Titania-Modified Silver Electrocatalyst for Selective CO2 Reduction to CH3OH and CH4 from DFT Study

5 years ago

Titania-Modified Silver Electrocatalyst for Selective CO2 Reduction to CH3OH and CH4 from DFT Study

Chaonan Cui, Lina Zhai, Qingfeng Ge, Hua Wang, Jinyu Han, Xinli Zhu, Yuntao Zhao

Electrochemical reduction of CO₂ to produce useful fuels and chemicals is one of the attractive means to reuse CO₂. Herein, we constructed a (TiO₂)₃/Ag(110) model electrocatalyst and examined CO₂ reduction pathways. Our results show that the interface between oxide and supporting Ag provides the active sites for CO₂ adsorption and activation. These active sites enable the electron transfer to the adsorbed CO₂. In this setup, Ag acts as an electron donor, partially reducing the supported (TiO₂)₃ and supplies the needed electrons to the adsorbed CO₂. Once CO₂* is formed at the interface, the subsequent hydrogenation steps take place sequentially. Our results further indicate that the dominating pathway to produce CH₃OH is via the H₂COOH* intermediate following the formation of HCOO*. The formation of H₂COOH* with a free energy of 0.47 eV is the potential-limiting step. Furthermore, protonating H₂COOH* followed by dehydration to CH₃O* and hydrogenation of CH₃O* leads to CH₄ formation. The COOH* pathway may converge to the same H₂COOH* intermediate instead of forming CO*. These results demonstrated the benefit of metal supported metal oxides as electrocatalysts to produce CH₃OH or CH₄ from electrochemical reduction of CO₂.

Publisher URL: http://dx.doi.org/10.1021/acs.jpcc.7b03314

DOI: 10.1021/acs.jpcc.7b03314