title: Atomic layer confined vacancies for atomic-level insights into carbon dioxide electroreduction.
abstract: The role of oxygen vacancies in carbon dioxide electroreduction remains somewhat unclear. Here we construct a model of oxygen vacancies confined in atomic layer, taking the synthetic oxygen-deficient cobalt oxide single-unit-cell layers as an example. Density functional theory calculations demonstrate the main defect is the oxygen(II) vacancy, while X-ray absorption fine structure spectroscopy reveals their distinct oxygen vacancy concentrations. Proton transfer is theoretically/experimentally demonstrated to be a rate-limiting step, while energy calculations unveil that the presence of oxygen(II) vacancies lower the rate-limiting activation barrier from 0.51 to 0.40 eV via stabilizing the formate anion radical intermediate, confirmed by the lowered onset potential from 0.81 to 0.78 V and decreased Tafel slope from 48 to 37 mV dec-1. Hence, vacancy-rich cobalt oxide single-unit-cell layers exhibit current densities of 2.7 mA cm-2with ca. 85% formate selectivity during 40-h tests. This work establishes a clear atomic-level correlation between oxygen vacancies and carbon dioxide electroreduction.
authors.affiliation: Hefei National Laboratory for Physical Sciences at Microscale, CAS Center for Excellence in Nanoscience, University of Science and Technology of China, Hefei 230026, China.
authors.forename: Shan
authors.initials: S
authors.lastname: Gao
authors.affiliation: Hefei National Laboratory for Physical Sciences at Microscale, CAS Center for Excellence in Nanoscience, University of Science and Technology of China, Hefei 230026, China.
authors.forename: Zhongti
authors.initials: Z
authors.lastname: Sun
authors.affiliation: National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Liu
authors.affiliation: Hefei National Laboratory for Physical Sciences at Microscale, CAS Center for Excellence in Nanoscience, University of Science and Technology of China, Hefei 230026, China.
authors.forename: Xingchen
authors.initials: X
authors.lastname: Jiao
authors.affiliation: Hefei National Laboratory for Physical Sciences at Microscale, CAS Center for Excellence in Nanoscience, University of Science and Technology of China, Hefei 230026, China.
authors.forename: Xiaolong
authors.initials: X
authors.lastname: Zu
authors.affiliation: Hefei National Laboratory for Physical Sciences at Microscale, CAS Center for Excellence in Nanoscience, University of Science and Technology of China, Hefei 230026, China.
authors.forename: Qitao
authors.initials: Q
authors.lastname: Hu
authors.affiliation: Hefei National Laboratory for Physical Sciences at Microscale, CAS Center for Excellence in Nanoscience, University of Science and Technology of China, Hefei 230026, China.|Hefei Science Center of CAS, Hefei, Anhui 230061, China.
authors.forename: Yongfu
authors.initials: Y
authors.lastname: Sun
authors.affiliation: National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Yao
authors.affiliation: Hefei National Laboratory for Physical Sciences at Microscale, CAS Center for Excellence in Nanoscience, University of Science and Technology of China, Hefei 230026, China.
authors.forename: Wenhua
authors.initials: W
authors.lastname: Zhang
authors.affiliation: National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, China.|Hefei Science Center of CAS, Hefei, Anhui 230061, China.
authors.forename: Shiqiang
authors.initials: S
authors.lastname: Wei
authors.affiliation: Hefei National Laboratory for Physical Sciences at Microscale, CAS Center for Excellence in Nanoscience, University of Science and Technology of China, Hefei 230026, China.|Hefei Science Center of CAS, Hefei, Anhui 230061, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Xie