Single-Atomic Cu with Multiple Oxygen Vacancies on Ceria for Electrocatalytic CO₂ Reduction to CH₄

Abstract

The electrocatalytic reduction of CO2 into value-added chemicals such as hydrocarbons has the potential for supplying fuel energy and reducing environmental hazards, while the accurate tuning of electrocatalysts at the ultimate single-atomic level remains extremely challenging. In this work, we demonstrate an atomic design of multiple oxygen vacancy-bound, single-atomic Cu-substituted CeO2 to optimize the CO2 electrocatalytic reduction to CH4. We carried out theoretical calculations to predict that the single-atomic Cu substitution in CeO2(110) surface can stably enrich up to three oxygen vacancies around each Cu site, yielding a highly effective catalytic center for CO2 adsorption and activation. This theoretical prediction is consistent with our controlled synthesis of the Cu-doped, mesoporous CeO2 nanorods. Structural characterizations indicate that the low concentration (<5%) Cu species in CeO2 nanorods are highly dispersed at single-atomic level with an unconventionally low coordination number ∼5, suggesting the direct association of 3 oxygen vacancies with each Cu ion on surfaces. This multiple oxygen vacancy-bound, single atomic Cu-substituted CeO2 enables an excellent electrocatalytic selectivity in reducing CO2 to methane with a faradaic efficiency as high as 58%, suggesting strong capabilities of rational design of electrocatalyst active centers for boosting activity and selectivity.

Cu2O Nanoparticles with Both {100} and {111} Facets for Enhancing the Selectivity and Activity of CO2 Electroreduction to Ethylene

“…Ethylene (C 2 H 4 ), an important raw material, is one of the main C2 products over Cu electrodes . However, due to the simultaneous production of H 2 and other C1 species (i.e., CO, CH 4 ), the Faradaic efficiency for the production of C 2 H 4 (FE C2H4 ) on metallic Cu is usually low . Efforts to improve the FE C2H4 of Cu‐based catalysts have focused on optimizing the sizes, morphologies, and exposed crystal facets of metallic Cu NPs .…”

A Disquisition on the Active Sites of Heterogeneous Catalysts for Electrochemical Reduction of CO2 to Value‐Added Chemicals and Fuel

“…Wang et al proposed the design of multiple oxygen vacancies formation by doping single atomic Cu metal (4% doping level) into Ce nanorods to optimize CO 2 RR to CH 4 , attaining a FE CH4 of 58% at −1.8 V with good stability ( Figure 11 ). Moreover, as indicated in Figure , variation in Cu doping level can alter the product selectivity of CO 2 RR. Moreover, theoretical DFT calculations further confirmed that three‐oxygen vacancies bound Cu structure could efficiently activate CO 2 and convert it to CH 4 (Figure c–g).…”

“…Data from refs. . The detailed catalytic activity of these catalysts is presented in Table S3 (Supporting Information).…”

“…f,g) Structure models of oxygen‐vacancy‐bound single‐atomic Cu site on CeO 2 for CO 2 adsorption and activation. Reproduced with permission . Copyright 2018, American Chemical Society.…”

Nonsiliceous Mesoporous Materials: Design and Applications in Energy Conversion and Storage

“…TiO 2 :Ru with Ti 3+ and Ru 5+ achieved high H 2 evolution reaction activity with appropriate H 2 adsorption Gibbs free energies. In mesoporous CeO 2 nanorods, substitution of single Cu atoms in the CeO 2 (110) surface can stably enrich up to three oxygen vacancies around each Cu site; this phenomenon yields a highly effective catalytic center for CO 2 adsorption and activation …”