Pt supported on nano-tungsten carbide as a beneficial catalyst for the oxygen reduction reaction in alkaline solution

Abstract

Platinum nanocatalyst at nano-tungsten carbide was synthesized, characterized and tested for oxygen reduction reaction (ORR) in 0.1 mol dm−3 NaOH, at 25 °C. Tungsten-carbide islands on nano-tungsten particles (WC) was synthesized from gel prepared by using nanoparticles of WO3, previously produced from W-powder oxidized in H2O2. The support was porous material with high specific surface area (177 m2 g−1).The WC supported Pt (10 wt.%) catalyst was prepared by borohydride reduction method.X-ray diffraction of the catalyst demonstrates successful reduction of Pt precursor to metallic form. STEM analysis of Pt/WC catalyst showed the existence of Pt particles lower than 2 nm in size, even the clusters of Pt atoms.Electrochemically active surface area of Pt was determined from adsorption/desorption charge of hydrogen atoms.Catalytic activity of the synthesized catalyst for ORR was studied by cyclic voltammetry and linear sweep voltammetry at rotating disk electrode. The onset potential on Pt/WC for ORR, comparing with Pt/Vulcan, was shifted to the positive potentials for about 150 mV. Pt/WC catalyst shows one Tafel slope of −0.105 V dec−1, remarkable catalytic activity expressed either through the value of the current density per real surface area, or through the mass activity and excellent stability.