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Abstract

The strategy for converting CO₂ into high-value chemicals through electroreduction is feasible and promising; however, its selectivity and current densities are highly dependent on the selection and modulation of catalysts. Herein, In₂O₃ nanosheets were successfully fabricated and then converted into oxide-derived In nanosheets under the same CO₂ electroreduction condition, where the in-situ X-ray diffraction and in-situ Raman results clearly revealed the surface dynamic regulation process. The oxide-derived In nanosheets possess more abundant active sites in comparison to bulk In, which largely improved CO₂ adsorption capacity, affirmed by their active electrochemical active surface areas and CO₂ temperature programmed desorption spectra. Density-of-states calculation demonstrated the d-band center of oxide-derived (OD)-In nanosheet slab visibly shifted toward the Fermi level relative to the bulk In slab, which enabled the former’s faster electron transfer, verified by the corresponding electrochemical impedance spectroscopy. Moreover, in-situ Fourier transform infrared spectra and Tafel slopes indicate that the key intermediate is ∗CO₂⁻ radical, where the metallic In could facilitate the adsorption of CO₂ and stabilize ∗CO₂⁻, thus favoring highly active CO₂ reduction to formate. Based on these advantages, the oxide-derived In nanosheets achieved a formate Faradic efficiency up to nearly 100% at 400 mA ·cm⁻² and stability of 300 h.