Unveiled the Structure-Selectivity Relationship for Carbon Dioxide Reduction Triggered by Bi-Doped Cu-Based Nanocatalysts

Abstract

To investigate synergistic effect between geometric and electronic structures on directing CO₂ RR selectivity, water phase synthetic protocol and surface architecture engineering strategy are developed to construct monodispersed Bi-doped Cu-based nanocatalysts. The strongly correlated catalytic directionality and Bi³⁺ dopant can be rationalized by the regulation of [*COOH]/[*CO] adsorption capacities through the appropriate doping of Bi³⁺ electronic modulator, resulting in volcano relationship between FE_CO /TOF_CO and surface EVBM values. Spectroscopic study reveals that the dual-site binding mode ([Cu─μ─C(═O)O─Bi³⁺ ]) enabled by Cu₁ Bi³⁺ ₂ motif in single-phase Cu₁₅₀ Bi₁ nanocatalyst drives CO2-to-CO conversion. In contrast, the study of dynamic Bi speciation and phase transformation in dual-phase Cu₅₀ Bi₁ nanocatalyst unveils that the Bi⁰ -Bi⁰ contribution emerges at the expense of BOC phase, suggesting metallic Bi⁰ phase acting as [H]^˙ formation center switches CO₂ RR selectivity toward CO2-to-HCOO^- conversion via [*OCHO] and [*OCHOK] intermediates. This work provides significant insight into how geometric architecture cooperates with electronic effect and catalytic motif/phase to guide the selectivity of electrocatalytic CO₂ reduction through the distinct surface-bound intermediates and presents molecular-level understanding of catalytic mechanism for CO/HCOO^- formation.

Keywords: Bi oxidation state; CO2 reduction; catalytic mechanism; electronic effect; geometric effect.