Electrocatalytic oxidation of methanol at Ni–Al layered double hydroxide film modified electrode in alkaline medium

Ni–Al–NO3 layered double hydroxides (LDH) are electrodeposited on the glassy carbon (GC) electrodes and the electrocatalytic activities of the modified electrodes toward methanol oxidation are studied in detail by cyclic voltammetry and chronoamperometry. Various factors affecting the electro-oxidation of methanol are investigated for optimizing the electrocatalytic properties and making the mechanism clearly such as methanol concentration, scan rate, KOH concentration, Ni:Al ratio of Ni–Al LDH used. The results show that Ni–Al–NO3 LDH exhibit higher electrocatalytic activity for methanol oxidation and better stability than that of Ni(OH)2 prepared under the same condition. The LDH with Ni:Al ratio of 3:1 display a good electrocatalytic activity for methanol oxidation in 0.5 M KOH. The mechanism of methanol oxidation on Ni–Al LDHf/GC electrode is also proposed according to the experimental results, involving in both a chemical oxidation via Fleischmann's mechanism and a direct electro-oxidation on the Ni3+ oxide surface.

► Low-cost Ni–Al–NO3 LDH exhibits high electrocatalytic activity for methanol oxidation in alkaline medium.
► The electrocatalytic activity can be improved by adjusting Ni:Al radio and KOH concentration.
► The catalytic oxidation of methanol involves in both a chemical oxidation and a direct electro-oxidation.
► The Ni–Al LDH film modified electrode is more stable than Ni(OH)2 modified electrode.