Revolutionizing CO Electrolysis: Fluent Gas Transportation within Hydrophobic Porous CuO.

The success of electrochemical CO reduction at high current densities hinges on precise interfacial transportation and the local concentration of gaseous CO. However, the creation of efficient CO transportation channels remains an unexplored frontier. In this study, we design and synthesize hydrophobic porous CuO spheres with varying pore sizes to unveil the nanoporous channel's impact on gas transfer and triple-phase interfaces. The hydrophobic channels not only facilitate rapid CO transportation but also trap compressed CO bubbles to form abundant and stable triple-phase interfaces, which are crucial for high-current-density electrocatalysis. In CO electrolysis, spectroscopy and density functional theory results reveal that atomic edges of concave surfaces promote C-C coupling an energetically favorable OC-COH pathway, leading to overwhelming CO-to-C conversion. Leveraging optimal gas transportation and active site exposure, the hydrophobic porous CuO with a 240 nm pore size (P-CuO-240) stands out among all the samples and exhibits the best CO-to-C productivity with remarkable Faradaic efficiency and formation rate up to 75.3 ± 3.1% and 2518.2 ± 8.1 μmol h cm, respectively. This study introduces a novel paradigm for efficient electrocatalysts that concurrently addresses active site design and gas-transfer challenges.