Cu<i>_x</i>Ir_1–<i>x</i> Nanoalloy Catalysts Achieve Near 100% Selectivity for Aqueous Nitrite Reduction to NH₃

Nitrite (NO₂^–) is an abundant contaminant in nature that threatens human health. A catalytic process that converts NO₂^– to less harmful products has been proven to be an effective strategy for NO₂^– removal. Most previous studies, however, targeted selectivity toward N₂ using Pd catalysts, which severely limits the potential for the recovery of value-added byproducts from the catalytic process. Here, we report experimental and theoretical evidence that both Ir and Cu_<i>x</i>Ir_{(100–<i>x</i>)} nanoparticles possess near 100% NH₃ selectivity for NO₂^– reduction compared to the <1% NH₃ selectivity achieved by nano-Pd. These NH₃-selective catalysts could be useful for both water purification and ammonia production.