The nature of the cations in an electrolyte has a substantial impact on the performance of the electrochemical CO₂ and CO reduction reaction (CO₍₂₎RR), however, its mechanism at the molecular level remains the subject of debate. Major gaps in our understanding include how cations affect key physicochemical variables at electrochemical interfaces and the elementary steps of the CO₍₂₎RR. In this work, we have quantitatively determined the impact of cations on the enthalpy and entropy of CO adsorption on Cu under electrochemical conditions. CO adsorption becomes increasingly unfavourable in the sequence Li⁺ > Na⁺ > K⁺ > Cs⁺ with a substantial enthalpy–entropy compensation effect. Importantly, cations affect the stability of the initial and transition states of the CORR in opposite directions. Our results provide insights into the effect of cations on individual elementary steps in the CORR and demonstrate that the ability to stabilize the transition state in the conversion of adsorbed CO is a decisive factor.

电解质中阳离子的性质对电化学CO ₂和CO还原反应(CO ₍₂₎ RR)的性能具有重大影响，然而，其在分子水平上的机制仍然存在争议。我们理解中的主要差距包括阳离子如何影响电化学界面的关键物理化学变量以及 CO ₍₂₎ RR 的基本步骤。在这项工作中，我们定量测定了电化学条件下阳离子对 Cu 上 CO 吸附的焓和熵的影响。 CO 吸附在 Li ⁺ > Na ⁺ > K ⁺ > Cs ⁺序列中变得越来越不利，并具有显着的熵补偿效应。重要的是，阳离子以相反的方向影响 CO2RR 的初始态和过渡态的稳定性。我们的结果深入了解了阳离子对 CO2RR 中各个基本步骤的影响，并证明稳定吸附 CO 转化中过渡态的能力是一个决定性因素。