The use of a hierarchically platinum-free electrode composed of tin oxide decorated polypyrrole on nanoporous copper in catalysis of methanol electrooxidation

• Nanoporous copper–zinc substrates were formed by chemical leaching of zinc.
• Polypyrrole thin film was electrodeposited on nanoporous copper.
• Thin oxide nanoparticles were synthesized electrochemically on polypyrrole layer.
• The catalytic performance of the electrodes was evaluated for methanol oxidation.

Tin oxide nanoparticles were synthesized through a galvanostatic pathway on polypyrrole, PPy, coated nanoporous copper. The morphology and surface analysis of the assemblies were evaluated by field emission scanning electron microscopy, FESEM, and energy dispersive X-ray, EDX, analysis, respectively. The electrocatalytic behavior of electrodes was studied by cyclic voltammetry and chronoamperometry tests in methanol solution. FESEM results showed that uniformly distributed nanoparticles with diameters of about 20–30 nm have been dispersed on PPy matrix. Cyclic voltammetry and chronoamperometry tests in methanol solution showed a significant enhancement in the catalytic action of PPy after decoration of tin oxide nanoparticles. Porous Cu/PPy/SnOx electrodes showed enhanced anodic peak current density for methanol oxidation compared to smooth Cu/PPy/SnOx and porous Cu/PPy. The effects of synthesis current density and time on the electrocatalytic behavior of the electrodes were evaluated. The significant enhancement of electrocatalytic behavior of the Cu/PPy electrode after decoration of SnOx overlayer was attributed to the effect of tin oxide on the adsorption of intermediates of methanol oxidation as well as oxidation of bi-products such as CO; huge tendency of tin oxides for dehydrogenation of the alcohols and the increase in microscopic surface area of the electrodes were introduced as other affecting factors.