Boosting Pd-catalysis for electrochemical CO₂ reduction to CO on Bi-Pd single atom alloy nanodendrites

Pd is a catalyst for electrochemical CO₂ reduction to CO but often disturbed by H₂ and formate formation at low overpotentials due to its strong affinity to H atoms. Herein, guided by density functional theory (DFT) calculations, Bi-Pd single atom alloy (SAA) nanodendrites (NDs) with Bi atomically dispersed in Pd matrices have been developed for efficient CO₂ reduction to CO. The Faradic efficiencies (FEs) of CO on the Bi₆Pd₉₄-SAA ND catalyst reach 90.5 % and 91.8 % in H-type and gas diffusion flow cells with overpotentials of only 290 and 200 mV, respectively, which are among the best of the reported Pd-based electrocatalysts. The greatly enhanced CO formation on the Bi₆Pd₉₄-SAA NDs can be attributed to the increased reaction barriers for H₂ formation due to a lower H coverage resulted from Bi doping, and the decreased free energy for *COOH generation which is a key intermediate for CO production.