Hypo-electronegativity Atoms Induce Bader Charge Enrichment on the Pt Surface to Promote Ampere-Level Electrocatalytic Ammonia Oxidation.

The efficient development of electrocatalysts for ammonia oxidation anodes represents a critical challenge which hinders the commercialization of direct ammonia fuel cells (DAFCs) and the realization of energy transition goals. Platinum (Pt)-based catalysts play a key role in ammonia oxidation reactions (AOR); however, their reaction kinetics are sluggish at low temperatures and are susceptible to toxicity from intermediate species such as *N, which limits their applicability at ampere-level currents. Drawing inspiration from the "stepwise dehydrogenation mechanism" and the concept of "Bader charge", we have designed a hypo-electronegativity atom mediated Pt-based high-entropy alloy regulation strategy. This approach exploits the electronegativity difference between Zn and Pt to induce the enrichment of Bader charges on the Pt atom surface, thereby enhancing the adsorption properties of Pt atoms and lowering the reaction energy barriers during the AOR process. Consequently, the appropriately Zn-mediated Pt-based high-entropy alloy achieves a peak current density of 351.5 A g at ambient temperature (25 °C), which is 2.5 times higher than that of commercial Pt/C under comparable conditions. Notably, a peak power density of 4.67 mW cm can be achieved at 25 °C for a low-temperature DAFC using the Pt-6HEAs-Zn18 as the anode catalyst. The Zn-mediated Pt-based high-entropy alloy strategy we designed provides valuable insights for the development of other efficient AOR catalysts that can achieve ampere-level current densities.