Synthesis of Ni-SiO2/C Supported Platinum Catalysts for Improved Electrochemical Activity Towards Ethanol Oxidation.

ABSTRACT

A series of Pt/Ni-SiO2/C catalysts with different mass proportions of Ni-SiO2/C (0100, 3070, 5050, 7030 and 1000) were prepared and studied towards ethanol electrochemical oxidation in acid medium. The support silica particles were initially synthesized via sol-gel and then modified with NiCl2. The Ni deposited on the silica surface plays a role promoting nucleation sites for the reduction of platinum. Pt was further chemically reduced onto Ni-SiO2 using formic acid and loaded onto carbon Vulcan XC-72 R. The Pt/Ni-SiO2/C catalysts were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, temperature-programmed reduction, X-ray photoelectron spectroscopy, transmission electron microscopy and inductively coupled plasma-optical emission spectroscopy. The physical characterizations reveal the formation of oxide-metal composite and strong interaction between Pt and the Ni-SiO2 composite. The Pt/Ni-SiO2/C catalyst with meso/macroporous structure exhibits higher electrocatalytic activity towards ethanol oxidation and better stability, after 48 h of electrolysis, than a commercial Pt/C catalyst. These improved features could be due to presence of Ni-SiO2 composite that promotes corrosion resistance of the support and prevents the aggregation of Pt nanoparticles and their detachment from the support. The low poisoning of the Pt/Ni-SiO2/C catalyst is probably due to the enhanced oxygen content on the composite surface. The high electrocatalytic activity and enhanced electrochemical stability of the Pt/Ni-SiO2/C catalyst make it promising for further fuel cell applications.