Single-Product Faradaic Efficiency for Electrocatalytic of CO2 to CO at Current Density Larger than 1.2 Acm~(-2) in Neutral Aqueous Solution by a Single-Atom Nanozyme

摘要

Electroreduction of CO2 to CO is a promising approach for the cycling use of CO2, while it still suffers from impractical current density and durability. Here we report a single-atom nanozyme (Ni-N5-C) that achieves industrial-scale performance for CO2-to-CO conversion with a Faradaic efficiency (FE) exceeded 97 over -0.8-2.4 V vs. RHE. The current density at -2.4 V vs. RHE reached a maximum of 1.23 Acm~(-2) (turnover frequency of 69.7 s~(-1)) with an FE of 99.6 . No obvious degradation was observed over 100 hours of continuous operation. Compared with the planar Ni-N4 site, the square-pyramidal Ni-N5 site has an increase and a decrease in the d_(z2) and d_(xz/yz) orbital energy levels, respectively, as revealed by density functional theory calculationes. Thus, the Ni-N5 catalytic site is more superior to activate CO2 molecule and reduce the energy barriers as well as promote the CO desorption, thus boosting the kinetic activation process and catalytic activity.