Regulating the Interfacial Microenvironment of Pd through the Synergistic Effect of Spontaneous Polarization Electric Field and Nitrogen Coordination for Enhanced Formic Acid Oxidation

Abstract Direct formic acid fuel cells (DFAFCs) require highly active and CO-tolerant Pd-based catalysts to enable efficient anodic formic acid oxidation (FAO). Herein, we report a ferroelectric polarization-assisted catalytic system, in which Pd nanoparticles are anchored on nitrogen-doped carbon-coated BaTiO3 (Pd/BTO@NC). The spontaneous polarization electric field (SPEF) of BaTiO3 cooperates with Pd–N coordination from the carbon shell to regulate the electronic structure and interfacial microenvironment of Pd. The optimized Pd/BTO@NC catalyst delivers a specific activity of 10.57 mA·cm−2, representing a 5.84-fold enhancement over commercial Pd/C, along with markedly improved CO tolerance, evidenced by a significantly lowered CO desorption onset potential and an early desorption ratio of 42.28%. Comprehensive experimental characterizations combined with density functional theory (DFT) calculations reveal that nitrogen doping induces a downshift of the Pd d-band center, suppressing the CO-producing dehydration pathway, while the SPEF further enhances OH adsorption and facilitates oxidative CO removal. As a result, FAO preferentially proceeds via the formate pathway. This work demonstrates that coupling ferroelectric polarization with heteroatom-doped interfaces provides a viable strategy for designing high-performance electrocatalysts for small-molecule oxidation reactions.