Ga-Induced Reversal of Pd Electronic States in ZrO2-Supported Pd2Ga1 Nanoparticles for Enhanced Ethanol Electrooxidation via the C1 Pathway.

Direct ethanol fuel cells (DEFCs) are recognized as a promising energy conversion technology due to their high energy density and the renewable, eco-friendly nature of ethanol. However, their commercialization is hindered by the lack of anode catalysts that simultaneously offer high activity, stability, and selectivity toward the C1 pathway in the ethanol oxidation reaction (EOR). Herein, we report a rationally designed Pd2Ga1-ZrO2@NC electrocatalyst, in which Pd2Ga1 alloy nanoparticles are anchored on a nitrogen-doped carbon-encapsulated ZrO2 nanoframework. In alkaline media, this catalyst exhibits exceptional EOR performance, achieving a remarkable mass activity of 27.3 A mgPd -1, 3.6 and 21.8 times higher than those of Pd-ZrO2@NC and commercial Pd/C, respectively. Furthermore, it demonstrates a high C1 pathway selectivity of 58.7% at 0.8 VRHE and retains 48.9% of its initial activity after 2000 accelerated durability test cycles, significantly outperforming state-of-the-art benchmarks. Combined experimental and DFT studies reveal the crucial function of Ga as an electron donor, which reverses the electron transfer around Pd from outward (in Pd-ZrO2@NC) to inward (in Pd2Ga1-ZrO2@NC), creating an electron-rich Pd state. This electronic restructuring thereby lowers the *CO oxidation barrier, strengthens *OH adsorption, and enhances metal-support interaction, collectively boosting both the C1 pathway selectivity and the overall EOR performance. This work provides valuable insights for the design of high-performance alloy-oxide composite electrocatalysts.