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Electrochemical CO2 reduction reaction (CO2RR) offers a sustainable strategy for producing fuels and chemicals. However, it suffers from sluggish CO2 activation and slow water dissociation. In this work, we construct a (P−O)δ− modified In catalyst that exhibits high activity and selectivity in electrochemical CO2 reduction to formate. A combination of in situ characterizations and kinetic analyses indicate that (P−O)δ− has a strong interaction with K+(H2O)n, which effectively accelerates water dissociation to provide protons. In situ attenuated total reflectance surface‐enhanced infrared absorption spectroscopy (ATR‐SEIRAS) measurements together with density functional theory (DFT) calculations disclose that (P−O)δ− modification leads to a higher valence state of In active site, thus promoting CO2 activation and HCOO* formation, while inhibiting competitive hydrogen evolution reaction (HER). As a result, the (P−O)δ− modified oxide‐derived In catalyst exhibits excellent formate selectivity across a broad potential window with a formate Faradaic efficiency as high as 92.1 % at a partial current density of ~200 mA cm−2 and a cathodic potential of −1.2 V vs. RHE in an alkaline electrolyte. [ABSTRACT FROM AUTHOR]

Understanding the structure-stability relationship of catalysts is imperative for the development of high-performance electrocatalytic devices. Herein, we utilize operando attenuated total reflectance surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) to quantitatively monitor the evolution of Cu single-atom catalysts (SACs) during the electrochemical reduction of CO2 (CO2RR). Cu SACs are converted into 2-nm Cu nanoparticles through a reconstruction process during CO2RR. The evolution rate of Cu SACs is highly dependent on the substrates of the catalysts due to the coordination difference. Density functional theory calculations demonstrate that the stability of Cu SACs is highly dependent on their formation energy, which can be manipulated by controlling the affinity between Cu sites and substrates. This work highlights the use of operando ATR-SEIRAS to achieve mechanistic understanding of structure-stability relationship for long-term applications. Understanding the structure-stability relationship of catalysts is imperative for the development of high performance electrocatalytic devices. Here the authors use operando attenuated total reflectance surface-enhanced infrared absorption spectroscopy to quantitatively monitor the evolution of Cu single-atom catalysts in electrochemical CO2 reduction. [ABSTRACT FROM AUTHOR]