Oxygen Vacancies Confined in Nickel Molybdenum Oxide Porous Nanosheets for Promoted Electrocatalytic Urea Oxidation

The direct urea fuel cell (DUFC), as an efficient technology for generating power from urea, shows great potential for energy-sustainable development but is greatly hindered by the slow kinetics of the urea oxidation reaction (UOR). Herein, we highlighted a defect engineering strategy to design oxygen vacancy-rich NiMoO4 nanosheets as a promising platform to study the relationship between O vacancies and UOR activity. Experimental/theoretical results confirm that the rich O vacancies confined in NiMoO4 nanosheets successfully bring synergetic effects of higher exposed active sites, faster electron transport, and lower adsorption energy of urea molecules, giving rise to largely improved UOR activity. As expected, the r-NiMoO4/NF 3D electrode exhibits a higher current density of 249.5 mA cm–2, which is about 1.9 and 5.0 times larger than those of p-NiMoO4/NF and Ni-Mo precursor/NF at a potential of 0.6 V. Our finding will be a promising pathway to develop non-noble materials as highly efficient UOR catalysts.