Bimetallic PtCu-decorated reduced graphene oxide (RGO)-TiO2 nanocomposite for efficient oxygen reduction reaction

Abstract

To exploit the full advantages of electrocatalysts for fuel cell reactions, a promising support is essential to disperse electrocatalytically active metal nanoparticles. Here, at first a graphene oxide-titanium dioxide composite support (GO-TiO2) is fabricated by a sol–gel method. Later, a facile chemical reduction method is demonstrated to simultaneously reduce Pt4+, Cu2+ and GO-TiO2 to form bimetallic PtCu nanoparticles (15 wt% Pt + 5 wt% Cu) on a reduced graphene oxide-titanium dioxide (RGO-TiO2) composite support. A combined action of ethylene glycol and ascorbic acid play a positive role in attaining well dispersed PtCu with a size of 7 nm particles on RGO-TiO2 sheets. The resulting PtCu/RGO-TiO2 nanocomposite exhibits superior electrode-area normalized ORR limiting current density (6.14 mA/cm2-geo) when compared to commercial Pt/C (3.61 mA/cm2-geo) and in-house synthesized PtCu/RGO (4.68 mA/cm2-geo) and Pt/RGO (3.95 mA/cm2-geo) catalysts. The synthesized catalysts are characterized for structural, morphological and surface elemental features by using a combination of diffraction, spectroscopy and electron microscopy techniques. The positive role played by PtCu and RGO-TiO2 composite support assists the improved ORR activity. The versatile synthesis methodology presented here is convenient to fabricate other similar electrocatalytic nanostructures for fuel cell reactions.