Triple-Phase Interface Engineering over an InO Electrode to Boost Carbon Dioxide Electroreduction.

The electrocatalytic reduction of CO is deemed to be a promising method to ease environmental and energy issues. However, achieving high efficiency and selectivity of CO electroreduction remains a bottleneck due to huge limitation of CO mass transfer and competition of hydrogen evolution reaction (HER) in aqueous solution. In this work, we propose to utilize triple-phase interface engineering over an InO electrode to enhance its CO reduction reaction (CORR) performance. Notably, distinguishing from other research studies (doping, defect introduction, and heterojunction construction) that regulate the nature of InO-based catalysts themselves, we herein tune interfacial wettability of InO using facile fluoropolymer coating for the first time. In contrast to the hydrophilic InO electrode [Faraday efficiency (FE) ∼ 62.7% and FE ∼ 24.1% at -0.67 V versus RHE], the hydrophobic fluoropolymer (taking polyvinylidene fluoride as an example)-coated InO electrode delivers a significantly enhanced FE of 82.3% and a decreased FE of 5.7% at the same potential. Upon combining contact angle measurements, density functional theory calculation, and ab initio molecular dynamics simulation, the enhanced CORR performance is revealed to be attributed to the rich triple-phase interfaces formed after fluoropolymer coating as an "aerophilic sponge", which increases the local concentration of CO near InO active sites to improve CO reduction and meanwhile reduces the accessible water molecules to suppress competitive HER. This work presents a feasible approach for the enhanced selectivity of HCOOH yield over InO by triple-phase interface engineering, which also provides a convenient and effective method for developing other materials used in gas-consumption reactions.