Hydrogen evolution and capacitance behavior of Au/Pd nanoparticle-decorated graphene heterostructures

The outstanding properties of two-dimensional materials such as graphene offer the possibility to produce novel hybrid materials with boosted functionality for use in catalysis and electrochemical energy storage. The hydrogen evolution reaction and interfacial capacitance performance of monolayer graphene sheets decorated with various metal nanoparticles are studied herein. Chemical vapor deposition grown graphene monolayer was decorated with Au and/or Pd nanoparticles, either on one side or both sides, forming single- or bi metal graphene heterostructures. These asymmetrically decorated graphene nanocomposites were characterized using high-resolution scanning transmission electron microscopy and 3D electron tomography. Electrochemical characterization reveals enhanced hydrogen evolution activity and outstanding capacitance for the resultant composite materials in comparison to pristine graphene and other recently developed graphene-based energy storage devices

Ag and Au nanoparticles/reduced graphene oxide composite materials: Synthesis and application in diagnostics and therapeutics

The exceptional electrical, thermal, optical and mechanical properties have made two dimensional sp2 hybridized graphene a material of choice in both academic as well as industrial research. In the last few years, researchers have devoted their efforts towards the development of graphene/polymer, graphene/metal nanoparticle and graphene/ceramic nanocomposites. These materials display excellent mechanical, electrical, thermal, catalytic, magnetic and optical properties which cannot be obtained separately from the individual components. Fascinating physical and chemical properties are displayed by noble metal nanomaterials and thus they represent model building blocks for modifying nanoscale structures for diverse applications extending from catalysis, optics to nanomedicine. Insertion of noble metal (Au, Ag) nanoparticles (NPs) into chemically derived graphene is thus of primary importance to open new avenues for both materials in various fields where the specific properties of each material act synergistically to provide hybrid materials with exceptional performances. This review attempts to summarize the different synthetic procedures for the preparation of Ag and Au NPs/reduced graphene oxide (rGO) composites. The synthesis processes of metal NPs/rGO composites are categorised into in-situ and ex-situ techniques. The in-situ approach consists of simultaneous reduction of metal salts and GO to obtain metal NPs/rGO nanocomposite materials, while in the ex-situ process, the metal NPs of desired size and shape are first synthesized and then transferred onto the GO or rGO matrix. The application of the Ag NPs and Au NPs/rGO composite materials in the area of biomedical (drug delivery and photothermal therapy) and biosensing are the focus of this review article

Ag and Au nanoparticles/reduced graphene oxide composite materials: Synthesis and application in diagnostics and therapeutics

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Palladium nanoparticle functionalized graphene xerogel for catalytic dye reduction

We report a method to synthesize a palladium-functionalized porous graphene xerogel structure. A graphene xerogel nanocomposite with a three-dimensional microstructure was obtained by chemical reduction of an aqueous dispersion of graphene oxide at mild temperature. After the graphene hydrogel has been placed in a K2PdCl4 solution, the spontaneous redox reaction between the reduced graphene and Pd2+ takes place, leading to the formation of nanohybrid materials consisting of a graphene porous matrix decorated with Pd nanoparticles. The final porosity of the material was tuned through drying the graphene hydrogel by solvent evaporation. The porous palladium functionalized graphene xerogels were successfully used for the catalytic reduction of Rhodamine 6G

Biocompatible functionalized AuPd bimetallic nanoparticles decorated on reduced graphene oxide sheets for photothermal therapy of targeted cancer cells

Graphene, which is a unique 2D nanomaterials has received widespread attention for photothermal therapy (PTT) application. Here, we have designed the nanocomposite using polydopamine (PDA) functionalized reduced graphene oxide (rGO) nanosheets and bimetallic AuPd nanoparticles (NPs). The bimetallic AuPd nanoparticles decorated PDA functionalized rGO (AuPd-rGO/PDA) nanocomposite is synthesized by simple chemical reduction technique resulting in an average size of AuPd bimetallic nanostructure of 4.18 nm. The photothermal activity of the AuPd-rGO/PDA nanocomposite is explored under the irradiation of near infrared (NIR) laser sources of wavelength 915 nm. The temperature rises nearly 51 ± 3 °C within 3 min of irradiation NIR laser light resulting in the ablation of MDAMB-231 cancer cells up to concentration of 25 μg mL−1 of AuPd-rGO/PDA nanocomposite. This high performance of the ablation of cancer cells by photothermal therapy technique was facilitated using a low concentration of the nanocomposite by the synergistic effects of the bimetallic AuPd as well as rGO and PDA functionalization. The AuPd-rGO/PDA nanocomposite demonstrated the high biocompatibility towards normal healthy cell lines (L929) and exhibits survival efficiency of more than 85%. We also demonstrated the biocompatibility of the AuPd-rGO/PDA nanocomposite materials on the zebrafish embryos (Danio rerio). This work thus illustrates that the AuPd-rGO/PDA nanocomposite could behave as favourable nanoplatform for tumor therapeutics. © 2020 Elsevier B.V

Reduced graphene oxide nanosheets decorated with Au-Pd bimetallic alloy nanoparticles towards efficient photocatalytic degradation of phenolic compounds in water

Reduced graphene oxide nanosheets decorated with Au-Pd bimetallic alloy nanoparticles are successfully prepared via a chemical approach consisting of reducing the metal precursors using ascorbic acid as reductant at an elevated temperature. The prepared nanocomposite is employed as a photocatalyst for the degradation of organic contaminants such as phenol, 2-chlorophenol (2-CP), and 2-nitrophenol (2-NP). The complete degradation of phenol is achieved after 300 min under natural sunlight irradiation whereas the degradation of 2-CP and 2-NP is completed after 180 min. The activity of the photocatalyst is evaluated considering several parameters such as the initial phenol concentration, the photocatalyst loading, and the pH of the solution. The degradation kinetics of all the compounds is carefully studied and found to follow a linear Langmuir-Hinshelwood model. Furthermore, the reusability of the photocatalyst is successfully achieved up to five cycles and the catalyst exhibits an excellent stability