Other affiliations: Massachusetts Institute of Technology, National Chemical Laboratory, PES University ...read more
Bio: Sivaprakasam Radhakrishnan is an academic researcher from Council of Scientific and Industrial Research. The author has contributed to research in topic(s): Polypyrrole & Cyclic voltammetry. The author has an hindex of 36, co-authored 144 publication(s) receiving 4949 citation(s). Previous affiliations of Sivaprakasam Radhakrishnan include Massachusetts Institute of Technology & National Chemical Laboratory.
Abstract: Electrochemical energy storage (EES) devices play an important role in meeting the demand for the electrical energy. Particularly, electrochemical hybrid capacitors (HCs) are considered as one of the potential candidates for fulfilling the energy requirement. In this work, aqueous electrolyte-based high voltage HC is fabricated and its electrochemical characteristics are analyzed. Here, electrochemically prepared NiCo and Bi thin films on stainless steel substrate were used as positive and negative electrodes, respectively. The phase structure and crystalline size of the electrodeposited films are confirmed from XRD and AFM. It is observed that the as prepared NiCo film showed an excellent specific capacitance value of 83.33 mF cm−2 at 0.5 mA cm−2; on the other side, Bi film also showed a good storage capacity of 32.2 μA h cm−2 at 1 mA cm−2; To realize the high energy density, Bi||NiCo combination of the thin film HC is fabricated and the HC devices showed excellent performance at a tested potential window of 1.5 V. The cell plateau voltage is observed at 0.8 V. The maximum specific energy density of 7.3 μW h was achieved at a specific power density is 0.3 mW cm−2. Maximum specific power of 7.5 mW cm−2 at an energy density of 1.875 μW h was obtained from HSC. This indicates the excellent performance of the HC at various conditions. Thus, the binder-free, electrodeposited active electrode materials of the present work will play a significant role in the various electronic applications by supplying the energy demand.
Abstract: A porous sphere of CuO@SiO2 was obtained by simple calcination of the copper silicate (CuSiO3) sphere. The formation of the porous sphere was studied in detail with the support of various physical characterization techniques. The CuO@SiO2 was coated on an electrode surface where it demonstrates high catalytic activity for the electro-oxidation of vanillin in phosphate buffer solution (PBS; pH 7.0). The modified electrode has good surface adsorption (1.861 × 10−10 mol cm−2) and rate constant (2.866 × 105 cm3 mol−1 s−1) characteristics for vanillin detection. The CuO@SiO2-modified surface exhibited good linear range (0.05 μM–1.2 μM and 6.2 to 111.2 μM), detection limit (53 nM), sensitivity (2.88 μA μM−1 cm−2), selectivity, stability, and reproducibility. The CuO@SiO2-modified electrode was further examined for the determination of vanillin in real samples including biscuits and chocolates with satisfactory recoveries.
Abstract: In this work, we prepared network-structured carbon nanofibers using polyacrylonitrile blends (PAN150 and PAN85) with different molecular weights (150,000 and 85,000 g mol-1) as precursors through electrospinning/hot-pressing methods and stabilization/carbonization processes. The obtained PAN150/PAN85 polymer nanofibers (PNFs; PNF-73, PNF-64 and PNF-55) with different weight ratios of 70/30, 60/40 and 50/50 (w/w) provided good mechanical and electrochemical properties due to the formation of physically bonded network structures between the blended PAN nanofibers during the hot-processing/stabilization processes. The resulting carbonized PNFs (cPNFs; cPNF-73, cPNF-64, and cPNF-55) were utilized as anode materials for supercapacitor applications. cPNF-73 exhibited a good specific capacitance of 689 F g-1 at 1 A g-1 in a three-electrode set-up compared to cPNF-64 (588 F g-1 at 1 A g-1) and cPNF-55 (343 F g-1 at 1 A g-1). In addition, an asymmetric hybrid cPNF-73//NiCo2O4 supercapacitor device also showed a good specific capacitance of 428 F g-1 at 1 A g-1 compared to cPNF-64 (400 F g-1 at 1 A g-1) and cPNF-55 (315 F g-1 at 1 A g-1). The cPNF-73-based device showed a good energy density of 1.74 W h kg-1 (0.38 W kg-1) as well as an excellent cyclic stability (83%) even after 2000 continuous charge-discharge cycles at a current density of 2 A g-1.
