PtRu/Carbon Nanotube Nanocomposite Synthesized in Supercritical Fluid:  A Novel Electrocatalyst for Direct Methanol Fuel Cells

Abstract

Platinum/ruthenium nanoparticles were decorated on carbon nanotubes (CNT) in supercritical carbon dioxide, and the nanocomposites were characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). TEM images show that the particles size is in the range of 5-10 nm, and XRD patterns show a face-centered cubic crystal structure. Methanol electrooxidation in 1 M sulfuric acid electrolyte containing 2 M methanol were studied onPtRu/CNT (Pt, 4.1 wt%; Ru, 2.3 wt%; molar ratio approximately Pt/Ru = 45:55) catalysts using cyclic voltammetry, linear sweep voltammetry, chronoamperometry, and electrochemical impedance spectroscopy. All the electrochemical results show that PtRu/CNT catalysts exhibit high activity for methanol oxidation which resulted from the high surface area of carbon nanotubes and the nanostructure of platinum/ruthenium particles. Compared with Pt/CNT, the onset potential is much lower and the ratio of forward anodic peak current to reverse anodic peak current is much higher for methanol oxidation, which indicates the higher catalytic activity of PtRu/CNT. The presence of Ru with Pt accelerates the rate of methanol oxidation. The results demonstrated the feasibility of processing bimetallic catalysts in supercritical carbon dioxide for fuel cell applications.

The correlation of electrochemical and fuel cell results for alcohol oxidation in acidic and alkaline media

“…For PtRu on CNT support neither here nor previously [150] has reported any shift. Furthermore, with PtRu/FWCNT an additional feature appears in the oxide formation region (0.55 V) that is observed also in Figure 27 and is related to the acid treatment reported previously by other groups [150][151][152]. This feature have been reported only on CNTs and not on GNFs even though they have both been acid treated, indicating that different surface groups are formed on each support.…”

Multiwalled Carbon Nanotubes Composited with Palladium Nanocatalysts for Highly Efficient Ethanol Oxidation

“…The R ct values of the nanocatalysts are estimated by fitting the EIS curves using the software ZsimpWin based on an equivalent electric circuit as shown inset of Figure 8. 78 In this R s (R ct CPE) circuit, R s represents the uncompensated solution resistance, R ct represents the charge-transfer resistance while the constant phase element (CPE) is related to a capacitor property, The parallel combination of the R ct and CPE takes into account the thin electrode film as well as ethanol adsorption and oxidation. The values for all the parameters R s , R ct , CPE and their associated % error are summarized in Table III.…”

Graphene-Supported Platinum and Platinum-Ruthenium Nanoparticles for Fuel Cell Applications

“…In order to enhance catalytic activity and to reduce the usage of Pt-based catalysts, one strategy is to explore novel carbon materials as catalyst supports and to effectively disperse Pt-based particles on these supports (Chen et al, 2007;Sanganna Gari et al, 2010;Girishkumar et al, 2006;Halder et al, 2009;Maiyalagan, 2008;Selvaraj & Alagar, 2007;Rajesh et al, 2003;Tang et al, 2004;Tsai et al, 2006;Zhao et al, 2004). Vulcan XC-72R carbon black has been the most widely-used catalyst support for the preparation of fuel cell catalysts because of its exceptional electronic conductivity and surface area (Guo et al, 2008;Lin et al, 2005;Maiyalagan et al, 2005). During the past several years, a few research groups have investigated graphene, one type of novel carbon nanostructures, as a catalyst support and have demonstrated that graphene can improve the electrocatalytic activity of Pt nanoparticles more effectively for methanol and ethanol oxidation than Vulcan XC-72R carbon black Seger et al, 2009;Yoo et al, 2009).…”