methane Production.

The electrochemical reduction of CO₂ to CH₄ offers a promising pathway for renewable energy storage, yet remains limited by sluggish kinetics, poor catalyst stability, and competing hydrogen evolution reactions (HER). Herein, a host-guest strategy is reported for engineering metal-organic frameworks (MOFs) through the encapsulation of conductive polymers to stabilize reticular skeletons and regulate interfacial water for efficient CO₂-to-CH₄ conversion. Specifically, polypyrrole (PPy) and polyaniline (PANI) are confined within Cu-anchored UiO-67 frameworks, resulting in hybrid catalysts-PPy@Cu-UiO-67 and PANI@Cu-UiO-67-with preserved crystallinity and enhanced electronic conductivity. Among them, PANI@Cu-UiO-67 exhibits superior CH₄ Faradaic efficiency (FE_CH4 up to 71.1%), outperforming PPy@Cu-UiO-67 and unmodified Cu-UiO-67. Spectroscopic analysis reveals that the polymers reinforce structural integrity and induce distinct perturbations in the interfacial water network. In situ Raman and attenuated total reflection surface-enhanced infrared absorption spectroscopy measurements identify the dominance of weakly hydrogen-bonded water (2-HB·H₂O) at the PANI-modified interface, which supports rapid proton transfer while suppressing HER. This study offers a rational design strategy for MOF electrocatalysts by integrating conductive polymers to modulate both the electronic and interfacial environments for high-efficiency methane production.