Defect-engineered CoMoO4 ultrathin nanosheet array and promoted urea oxidation reaction

CoMoO4 ultrathin nanosheets@nickel foam (NF) array electrode is fabricated by a facile in-situ assembly approach, and the oxygen defect (VO) concentration can be simply controlled by controlling annealing atmosphere. Moreover, the effects of VO and Mo (V) species on UOR activity are investigated. It is found that the VO-rich CoMoO4@NF arrays exhibit an excellent current efficiency of 144.29 mA cm(-2) at 550 mV for UOR, which is about 7 times higher than that of the VO-poor CoMoO4@NF arrays. The remarkably improved activity of VO-rich CoMoO4@NF arrays is mainly attributed to the high VO concentration, as well associated Mo (V). VO as the active sites for the adsorption and activation of urea and Mo (V) sites as an electron transfer bridge have greatly enhanced the UOR activity. This work demonstrates that accurate control of VO concentration, as well associated metal species, favors for the development of efficient non-precious metals catalysts.