Inherent properties of graphene can be experienced by integrating it with different nanomaterials to form unique composite materials. Decorating the surface of graphene sheets with nanoparticles (NPs) is one of the recent approaches taken up by scientists all over the world. This article describes a simple synthesis route to preparing stable Ni NP-reduced graphene oxide (Ni-RGO) composite material. The otherwise unstable bare Ni NPs are stabilized when embedded in the RGO sheets. This synthesized composite material has a potential application in the formic acid-induced reduction of highly toxic aqueous Cr(VI) at room temperature (25 °C). The reduction of dichromate using formic acid as a reducing agent is a well-known redox reaction. However, the rate of the reaction is very slow at room temperature, which can be enhanced very significantly in the presence of Ni-RGO by introducing an intermediate redox step with formic acid. The Ni-RGO composite material is an easy to prepare, cheap, stable, reusable material that has the potential to replace costly Pd NPs used in this context. Ni-RGO is also found to be very active in enhancing the rate of reduction of other metal ions in the presence of formic acid at room temperature.

Synthesis of Cu2O-amine-functionalized graphite nanosheet (AFGNS) composite has been accomplished at room temperature. In the first step, AFGNS is synthesized by wet chemical functionalization where the -NH2 groups formed on nanosheet surface help to anchor the Cu(2+) ions homogeneously through coordinate bonds. Reduction of Cu(2+) (3.4 × 10(-2) mmol) in the presence of NaBH4 (1.8 mmol) can be restricted to Cu(1+) on AFGNS surface at room temperature. This leads to the formation of uniform Cu2O nanoparticles (NP) on AFGNS. The role played by the -NH2 groups in anchoring Cu(2+) ions and followed by stabilizing the Cu2O NP on AFGNS was understood by controlled reactions in the absence of -NH2 groups and without any graphitic support, respectively. The prepared Cu2O-AFGNS composite shows excellent catalytic activity toward degradation of an azo dye, methyl orange, which is an environmental pollutant. The dye degradation proceeds with high rate constant value, and the composite shows high stability and excellent reuse capability.

A Pd-Ni alloy nanoparticle (NP) doped mesoporous SiO2 film was synthesized using a one pot inorganic-organic sol-gel process in the presence of structure director P123. Pure Pd and Ni NP containing films were also synthesized as controls. Overall a composition of 10 mol% metal (in the case of Pd-Ni, 5 mol% of each metal) and 90 equivalent mol% SiO2 was maintained in the heat-treated films. Grazing incidence X-ray diffraction and transmission electron microscopy studies of the final heat-treated Pd-Ni doped films revealed the (111) oriented growth of the Pd-Ni alloy NPs, with an average size of 5.3 nm, residing inside the mesopores of the SiO2 film. We performed the C-C coupling reaction employing the film-catalysts and the progress of the reaction was monitored using a fluorimeter. Overall, only the Pd-Ni alloy NP doped film showed good catalytic activity with excellent recyclability. It has been determined that the higher oxidising ability of metallic Ni restricted the oxidation of Pd in the Pd-Ni alloy catalyst under the reaction conditions, leading to the maintained reusability in consecutive cycles.

The fabrication of black and electrically conducting films on glass substrate derived from covalently functionalized reduced graphene oxide (FRGO) has been reported in this work. Graphene oxide (GO) was first prepared following the Hummers method and then functionalized using an organically modified silicon alkoxide, 3-glycidoxypropyltrimethoxysilane (GLYMO) in an ordered fashion. Catalyst (aluminium acetylacetonate) induced selective polymerization of the epoxy groups of GO and GLYMO was found to occur via the formation of ethereal (-C-O-C-) linkages. The formation of such linkages was confirmed by IR, Raman, TGA, X-Ray diffraction and TEM studies. Finally the functionalized graphene oxide (FGO) films were subjected to thermal reduction in an inert (N 2 ) atmosphere to obtain FRGO films. These hard FRGO films are electrically conducting and appeared as black coatings on glass. By varying the loading (20-30 wt%) of GO with the covalently bonded organically modified silica, the sheet resistance values can be tuned in a linear way from 0.8 Â 10 6 to 1.4 Â 10 3 U , À1 . The uniform current-voltage (I-V) characteristics of the films can be nicely correlated with the sheet resistance values.

A facile route to synthesize amine (-NH 2 ) functionalized graphite nanosheets (AFGNS) by 2-step controlled chemical modification of microcrystalline graphite is described. The method begins with nitration by mixed acid (HNO 3 : H 2 SO 4 in 1 : 1 v/v ratio), followed by reduction with Na 2 S to form AFGNS. The AFGNS was reacted with carboxylic acid-terminated polyethylene glycol (PEG) chains (MeO-mPEG-COOH, M W = 5000 Da) in the presence of a carbodiimide coupling agent to obtain a water-soluble PEGylated AFGNS (P-AFGNS) composite.Anticancer drug doxorubicin (DOX) was loaded on this composite with a loading capacity of 0.296 mg mg À1for an initial concentration of 0.232 mg mL À1 DOX and 0.136 mg mL À1 of P-AFGNS and the release of DOX from this water-soluble DOX loaded P-AFGNS composite at two different temperatures was found to be strongly pH dependent.

The present work demonstrates the C–S cross-coupling reaction between aryl halides and thiols using nickel nanoparticles (Ni NPs) supported on reduced graphene oxide (Ni/RGO) as a heterogeneous catalyst. It is observed that the uniformly dispersed Ni NPs supported on RGO could exhibit excellent catalytic activity in C–S cross-coupling reactions and the catalytic application is generalized with diverse coupling partners. Although the electron-rich planar RGO surface helps in stabilizing the agglomeration-free Ni NPs, the catalytic process is found to occur involving Ni(II) species and the recovered catalyst containing both Ni(0)/Ni(II) species is equally efficient in recycle runs. A correlation of loading of Ni species, size of NPs and the intermediate Ni-related heterostructures formed during the catalytic process has been established for the first time, and found to be best in the C–S cross-coupling reaction for Ni(0) and Ni(II) NPs of the average sizes 11–12 nm and 4 nm, respectively.

The synthesis of a mesoporous γ‐Al2O3 nanorod/reduced graphene oxide (γ‐Al2O3NR/RGO) composite with a higher surface area and thermal conductivity than unmodified γ‐Al2O3 has been accomplished, and these materials were characterized in detail. The composite was used successfully as a support for poly(ethylenimine) (PEI) to capture CO2 at high temperature. The PEI‐modified composite (γ‐Al2O3NR/RGO/PEI) showed an excellent CO2 adsorption from simulated flue gas at 75 °C and complete desorption at 100 °C with recyclability. The maximum CO2 adsorption capacity of this material was 200.6 mg gPEI−1 (1.14 mmol CO2 gadsorbent−1) with an amine efficiency of 0.22, which is higher than that of bare γ‐Al2O3/PEI. As a result of its high thermal conductivity, the overheating of the adsorbent during exothermic CO2 adsorption by PEI was restricted and as a result the thermal degradation of PEI was prevented. Accordingly, the adsorption capacity of γ‐Al2O3NR/RGO/PEI does not deteriorate like that of bare γ‐Al2O3/PEI during repeated CO2 adsorption–desorption cycles.

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