Electronic-Structure Modulation in NiRu Alloys To Alleviate Hydrogen Poisoning for Robust Photothermal Ammonia Decomposition

Ammonia (NH3) is a promising hydrogen carrier, yet its efficient decomposition is impeded by the strong adsorption of reaction intermediates, particularly hydrogen species that poison the catalyst. The development of low-cost, active, poisoning-resistant, and durable catalysts remains challenging. Herein, we report a NixRuy alloy catalyst for photothermal NH3 decomposition. The Ni40Ru60 catalyst exhibits a lower apparent activation energy (71.36 kJ·mol–1) than that of Ru (78.68 kJ·mol–1). Under 1.7 W·cm–2 irradiation, a hydrogen production rate of 3.1 mol·gcat–1·h–1 is achieved over Ni40Ru60, surpassing that of the Ru catalyst (1.7 mol·gcat–1·h–1). The order of the ammonia reaction in a H2/NH3 atmosphere is close to zero (0.13), which is lower than that of Ru (0.23), confirming the effective suppression of hydrogen poisoning and stable operation beyond 2500 h. Density functional theory reveals that alloying shifts the electron density from Ni to Ru, downshifting the Ru d-band center by 0.04 eV, which weakens intermediate adsorption and inhibits poisoning. Notably, Ni40Ru60 operates stably outdoors under natural sunlight, providing a practical pathway toward future hydrogen-energy systems.