Fujian Normal University, China
Title: Synthesis of Pt-WO3@W/GNs as a bifunctional electro-photo catalyst for catalyzing methanol oxidation and oxygen reduction reaction
Biography: Shen Lin
Direct methanol fuel cells (DMFCs) have attracted increasing attention due to its low cost, high power density, ease of handling, and low operating temperature. And the multifunctional electro-catalysts which can be used simultaneously in both the anode (methanol oxidation reaction, MOR) and cathode (oxygen reduction reaction, ORR) are eagerly needed. So in this work, a bifunctional electro-photo catalyst Pt-WO3@W/GNs was synthesized by high temperature solid phase synthesis method, with two-dimensional plane structure graphene (GNs) as a support, and it was characterized by TEM, HAADF-STEM, XRD, XPS and Raman. It is found that Pt-WO3@W/GNs has two forms of W at the same time, that is the metal state (W) on the surface and the internal oxidation state (WO3), which is due to that only partial surface of WO3 is reduced during high temperature solid phase reaction. Furthermore, it is observed that its substrate GNs show an obvious wrinkle undergoing the high temperature process, and Pt-WO3@W nanoparticles are evenly dispersed on the surface of GNs, with the average particle size about 7.5 nm. Electro-catalytic properties of Pt-WO3@W/GNs were investigated by cyclic voltammetry (CV), linear sweep voltammetry (LSV), chronoamperometry, and electrochemical impedance spectrum (EIS), to discuss the effect of W oxophilic property and its different states on its catalytic properties towards MOR and ORR. The results indicate that both W and WO3 in Pt-WO3@W/GNs have a promoting effect on catalyzing MOR and ORR, resulting in a superior electro-catalytic property than that of commercial Pt-Ru/C. Especially, the presence of some W (0) can endow semiconductor WO3 different contact modes (Ohmic and Schottky contact) between W or Pt, which leads to a strong charge separation efficiency under light irradiation, so an efficient electro-photo-synergistic catalytic properties towards MOR and ORR under simulated sunlight was achieved. The founding in this work is helpful for converting solar energy into electric energy during traditional electro-catalytic process.