The role of the support in CO_adsmonolayer electrooxidation on Ptnanoparticles: Pt/WO_xvs.Pt/C

Abstract

The electrocatalytic properties of home-made Pt nanoparticles supported onto WO(x) were determined for the electrooxidation of a CO(ads) monolayer and compared with that of a commercial Pt/C having the same Pt particle size. By combining electrochemical and spectroscopic techniques, we found that Pt/WO(x) nanoparticles exhibit a very high tolerance to CO at low electrode potentials (E = 0.1 V vs. RHE), which was never reported in the literature before. CO adsorption at E = 0.1 V vs. RHE on Pt/WO(x) yields CO(2) production as observed by Fourier-transform infrared spectroscopy (FTIR). When the gas bubbling in solution changes from CO to Ar, the current attenuates and the CO(2) production vanishes. This points towards a limited number of "active sites" and a slow step in the electrocatalytic process. When H(2) is used to purge the electrolyte from CO, a steep and continuous increase of the H(2) electrooxidation current is observed pointing towards continuous liberation of the Pt catalytic sites. The high tolerance to CO of Pt/WO(x) is discussed in terms of strong metal-support interaction (SMSI), which involves formation of a metal-oxide film partially covering the Pt nanoparticles (encapsulation) and creation of W-OH groups upon H(+) insertion at low electrode potentials.

Preparation and characterization of novel Ti0.7W0.3O2–C composite materials for Pt-based anode electrocatalysts with enhanced CO tolerance

“…It is clearly seen from In good agreement with literature [9,77], our results suggest that Ti 0.7 W 0.3 O 2 -C composite materials only slightly modify the electronic density of the Pt nanoparticles.…”

“…On samples prepared by Routes I and II ( Fig. 5d and 5e, respectively) the "pre-peak" appeared between ~240 and ~550 mV followed by two CO ads electrooxidation peaks at 710 and It is necessary to mention that the Ar-purged CO ads stripping voltammograms obtained for catalysts presented in this paper resemble those commonly observed in the literature for CO tolerant W-modified Pt catalysts [1,2,8,77,78]. The "pre-peak" is a characteristic feature for W-containing electrocatalysts [1], which in Refs.…”

“…As suggested in Refs. [8,9,77] on Pt/WO x and Pt-WO x /C catalysts this behaviour can be attributed not only to the deinsertion of protons from the tungsten bronzes H x WO 3 but may also signal the partial oxidation of the CO ads monolayer on Pt. In Ref.…”

“…In Refs. [2,6,8,77] these features were related to the redox reaction of tungsten oxides, such as WO 3 /WO 2 . As shown in Fig.…”

“…The "pre-peak" is a characteristic feature for W-containing electrocatalysts [1], which in Refs. [2,6,8,77] was associated with the formation of substoichiometric tungsten oxides WO 3-x . As suggested in Refs.…”