High Performance Pt Nanocatalysts for the Oxidation of Methanol and Ethanol in Acid Media by Effect of Functionalizing Carbon Supports with Ru Organometallic Compounds

Abstract

The Intermittent Microwave Heating (IMH) assisted polyol method was used to disperse Pt nanoparticles on Vulcan XC-72 (C) and reduced Graphene Oxide (rGO) functionalized with [(η 6-C6H5OCH2CH2OH)RuCl2]2 (Ru-dim) and [(η 6-C6H4(CHMe2)Me)RuCl2]2 (Ru-cym). The nanocatalysts were labeled as Pt/CRu-dim, Pt/CRu-cym, Pt/rGORu-dim and Pt/rGORu-cym. Their catalytic activity was evaluated for the Methanol (MOR) and Ethanol Oxidation Reactions (EOR). 1H and APT 13C NMR characterization showed the coordination of arene ligands with ruthenium atoms, supporting the formation of Ru-dim and Ru-cym. Raman spectroscopy indicated that C and rGO preserve their graphitic band structure after functionalization. Functionalization of the supports resulted in the development of several surface chemical groups. The electrochemical characterization showed that: i) Pt/CRu-dim was the nanocatalyst with the highest catalytic activity for the MOR, demonstrating also a high performance for the EOR; ii) Pt/rGORu-cym showed a good electrocatalytic behavior for both reactions at more negative potentials, nevertheless delivering lower current densities (j). In terms of the organic molecule, higher j values have been obtained from the MOR, compared to the EOR. The results showed that these nanocatalysts can be considered as anode materials in Direct Alcohol Fuel Cells applications.

Enhanced Performance of Sn@Pt Core-Shell Nanocatalysts Supported on Two Different Carbon Structures for the Hydrogen Oxidation Reaction in Acid Media

“…FFT analysis allows to characterization of the nanoparticles by generating SAED patterns (inset). Two interplanar distances have been determined: (i) 0.195 nm at the center of the nanoparticle, which has been ascribed to the (211) reflection of Sn [41], even though the (200) peak of Pt may have a somehow similar value [42]; (ii) 0.220 nm at the border of the nanoparticle, attributed to the (111) plane of Pt [43]. Figure 2(b) (bottom) shows the same analysis for Sn@Pt/ NG.…”

“…Two doublets due to the spinorbit splitting into the Pt4f 7/2 and Pt4f 5/2 states are observed. Pt 0 and Pt 2+ species are identified at the nanocatalyst[43], the former having a higher relative concentration (TableS2). Similar doublets can be seen at Pt/NG (Figure3(b)), also having a higher concentration of Pt 0 compared to Pt 2+ species (TableS2).Figures3(c) and 3(d) are the high-resolution spectra in the Pt 4f region of Sn@Pt/C and Sn@Pt/NG, respectively.…”