Pd Embedded in 1T-Rich MoS₂ With Island-Sea Confinement for C₂-Selective Ethanol Electrooxidation

Direct ethanol fuel cells (DEFCs) are hampered by sluggish C─C bond cleavage and CO poisoning during ethanol electrooxidation on Pd catalysts. Selective oxidation to acetate through the C₂ pathway circumvents CO formation, yet achieving near-exclusive C₂ selectivity remains challenging. Herein, we report a nitrogen-doping-induced expansion strategy that converts bulk 2H-MoS₂ into a metastable 1T-rich MoS_2-x support (NTMS_x) with enlarged interlayer spacing and abundant sulfur vacancies. Conductive 1T domains preferentially anchor Pd nanoparticles, creating an "island-sea" architecture that fosters pronounced electronic metal-support interaction (EMSI). Electron transfer from NTMS_x to Pd generates electron-rich Pd sites that weaken CO adsorption, while sulfur vacancies enhance hydroxyl adsorption. These synergistic effects steer ethanol electrooxidation toward the C₂-4e pathway and suppress CO formation. DFT calculations confirm favorable energetics for the C₂ pathway on Pd/NTMS_x. The catalyst delivers a high current density and 95.7% Faradaic efficiency for acetate of high added value, with no detectable CO intermediates and outstanding durability. In DEFCs, it achieves a maximum power density of 0.68 W cm^-2 and operates stably for over 500 h. This work establishes confined interfacial anchoring on phase-engineered metal dichalcogenides as a rational design principle for achieving high pathway selectivity in multielectron electrocatalysis.