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

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 Ni_xRu_y 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·g_cat^-1·h^-1 is achieved over Ni₄₀Ru₆₀, surpassing that of the Ru catalyst (1.7 mol·g_cat^-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.