Electrocatalytic activity of nano-flowered yavapaiite anchored on magnetic graphite oxide for nitrate selective reduction

Nano-flowered yavapaiite anchored on magnetic graphite oxide (YMGO) was firstly fabricated by one-pot with K2FeO4 as both oxidant and iron source to selectively reduce nitrate to N-2. The assembling cathode of carbon black and YMGO on carbon cloth (YMGO/CB-CC) exhibited complete nitrate conversion with excellent reusability in a wide pH range of 3-11 and Na2SO4 of 25 mM (3.55 g L-1). The corresponding N2 selectivity was found to be 60.9% and 96.3% in the absence or presence of NaCl. Iron in nano-flowered yavapaiite with empty d-orbital electrons and surrounding oxygen ions provided high-active sites and boosted electron transfer. It was found that Fe(III) active sites and chemical bonding between graphite oxide and yavapaiite (Fe-O-C) reduced iron leaching, which critically dominated reusability and electrocatalytic activity. The catalytic activity of yavapaiite for spontaneously adsorbed nitrate on the Fe(III) activity sites through two-fold coordination and NO3- reduction to N-2 pathway were revealed by density functional theory calculations. Experimental results of nitrate removal from domestic wastewater demonstrated that yavapaiite catalyst may have potential for practical application in wastewater treatment for nitrate reduction.