(a) Calculated work functions (Wf) for (a) Er2O3 (b) Cu-Er2O3. (c) Plot of electron localization function of Cu-Er2O3. (d) Adsorption energy of CO2 on Er2O3 and Cu-Er2O3. (e) The calculated density of states for *CHO absorbed on Cu-Er2O3. (IMAGE)
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DFT theoretical calculations were carried out to clarify how Cu doping modifies the electronic structure and catalytic behavior of Er2O3. Cu incorporation reduces the catalyst work function and triggers charge redistribution, forming a strong built-in electric field (BIEF) with positively charged Cu sites and negatively polarized Er2O3 matrix. This BIEF greatly enhances CO2 adsorption, shifts the d-band center upward to strengthen binding of the key *CHO intermediate, and facilitates water dissociation to generate abundant active *H species with optimized adsorption-desorption energy. AIMD simulations confirm that the electric field reorients interfacial water into an H-near configuration, shortening the distance between hydrogen atoms and the catalyst surface and enriching near-surface protons. The Gibbs free energy pathway identifies *CHO→*CH2O as the rate-determining step, whose energy barrier is drastically lowered on Cu-Er2O3, especially under the favorable H-near water arrangement. Electron density difference and COHP analyses prove Cu-Er2O3 transfers more electrons to *CHO and forms stronger orbital coupling with this intermediate than pure Er2O3. Overall, Cu doping-induced BIEF engineering optimizes electronic configuration, interfacial water microenvironment, intermediate adsorption and reaction energy barriers, jointly improving the activity and CH4 selectivity of CO2 electroreduction.
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Nano Research, Tsinghua University Press
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