Near-100% C1-Pathway Selective Ethanol Oxidation on Turing-Type Pd-Based Crystalline/Amorphous Heterointerfaces.

Abstract

Direct ethanol fuel cells are hindered by the ethanol oxidation reaction (EOR) that favors the low-efficiency C2 pathway over the desirable C1 pathway. Here, we report a catalyst design integrating an ultrathin Turing-type nanonet with a Pd-based crystalline/amorphous (C/A) heterointerface, achieving a near-complete C1-pathway selectivity of 97.1% for alkaline EOR, which is the highest reported to date. Inspired by spatially decoupling C─C cleavage and CO oxidation, we engineer two intimately integrated phases: strained interstitial-carbon-doped PdO (C_int-PdO) enriched with oxygen vacancies and defective amorphous PdC_x (a-PdC_x). This heterostructure is realized via a "carbon engineering" strategy combining salt-melt templating with secondary annealing. Atomic-resolution studies confirm atomically sharp C/A interfaces and the highly unsaturated a-PdC_x phase. In situ Fourier-transform infrared spectroscopy (FTIR) directly visualizes CO₂ emergence at ultralow overpotentials, while high-performance liquid chromatography (HPLC) verifies the near-complete C1 pathway. Density functional theory (DFT) reveals a dual-cooperative mechanism: C_int-PdO steers the EOR toward C1 pathway by facilitating CH₃CO* dehydrogenation and subsequent C─C cleavage via CH₂CO*, thereby suppressing acetate formation; concurrently, a-PdC_x dramatically accelerates CO oxidation and may also contribute to C─C cleavage via an alternative direct CH₃CO* pathway. This work establishes carbon-engineered C/A heterointerfaces as a powerful platform for overcoming the EOR selectivity bottleneck.