Mechanistic insights into potential dependence of CO electrochemical reduction into C1 products based on a H coverage-dependent Cu(111)/H2O interface model. Issue 36 (14th September 2020)

• Record Type: Journal Article
• Authors: Ou, Lihui; He, Zixi; Chen, Yuandao; Jin, Junling
• Is Part Of: Physical chemistry chemical physics. Volume 22:Issue 36(2020)
• Page Start: 20444
• Page End: 20452
• Publication Date: 2020-09-14
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/d0cp03274c
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : A high overpotential led to the formation of CH4, and CH3 OH may be produced via a CH3 O intermediate. Abstract : A H coverage-dependent Cu(111)/H2 O interface model incorporated with electronic structure analysis is employed to investigate the potential dependence of CO electroreduction into C1 products with the aim of solving the long dispute over CO2 electrocatalytic reduction mechanisms. The results indicate that CH4 formation mainly proceeds through CO, CHO, CH2 O, CH2 OH and CH x ( x = 2 and 3) species at various applied potentials. CH3 OH may be formed via a CH3 O intermediate at high overpotential and the present study can confirm that CH3 OH is only produced in a trace amount as detected in experiments. The high overpotential results in the formation of CH4, explaining the experimentally required high overpotential on Cu. The calculated energetics concludes that CO electroreduction into CHO may be a potential-limiting step, being regarded as the origin of the required high overpotentials for CO2 electroreduction in this paper. The electronic structure calculations show that more electronic transfer to the adsorbed H atoms occurs with increasing H coverage, which can be considered as the origin of the more negative electrode potentials. Interestingly, it is observed that the s orbital of the C atom in the valence shell of the adsorbed CO molecule gains more and more electrons, whereas the s orbital of the O atom gains less and less electrons, and even loses electrons with increasing H coverage, implying easier and easier proton transfer towards the C-center site. Thus, the easier occurrence of CO electroreduction may be ascribed to the more electron transfer into the s orbital of the C atom at high overpotential. We believe that the present study represents theoretical progress to systematically study potential-dependent CO2 electroreduction mechanisms on Cu electrodes.