Industrial-current-density CO2-to-formate conversion with low overpotentials enabled by disorder-engineered metal sites
Zhiqiang Wang, Xiaolong Zu, Xiaodong Li, Li Li, Yang Wu, Shumin Wang, Peiquan Ling, Yuan Zhao, Yongfu Sun, Yi Xie
Abstract
CO2 electroreduction to formate is technically feasible and economically viable, but still suffers from low selectivity and high overpotential at industrial current densities. Here, lattice-distorted metallic nanosheets with disorder-engineered metal sites are designed for industrial-current-density CO2-to-formate conversion at low overpotentials. As a prototype, richly lattice-distorted bismuth nanosheets are first constructed, where abundant disorder-engineered Bi sites could be observed by high-angle annular dark-field scanning transmission electron microscopy image. In-situ Fourier-transform infrared spectra reveal the CO2•−* group is the key intermediate, while theoretical calculations suggest the electron-enriched Bi sites could effectively lower the CO2 activation energy barrier by stabilizing the CO2•−* intermediate, further affirmed by the decreased formation energy from 0.49 to 0.39 eV. As a result, the richly lattice-distorted Bi nanosheets exhibit the ultrahigh current density of 800 mA·cm−2 with 91% Faradaic efficiencies for CO2-to-formate electroreduction, and the formate selectivity can reach nearly 100% at the current density of 200 mA·cm−2 with a very low overpotential of ca. 570 mV, outperforming most reported metal-based electrocatalysts.