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 analogue) 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 mgcat-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 15N isotope labeling experiments. In addition, 30Cu-Co3O4 catalyst has certain application potential in the synthesis of ammonia from nitrate-containing industrial wastewater.