Controlled synthesis of Pt nanoparticle supported TiO₂ nanorods as efficient and stable electrocatalysts for the oxygen reduction reaction

The development of adequate cathode materials is one of the principal tasks for the fabrication of efficient proton-exchange membrane fuel cells (PEMFCs), which are envisaged as clean energy sources for future transport and portable electrodomestic applications. Here, we present a platinum nanoparticle (NPs)-decorated one-dimensional (1D) titanium dioxide nanorod (PtNPs/TiO₂NRs) nanocomposite with enhanced electrocatalytic performance towards the oxygen reduction reaction (ORR). The TiO₂NRs were prepared through a green approach, utilizing seaweed extract that not only acts as a reducing agent but also serves as a soft template for the directional growth of TiO₂ nanostructures. PtNPs of about 3.0 nm average size were decorated over pre-synthesized TiO₂NRs through the chemical reduction of Pt ions using sodium borohydride. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy analyses confirmed the presence of strong metal-support interactions (SMSI) in the prepared hybrid nanocomposite. The as-prepared PtNPs/TiO₂NRs composite nanostructures exhibited significantly enhanced electrocatalytic performance and stability towards the ORR, with specific and mass activities of 0.428 mA cm⁻² at 0.55 V and 128 mA mg⁻¹ Pt, respectively. These values are 7.2 and 3.5 fold higher than that of standard Pt/C catalysts (0.059 mA cm⁻² and 36 mA mg⁻¹ Pt), respectively. The enhanced catalytic activity and high stability of the composite catalyst are mainly due to the unique 1D morphology of the TiO₂ nanostructures, which provides a greater surface area, and the SMSI enhancing electron transfer rate at their functional interface. The green approach utilized to fabricate the Pt/TiO₂NRs composite in the present study provides a new, low-cost strategy for the development of metal-oxide hybrid nanostructures of high electrocatalytic activity for fuel cell applications.