Fabrication of a nano-structured Pt-loaded cerium oxide nanowire and its anode performance in the methanol electro-oxidation reaction

Abstract

A cerium oxide (CeO_x) nanowire of approximately 35 nm diameter was fabricated using an alco-thermal method. Platinum nanoparticles were formed at the interface between Ce(OH)₃ and CeO_x nanowire which consisted of slightly ionized Pt, Ce³⁺ and Ce⁴⁺. Additionally, Pt nanoparticle sizes were found to be less than 2 nm. The electrochemically active surface area of the Pt–CeO_x nanowire/C electrode reaches 152 m² g_Pt⁻¹. It is quite high as compared with the same parameter observed for commercially available Pt/C electrodes of 51 m² g_Pt⁻¹. This indicates that both CeO_x nanowire and Ce(OH)₃ can provide useful interfacial reaction space at the nanoscale for formation of small Pt particles. The platinum content of Pt-loaded CeO_x nanowire/C can be low such as 0.975 mg ml⁻¹ using this interface reaction space, as compared to 3.90 mg ml⁻¹ in current industrial fuel cell anode materials. While the Pt content in the present nanostructured Pt–CeO_x nanowire/C anode is much lower than commercially available Pt/C anodes, the carbon monoxide (CO) tolerance of Pt in the present nanostructured Pt–CeO_x nanowire/C anode is superior in the methanol electro-oxidation reaction, which is an important electrode reaction at the anodic side of fuel cells. Based on the experimental data, it is concluded that the interface between Pt and CeO_x nanowire plays a key role in enhancement of the electrochemically active surface area of the Pt–CeO_x nanowire/C electrode and improvement of CO tolerance of Pt in Pt–CeO_x nanowire/C for fuel cell applications.