Abstract: To address the critical challenges of insufficient active sites, poor conductivity, and sluggish reaction kinetics in nickel-based electrocatalysts for methanol oxidation reaction (MOR), this study proposes a lattice doping engineering strategy. By employing a low-cost ammonium molybdate precursor coupled with a calcination process, we successfully constructed Mo-doped NiO catalysts synergistically enhanced by oxygen vacancies and Ni3? active sites. Experimental results demonstrate that as the Mo doping level increases from 0 to 28 at%, the oxygen vacancy concentration on the catalyst surface escalates progressively from 30.18% to 56.59%, while the proportion of Ni3+ species rises from 65.55% to 85.91%. At an optimal Mo doping content of 28 at%, the catalyst achieves a current density of 280.8 mA·cm?2 at 1.7 V vs. RHE in 1.0 M KOH/1.0 M CH?OH electrolyte, representing a 12.9-fold enhancement compared to undoped NiO (21.7 mA·cm-2). Furthermore, the Tafel slope decreases significantly from 63 mV·dec?1 to 25 mV·dec?1. Systematic characterizations via XRD, SEM, TEM, and XPS elucidate the formation mechanism of Mo-doped NiO catalysts with tunable oxygen vacancy concentrations and Ni3?/Ni2? ratios, as well as their MOR electrocatalytic performance. A preliminary structure-activity relationship is established, revealing the underlying principles of enhanced activity. This work provides a novel approach for designing efficient anode catalysts for direct methanol fuel cells (DMFCs) with high active site density.

Key words: Oxygen vacancy, MOR, Mo-doping