Anchu Ashok

Cellulose assisted combustion synthesis of porous Cu–Ni nanopowders

Porous nanopowders of Cu–Ni were synthesized using cellulose fibres as impregnation media at ambient pressure using combustion based techniques. The synthesized nanopowders were characterized using XRD, BET, SEM, TEM etc. The phase development during the synthesis process was evaluated by performing TGA/DTA experiments. The effect of the amount of precursor on the microstructure and porosity of the nanomaterials was investigated and compared with Cu–Ni synthesized using the Solution Combustion Synthesis (SCS) method. The syntheses of nanopowders proceed via ignition in the reaction media containing metal precursors which is followed by high temperature cellulose combustion. Total pore volume and average pore diameter in case of cellulose assisted synthesized samples were found to be greater as compared to SCS samples.

Carbon Management: Regional Solutions Based on Carbon Dioxide Utilization and Process Integration

Abstract Improving the efficiency of Carbon Capture and Storage (CCS) will become increasingly important, as currently the implementation of most of the CO 2 capture processes is not economically feasible. It is anticipated that CO 2 will become available from different sources, and focusing on the Middle East these sources will include power plants, refineries and Gas-To-Liquid plants, and gas processing plants and LNG production facilities. In this work, we propose an integrated solution where CO 2 utilization is the key aspect. New production routes using CO 2 as a feedstock for the direct conversion or in algae-based processes are being evaluated. Process design studies are being conducted to optimize the integration of CO 2 utilization technologies with existing and new facilities.

Surface Alloying in Silver-Cobalt through a Second Wave Solution Combustion Synthesis Technique

Herein, we report the synthesis of silver-cobalt nanopowders using three different modes of solution combustion synthesis, and we present the effects of the synthesis conditions on particle morphology. The synthesized nanoparticles were characterized using X-ray diffraction (XRD), Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), UV-Visible spectrophotometer (UV-vis), Transmission electron microscopy (TEM), and X-Ray Photoelectron Spectroscopy (XPS) to understand the structural and elemental properties. When Co is synthesized over Ag in a second wave of combustion, peak shifts observed in XRD and XPS show a change in the cell parameters and prove the existence of a strong electronic interaction between Ag and Co. Better control of mixing and alloying through the second wave combustion synthesis mode (SWCS) was evident. The sequence of combustion affects the structure and composition of the material. SWCS reduces the amount of carbon content, as compared to single-stage combustion, and the combustion of carbon is followed by a rearrangement of atoms.

Synthesis of Highly Efficient Bifunctional Ag/Co3O4 Catalyst for Oxygen Reduction and Oxygen Evolution Reactions in Alkaline Medium

Ag/Co3O4 catalysts using three different modes of solution combustion synthesis were developed and characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy to identify crystallite size, oxidation state, composition, and morphology. Cyclic voltammetry and linear sweep voltammetry measurements for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) confirm the bifunctionality of the electrocatalysts. The electrochemical evaluation indicates that a synergic effect between Ag and Co enhances the activity through the fast breaking of O–O bond in the molecular oxygen to enhance the reduction mechanism. The high content of cobalt (Co) in the catalyst Ag/Co3O4-12, synthesized by second wave combustion, improves the activity for ORR, and the reaction mechanism follows a 3.9 number of electron transfer in overall reaction. The kinetic and limiting current densities of Ag/Co3O4-12 are maximum when compared to those of other Ag/Co3O4 catalysts and are very close to commercial Pt/C. Moreover, the maximum current density of OER for Ag/Co3O4-12 makes it a promising candidate for various bifunctional electrocatalytic applications such as fuel cells and metal–air batteries.

Single step synthesis of transition metal nanoparticles in aqueous phase for catalytic applications

Pure metal nanoparticles have shown exceptional catalytic properties which have motivated modern researchers to come up with innovative ideas to synthesize nanoparticles in a cost effective manner. Apart from catalysis, potential applications of metal nanoparticles are well known in other fields such as: pigments, electronic and magnetic materials, drug delivery etc. Here we report solution combustion synthesis method to synthesize transition metals (Ni, Cu and Co) in a single step process. Metal nitrates and glycine are used as synthesis precursors and dissolved in water to make a homogeneous aqueous solution which is combusted to produce metal nanoparticles with desired composition.

Modeling of Reaction Front Movement in Combustion Synthesis for Catalyst Preparation

Abstract One of the innovative combustion methods for the synthesis of high surface area catalysts is the Impregnated Layer Combustion Synthesis (ILCS). This method provides better control over the synthesis process compared to the conventional combustion synthesis methods where explosion like behavior could exist. To start the process, catalyst precursors and fuel are impregnated as a thin layer (e.g. on catalyst supports, or cellulose paper etc.) and dried. Then, by providing ignition (flux), at one end, for a short period of time, a combustion front is generated and starts moving in a self-sustained manner leaving the products behind. Having a stable combustion front movement is required for large scale synthesis of nanomaterials. In this work, the effect of heat transfer and reaction parameters, mainly heat flux (ignition source), heat of reaction, and activation energy, on the stability of the combustion front is investigated by using a one dimensional model for combustion reaction front movement.