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

Abstract

A cerium oxide (CeOx) 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 CeOx 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–CeOx nanowire/C electrode reaches 152 m2 gPt−1. It is quite high as compared with the same parameter observed for commercially available Pt/C electrodes of 51 m2 gPt−1. This indicates that both CeOx 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 CeOx 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–CeOx nanowire/C anode is much lower than commercially available Pt/C anodes, the carbon monoxide (CO) tolerance of Pt in the present nanostructured Pt–CeOx 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 CeOx nanowire plays a key role in enhancement of the electrochemically active surface area of the Pt–CeOx nanowire/C electrode and improvement of CO tolerance of Pt in Pt–CeOx nanowire/C for fuel cell applications.