BITS Faculty Publications

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Author: search.filters.author.Pande, SurojitSubject: search.filters.subject.Synthesis

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    Facile synthesis of ZnO/ZnS hollow nanorods via Kirkendall effect with enhanced photocatalytic degradation of methylene blue
    (Springer, 2023-03) Pande, Surojit
    Because of the growing concerns about environmental issues, the search of proficient semiconductor catalysts for pollutants degradation from contaminated water is one of the interesting areas of research. Due to the larger surface area, hollow nanomaterials with hollow interior and outer thickness illustrate a class of significant nanostructured materials. The enhanced surface area provides remarkable applications of the hollow nanomaterials in catalysis. In Kirkendall effect, pores are formed owing to the diverse diffusion rates of two nanomaterials in a diffusion couple. Here, we have introduced the facile hydrothermal synthesis of hollow nanorods of ZnO/ZnS via Kirkendall effect using ZnO nanorods (NRs). The morphologies, optical properties, compositions, and crystal structures of the as synthesized materials are systematically studied using UV–vis, PXRD, FESEM, TEM, EDS, XPS, etc. The process of synthesis and growth mechanism of hollow NRs is suggested based on the Kirkendall effect. A hollow nanomaterial, envisaged being highly efficient for molecule adsorption on its surface, the as synthesized materials were used for the photocatalytic degradation of methylene blue (MB) dye. MB degradation efficiency of 96% within 60 min was performed over ZnO/ZnS hollow NRs, which was 2.6-fold greater than that of ZnO. The rate constant of ZnO/ZnS heterostructure was 0.045 min−1, which was 5.5 times larger than that of bare ZnO. We have concluded our work in the directions towards the synthesis of various semiconductor hollow nanostructures for the varied catalytic reactions
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    Synthesis, characterization, and electrocatalysis using Pt and Pd dendrimer-encapsulated nanoparticles prepared by galvanic exchange
    (RSC, 2011) Pande, Surojit
    In this report we present the synthesis and characterization of Pt and Pd dendrimer-encapsulated nanoparticles (DENs) using the method of galvanic exchange. Sixth-generation hydroxyl-terminated poly(amidoamine) dendrimers were used to prepare Cu DENs composed of 55 atoms. In the presence of either PtCl42− or PdCl42−, the less noble Cu DENs oxidize to Cu2+ leaving behind an equal-sized DEN of Pt or Pd, respectively. DENs prepared by direct reduction with BH4−, which is the common synthetic route, and those prepared by galvanic exchange have the same composition, structure, and properties as judged by UV-vis spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, and electrochemical methods. However, the galvanic exchange synthesis is much faster (3 h vs. 96 h), and the yield of reduced DENs is significantly higher (nearly 100% in the case of galvanic exchange).
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    Synthesis of ZnO/Au and ZnO/Ag nanoparticles and their photocatalytic application using UV and visible light
    (RSC, 2014-05-20) Pande, Surojit; Gangopadhyay, Subhashis
    We report a simple and convenient method for the synthesis of a ZnO/Au and ZnO/Ag heterostructure nanoflower by applying a surfactant mediated route. Initially, pure ZnO nanoflowers have been synthesized followed by Au and Ag deposition on ZnO surface using hydrazine hydrate as reducing agent. Structure, crystallinity, and morphology have been assessed by X-ray diffraction, X-ray photoelectron spectroscopy, and electron microscopy techniques. The influences of the deposited metal nanoparticles (Au and Ag) on the surface of ZnO have been emphasized by applying the as-synthesized nanostructure in dye degradation under illumination of UV and visible light. The basic motivation behind this work is to find a superior photocatalyst, which can work under UV as well as visible light i.e., to cover the whole range of the solar spectrum. Photocatalytic performances of bare ZnO, ZnO/Au, and ZnO/Ag have been studied thoroughly. Photodegradation results under UV and visible light demonstrated that the incorporation of noble metal nanoparticles significantly (or drastically) increases the catalytic efficiency by promoting the photogenerated charge carrier separation. The main advantage of the proposed ZnO/Au and ZnO/Ag semiconductor is that it delays the recombination process of the electron–hole pairs generated by the photon absorption, which in lieu increases the photocatalytic efficiency. It is a challenging issue to fabricate stable photocatalysts which can work under visible light as it covers 43% of sunlight. To investigate the role of photogenerated electrons and holes in dye degradation, scavenging experiments using different scavengers have also been performed.
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    Graphitic-carbon nitride support for the synthesis of shape-dependent ZnO and their application in visible light photocatalysts
    (RSC, 2015) Pande, Surojit
    Shape-dependent synthesis of ZnO has been developed on the surface of g-C3N4 following a simple and reproducible strategy. Initially, graphitic-carbon nitride (g-C3N4) was synthesized by pyrolysis of urea which was further used to grow ZnO nanostructures via refluxing conditions. Different hydrolyzing agents, such as hexamethylenetetramine (HMT) and ammonia were used to synthesize dumbbell and cone structures, respectively. Apart from hydrolyzing agents, cetyltrimethylammoniumbromide (CTAB) was also used as a growth controlling agent. Structural, morphological and optical characterizations of the as-synthesized materials were performed by using FESEM, TEM, XRD, XPS, UV-vis etc. techniques. After successful synthesis, the as-synthesized heterostructures were explored as visible light driven photocatalysts towards organic pollutant (methylene blue and phenol) degradation. The photocatalytic performances of bare ZnO, dumbbell and cone structures of g-C3N4/ZnO as well as g-C3N4, have been examined thoroughly. Photocatalytic results revealed that g-C3N4/ZnO heterostructures exhibit a higher efficiency under the illumination of visible light as compared to pure g-C3N4. Superior photodegradation activity of the g-C3N4/ZnO heterostructure originated from the synergistic effect and high charge separation at the interface of g-C3N4 and ZnO has also been discussed.
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    Functionalized pyranopyrazole molecules as corrosion inhibitors for mild copper metal in HCl solution: synthesis, theoretical studies, and physical investigations
    (IOP, 2018-02-07) Shukla, Paritosh; Manohar, Prashant Uday; Pande, Surojit; Dalvi, Anshuman
    Five substituted pyranopyrazole (PPZ) derivatives were chemically synthesized by conventional and microwave assisted synthesis (MWA) methodology. Their differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) analyses, and the corrosion inhibitor properties on mild copper metal in 1 M HCl solution were investigated by SEM (Scanning Electron Microscopy), EDS (Energy Dispersive Spectroscopy), and XRD (x-ray Diffraction) all of which showed good anti-corrosion behavior. Further, mechanical property investigations were also performed by measuring the tensile strength of the PPZ-adsorbed Cu-strips. Finally, the inhibition action was evaluated by quantum chemical parameters. All the experimental results pointed that the molecules acted as excellent anti-corrosion surface active agents for copper metal.