Electronic metal-support interaction modulates Cu electronic structures for CO₂ electroreduction to desired products

Area of Science:

• Materials Science
• Catalysis
• Electrochemistry

Background:

• Electrochemical CO2 reduction reaction (CO2RR) is crucial for sustainable energy. Single-atom catalysts (SACs) offer high efficiency but require precise tuning.
• Metal-oxide supported copper SACs (Cu SACs) are promising for CO2RR, but understanding structure-performance relationships is key.
• Electronic metal-support interactions (EMSI) significantly influence the electronic structure of metal sites in SACs.

Purpose of the Study:

• To theoretically investigate the correlation between the electronic structures of Cu SACs and their CO2RR performance.
• To elucidate how EMSI modulates Cu electronic states and influences catalytic pathways on different metal oxide supports (Al2O3, CeO2, TiO2).
• To identify the optimal catalyst for efficient and selective methane production.

Main Methods:

• Theoretical modeling using DFT (Density Functional Theory) to simulate Cu SACs on Al2O3, CeO2, and TiO2 supports.
• Analysis of electronic structures, focusing on the highest occupied molecular orbital (HOMO) and charge transfer.
• Calculation of reaction energy barriers for key steps in CO2RR and hydrogen evolution reaction (HER).

Main Results:

• Al2O3-CuSAC: Enhanced CO adsorption and C-C coupling via 3d(yz) orbital back-donation, promoting multicarbon products.
• TiO2-CuSAC: Accelerated H2O activation via 3d(z2) orbital, leading to increased HER and hindering CH4 selectivity.
• CeO2-CuSAC: Promoted CO2 activation and localized electronic states inhibiting C-C coupling, with moderate water activity facilitating CH4 production with 70.3% Faradaic efficiency at 400 mA cm-2.

Conclusions:

• The specific HOMO of Cu SACs, influenced by EMSI, dictates CO2RR pathways and product selectivity.
• CeO2-CuSAC demonstrates superior performance for CH4 production due to balanced CO2 activation and suppressed HER.
• Tailoring EMSI through support selection is a viable strategy for designing high-performance CO2RR electrocatalysts.