Nanostructured RuO2 on MWCNTs: Efficient catalyst for transfer hydrogenation of carbonyl compounds and aerial oxidation of alcohols

Multiwall carbon nanotubes (MWCNTs)/ruthenium dioxide nanoparticles (RuO2NPs) composite was prepared by a straightforward ‘dry synthesis’ method. After being well characterized, the prepared composite was used as a nanocatalyst (RuO2/MWCNT) for the transfer hydrogenation of carbonyl compounds. The excellent adhesion of RuO2NPs on the anchoring sites of MWCNTs was confirmed by TEM and Raman analyses. The weight percentage (7.97 wt%) and the chemical state (+4) of Ru in RuO2/MWCNT was confirmed by EDS and XPS analyses, respectively. It was found that the RuO2/MWCNT has a higher specific surface area of 189.3 m2 g?1. Initially the reaction conditions were optimized and then the scope of the catalytic system was extended with a wide range of carbonyl compounds. The influence of the size of RuO2NPs on the transfer hydrogenation of carbonyl compounds was also studied. The RuO2/MWCNT is highly chemoselective, heterogeneous in nature, reusable and highly stable. Owing to the high stability of the used catalyst (u-RuO2/MWCNT), it was further calcinated at high temperature to obtain RuO2 nanorods (NRs) hybrid MWCNTs. Then the hybrid material was used as a catalyst (r-RuO2/MWCNT) for the aerial oxidation of alcohols and the result was found to be good.ArticleApplied Catalysis A. 484(22):84-96 (2014)journal articl

Structural and mechanical properties of cellulose acetate/graphene hybrid nanofibers: Spectroscopic investigations

Cellulose acetate/graphene (CA/graphene) and cellulose acetate/graphene-COOH (CA/graphene-COOH) hybrid nanofibers were fabricated via electrospinning technique, and their morphologies, crystallinity and mechanical properties were investigated. The added amounts of graphene and graphene-COOH were varied from 0.5 to 5.0 wt%. The crystal structures and morphologies of the resultant hybrid nanofibers were investigated by wide angle X-ray diffraction (WAXD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), respectively. Graphene-COOH incorporated CA nanofiber mats showed higher Young’s modulus of about 910 MPa among than those of CA/graphene nanofibers, which is due to molecular interactions between –COOH groups in acid-treated graphene and C=O groups in CA via hydrogen bonding. This specific interaction was demonstrated by spectroscopic studies (Raman and Fourier transform infrared (FT-IR) spectroscopies)

Photodegradation of dyes by a novel TiO2/u-RuO2/GNS nanocatalyst derived from Ru/GNS after its use as a catalyst in the aerial oxidation of primary alcohols (GNS = graphene nanosheets)

Ruthenium nanoparticles (RuNPs) supported on graphene nanosheets (GNS), a composite (Ru/GNS), were prepared by a dry synthesis method and were used as nanocatalysts for the aerial oxidation of various primary alcohols. Ru/GNS was highly efficient, selective, stable and heterogeneous in nature. Owing to the high stability of the used catalyst (u-Ru/GNS), it was further applied in a different catalytic system viz photocatalytic degradation, after suitable modifications. We have obtained a novel TiO2/u-RuO2/GNS catalyst from u-Ru/GNS by the sol-gel method. The catalytic activity of TiO2/u-RuO2/GNS toward the photodegradation of methyl orange (MO) and acridine orange (AO) was found to be excellent. Overall, the sustainable use of these recyclable materials (Ru/GNS and TiO2/u-RuO2/GNS) could lead to economic and environmental benefits.Reaction Kinetics, Mechanisms and Catalysis. 115(2):759-772 (2015)journal articl