(449c) Efficient and Robust Electrochemical CO2-to-Formate Conversion at Pd/C60 Interface

The electrochemical reduction of CO₂ to formate attracts significant attention owing to its promising technological and economic prospects. Among the potential catalyst candidates, Pd-based materials stand out for delivering high formate selectivity at near-equilibrium potential. However, the efficiency of Pd is hindered at elevated overpotentials due to phase transition from α-PdH to β-PdH and CO poisoning, severely restricting the formate activity within narrow potential window (0 V to –0.3 V vs. RHE), minimizing current density and undermining stability. Herein, by constructing the palladium/fullerene interface to stabilize Pd^δ+ species through interfacial charge transfer, the resistance to deactivation was significantly achieved. The advancement enables formate production within a broadened potential window (0 V to –0.6 V vs. RHE), achieves high current density (up to 80 mA cm^–2 in flow electrolyzer) and demonstrates feasible stability (30 hours at ~ 10 mA cm^–2), outperforming the Pd-based benchmark electrocatalysts for CO₂ to formate conversion (i.e., PdNPs and Pd/C, with limited formate activity ＜ 5 mA cm^–2). Through the combination of electrochemical surface analysis, in situ techniques (in situ-XRD and in situ-ATR-SEIRAS) and density functional theory (DFT) calculations, we revealed the suppressed phase transition and inhibited CO poisoning upon the stabilized Pd^δ+ species originated from palladium/fullerene interface, which ensures robust formate production over widened potential window and at remarkable current density. Additionally, by integrating the in situ methodologies and theoretical investigations, we hypothesized the interplay among phase transition, CO poisoning and overpotential: both phase transition and CO poisoning stem from elevated overpotential; while phase transition to β-PdH exacerbates CO poisoning and deactivation. Our discoveries offer a rational design strategy for Pd-catalyzed CO₂-to-formate conversion by stabilizing Pd^δ+ species via the Pd-substrate interface, and contribute to the understanding of potential-driven deactivation process on Pd during CO₂ reduction.