Efficient Methanol Electrooxidation Catalyzed by Potentiostatically Grown Cu–O/OH(Ni) Nanowires: Role of Inherent Ni Impurity
Sengeni Anantharaj, Taiki Nagamatsu, Shohei Yamaoka, Mochen Li, Suguru Noda
Abstract
Complete electrooxidation of methanol in alkaline conditions is catalyzed efficiently by 3d transition metal-based oxides and hydroxides with no issues of mass-transport limitations. Among them, the oxides and hydroxides of Cu prepared using various methods were said to be exceptional. In this work, the methanol oxidation reaction (MOR) activity of such a copper oxide/hydroxide catalyst is advanced by making use of the three-dimensional (3D) configuration of the Cu foam substrate and inherent Ni impurity present in it. The 3D configuration of the Cu foam substrate enabled a larger active surface area per unit geometrical area. The MOR current densities 110 and 310 mA cm–2 at 0.60 and 0.75 V vs Hg/HgO, respectively, testify the outstanding MOR activity of Cu–O/OH nanowires with Ni impurity (Cu–O/OH(Ni)). Excellent chronoamperometric stability at 0.55 V vs Hg/HgO and relatively lower activation energy at all potentials in the catalytic turnover region further ascertain the superiority of Cu–O/OH(Ni). Specific activity measurements implied that Cu–O/OH(Ni) benefited from intrinsic activity enhancement by the presence of inherent Ni impurity. This work, thus, reveals a facile way of enhancing the MOR activity of Cu-based MOR electrocatalysts.