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

Abstract

Ti-based electroconductive mixed oxides were deposited onto activated carbon by using three different sol-gel-based multistep synthesis routes. As demonstrated by X-ray diffraction, high crystallinity of the tungsten-loaded rutile was achieved by a sequence of annealing in inert atmosphere at 750°C and a short reductive treatment at 650°C.Formation of the rutile phase on the carbon support before the high temperature treatment has been proved to be the prerequisite for complete W incorporation into the rutile lattice. The structural and compositional properties of the mixed oxides were explored by transmission electron microscopy, temperature programmed reduction and X-ray photoelectron spectroscopy. Anode electrocatalysts were formulated by loading the composite of the activated carbon and the Ti-based electroconductive mixed oxides with 40 wt% Pt. Enhanced CO tolerance along with considerable stability was demonstrated for the electrocatalyst prepared using the Ti 0.7 W 0.3 O 2 -C composite material with high degree of W incorporation.

Effect of Mo incorporation on the electrocatalytic performance of Ti–Mo mixed oxide–carbon composite supported Pt electrocatalysts

“…The micrographs reveal the coexistence of a few large, faceted nanorod-like mixed oxide rutile crystallites (indicated by white arrows) with the carboncontaining composite material; their presence is attributed to the relatively high mixed oxide content of the samples, as in micrographs of a composite with 50 wt% mixed oxide -50 wt% active carbon no such crystallites were observed [22,23].…”

“…The results are also summarized in Table 2. Upon preparation of the Ti 0.7 W 0.3 O 2 -C composite materials we have found [22,23] that preliminary formation of the rutile-TiO 2 phase is a necessary condition for complete isovalent W incorporation into the rutile lattice upon the following reductive treatment. Accordingly, in the course of preparation of Mo-containing composite materials, our goals were: (i) to produce Ti (1-x) Mo x O 2 rutile phase with high crystallinity and (ii) to transform of Mo into oxidation state of four.…”

Design and Preparation of CO Tolerant Anode Electrocatalysts for PEM Fuel Cells

“…Accordingly, we have developed a new multistep sol-gel synthesis method optimized for preparation of Ti (1−x) W x O 2 -activated carbon composites with almost exclusive tungsten incorporation into the rutile lattice. The optimization of the synthesis route, along with a structural and functional assessment of the synthesis products were described in a previous publication [10]. In the present work our aim is to give a more elaborate insight into the formation of the Ti 0.7 W 0.3 O 2 -C composite material.…”

“…Detailed description of the synthesis procedure and its optimization can be found in [10]. Here the main features of the optimized process are briefly summarized (Fig.…”

“…The presence of the activated carbon makes the synthesis complicated, since earlier studies showed that it prefers the formation of segregated titania and tungstenoxide phases, and the titania is presented in anatase phase that is disadvantageous for the incorporation of W [10]. Accordingly, we have developed a new multistep sol-gel synthesis method optimized for preparation of Ti (1−x) W x O 2 -activated carbon composites with almost exclusive tungsten incorporation into the rutile lattice.…”