Fermi-Level Compression in Zn-Cu Alloys through ZnO/CuO Ratio Control for Selective CO 2 Reduction

Le résumé fourni par la source

Electrochemical reduction of CO 2 to CO is a promising route for carbon utilization but often suffers from low selectivity due to competing hydrogen evolution reaction (HER) and unbalanced adsorbate binding. Here, ZnO-CuO bimetallic oxides with varying Zn:Cu ratios were synthesized via a co-precipitation-calcination method and electrochemically transformed into partially alloyed ZnCu structures at −1.2 V. The ratio of Zn to Cu critically governs catalyst performance: an intermediate ratio (4ZnO-CuO) enables optimal alloy formation, generating a highly interconnected honeycomb-like porous morphology that increase electrochemically active surface area, enhance CO 2 transport, and expose abundant Zn and Cu-rich active sites. Alloying induces bidirectional d-band compression, with Zn shifting upward (+2.47 eV) and Cu downward (−2.80 eV), promoting * COOH formation while suppressing HER through weakened H adsorption. Simultaneously, CO binding is tuned for facile desorption. This synergistic combination of structural and electronic effects at the optimal Zn:Cu ratio achieves a peak CO Faradaic efficiency of 91.6% at −1.2 V vs RHE, a minimal H 2 side-product (8.3%), and a stable current density of ∼75 mA cm −2 over 11 h, highlighting the importance of precise Zn:Cu composition in directing selective CO 2 RR.

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