Pt supported on one-dimensional titanium dioxide nanowire-carbon composite for efficient oxygen eduction reaction

Abstract

Proton exchange membrane fuel cells (PEMFCs) have been widely regarded as promising energy-conversion devices for hydrogen-energy applications because of their high energy efficiency and near-zero pollutant emissions. However, the electrochemical performance of conventional platinum (Pt)-based catalysts is severely degraded because carbon supports are susceptible to corrosion under fuel-cell operating conditions. To address this issue, a Pt-supported one-dimensional titanium dioxide nanowire/Vulcan XC-72 R carbon black composite catalyst (Pt/TiO2NWs-C) was prepared via an ethylene glycol reduction method, and TiO2NWs were synthesized through a hydrothermal process. Morphological characterization revealed that the carbon support was intimately integrated with TiO2NWs, while Pt nanoparticles (NPs) were uniformly dispersed on the TiO2NWs-C surface with an average particle size of approximately 2.48 nm. The binding-energy shifts in the Pt and Ti x-ray photoelectron spectroscopy spectra indicated the presence of a strong metal-support interaction between Pt NPs and TiO2NWs. Electrochemical measurements demonstrated that Pt/TiO2NWs-C exhibited superior oxygen reduction reaction activity and durability compared with Pt/C. The electrochemically active surface area (ECSA) of Pt/TiO2NWs-C was calculated to be 110.21 m2 gPt−1, which was 1.56 times that of Pt/C. A half-wave potential of 0.87 V (vs RHE) was obtained for Pt/TiO2NWs-C, which was approximately 30 mV higher than that of Pt/C, and a limiting current density of 5.79 mA cm−2 was achieved. After 20 000 accelerated durability test cycles, only a 13.5% decrease in ECSA and a negligible shift in half-wave potential were observed for Pt/TiO2NWs-C, whereas Pt/C showed a 35.8% ECSA loss and an 18 mV negative shift in half-wave potential. These results indicate that Pt/TiO2NWs-C can serve as an effective composite catalyst for improving the electrochemical performance and durability of PEMFCs.