Pt nanoparticles deposited on TiO2 based nanofibers: Electrochemical stability and oxygen reduction activity

Abstract

This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues.Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. The electrochemical stability of Pt deposited on TiO 2 based nanofibers was compared with commercially available carbon supported Pt. Prior to the Pt deposition the TiO 2 material, which was either undoped or Nb doped, was air calcined. In one case the undoped TiO 2 was also reduced in a hydrogen atmosphere. XRD analysis revealed that the unreduced TiO 2 was present in the anatase phase, irrespective of whether the Nb dopant was present, whereas the rutile phase was formed due to reduction with H 2 . The diameter of the TiO 2 fibers varied from 50 to 100 nm, and the average Pt particle diameter was approximately 5 nm. Pt supported on TiO 2 was more stable than Pt supported on C when subjected to 1000 voltammetric cycles in the range of 0.05-1.3 V vs. RHE. Nb doped TiO 2 showed the highest stability, retaining 60% of the electrochemically active surface area after 1000 cycles compared to the state after 100 cycles, whereas the carbon supported catalyst retained 20% of the active surface area. The commercial catalyst had the highest oxygen reduction activity due to its larger specific area (17.1 m 2 g −1 vs. 5.0 m 2 g −1 for Pt/TiO 2 -Nb, measured after 100 cycles) and the higher support conductivity. The Pt supported on Nb doped or on H 2 reduced TiO 2 was more active than Pt supported on air calcined and otherwise unmodified TiO 2 .Crown

Nanotechnology for environmentally sustainable electromobility

“…400-750 °C for 0.5-12 hours 28 ) compared to the solid-state methods. Energy use for electrospinning itself is associated only with high-voltage power supply and syringe pump 29 as it may be performed at room temperatures 42 , but the subsequent calcination requires high temperatures of about 500-900 °C 42,43 . Even though the mechanical milling process only requires energy for the milling equipment and can work at low temperatures 27 , high-energy mechanical milling requires high temperatures for calcination (e.g.…”

Improved stability of mesoporous carbon fuel cell catalyst support through incorporation of TiO2

“…4). Said peaks represent interactions with functional groups on the carbon surface [18]. The peaks obtained during the anodic sweep at higher potentials, i.e.…”

“…Since rutile has only a slightly lower band gap relative to anatase one can expect that no activity enhancement would result from replacing anatase with rutile [31][32][33]. However, doping the titania with e.g., Nb would enhance the conductivity (and stability) and may therefore further improve the ORR activity of Pt/TiO 2 -C [18].…”

“…Several research groups investigated titanium, tungsten and zirconium oxide supports with size features in the nanometer range [12][13][14][15][16][17][18]. Recent results in our group showed that Pt supported on titanium dioxide nanofibers is more stable compared to conventional carbon black [18]. However, the relatively low conductivity of titania imposes a certain limitation on the performance.…”

On the stability of platinum-composite electrocatalysts prepared with different substrate materials

“…There are studies showing better MEA stability and activity of Pt nanoparticles supported on mesoporous TiO 2 in comparison to commercial carbon as a support [14,15]. However, there are rather opposite findings for the influence of TiO 2 to Pt electrocatalysis; there are papers reporting the improvement for oxygen reduction kinetics [16,17] and the activity in H 2 evolution [18], but some results show that TiO 2 -supported Pt suffers from significantly lower activity in H 2 and O 2 reactions than Pt supported on carbon [19]. Hence, it could be of interest to take into consideration new approaches in composite catalyst synthesis and more detailed analysis of electrocatalytic properties of synthesized materials, able to mutually produce new findings and benefits for Pt catalysts supported on materials other than carbon of rather modest properties.…”