Debanjan Guin

Bio: Debanjan Guin is an academic researcher from Banaras Hindu University. The author has contributed to research in topics: Catalysis & Silver nanoparticle. The author has an hindex of 15, co-authored 31 publications receiving 1126 citations. Previous affiliations of Debanjan Guin include University of Arizona & Council of Scientific and Industrial Research.

Large scale synthesis of graphene quantum dots (GQDs) from waste biomass and their use as an efficient and selective photoluminescence on–off–on probe for Ag+ ions

Abstract: Graphene quantum dots (GQDs) are synthesized from bio-waste and are further modified to produce amine-terminated GQDs (Am-GQDs) which have higher dispersibility and photoluminescence intensity than those of GQDs. A strong fluorescence quenching of Am-GQDs (switch-off) is observed for a number of metal ions, but only for the Ag(+) ions is the original fluorescence regenerated (switch-on) upon addition of L-cysteine.

Photoreduction of Silver on Bare and Colloidal TiO2 Nanoparticles/Nanotubes: Synthesis, Characterization, and Tested for Antibacterial Outcome

Abstract: Silver nanoparticles of particle size around 15 nm were synthesized by following a simple and green methodology of photoreduction of silver nitrate (AgNO3) using bare titania and polyvinyl alcohol (PVA)-capped colloidal titanium dioxide nanoparticles/nanotubes under UV−vis light (λ = 365 nm). The synthesized pure TiO2 nanoparticles/tubes, Ag−TiO2 nanocomposites and PVA-capped colloidal Ag−TiO2 nanocomposites are characterized for their structure and morphology by X-ray diffraction (XRD) and transmission electron microscopy (TEM) and for their electronic structure by X-ray photoelectron spectroscopy (XPS). The antibacterial efficiency of all nanocomposites were investigated on Escherichia coli using standard procedures. The synthesized metal−metal oxide nanocomposites are shown to be very efficient toward destroying Gram negative bacteria Escherichia coli.

A simple chemical synthesis of nanocrystalline AFe2O4 (A = Fe, Ni, Zn): An efficient catalyst for selective oxidation of styrene

Abstract: Nanosized spinel ferrite (AFe2O4, A = Ni, Fe, Zn) catalysts are prepared by ‘bottom-up’ approach, i.e. first forming the nanostructured building blocks and then assembling them into the final material with average particle size of 7–12 nm and surface area of 80–100 m2/g. The synthesized nanocrystallites were characterized by thermal analysis, powder X-ray diffraction, transmission electron microscopy and inductively coupled plasma (atomic emission spectroscopy) technique for evaluating phase, structure and morphology and stoichiometry. These materials were found to be very good catalysts for the oxidation of styrene to benzaldehyde in the presence of hydrogen peroxide. Of the several catalysts tried, magnetite (Fe3O4) has shown to have the best catalytic activity for the above reaction. The effects of solvent medium used, styrene:hydrogen peroxide molar ratio, reaction temperature, time and reaction atmosphere required for the complete conversion of styrene to benzaldehyde were also studied. Based on our findings, a plausible mechanism involved in the catalytic reaction is proposed.

Magnetic Iron Oxide Nanoparticles: Synthesis and Surface Functionalization Strategies

Abstract: Surface functionalized magnetic iron oxide nanoparticles (NPs) are a kind of novel functional materials, which have been widely used in the biotechnology and catalysis. This review focuses on the recent development and various strategies in preparation, structure, and magnetic properties of naked and surface functionalized iron oxide NPs and their corresponding application briefly. In order to implement the practical application, the particles must have combined properties of high magnetic saturation, stability, biocompatibility, and interactive functions at the surface. Moreover, the surface of iron oxide NPs could be modified by organic materials or inorganic materials, such as polymers, biomolecules, silica, metals, etc. The problems and major challenges, along with the directions for the synthesis and surface functionalization of iron oxide NPs, are considered. Finally, some future trends and prospective in these research areas are also discussed.

Review on Modified TiO2 Photocatalysis under UV/Visible Light: Selected Results and Related Mechanisms on Interfacial Charge Carrier Transfer Dynamics

Abstract: Titania is one of the most widely used benchmark standard photocatalysts in the field of environmental applications. However, the large band gap of titania and massive recombination of photogenerated charge carriers limit its overall photocatalytic efficiency. The former can be overcome by modifying the electronic band structure of titania including various strategies like coupling with a narrow band gap semiconductor, metal ion/nonmetal ion doping, codoping with two or more foreign ions, surface sensitization by organic dyes or metal complexes, and noble metal deposition. The latter can be corrected by changing the surface properties of titania by fluorination or sulfation or by the addition of suitable electron acceptors besides molecular oxygen in the reaction medium. This review encompasses several advancements made in these aspects, and also some of the new physical insights related to the charge transfer events like charge carrier generation, trapping, detrapping, and their transfer to surface are d...

Magnetically recoverable nanocatalysts.

Abstract: We gratefully acknowledge funding and support from King Abdullah University of Science and Technology (KAUST). Thanks are also due to the KAUST communication department for designing several images for this Review.