Efficient Nitrate Generation through Electrochemical N 2 Oxidation with Nickel Oxyhydroxide Decorated Copper Hydroxide Driven by Solar Cells.

Electrocatalytic nitrogen oxidation reaction (NOR) into nitrate under ambient conditions, as an alternative to replace traditional industrial method, is a promising artificial N 2 fixation strategy, especially powered by renewable energy. Here, through skillfully balancing competitive relationships between NOR and oxygen evolution reaction (OER), the nickel oxyhydroxide decorated Cu(OH) 2 hybrid electrocatalyst with Cu:Ni molar ratio of 1:1 is developed, which achieves outstanding Faradaic efficiency (FE) of 18.7% and yield rate of 228.24 µmol h -1  g cat -1 at 2.0 V versus reversible hydrogen electrode (RHE) in the electrolyte of 0.1 m Na 2 SO 4 . Also, the hybrid catalyst maintained over five cycles (10 h each cycle) with negligible decay in performance. The synergetic effect between the components of nickel oxyhydroxide and Cu(OH) 2 is found to remarkably activate N 2 and suppress the activity of competitive OER, which enhances NOR performance eventually. Moreover, the conversion efficiency of solar-to-nitrate (STN) with 0.025% was obtained by coupling with a commercial solar cell. This work provides a novel avenue of rational catalysts design strategies and realizes solar-to-nitrate synthesis.