Nickel phosphide on Ni foam as anode and peroxymonosulfate as the chemical oxidizer for effective direct urea fuel cell

The direct urea fuel cell (DUFC) is a low cost and competitive approach for contemporaneous urine or urea-contaminated wastewater treatment and electricity generation. However, the lack of efficient urea oxidation reaction (UOR) electrocatalysts and suitable electron acceptors remains a challenge for practical applications. Here, we developed a DUFC system using Ni 2 P@Ni foam as the anode and peroxymonosulfate (PMS) as the chemical oxidizers . The Ni 2 P@Ni foam anode showed a high oxidation activity for UOR with an onset potential of 0.30 V vs. Ag/AgCl and Tafel slope of 34.4 mV/dec. PMS with high theoretical potential improved the cell voltage to 1.43 V. A power density of DUFC up to 4.91 mW/cm 2 was achieved using PMS at room temperature, which was approximately twice as high as using H 2 O 2 (2.38 mW/cm 2 ). Ni II /Ni III was the redox active species on the Ni 2 P anode in the DUFC process, and Ni II was electrochemically oxidized to Ni III , which reverted to Ni II by urea reduction. When real human urine was used as the fuel, a power density of 4.46 mW/cm 2 can be achieved at room temperature. This DUFC with high cell performance showed potential application in urea wastewater treatment.