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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.