Abstract: Nickel based materials with nanoscale is great attention in various electrochemical application owing to their good redox characteristics, easy preparation, low cost and less toxic in nature. In the present work, simple and ultra-small size of nickel oxide nanoparticles (NiO NPs) was prepared by simple calcination of nickel and p-Phenylene diammine complex. The synthesized NiO NPs were studied by FE-SEM, XRD, and cyclic voltammetry. The NiO NPs modified glassy carbon electrode (GCE) demonstrated good electro-catalytic performance for glucose oxidation with higher oxidation peak current (ipa :46.9 ± 0.2 µA) when correlated to that of bulk NiO (ipa : 10.3 ± 0.3 µA) and unmodified GCE (ipa: 1.7 ± 0.3 µA) electrodes. Further, the NiO NPs coated electrode surface exhibited good linear range (5 µM–2.49 mM), high sensitivity (0.310 µA µM−1 cm−2), low detection limit (3.5 µM), good response time (
Abstract: Porous CuO nanoparticles were obtained by calcinations of Cu-BTC MOF at different temperature. The formation mechanism of porous CuO nanoparticles from Cu-MOF was systematically investigated by XRD, FE-SEM and cyclic voltammogram. The CuO coated electrode exhibited good catalytic activity for caffeic acid detection. The modified electrode exhibited wide linear range (0.05–229.5 µM), lower detection limit (40 nM), good sensitivity, and reproducibility. The excellent analytical performance of CuO modified electrode has been further extended into the identification of caffeic acid in wine samples of satisfactory recoveries.
Abstract: The difficulty to achieve rapid detection is the limitation of many enzyme-free sensors today. Thus, designing tri-functional sensors with ultra-fast and efficient determination is a challenging task in biological science. Herein, curly fish scales-like Ni2.5Mo6S6.7 active materials was anchored on poly (3,4-ethylenedioxythiophene)-reduced graphene oxide (PEDOT-rGO) hybrid membranes with uneven surface (Ni2.5Mo6S6.7/PEDOT-rGO) as a high-performance tri-functional catalyst for glucose, nitrite and hydrogen peroxide determination. The sensor constructed under optimal conditions exhibited ultrafast response performance towards glucose and nitrite within 2 s, and hydrogen peroxide within 1 s. Meanwhile, it provided the wide linear range with a low detection limit towards glucose (as low as 0.001 mM and up to 15.000 mM, and 0.33 μM), nitrite (as low as 0.001 mM and up to 10.000 mM, and 0.33 µM) and hydrogen peroxide (from 0.010 mM to 7.000 mM, and 0.79 μM), respectively. In addition, the sensor demonstrated satisfied selectivity, repeatability, reproducibility and stability. Furthermore, the sensor has potential application in real samples. This study may provide a new strategy for the construction of tri-functional electrode materials with the ultra-fast response.
Abstract: A defects-enriched CoMoO4/carbon dot (CD) with CoMoO4around 37 nm is achieved via hydrothermal reaction by introducing CDs to buffer large volume changes of CoMoO4during lithiation-delithiation and enhance rate performance. The phase, morphology, microstructure, as well as the interface of the CoMoO4/CD composites were investigated by x-ray diffraction, scanning electron microscopy, transmission electron microscopy and x-ray photoelectron spectroscopy. When employed as Li-ion battery anode, the CoMoO4/CD exhibits a reversible capacity of ∼531 mAh g-1after 400 cycles at a current density of 2.0 A g-1. Under the scan rate at 2 mV s-1, the CoMoO4/CD shows accounts for 81.1% pseudocapacitance. It may attribute to the CoMoO4with surface defects given more reaction sites to facilitate electrons and lithium ions transfer at high current densities. Through galvanostatic intermittent titration technique, the average lithium ion diffusion coefficient calculated is an order of magnitude larger than that of bulk CoMoO4, indicating that the CoMoO4/CD possesses promising electrons and lithium ions transportation performance as anode material.
