Efficient and Robust Carbon Dioxide Electroreduction Enabled by Atomically Dispersed Snδ+ Sites

Abstract Electrocatalytic CO 2 reduction at considerably low overpotentials still remains a great challenge. Here, a positively charged single‐atom metal electrocatalyst to largely reduce the overpotentials is designed and hence CO 2 electroreduction performance is accelerated. Taking the metal Sn as an example, kilogram‐scale single‐atom Sn δ + on N‐doped graphene is first fabricated by a quick freeze–vacuum drying–calcination method. Synchrotron‐radiation X‐ray absorption fine structure and high‐angle annular dark‐field scanning transmission electron microscopy demonstrate the atomically dispersed Sn atoms are positively charged, which enables CO 2 activation and protonation to proceed spontaneously through stabilizing CO 2 •− * and HCOO − *, affirmed by in situ Fourier transform infrared spectra and Gibbs free energy calculations. Furthermore, N‐doping facilitates the rate‐limiting formate desorption step, verified by the decreased desorption energy from 2.16 to 1.01 eV and the elongated SnHCOO − bond length. As an result, single‐atom Sn δ + on N‐doped graphene exhibits a very low onset overpotential down to 60 mV for formate production and shows a very large turnover frequency up to 11930 h −1 , while its electroreduction activity proceeds without deactivation even after 200 h. This work offers a new pathway for manipulating electrocatalytic performance.