Selective Etching Quaternary MAX Phase toward Single Atom Copper Immobilized MXene (Ti3C2Clx) for Efficient CO2 Electroreduction to Methanol

Qi Zhao; Chao Zhang; Riming Hu; Zhiguo Du; Jianan Gu; Yanglansen Cui; Xiao Chen; Wenjie Xu; Zongju Cheng; Songmei Li; Bin Li; Yuefeng Liu; Weihua Chen; Chuntai Liu; Jiaxiang Shang; Li Song; Shubin Yang

doi:10.1021/acsnano.0c09755

Selective Etching Quaternary MAX Phase toward Single Atom Copper Immobilized MXene (Ti₃C₂Cl_x) for Efficient CO₂ Electroreduction to Methanol

ACS Nano. 2021 Mar 23;15(3):4927-4936. doi: 10.1021/acsnano.0c09755. Epub 2021 Feb 22.

Authors

Qi Zhao¹, Chao Zhang¹, Riming Hu¹, Zhiguo Du¹, Jianan Gu¹, Yanglansen Cui¹, Xiao Chen², Wenjie Xu³, Zongju Cheng¹, Songmei Li¹, Bin Li¹, Yuefeng Liu⁴, Weihua Chen⁵, Chuntai Liu⁵, Jiaxiang Shang¹, Li Song³, Shubin Yang¹

Affiliations

¹ Key Laboratory of Aerospace Advanced Materials and Performance of Ministry of Education, School of Materials Science & Engineering, Beihang University, Beijing 100191, China.
² Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China.
³ National Synchrotron Radiation Laboratory, Hefei National Laboratory for Physical Sciences at the Microscale, CAS Center for Excellence in Nanoscience, University of Science and Technology of China, Hefei, Anhui 230029, China.
⁴ Dalian National Laboratory for Clean Energy (DNL), Dalian Institute of Chemical Physics, Chinese Academy of Science, 457 Zhongshan Road, 116023 Dalian, China.
⁵ Key Laboratory of Materials Forming and Mold Technology (Ministry of Education), Zhengzhou University, Zhengzhou 450002, China.

PMID: 33617242
DOI: 10.1021/acsnano.0c09755

Abstract

Single atom catalysts possess attractive electrocatalytic activities for various chemical reactions owing to their favorable geometric and electronic structures compared to the bulk counterparts. Herein, we demonstrate an efficient approach to producing single atom copper immobilized MXene for electrocatalytic CO₂ reduction to methanol via selective etching of hybrid A layers (Al and Cu) in quaternary MAX phases (Ti₃(Al_1-xCu_x)C₂) due to the different saturated vapor pressures of Al- and Cu-containing products. After selective etching of Al in the hybrid A layers, Cu atoms are well-preserved and simultaneously immobilized onto the resultant MXene with dominant surface functional group (Cl_x) on the outmost Ti layers (denoted as Ti₃C₂Cl_x) via Cu-O bonds. Consequently, the as-prepared single atom Cu catalyst exhibits a high Faradaic efficiency value of 59.1% to produce CH₃OH and shows good electrocatalytic stability. On the basis of synchrotron-based X-ray absorption spectroscopy analysis and density functional theory calculations, the single atom Cu with unsaturated electronic structure (Cu^δ+, 0 < δ < 2) delivers a low energy barrier for the rate-determining step (conversion of HCOOH* to absorbed CHO* intermediate), which is responsible for the efficient electrocatalytic CO₂ reduction to CH₃OH.

Keywords: MXenes; carbon dioxide reduction reaction; electrocatalysis; selective etching; single atom catalysts.