Triggering specific adsorption of alkali cations at electrode–electrolyte interfaces for acidic CO 2 electroreduction

Abstract Alkali cations impose a conducive effect for acidic electrocatalytic CO 2 reduction reaction (eCO 2 RR) to high‐value chemicals. However, the intrinsic configuration of active cations at complex electrode–electrolyte interfaces remains elusive, limiting the deployment of the cation effect. Herein, we identify the crucial effect of specific adsorption of K + at electrode–electrolyte interfaces on improving acidic eCO 2 RR. The specifically adsorbed K + occurs at electrode–electrolyte interfaces after implanting sulfonic acid groups on the system of carbon nanotubes and nickel phthalocyanine (NiPc/CNT−SO 3 H). Importantly, specifically adsorbed K + on NiPc/CNT−SO 3 H generates a 2.3‐fold enhancement of acidic eCO 2 RR and enables attaining high CO Faraday efficiency of >90% at −450 mA cm −2 in acid, surpassing most reported catalysts. Specifically adsorbed K + residing in the inner Helmholtz plane can promote *CO 2 to *COOH and disrupt the hydrogen‐bonding network connectivity, thus facilitating the eCO 2 RR process. This work identifies the novel feature of alkaline cations and provides an effective platform to improve electrocatalysis.