Iron oxide promoted nickel/nickel oxide rough nanorods for efficient urea assisted water splitting

Abstract

The sluggish kinetics of urea elecroooxidation restricts the application of the electrochemical approach in dealing with urea-rich wastewater. Herein, urea-assisted water electrolysis was demonstrated efficiently on the catalyst system of iron oxide promoted nickel/nickel oxide rough nanorods. With the help of a series of physical characterization and electrochemical measurements, the content of iron oxide in the system was found to largely influence the crystal structure, roughness and electrochemically active surface area as well as the electrochemical mechanism. The sample with the Fe/Ni ratio of 0.5:1 showed the best water and urea oxidation catalytic performance because of the largest surface area and rapid charge transfer rate and efficient kinetics in the rate-determining step. As a urea-assisted water electrolysis catalyst, the current density can reach 30 mA cm−2 at 1.45 V, about 20 times higher than that of pure water oxidation; the cell voltage as low as 1.49 V can afford 10 mA cm−2 for urea electrolysis, about 120 mV lower than that of pure water electrolysis in the two-electrode catalytic systems. Considering the low price of Ni and Fe and anti-corrosion ability in the electrolyte, the current work is instructive for the efficient catalyst fabrication and urea-containing wastewater purifying.