Chemistry - Research Publications

Permanent URI for this collectionhttps://kr.cup.edu.in/handle/32116/37

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Author: search.filters.author.Biswas, RathindranathSubject: search.filters.subject.Nanocatalysts

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    DNA Origami-Templated Bimetallic Core-Shell Nanostructures for Enhanced Oxygen Evolution Reaction
    (American Chemical Society, 2022-04-15T00:00:00) Kaur, Gagandeep; Biswas, Rathindranath; Haldar, Krishna Kanta; Sen, Tapasi
    Hydrogen generation through electrocatalytic water splitting offers promising technology for sustainable and clean energy production as an alternative to conventional energy sources. The development of highly active electrocatalysts is of immense interest for improving the efficiency of gas evolution, which is strongly hindered due to the sluggish kinetics of oxygen evolution reaction (OER). Herein, we present the design of Ag-coated Au nanostar (core-shell-type Au@Ag nanostar) monomer structures assembled on rectangular DNA origami and study their electrocatalytic activities through OER, which remains unexplored. Our designed DNA origami-templated bimetallic nanostar catalyst showed excellent OER activity and high stability without using any external binder and exhibited a current density of 10 mA cm-2at a low overpotential of 266 mV, which was smaller than those of ss-DNA-functionalized Au@Ag nanostars and DNA origami-templated pure Au nanostars. Our results reveal that DNA origami-assembled core-shell Au@Ag nanostars show better electrocatalytic performance as compared to pure-core Au nanostars immobilized on DNA origami, owing to the presence of a highly conductive Ag layer. Such controlled assembly of bimetallic nanostructures on a DNA origami template can provide additional electrochemical surface area and a higher density of active sites resulting in enhanced electrocatalysis. � 2022 American Chemical Society. All rights reserved.
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    Green Approach for the Fabrication of Au/ZnO Nanoflowers: A Catalytic Aspect
    (American Chemical Society, 2021-03-19T00:00:00) Biswas, Rathindranath; Banerjee, Biplab; Saha, Monochura; Ahmed, Imtiaz; Mete, Shouvik; Patil, Ranjit A.; Ma, Yuan-Ron; Haldar, Krishna Kanta
    An easy, environmentally benign, and biomimetic approach employing Azadirachta indica (neem) leaf extract as a reducing as well as capping agent was used for the fabrication of gold (Au)/zinc oxide (ZnO) hybrid nanoflowers in one pot without utilizing any hazardous chemicals. The different phytoconstituents, for example, nimbolide, azadirachtin, ascorbate, etc., present in A. indica (neem) leaf extract synergistically reduce gold(III) ions to gold(0), which later on acts as an active surface for the growth of zinc oxide (ZnO) via thermal decomposition of sodium zincate [Na2Zn(OH)4]. The development of Au/ZnO hybrid nanoflowers was observed by estimating the absorption maxima at various time intervals in the wake of adding a Au precursor to the aqueous extract. X-ray diffraction (XRD) studies and X-ray photoelectron spectroscopy (XPS) investigation unambiguously confirm the formation of highly crystalline Au/ZnO composed of Au(0) and ZnO. The as-synthesized Au/ZnO hybrid nanoflowers were analyzed utilizing different spectroscopic and microscopic techniques. The transmission electron microscopy (TEM) images clearly show that the synthesized hybrid Au/ZnO nanoflowers are monodisperse and uniform. The fabricated Au/ZnO nanoflowers were used as a catalyst for the efficient reduction of various aromatic nitro compounds to corresponding amino compounds with excellent yield (76-94%) in the presence of reducing agent sodium borohydride. The superior catalytic properties were credited to the extraordinary nanoflower morphology and the synergistic impact of the typified Au nanoparticles. � 2021 American Chemical Society.