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We report a facile one-step method for the preparation of vertical graphene oxide (VGO) nanosheets from graphene oxide (GO). Here, the GO dispersion with appropriate concentration is thermally heated to obtain a thin layer of VGO sheets at the surface of the solution. The vertical structure of GO sheets is confirmed by the surface morphology studies showing its presence in an area of 7 × 13 μm2 in size over the SiO2/Si substrate. The VGO nanosheets are also observed to form by heating the parent GO solution at different temperatures ranging from 110 to 140°C, while the growth time may vary. We have investigated the potential of prepared vertical graphene oxide for infrared (IR) sensing. The fabricated device based on VGO sheets demonstrated a maximum photosensitivity ∼190%, when illuminated with infrared radiation. The sensor demonstrates good repeatability in its photoresponse with response-recovery times of 68 ms and 63 ms, respectively, indicating a reliable and fast IR sensing. We also observe that the photosensitivity of the sensor towards IR illumination varies from 188.7% to 68.6% as the intensity varies from 28.7 to 6.4 mW/cm2. The findings presented here demonstrate the potential of vertical graphene oxide nanosheets for potential IR sensing.

Abstract: Chemically derived graphene (CDG) was prepared by hydrazine hydrate reduction of graphene oxide and used as support for palladium nanoparticles (Pd NPs) generated ex situ with controllable particle size and dispersion. The Pd NPs supported on CDG were well characterized by using a combination of advance analytical techniques and employed as catalyst in the dehydrogenation and hydrolysis of ammonia borane (AB) in organic solvents and aqueous solutions, respectively. Monodisperse Pd NPs of 4.5 nm were prepared from the reduction of palladium(II) acetylacetonate by tert-butylamine borane in the presence of oleylamine. They were readily impregnated on CDG which has BET surface area of 500 m2 g−1. Pd NPs retain their particle size dispersion and stability when supported on chemically derived graphene. The resulting materials are highly active and stable catalyst for the dehydrogenation and hydrolysis of AB. In addition to their high activity and stability, these Pd NPs are also reusable catalyst in both dehydrogenation and hydrolysis of AB preserving 85% and 95% of initial activity after 5th and 10th runs, respectively. [Copyright &y& Elsevier]

A hybrid glucose biosensor was developed based on glucose oxidase immobilized on platinum nanoparticles (PtNPs) decorated chemically derived graphene (CG) and carbon nanotube electrode platform for highly sensitive and selective glucose sensing. Chemically derived graphene and carboxylic groups functionalized multiwalled carbon nanotubes composite (C@MWCNTs) were synthesized using one step solvothermal technique to result in a suspension of the synthesized nanocomposite. The nanocomposite solution was drop casted on the gold electrode to form a thin film onto which PtNPs was electrochemically deposited. Glucose oxidase was immobilized on the nanostructured electrode and subsequently coated with nafion for selective glucose sensing. The fabricated hybrid biosensor exhibited good electrocatalytic activity towards glucose with a linear dynamic range of 0.5 mM to 13.5 mM with a fast response time of <5 s. A high sensitivity of 26.5 μA/mM cm2 and a low detection limit of 1.3 μM were observed. The biosensor exhibited a negligible response to common interference species such as uric acid, ascorbic acid and acetaminophen. The pH profile of the hybrid biosensor revealed an optimal pH operating range of 6.5 to 7, whereas the temperature profile revealed increasing oxidation current response with the increase in temperature. The obtained results thus indicate that the nanostructured composite material offers a large surface area and high electrocatalytic activity towards glucose and is a potential candidate material for glucose biosensors. • Chemically derived graphene and carbon nanotube nanocomposites are synthesized. • PtNPs was electrochemically deposited on the surface of the nanocomposite film. • The synergy between PtNPs and CG/f@MWCNTs enhances the electrocatalytic activity • Glucose oxidase was immobilized to enhance the selectivity towards glucose. • The amperometric biosensor demonstrated great analytical performance. [ABSTRACT FROM AUTHOR]