The effective electrocatalytic carbon dioxide reduction (CO2RR) reaction of Cu-based electrocatalytic materials is a C2+ product, but the excellence and stability of the Cu oxidation state are still worthy of study. Based on this,Professor Li Zhenxing of China University of Petroleum (Beijing) and othersThree different oxidation states of Cu-based electrocatalysts were reported to study their valence-activity relationships. In these Cu-based electrocatalysts, the thickness is only 0Cu2O nanosheets at 9 nm (Cu2O-NS) exhibit extremely high C2+ Faraday efficiency (FeC2+) of approximately 81%, which is a 37% improvement over the conventional Cuox phase.
VASP Interpretation
Using DFT calculations, the authors studied the adsorption behavior of chemical intermediates. Compared with Cu-NS, the Cu-based catalyst in the oxidized state is more likely to achieve CO2 hydroactivation to form *COOH, and then convert it into the adsorbed *CO. However, the δg value of the transition from *CoOh to *Co on Cu2O-ns and CuO-Ns was greater than the corresponding value on Cu-Ns, indicating that the adsorption capacity of Cu to Co after oxidation was significantly improved.
When Cu-Co has high binding energy, the C2+ product selectivity is low due to the difficulty of C-C coupling. When the Cu-Co binding energy is significantly lower, the selectivity of Co is increased, and the amount of C2+ generation is reduced. Therefore, it is crucial to obtain a suitable binding energy between CO and CU.
The authors compared the effects of Cu+ content on CO coverage and C2+ product selectivity, and Cu2O-NS was significantly better than the other two catalysts in all aspects, indicating that Cu+ was the most superior oxidation state. The further hydrogenation of *CO to *CHO is a rate-determining step (RDS) of the whole reaction pathway, and the ΔG of RDS on Cu2O-NS is the smallest, indicating that the Cu-Co bond strength on Cu2O-NS is moderate, which is conducive to hydrogenation. The Bader charge analysis showed that the Cu2O-Ns surface had more partial positive charge than the Cu-Ns and CuO-Ns surfaces, so the presence of coordination defects and oxygen vacancies contributed to the stabilization of the Cu oxidation state.
sub-1 nm cu2o nanosheets for the electrochemical co2 reduction and valence state-activity relationship. j. am. chem. soc.,, doi: ht-tps: