The electrochemical CO2 reduction reaction (CO2RR) is a promising carbon mitigation strategy because it can operate at high reaction rates and excellent efficiency at ambient conditions and in environmentally friendly aqueous electrolytes. Here, we use experimental and computational techniques to characterize the electronic structure and reactivity of ~2 nm thiol-capped gold-copper nanoparticles for electrochemical CO2RR. Laboratory and synchrotron-based X-ray spectroscopies characterized Au/Cu NPs containing between 0-64% Cu. NPs containing 49% Cu showed the best activity and product selectivity with performance that exceeded pure Au. We obtained a steady state conversion of CO2 into CO with 100 ± 6% Faradaic efficiency and average mass activity of ~500 mA/mg during long-term electrolysis experiments. Complementary density functional theory (DFT) calculations showed that unique copper-thiol surface sites at the NP-ligand interface boosted reactivity by stabilizing key CO2RR intermediates and preventing competitive H2 evolution. This study shows that atomic composition can be used to tune the electronic structure and chemical reactivity of small bimetallic NPs.

Selective CO2 reduction at thiol-capped Au/Cu nanocatalysts

2019 Spring National Meeting

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