Effect of fuel content on the electrocatalytic methanol oxidation performance of Pt/ZnO nanoparticles synthesized by solution combustion

We report the effect of combustion synthesis conditions on Pt nanoparticle (NP) supported on ZnO (Pt/ZnO) electrocatalysts for methanol oxidation reaction (MOR). The Pt/ZnO NPs are prepared by solution combustion synthesis (SCS) using metal nitrate precursors and glycine fuel, which is varied with a fixed Pt:Zn ratio at 1:1 for fuel-high (Pt/ZnO (H)) and fuel-low (Pt/ZnO (L)) electrocatalysts. X-ray diffractometry, transmission electron microscopy and scanning electron microscopy are used for crystallite size, particle distribution and elemental composition studies, respectively. High angle annular dark field-scanning transmission electron microscopy attached to energy dispersive X-ray spectroscopy was used for elemental distribution in Pt/ZnO NPs and X-ray photoelectron spectroscopy (XPS) was used to identify the surface composition and electronic state of the elements. Cyclic voltammetry is applied for the electrocatalysis of CH3OH in an alkaline medium, which reveals that Pt/ZnO (H) system has an improved MOR activity in comparison to commercial Pt/C. The onset potential of MOR on Pt/ZnO is earlier than that of Pt/C. The stability test conducted by chronoamperometry on Pt/ZnO and Pt/C shows a stable high current density for Pt/ZnO (H) compared to Pt/C and Pt/ZnO (L). The crystallite size, surface morphology and the electrochemical properties of Pt/ZnO samples are affected by the variation in the fuel amount during synthesis.