Selecting between Ammonia and Water Oxidation: Electrochemical Oxidation of Ammonia in Water Using an Organometallic–Inorganic Hybrid Anode

Electrocatalytic ammonia oxidation (AO) under ambient conditions in an aqueous solvent enables an ecofriendly production of nitrite and nitrate. Conventional formation of nitrite and nitrate by AO on noble metals often yields undesired dinitrogen and leads to detrimental nitride surface poisoning. We now find that our previously reported “Blue Layer” (BL), an organometallic–inorganic hybrid anode based on [IrO2]x nanoclusters (x ∼ 5), is active for selective AO in aqueous solution. Through adjustment of both pH and applied potential (Eapp), we identified optimal operating conditions (pH 8.0, 1.00 V) for AO, where BL achieves optimum selectivity toward nitrate (90.5%), effectively minimizing competitive water oxidation while maintaining activity against ammonia-induced degradation of the electrode.