No abstract

Metal nanoparticles anchored on a graphene substrate find many applications such as sensors, catalysts, lithium ion batteries, etc. However, to date, graphene-metal nanohybrids have been synthesized by either covalent or ionic interactions between the graphene substrate and the metal nanoparticles. In this manuscript, we report a green and facile method to "bubble pack" metal nanoparticles on a graphene substrate by a simple process utilizing eco-friendly ionic liquids in conjunction with microwave heating. Copper nanoparticles bubble packed on graphene showed enhanced glucose sensing when compared to covalently bonded copper/graphene hybrids. Titania nanoparticles bubble packed on graphene when applied as anode materials in lithium ion batteries exhibited two times more lithium ion retention when compared to covalently bonded titania/graphene hybrids. "End of life" disposal of nanomaterials into the environment is a growing area of concern in recent days. One way of dealing with this problem is to extend the life cycle of nanomaterials by reusing the nanomaterials in multiple applications. In this report, we also show the recyclability of our novel bubble packaging material, by etching out the metal nanoparticles resulting in a unique 3D hierarchical graphene nanocup decorated graphene. The applicability of this recycled material in super capacitors is also reported.

3D graphene–carbon nanotube–nickel nano-architectures were synthesized from isocyanate treated 2D graphene oxide and applied as anodes in sodium ion batteries.

Even though metal organic frameworks (MOFs) have rapidly emerged as useful materials in many applications, their inherent low conductivity necessitate hybridizing them with conductive carbon nanostructures like graphene or carbon nanotubes (CNTs) or carbon black especially in energy storage and energy generation applications like batteries, super capacitors, and electro-catalysts in oxygen reduction reaction (ORR). However, to date the synthesis of MOF/CNT is carried out by mixing pre-synthesized MOFs with oxidized or chemically modified CNTs. In this article, we report synthesis of nanometer-sized Ni-MOF/CNT by the reaction of nickelocene-derived nickel oxide-decorated CNTs with terepthalic acid synthesized from waste polyethylene terephthalate (PET ). Morphological studies by scanning electron microscopy and transmission electron microscopy shows nanometer-sized Ni-MOF particles anchored on defect-rich carbon nanotubes, whereas the chemical changes associated wit transformation of NiO@CNT into nanometer-sized Ni-MOF/CNT were evaluated by X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy analysis. The utility of nanometeric Ni-MOF/CNT as an electro-catalyst in urea oxidation reactions and removal of arsenic from contaminated water is reported. The applicability of our developed technique to synthesize nanometer Fe-MOF/CNT is also demonstrated.

Although though ionic liquids (IL) are rapidly emerging as highly efficient reagents for the depolymerization of waste plastics, their high cost and adverse impact on the environment make the overall process not only expensive but also environmentally harmful. In this manuscript, we report that graphene oxide (GO) facilitates the transformation of waste polyethylene terephthalate (PET) to Ni-MOF (metal organic framework) nanorods anchored on reduced graphene oxide (Ni–MOF@rGO) through NMP (N-Methyl-2-pyrrolidone)-based coordination in ionic liquids. Morphological studies using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed mesoporous three-dimensional structures of micrometer-long Ni-MOF nanorods anchored on reduced graphene substrates (Ni–MOF@rGO ), whereas structural studies using XRD and Raman spectra demonstrated the crystallinity of Ni-MOF nanorods. Chemical analysis of Ni–MOF@rGO carried out using X-ray photoelectron spectroscopy demonstrated that nickel moieties exist in an electroactive OH-Ni-OH state, which was further confirmed by nanoscale elemental maps recorded using energy-dispersive X-ray spectroscopy (EDS). The applicability of Ni–MOF@rGO as an electro-catalyst in a urea-enhanced water oxidation reaction (UOR) is reported. Furthermore, the ability of our newly developed NMP-based IL to grow MOF nanocubes on carbon nanotubes and MOF nano-islands on carbon fibers is also reported.

Correction for ‘3D graphene–carbon nanotube–nickel ensembles as anodes in sodium-ion batteries’ by Deepa Gangaraju et al., RSC Adv., 2016, 6, 99914–99918.