Selective Electrosynthesis of Nitrite from Nitrate Catalyzed by Perovskite Hydroxide CuSn(OH)6

Nitrite (NO 2 – ) is an important nitrogenous compound widely used in the chemical and pharmaceutical industries. The electrochemical reduction of earth-abundant nitrate (NO 3 – ) is an appealing strategy for the sustainable synthesis of NO 2 –, but its practical use is limited by poor selectivity due to the lack of effective electrocatalysts. Herein, the perovskite hydroxide CuSn(OH) 6 is developed as an efficient electrocatalyst for the selective electrosynthesis of NO 2 – from NO 3 – . The Cu and Sn cations of CuSn(OH) 6 work cooperatively for efficient catalysis, in which the NO 3 – is preferentially adsorbed by the Sn sites and then catalyzed to NO 2 – by the Cu sites. Because the robust Sn(OH) 6 octahedrons in the perovskite hydroxide prevent the Cu 2+ from being reconstructed into metallic Cu with strong hydrogenation activity, further reduction of NO 2 – is eliminated. Consequently, the efficient and selective conversion of NO 3 – to NO 2 – is achieved over Sn(OH) 6 . Even though the electrode potential is as negative as −0.7 V, CuSn(OH) 6 shows a high NO 2 – yield of 145.8 μmol h –1 mg cat –1 (6851.1 μg h –1 mg cat –1 ) and selectivity of 97% with excellent stability in 100 mM Na 2 SO 4 electrolyte containing 10 mM NaNO 3 . This study offers an efficient catalyst for selective electrosynthesis of NO 2 – from NO 3 – and also a novel technique for designing and regulating Cu-based catalysts for diverse applications.