CoMoO₄ ultrathin nanosheets@nickel foam (NF) array electrode is fabricated by a facile in-situ assembly approach, and the oxygen defect (V_O) concentration can be simply controlled by controlling annealing atmosphere. Moreover, the effects of V_O and Mo (V) species on UOR activity are investigated. It is found that the V_O-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 V_O-poor CoMoO₄@NF arrays. The remarkably improved activity of V_O-rich CoMoO₄@NF arrays is mainly attributed to the high V_O concentration, as well associated Mo (V). V_O 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 V_O concentration, as well associated metal species, favors for the development of efficient non-precious metals catalysts.

CoMoO ₄超薄纳米片@泡沫镍（NF）阵列电极是通过一种简便的原位组装方法制造的，通过控制退火气氛可以简单地控制氧缺陷（V _O）的浓度。此外，还研究了V _O和Mo（V）物种对UOR活性的影响。据发现，在V _ø富含的CoMoO ₄ @NF阵列表现出144.29毫安厘米优异的电流效率^-2在550毫伏UOR，这是约7倍比的更高V _ø国定贫困的CoMoO ₄ @NF阵列。富含V _O的CoMoO _4的活性显着提高@NF阵列主要归因于高V _O浓度以及相关的Mo（V）。V _O作为尿素吸附和活化的活性位点以及Mo（V）作为电子转移桥的位点大大提高了UOR活性。这项工作表明，准确控制V _O浓度以及相关的金属种类有助于开发有效的非贵金属催化剂。