One pot aqueous synthesis of nanoporous Au85Pt15 material with surface bound Pt islands: an efficient methanol tolerant ORR catalyst

Abstract

For the first time, we are reporting the synthesis of Au_100−xPt_x nanoporous materials in the size range of 7–10 nm through the galvanic replacement of Ag by Pt from Au_100−xAg_2x spherical nano-alloys (x = 20, 15, 10 and 5) in an aqueous medium. The galvanic replacement reaction follows the ‘Volmer–Weber’ growth mode, resulting in the formation of surface bound platinum islands on a nanoporous gold surface. The high angle annular dark field image and low angle X-ray diffraction studies confirm the presence of nanoporous Au_100−xPt_x NPs. The electrochemical studies using the Au₈₅Pt₁₅/C catalyst show excellent methanol tolerance behaviour and better performance towards oxygen reduction reaction (ORR) in terms of high mass activity, mass-specific activity and figure of merit (FOM) when compared to HiSPEC Pt/C commercial catalyst. Preliminary studies on a full cell using nanoporous Au₈₅Pt₁₅/C (loading 1.0 mg cm⁻²) as the cathode material and Pt-Ru/C (loading: 0.5 mg cm⁻²) as the anode material performed better (38 mW cm⁻²) than the HiSPEC Pt/C cathode material (16 mW cm⁻²).