Improved ORR Activity and Long-Term Durability of Pt Nanoparticles Deposited on TiO₂-Decorated Multiwall Carbon Nanotubes

Abstract

Titanium dioxide coatings of different thicknesses were deposited on the acid-treated multiwall carbon nanotubes (MWCNTs) using controlled atomic layer deposition (ALD). Pt nanoparticles (NP) were deposited on TiO 2 /MWCNT supports using two deposition methods, viz. sputter-deposition and photo-deposition. Scanning electron microscopy (SEM) and scanning transmission electron microscopy (STEM) measurements revealed successful application of ALD for the deposition of TiO 2 . Both magnetron sputtering and photo-deposition were found to be efficient and well-controlled techniques for the deposition of Pt NPs on oxide-carbon support. Electrochemical decontamination and characterization of the catalysts surface was carried out by CO stripping and cyclic voltammetry in 0.1 M KOH solution. The prepared Pt-TiO 2 /MWCNT catalyst showed comparable oxygen reduction reaction (ORR) activity to that of commercial Pt/C (20 wt%), while long-term durability test revealed better durability of the prepared catalysts due to strong metal-support interaction.

Catalyst overcoating engineering towards high-performance electrocatalysis

“…ALD overcoating of metal oxide layers with the thickness controlled by deposition cycle numbers could endow the as-fabricated catalysts with distinct catalytic reactivities. [188][189][190] Researchers have specifically developed the area-selective ALD technology in an attempt to precisely control overcoating sites and expose more preferred surface. 187 An organic mask molecule, i.e.…”

“…Forming strong metal-support interfacial structures. A wide assortment of metal oxides such as TiO 2 , 190,199 303 atoms with improved electrical conductivity is also employed. Apart from mitigating the corrosion of the carbon support and promoting the dispersion and utilization efficiency of the metal, 193,200,210,296,297 metal oxide species in the form of particles or thin films could strongly interact with the metal NPs immobilized on carbon support materials.…”

Ti/Pt−Pd‐Based Nanocomposite: Effects of Metal Oxides on the Oxygen Reduction Reaction

“…Studies in the literature have shown that carbon nanotubes (CNTs) nanocoated with TiO 2 employed as platinum (Pt) catalyst supports enhance Pt electroactivity and durability in ORR . In addition, riveted Pt/TiO 2 −C catalysts have been found to present significant improvements in stability for ORR .…”

Applications of Atomic Layer Deposition in Design of Systems for Energy Conversion

“…This effect is ascribed to an improved binding of the subsequently deposited platinum particles and also to better protection of the carbonaceous substrate from oxidative degradation. [145,146] Other oxidic layers were employed as the protective films of the carbonaceous Pt catalysts-SnO 2 deposited by action of acetic acid on Sn(OtBu) 4 to protect both, the active Pt-sites and the carbonaceous substrate from the degradation; [147] N-doped Ta 2 O 5 prepared by reaction of Ta(OEt) 5 and H 2 O as the precursors and a subsequent annealing in the ammonia vapors at 700 °C to protect the carbonaceous support of the catalysts; [148] titanium oxynitride (TiO x N y ) prepared from TiCl 4 and H 2 /N 2 plasma and a subsequent ambient oxidation to improve the activity of the Pt or Pt/Ni catalyst and to avoid their degradation. [149] However, these materials, although introducing some beneficial properties to the composites, often counteract these benefits by negatively altering some others (increased longevity versus lower catalytic activity etc.).…”

“…This effect is ascribed to an improved binding of the subsequently deposited platinum particles and also to better protection of the carbonaceous substrate from oxidative degradation. [ 145,146 ]…”