Nickel Based Nano-catalysts For Electrooxidation Of Ammonia And Related Chemicals

Urea,amino acids and ammonia,are common environmental polluents.Biological treatment of these N-cotaining pollutants is a cost effective method,but it has drawbacks such as long working time,C/N ratio and N concentration limitations.Electrochemical treatment can avoid above drawbacks.However,electrochemical treatment usually needs expensive electrode materials and vast electric power leading to high cost.In fact,urea,amino acids and ammonia all contain chemical energy,which can be used to generate electricity similar to hydrogen gas and methanol.Urea,amino acids and ammonia can be oxidized to nitrogen gas with electrons releasing spontaneously by using proper catalysts.In this way,N-containing wastewater is degraded with self-gernration of electricity via fuel cells,reducing the cost in electrochemical treatment.In this work,non-precious Ni-based nanomaterials were prepared as anode catalysts and characterized by XRD,XPS,SEM,TEM and electrochemical tests.Direct urea fuel cell(DUFC)and amino acids fuel cell(AAFC)are fabricated with Ni/C or NiCo/C catalysts.Results show that DUFC achieves a maximum power density of 1.4 mW cm-2 and 2.0 mW cm-2 with Ni/C and NiCo/C catalysts respectively.AAFC achieves a maximum power density of 1.9 mW cm-2 and 3.0 mW cm-2 with Ni/C and NiCo/C catalysts respectively.Besides,urine-Cr(VI)fuel cell is fabricated to degrade urine and Cr(VI)at the same time.The maximum power density reaches 3.4 W m-2 with open circuit voltage of 1.3 V.The removal efficiencies of total organic carbon and total nitrogen in urine are 79.2%and 78.4%,while the removal efficiency of Cr(VI)reaches 93%.Although Ni catalysts can be used as anode catalysts for electrooxidation of urea and amino acids,they are inactive toward amminoa acids.In order to solve this problem,novel NiCu bimetal catalyst and NiCu hydroxide nanowires catalyst are synthesized.Electrochemical tests show they have much better performance in the aspects of catalytic activity and stability than Ni and Pt based catalysts.