Cu/Cu+ Synergetic Effect in Cu2O/Cu/CF Electrocatalysts for Efficient Nitrate Reduction to Ammonia

Electrocatalytic nitrate reduction reaction (NO3 -RR) has been considered a promising technologyto produceammonia but is inhibited by poor electrocatalytic performances. Therefore,the development of efficient electrocatalysts and investigation ofcorresponding reaction mechanisms are critically important. Herein,an efficient dendritic Cu2O/Cu grown on Cu foam (D-Cu2O/Cu/CF) has been synthesized by a facile electrodepositionmethod, and the synergetic effect of Cu and Cu+ in NO3 -RR has been investigated. In situ and exsitu data testify the synergetic effect clearly that Cu sites areresponsible for the beginning of nitrate conversion to nitrite, whileCu(+) sites are the active center for subsequent nitritereduction to ammonia. In addition, in situ-generated active Cu+ sites further enhance the catalytic performances. Therefore,an extraordinarily high nitrate removal rate of 98.9% together witha relatively high ammonia yield rate of 11.2 mg h(-1) cm(-2) can be obtained in electrolytes containing90 ppm of nitrate. Apromising energy-saving technology for the green ammoniasynthesis and contamination treatment of nitrate-containing wastewaterhas been developed with a relatively high nitrate removal rate andammonia yield rate.