Abstract: We successfully designed and prepared hierarchical Ni3S2nanorod@nanosheet arrays on three-dimensional Ni foam via facile hydrothermal sulfuration. We conducted a series of time- and temperature-dependent experiments to determine the Ostwald ripening process of hierarchical Ni3S2nanorod@nanosheet arrays. The rationally hierarchical architecture creates an excellent supercapacitor electrode for Ni3S2nanorod@nanosheet arrays. The areal capacitance of this array reaches 5.5 F cm-2at 2 mA cm-2, which is much higher than that of Ni3S2nanosheet arrays (1.5 F cm-2). The corresponding asymmetric supercapacitor exhibits a wide potential window of 1.6 V and energy density up to 1.0 Wh cm-2when the proposed array is utilized as the positive electrode with activated carbon as the negative electrode. This electrochemical performance enhancement is attributable to the hierarchical structure and synergistic cooperation of macroporous Ni foam and well-aligned Ni3S2nanorod@nanosheet arrays. Our results represent a promising approach to the preparation of hierarchical nanorod@nanosheet arrays as high-performing electrochemical capacitors.
Abstract: Electrolysis of water is an environmentally friendly and promising hydrogen generation technology, which is one of the best ways to deal with the global energy crisis and environmental pollution. However, the slow anode reaction of water electrolysis is the bottleneck of limiting the efficient hydrogen production. Therefore, it is a key problem to explore an efficient and economical electrocatalyst to assist the anode reaction. Herein, a series of self-supporting M-NiCo2S4 /Ni3S2 (M=Mn, Fe, Cu, Zn) nanostructures grown on a nickel foam (NF) skeleton were prepared through one-step hydrothermal strategy. In this process, doping engineering is employed to adjust the electronic structure of catalyst and improve the performance of the catalyst. Among them, the introduction of Fe not only greatly changed the morphology, but also provided rich active sites. Specifically, the Fe-NiCo2S4/Ni3S2 electrode can achieve current densities of 50 and 100 mA cm−2 at overpotential of 159 and 210 mV in alkaline media for oxygen evolution reaction (OER). In addition, driving current densities of 50 and 100 mA cm−2 in 1.0 M KOH with 0.5 M urea only requires the ultra-small voltage of 1.37 and 1.39 V (vs. RHE) for urea oxidation reaction (UOR), indicating that UOR can well replace OER to reduce electrical energy consumption. The experimental results and density functional theory calculations (DFT) demonstrate that the superior activity of the catalyst can be attributed to the optimal water adsorption energy, faster electron transfer rate, more active site exposure and good electrical conductivity. This work extends the application of doping engineering in water electrolysis and provides a novel preparation method of efficient catalyst for OER and UOR.
Abstract: Durable and cost-effective electrode materials are essential for practical application of supercapacitors. Herein, large area NiCo2O4/reduced graphene oxide (NiCo2O4/rGO) composites with hierarchical structure were fabricated by a facile one-step ultrasonic spray on Ni foam and directly used as the binder-free electrodes for supercapacitors in aqueous KOH electrolyte. Owing to high electrical conductivity of rGO, hierarchical and layered structure of the electrode, as well as tight adhesion of active materials on the current collector, the as-obtained hybrid electrodes show a high specific capacitance of 871 F g−1 at current density of 1 A g−1, good rate performance and remarkable cycling stability with a capacitance retention of 134% after 30000 cycles. Besides, the assembled NiCo2O4/rGO//AC asymmetric supercapacitor (ASC) displays the maximum energy density of 29.3 Wh kg−1 at a power density of 790.8 W kg−1. Significantly, an ultralong cycling life of 102% capacitance retention is achieved for the ASC device after 30,000 charge/discharge cycles at 20 A g−1. The scalable fabrication route and excellent electrochemical performance of the NiCo2O4/rGO composites open the door for making novel hybrid electrodes of advanced supercapacitors.
Author's H-index: 36