Anup Kumar Roy

Nitrogen doped graphene via thermal treatment of composite solid precursors as a high performance supercapacitor

A novel method for nitrogen doping of graphene via solid-state impregnation was developed using graphene oxide (GO) as the raw substrate and aminoterephthalic acid as the doping agent via a facile thermal treatment at 750 °C. The structure, morphology and chemical composition of the synthesised N-doped graphene were characterised using XRD, SEM, EDS and XPS. The N-graphene product exhibits homogeneous doping with high nitrogen content (∼6 at%) in four configurations: pyridinic-N, pyrrolic-N, pyridinic-N-oxide and graphitic-N. The electric double layer capacitor (EDLC) fabricated using an N-doped graphene electrode attained a specific capacitance of 210 F g−1 (at a current density of 1 A g−1), which was greater than the values attained by pristine graphene and a GO electrode by factors of about two and six, respectively. Our synthesised N-graphene shows supercapacitance at a low electrolyte concentration compared to supercapacitors reported in the literature for high electrolyte concentrations with similar electrodes. The EDLC device we constructed based on N-graphene showed excellent charge–discharge stability for tests of up to 5000 cycles with high capacity retention (>90%). A comparison of the electrochemical performance of GO, graphene and N-graphene demonstrated that doping with nitrogen can dramatically enhance capacitance.

Doped graphene/Cu nanocomposite: A high sensitivity non-enzymatic glucose sensor for food

An amperometric non-enzymatic glucose sensor was developed based on nitrogen-doped graphene with dispersed copper nanoparticles (Cu-NGr). The sensing element was tested in conjunction with a modified glassy carbon electrode for glucose detection. The Cu-NGr composite was prepared by one pot synthesis from a mixture of graphene oxide, copper nitrate and uric acid, followed by thermal annealing at 900°C for 1h. Detailed characterizations showed homogeneous copper nanoparticle dispersion and the presence of significant proportion of graphitic nitrogen. The developed electrode presented high electrocatalytic activity towards glucose through synergetic effect of copper nanoparticles and nitrogen-doped graphene. Amperometric analysis confirmed high glucose sensitivity and ultra-low detection of 10nM glucose over a linear range. The sensor was tested for direct application to detect glucose in food samples for which the sensor displayed high selectivity with excellent reproducibility and recovery in complex food materials.

Surface Preparation of Fibres for Composite Applications

This chapter discusses about the surface preparation methods of fibres prior to use in composite materials to improve their performance or to introduce other essential characteristics. Chemical coatings, plasma and chemical surface modification techniques as well as mechanical treatments are presented. Also, advanced surface tailoring using nano-coating technology is included in this chapter.

Synthesis of nitrogen-doped graphene via thermal treatment of graphene oxide within methylimidazole and its capacitance performance as electric double layer capacitor

Nitrogen-doped graphene was successfully synthesised from graphene oxide (GO) and 2-methylimidazole composite via thermal treatment under argon flow at 700oC within 1h. This synthesised N-doped graphene exhibits homogeneous nitrogen doping with concentration of ~5% in three different nitrogen configuration namelypyridinic N, pyrrolic N and graphitic N. The electric double layer capacitor (EDLC) made up with this N-doped graphene showed excellent specific capacitance 274 F/g at current density of 1A/g, which was ~7 times higher than GO. This EDLC capacitor showed excellent cyclic stability up to 5000 cycles with capacity

A quadrafunctional electrocatalyst of nickel/nickel oxide embedded N-graphene for oxygen reduction, oxygen evolution, hydrogen evolution and hydrogen peroxide oxidation reactions

A multifunctional nano-heterostructured electrocatalyst of transition metal/metal oxide (nickel/nickel oxide) embedded on nitrogen-doped graphene is reported. The hybrid composite of N-doped graphene nanosheets with a high atomic percentage of nitrogen (8.2 at%) and embedded with highly distributed nickel/nickel oxide nanoparticles inside the graphene layers is synthesized by a one pot thermal annealing process. The resultant composite demonstrates excellent electrocatalytic activity utilizing the superior electrocatalytic properties of nickel/nickel oxide nanoparticles supported on nitrogen-doped graphene. The hybrid exhibits efficient oxygen reduction reaction (ORR) properties comparable with state-of-the-art electrode Pt/C with a four-electron transfer pathway and superior oxygen evolution reaction (OER) compared to the state-of-the-art electrode for the OER, Ru/C. Alternatively, this composite acts as an excellent electrode material for the hydrogen evolution reaction (HER) both in acidic and alkaline media. Nevertheless, this composite facilitates the hydrogen peroxide oxidation reaction (HPOR) in the presence of hydrogen peroxide, which is crucial for developing reversible fuel cells and fuel cells with liquid oxidant.