Trace Cobalt Doping and Defect Engineering of High Surface Area α-Ni(OH)2 for Electrocatalytic Urea Oxidation

Abstract

Owing to the intrinsically sluggish kinetics of urea oxidation reaction (UOR) involving a six-electron transfer process, developing efficient UOR electrocatalyst is a great challenge remained to be overwhelmed. Herein, by taking advantage of 2-Methylimidazole, of which is a kind of alkali in water and owns strong coordination ability to Co2+ in methanol, trace Co (1.0 mol%) addition was found to induce defect engineering on α-Ni(OH)2 in a dual-solvent system of water and methanol. Physical characterization results revealed that the synthesized electrocatalyst (WM-Ni0.99Co0.01(OH)2) was a kind of defective nanosheet with thickness around 5–6 nm, attributing to the synergistic effect of Co doping and defect engineering, its electron structure was finely altered, and its specific surface area was tremendously enlarged from 68 to 172.3 m2 g−1. With all these merits, its overpotential to drive 10 mA cm−2 was reduced by 110 mV. Besides, the interfacial behavior of UOR was also well deciphered by operando electrochemical impedance spectroscopy.