<p>Pd-based materials are among the best electrocatalysts with high CO₂-to-formate selectivity at near-equilibrium potential. However, the efficiency of Pd is severely hindered by its deactivation at elevated overpotentials, resulting in limited formate production activity within a narrow potential window. Herein, by constructing a palladium/fullerene (PdC₆₀) composite catalyst, we achieve improved activity towards formate production and enhanced resistance to deactivation at high overpotentials. As a result, the PdC₆₀ composite achieves practically relevant current density of 250 mA cm⁻² in 4 cm² membrane electrode assembly reactor with a modest cell voltage of 1.71 V, along with the energy efficiency up to 72% towards formate, demonstrating its promise for future implementation. Mechanistically, we pinpoint the enhanced performance of PdC₆₀ to the profound interfacial charge transfer from Pd to C₆₀ substrate, which suppresses Pd-H phase transition and alleviates CO poisoning during catalysis. Overall, our discoveries shed light on the complex potential-dependent interplays between the phase evolution of Pd-based catalysts and CO₂ electroreduction performance, highlighting its promise for energy-efficient CO₂ conversion.</p>