Prussian blue analog derived Cu doped Co₃O₄ catalyst for promoting electrocatalytic nitrate reduction to ammonia

Electrocatalytic reduction of nitrate to ammonia (ERNA) not only produces valuable ammonia, but also solves the problem of NO3- pollution in wastewater. Here, Co-Co PBA (Prussian blue analog) microcubes were applied as templates to synthesize Co3O4 catalyst. The transition metal Cu-doped Co3O4 catalyst effectively improved the performance of electrocatalytic nitrate reduction for ammonia synthesis. In 0.1 M KOH including 0.1 M NO3- electrolyte, 30Cu-Co3O4 catalyst (the doping amount was 30 mg) shows high Faraday efficiency (FE) of 92.4 % and large NH3 yield rate of 0.584 mmol h(-)1 mg(cat)(-1) at - 0.4 V Vs. RHE (Reversible hydrogen electrode), which benefiting from framework structure of PBA, abundant exposed active sites and beefed-up interfacial and electronic interactions between metals and metal oxides. Meanwhile, 30Cu-Co3O4 catalyst has greater stability in the longtime electrolysis process, NH3 (ammonia) originates from nitrate electroreduction was confirmed by N-15 isotope labeling experiments. In addition, 30Cu-Co3O4 catalyst has certain application potential in the synthesis of ammonia from nitrate-containing industrial wastewater.