Dynamic Bubbling Balanced Proactive CO₂ Capture and Reduction on a Triple-Phase Interface Nanoporous Electrocatalyst

The formation and preservation of the active phase of the catalysts at the triple-phase interface during CO₂ capture and reduction is essential for improving the conversion efficiency of CO₂ electroreduction toward value-added chemicals and fuels under operational conditions. Designing such ideal catalysts that can mitigate parasitic hydrogen generation and prevent active phase degradation during the CO₂ reduction reaction (CO₂RR), however, remains a significant challenge. Herein, we developed an interfacial engineering strategy to build a new SnO catalyst by invoking multiscale approaches. This catalyst features a hierarchically nanoporous structure coated with an organic F-monolayer that modifies the triple-phase interface in aqueous electrolytes, substantially reducing competing hydrogen generation (less than 5%) and enhancing CO₂RR selectivity (∼90%). This rationally designed triple-phase interface overcomes the issue of limited CO₂ solubility in aqueous electrolytes via proactive CO₂ capture and reduction. Concurrently, we utilized pulsed square-wave potentials to dynamically recover the active phase for the CO₂RR to regulate the production of C1 products such as formate and carbon monoxide (CO). This protocol ensures profoundly enhanced CO₂RR selectivity (∼90%) compared with constant potential (∼70%) applied at -0.8 V (V vs RHE). We further achieved a mechanistic understanding of the CO₂ capture and reduction processes under pulsed square-wave potentials via in situ Raman spectroscopy, thereby observing the potential-dependent intensity of Raman vibrational modes of the active phase and CO₂RR intermediates. This work will inspire material design strategies by leveraging triple-phase interface engineering for emerging electrochemical processes, as technology moves toward electrification and decarbonization.