Ag Single Atoms Anchored on CeO₂ with Interfacial Oxygen Vacancies for Efficient CO₂ Electroreduction

Abstract

Ag single-atom catalysts (SACs) have great potential in selective electrocatalysis of the CO2 reduction reaction (CO2RR) to CO, while it is still a challenge to achieve high current density and high atom efficiency simultaneously. Here, we present a new and simple in situ adsorption–reduction method to prepare Ag SACs supported on CeO2 (Ag1/CeO2). It is found that Ag single atoms are anchored on CeO2 through strong metal–support interaction (SMSI), and each Ag atom is accompanied with three interfacial oxygen vacancies. This Ag1/CeO2 exhibits high performance in the electrocatalytic CO2RR with a high CO faradaic efficiency (FE) of >95% under a wide potential range. The turnover frequency (TOF) value can reach 50,310 h–1 at FECO = 99.5% in H-cells. Notably, Ag1/CeO2 achieves an industrial-grade current density of 403 mA cm–2 with a high FECO of 97.2% in flow cells. Experimental results combined with density functional theory calculation revealed that this superior performance was mainly ascribed to the existence of interfacial oxygen vacancies, which lead to the formation of Ag–O–Ce3+ atomic interfaces, and activates the Ce3+–O structures as the synergistic active center of Ag, thus promoting CO2 adsorption and activation and reducing the reaction potential barrier of *COOH-to-*CO.

Deciphering Structure‐Activity Relationship Towards CO2 Electroreduction over SnO2 by A Standard Research Paradigm

“…In our proposed research methodology, the possible stable surface states can be acquired through the dynamic structure search, consequently leading to the building of the structure-property-activity relationships. In Figure 6e, we demonstrate the generalized research methodology to decipher the structure-property relationship for any electrocatalytic systems: A) for an unexplored catalyst material, the bulk Pourbaix should be analyzed to illustrate the stability under electrolysis; B) the surface Pourbaix analysis is then performed to investigate the most likely-exposed surface species; C) if the exposed surfaces possess rich defects, like C/N/O/P/S vacancies, [29] they are prone to undergo rearrangement, and thus we are supposed to search for the possible reconstructed states through the dynamic structure search, like GA [12a] or other MD methods; [16c] D) the structure-property-activity relationship can be discovered based on the determined surface states through theoretical and/or experimental analysis. Note that for Step B, surface Pourbaix may not be the only option to analyze the surface state-any methods that can unravel the electrochemistry-induced surface states (e.g., the much more expensive machine learning potential based study with explicit solvent) [9a] would be helpful for this analysis; however, surface Pourbaix analysis is so far a rather costeffective option.…”

Rare‐earth Element‐based Electrocatalysts Designed for CO2 Electro‐reduction

“…Liang et al prepared CeO 2supported Ag SACs (Ag 1 /CeO 2 ) by a simple in situ adsorptionreduction method (Figure 8f). [84] Ag single atoms are anchored on CeO 2 through SMSIs (Figures 8g, 8h), and there are three interfacial oxygen vacancies surrounding each Ag atom. The Ag 1 /CeO 2 SACs achieve an industrial-grade current density of 403 mA cm À 2 with a high FE CO of 97.2 % in flow cells.…”

“…Reprinted with permission from Ref. [84] Copyright 2023, American Chemical Society. i) Scheme of the self-sacrifice mechanism to protect Cu 2 + .…”

“…h) Elemental mappings of Ag (yellow), Ce (green), and O (red). Reprinted with permission from Ref [84]. Copyright 2023, American Chemical Society.…”

Advances and challenges in the electrochemical reduction of carbon dioxide

“…Through the chemisorption, the C O bond is stretched to activate the CO 2 molecule, and the energy barrier of the intermediate species is stabilized to a low value. 103 For example, Gao et al prepared an atomic-layered CO 3 O 4 material and deliberately created oxygen vacancies on the surface to conduct targeted investigation on its role, revealing that the V O -rich material surpasses the contrast sample without V O in all the catalytic properties ( Fig. 8a–e ).…”