Optimisation of the ethylene glycol reduction method for the synthesis of platinum-ceria-carbon materials as catalysts for the methanol oxidation reaction

Novel platinum-ceria-Ketjenblack carbon bifunctional electrocatalysts with flower-shaped ceria crystals were synthesised for conducting the methanol oxidation reaction. The deposition of flower-shaped ceria particles onto carbon support was achieved through the amino acid (L-histidine)-assisted solvothermal synthesis method. The ethylene glycol reduction method was modified to improve the Pt deposition efficiency, which was confirmed by the thermogravimetric analysis results. The key parameters influencing the polyol reduction reaction kinetics and growth of Pt nanoparticles (NPs) are the ultrasound sonication, the use of metallic sodium, the concentration of sodium ions and the amount of ethylene glycol in the reaction mixture. The microwave treatment in the polyol reduction synthesis increased the number of active sites for the formation of Pt NPs, which led to the increase of electrochemically active surface area from 24 to 55 m Pt 2 g Pt −1 . The physicochemical characterisation methods revealed the formation of the flower-shaped ceria crystals and the excellent distribution of small Pt NPs (3.0–4.2 nm) on the support surface. The catalysts synthesised were micro-mesoporous and specific surface area was 280–330 m 2 g −1 . There is specific interaction between Pt NPs and ceria particles. The cyclic voltammetry and chronoamperometry tests in 0.5 mol dm −3 H 2 SO 4 solution with 1 mol dm −3 CH 3 OH confirmed the high MOR activity of catalysts prepared. The accelerated durability tests were performed with most active catalysts.