Investigation of palladium-mesostructured silica nanoparticles (Pd-MSN) as anode electrocatalyst for alkaline direct methanol fuel cell

Abstract

The commercialization of fuel cells is hindered by the high cost of noble metal electrocatalysts, such as platinum. Mesostructured silica nanoparticles (MSNs), as a novel catalyst support, are added to active palladium nanoparticles to create a Pd-MSN electrocatalyst with low Pd content to improve catalytic efficacy and decrease costs. Wet impregnation method was used to prepare catalysts that comprise palladium nanoparticles supported on MSNs (i.e. 5 wt% Pd-MSN, 10 wt% Pd-MSN, 15 wt% Pd-MSN, 20 wt% Pd-MSN and 20 wt% Pd-C) to enhance electrocatalytic activity for methanol oxidation. The structures of the catalysts were characterized by X-ray diffraction (XRD), Fourier transform infrared spectrometry (FTIR), field-emission scanning electron microscopy (FESEM), energy-dispersive X-ray (EDX) and Brunauer–Emmet–Teller (BET) surface area analysis, and their electrocatalytic performance towards methanol oxidation was investigated by cyclic voltammetry (CV) and chronoamperometry (CA). Amongst the catalysts, 20 wt% Pd-MSN has the highest electrocatalytic activity (14.3 mA cm−2) and stability (3600 s) for methanol oxidation in alkaline medium at the constant potential of −0.2 V. This result indicates that 20 wt% Pd-MSN may be a promising anode material for direct methanol fuel cells. The improved electrocatalytic activity and stability of the electrocatalyst are attributed to the high specific surface area of MSN and the effective surface structure of Pd nanoparticles. Furthermore, MSN increases catalyst dispersion by producing new active sites, which results in the promotion of Pd utilization.