Subash Chandra Sahu

Graphene-induced Pd nanodendrites: A high performance hybrid nanoelectrocatalyst

AbstractA facile and green approach has been developed for the in situ synthesis of hybrid nanomaterials based on dendrite-shaped Pd nanostructures supported on graphene (RG). The as-synthesized hybrid nanomaterials (RG-PdnDs) have been thoroughly characterized by high resolution transmission electron microscopy, X-ray photoelectron spectroscopy, atomic force microscopy, Raman spectroscopy and electrochemical techniques. The mechanism of formation of such dendrite-shaped Pd nanostructures on the graphene support has been elucidated using TEM measurements. The RG induces the formation of, and plays a decisive role in shaping, the dendrite morphology of Pd nanostructures on its surface. Cyclic voltammetry and chronoamperometry techniques have been employed to evaluate the electrochemical performance of RG-PdnDs towards oxidation of methanol. The electrochemical (EC) activities of RG-PdnDs are compared with graphene-supported spherical-shaped Pd nanostructures, Pd nanodendrites alone and a commercial available Pd/C counterpart. The combined effect of the graphene support and the dendrite morphology of RG-PdnDs triggers the high electrocatalytic activity and results in robust tolerance to CO poisoning.

Sandwiched graphene with nitrogen, sulphur co-doped CQDs: an efficient metal-free material for energy storage and conversion applications

Here, a hybrid material composed of sandwiched reduced graphene oxide (rGO) and N,S co-doped carbon quantum dots (N,S-CQDs) was prepared following a facile synthetic route. This metal-free composite has demonstrated their dual performance as an electrode material for supercapacitors and fuel cell catalysts. It shows robust cyclic stability with high energy and power density without any binders. The enhanced activity of the composite can be ascribed to the CQDs present within the interlayer of the rGO which enhance the accessibility of the charged ions and increase the capacitance of the composite. In addition, the electrocatalytic activity of the composite has been assessed as a metal-free cathode catalyst towards the oxygen reduction reaction (ORR) for fuel cell applications. It shows better performance in terms of high reduction potential and high reduction current as compared to rGO. This can be ascribed to the significant contribution of electron rich heteroatom doped CQDs as well as the synergistic effect of both the CQDs and rGO for the electrocatalytic reduction of oxygen. The interesting dual performance of heteroatom doped CQDs and graphene hybrid composites hold potential for the development of energy storage and conversion devices.

A facile approach for morphosynthesis of Pd nanoelectrocatalysts

A facile approach has been developed for synthesis of highly-structured, anisotropic Pd nanostructures. The dendritic Pd nanostructures show superior performance toward oxidation of formic acid and methanol for fuel cell application.

A Bioinspired Approach for Shaping Au Nanostructures: The Role of Biomolecule Structures in Shape Evolution

A new approach for shaping Au nanostructures by tuning the molecular structure of biomolecules has been explored. Different molecules, such as catechol, rutin, and quercetin, which have structural similarity to the catechol ring, were used to induce Au nanostructures under similar conditions. The as-synthesized nanostructures are characterized by using TEM, XPS, XRD, and UV/Vis spectral measurements. The growth mechanism for the formation of these noble metal shapes and the role of the molecular structure of the stabilizing/reducing agent were investigated by using TEM and UV/Vis spectral measurements. The structure and functional groups of the reducing/stabilizing agent play a vital role in the shape evolution of nanostructures. The electrocatalytic activity of different nanostructures in the reduction of oxygen was investigated and was found to be shape-dependent.

Photoelectrocatalytic oxidation of NADH by visible light driven plasmonic nanocomposites

Here, we report the efficient photoelectrocatalytic oxidation of NADH by plasmonic nanocomposites driven by visible light. The reduction in the recombination of photogenerated holes and electrons expedite the electrocatalytic oxidation process, which substantially decreases the overpotential and increases the oxidation current.

A Bifunctional Nano‐Electrocatalyst Based on a Flower‐Like Gold/Palladium Bimetallic Alloy Nanostructure and Its Graphene Hybrid

This work demonstrates the one‐pot, seed‐free synthesis of unique flower‐like Au/Pd alloy nanostructures and their self‐assembly on a graphene support in an aqueous medium. The as‐prepared nanostructures were characterized thoroughly by TEM, UV/Vis spectrophotometry, XRD, and X‐ray photoelectron spectroscopy (XPS). The bifunctional electrocatalytic activity towards the oxidation of methanol and reduction of oxygen was investigated thoroughly. The results reveal that the Au/Pd alloy nanostructures show a composition‐dependent electrochemical activity. The Au/Pd alloy nanostructure with a flower‐like morphology shows superior electrocatalytic activity compared to its monometallic Pd counterpart and a commercially available Pd/C. Furthermore, the graphene support tunes the electrocatalytic performance of the Au/Pd alloy nanoflowers and substantiates their promising energy‐conversion applications for use in fuel cells.

Highly porous Pd nanostructures and reduced graphene hybrids: excellent electrocatalytic activity towards hydrogen peroxide

A facile approach has been developed for the synthesis of highly porous Pd nanostructures (PPd NSs) and their graphene hybrid (RG-PPd NSs). The PPd NSs are well-dispersed on the graphene support and retain their unique morphology. The RG-PPd NS modified electrode shows high sensitivity towards H2O2 without the usage of a redox mediator/enzyme.

Flower Shaped Silver Nanostructures: An Efficient Bacteria Exterminator

Materials in nanoscale range have dominated several areas of engineering science and technology. In the area of biotechnology nano materials have been used increasingly in biomedical analysis, fabrication of biosensors/biointerface, clinical diagnosis and therapy, drug delivery and so on (Cao, 2008; Mirkin et al., 1996; Alivasatos, 2004; Jena and Raj, 2006, 2011; Xiao et al., 2003; Sengupta et al., 2005; Wu et al., 2003; Brigger et al.,2002; Cui et al., 2001; Gao et al., 2004; Rosi and Mirkin, 2005). Particular interest has been focused on nanostructured noble metal particles for biotechnology application because of their biocompatibility, lower toxicity and higher affinity with wide range of biomolecules (Hazarika et al., 2004; Bae et al., 2005). Therefore, different processes have been adopted for tuning the surfaces of metal nanoparticles to explore the selective binding and monitoring of specific targets in biological sensing (Wang, 2005; Wang et al., 2006; Kneipp et al., 2006). Nanoparticles attached to biomolecules act as an artificial receptor and control the cellular processes for various biological applications such as inhibition of enzymatic activity, transcription regulations, etc (De et al., 2008).