Faculty Publications

Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736

Publications by NITK Faculty

Browse

Filters

2018 - 20192

Settings

Author: search.filters.author.Kumar, B.S.Subject: search.filters.subject.Electrocatalysts

Search Results

Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    Pyrolysis-controlled synthesis and magnetic properties of sol–gel electrospun nickel cobaltite nanostructures
    (Springer New York LLC barbara.b.bertram@gsk.com, 2018) Kumar, B.S.; Dhanasekhar, C.; Adyam, A.; Kalpathy, S.K.; Anandhan, S.
    Nickel cobaltite (NCO) is a binary transition-metal oxide, which is extensively used as an electrocatalyst and magnetic material. NCO nanofibers and NCO/graphene composite exhibit high electrochemical reactivity due to the directional bridging of NCO particles. This makes NCO a promising candidate electrode material for use in supercapacitors and batteries. Besides, NCO is also a promising magnetic material due to its unique structural composition, where the cations are seated in octahedral sites surrounded by oxygen vacancies. In the present work, a simple and reliable method was discovered for tuning the morphological and structural changes of nickel cobaltite (NCO) nanoparticles, which were reshaped along the NCO nanofibers, by controlling the pyrolysis soaking time. As the pyrolysis soaking time increases, NCO transforms from inverse spinel to normal spinel; and the morphology of NCO nanoparticles changes from spherical to rod-like. These changes were validated by the hypsochromic peak shifts in Raman, and FTIR spectroscopies. The magnetic measurements reveal changes in the shape of the hysteresis loop, which are explained on the basis of structural and morphological changes in the nanostructure. The net magnetisation increases and coercivity decreases, with an increase in pyrolysis soaking time. These changes in magnetic parameters are attributed to structural changes caused by the formation of oxygen vacancies, and surface effects due to switching in morphology of the NCO nanoparticle. [Figure not available: see fulltext.]. © 2018, Springer Science+Business Media, LLC, part of Springer Nature.
  • No Thumbnail Available
    Item
    Graphene nanoclusters embedded nickel cobaltite nanofibers as multifunctional electrocatalyst for glucose sensing and water-splitting applications
    (Elsevier Ltd, 2019) Kumar, B.S.; Gudla, V.C.; Ambat, R.; Kalpathy, S.K.; Anandhan, S.
    Nickel cobaltite (NCO) attains the apex of Sabatier-type volcano plot for electrochemical reaction compared to simple oxides due to synergetic effect of mixed transition metal cations. The combination of high surface area, aspect ratio, and porosity of electrospun NCO nanofibers (NCO-NF) enhance their electrocatalytic performance by improved electron mobility and more active sites. In the present study, NCO-NF fabricated using poly (styrene-co-acrylonitrile) (SAN) as a sacrificial polymer, were embellished with graphene nanoclusters (GNC), which augment the electrocatalytic performance of the NCO-NF. The in situ formed GNC along the NCO-NF are result of the interaction between the polar functional groups of the polymer, and the cations of precursor salts during the calcination of precursor nanofibers. The GNC/NCO-NF with least crystallite size and high aspect ratio having porous NCO nanoparticles and in situ grown GNC were developed using sol-gel electrospinning process assisted by calcination of precursor nanofibers. This simple, eco-friendly, and economical synthesis route with unique structure chemistry of SAN to form GNC and the presence of dual cations (Ni and Co) provides enhanced performance and multifunctionality to GNC/NCO-NF electrodes for electrocatalytic applications, such as biosensors and water-splitting. In the present study, the modified electrodes (GNC/NCO-NF/graphite electrode) exhibited excellent non-enzymatic glucose detection over a wide range of concentration with a lower limit of 1.2 ?M and sensitivity of 1827.5 ?A mM?1 mg?1 in 0.1 M NaOH. Further, the modified electrodes were also tuned for H2O2 detection to aid enzymatic glucose sensing. When examined for bifunctional water-splitting in 1 M NaOH, the electrode reached an onset potential of ?0.537 V and 0.735 V against reversible hydrogen reference electrode and a Tafel slope of 37.6 mV·dec?1 and 67.0 mV·dec?1 for hydrogen and oxygen evolution reactions, respectively. The results prove that GNC/NCO-NF are promising candidates as multifunctional electrocatalyst. © 2019 Elsevier Ltd and Techna Group S.r.l.