Faculty Publications
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Item Single step synthesis of rGO, copper oxide and polyaniline nanocomposites for high energy supercapacitors(Elsevier Ltd, 2018) Viswanathan, A.; Nityananda Shetty, A.N.Reduced graphene oxide, copper oxide and polyaniline (GCP) nanocomposites possessing energy densities close to many of Li-ion batteries are synthesized by facile in-situ single step chemical method by varying the weight percentage of each of the constituent materials. Of all the composites synthesized, the one with weight percentage of G12%: Cu2O/CuO40%: P48% (G12CP) exhibits the maximum specific capacitance of 684.93 F g?1, specific capacity of 821.91 C g?1, energy density of 136.98 W h kg?1, and power density of 1315.76 W kg?1 at the current density of 0.25 A g?1. The composite shows the retention of 84% of its initial capacitance up to 5000 cycles at a scan rate of 700 mV s?1. The electrochemical performance of G12CP is superior to the performances of other ternary composites and those of binary composites synthesized with respective weight ratios as that of G12CP composite. The potential of G12CP to act as a secondary power backup device is successfully demonstrated and the performance obtained is comparable with some of the previously reported similar works, and even superior to some others. © 2018 Elsevier LtdItem Real time magnetic supercapacitor with antiferromagnetic nickel hydroxide based nanocomposite(Elsevier Ltd, 2019) Viswanathan, A.; Nityananda Shetty, A.N.An antiferromagnetic, semiconducting nickel hydroxide (Ni(OH) 2 ), with a good theoretical capacitance is composited with reduced graphene oxide and polyaniline to synthesize the electrode material for energy storage in supercapacitors. The composite overcomes the limitation of low conductivity of nickel hydroxide. The conductivity and antiferromagnetic nature of nickel hydroxide are altered by applying magnetic field, which in turn enhances its energy storing capacity. A ternary composite with the weight percentages of 4%: 48%: 48% of reduced graphene oxide/nickel hydroxide/polyaniline (GN48P), respectively, exhibits a magnetic susceptibility of 850. The application of a magnetic field of 625 ?T results in an enhancement of performance of the composite, exhibiting a specific capacitance of 19.14 F g ?1 , specific capacity of 22.97 C g ?1 , energy density of 0.6649 W h kg ?1 , a power density of 17.57 W kg ?1 at a current density of 0.25 A g ?1 and retention of 85.19% of its original capacitance up to 5000 cycles. This premier study on the effect of magnetic field, on the electrochemical performance of the supercapacitor in a typical two electrode system showed 69.4% increase in its specific capacitance. © 2019 Elsevier LtdItem The high energy supercapacitor from rGO/Ni(OH)2/PANI nanocomposite with methane sulfonic acid as dopant(Academic Press Inc. apjcs@harcourt.com, 2019) Viswanathan, A.; Nityananda Shetty, A.N.The low energy densities of supercapacitors limit their utilization as energy storage and energy conversion devices. To overcome this limitation, here we present a ternary nanocomposite of reduced graphene oxide (rGO)/nickel hydroxide (Ni(OH)2/polyaniline (PANI), with methane sulfonic acid as dopant, having weight percentages of 14%:14%:72% (G14NP), respectively, as an electrode material for supercapacitor. With 1 M sulfuric acid (H2SO4) as the electrolyte, the supercapacitor yields a high energy density of 120.48 W h kg?1, comparable with those of Li-ion batteries. The G14NP also exhibits good electrochemical performance with a specific capacitance of 602.40 F g?1 and a power density of 2584.83 W kg?1, at a current density of 1 A g?1. The G14NP also exhibits a promising stability of its electrochemical performances even after 16,500 cycles at a potential scan of 400 mV s?1. Remarkably, the composite performs exceptionally well at a potential window available in an aqueous electrolyte. The sustainability to high current loading while charging and its power backup application is satisfactorily demonstrated, by charging with a commercial 9 V battery. © 2019 Elsevier Inc.Item Effect of dopants on the energy storage performance of reduced graphene oxide/polyaniline nanocomposite(Elsevier Ltd, 2019) Viswanathan, A.; Nityananda Shetty, A.N.The nanocomposites comprising of reduced graphene oxide (rGO) and polyaniline (PANI) were synthesized by facile insitu single step chemical methods, with glacial acetic acid (AA) and methane sulphonic acid (MSA) as dopants for PANI. The rGO/PANI nanocomposites synthesized with the similar weight percentages of constituents exhibited better electrochemical performance in the presence of MSA than in the presence of AA, in the real two-electrode supercapacitor cell system. The nanocomposite of weight percentages of rGO-6.7%, and PANI-93.33% (GP93MSA), with MSA as dopant exhibited a remarkable feature of increase in energy storage when the number of cycles was increased. It exhibited a maximum enhancement of 237.44% in its energy storage performance, after 13600 cycles as compared to the performance before the onset of cyclic test. The high performances obtained with GP93MSA include high specific capacitance of 512.82 F g?1, specific capacity of 615.38 C g?1, energy density of 102.56 W h kg?1 and a power density of 1.8954 kW kg?1 at 1 A g?1. The energy density of the supercapacitor with GP93MSA as the electrode material, is of the same order as that of Li-ion batteries. Also, GP93MSA showcased good cyclic stability up to 23000 cycles. © 2019 Elsevier LtdItem Quick responsive and durable supercapacitive performance of rGO/Zn(OH)2/PANI nanocomposites(Springer, 2021) Viswanathan, A.; Nityananda Shetty, A.; Bharath, S.P.; Mahendra, K.The quick responsive and durable supercapacitive performance was achieved from reduced graphene oxide/zinc hydroxide/polyaniline (rGO5.88%/Zn(OH)211.77%/PANI82.35%) (GZnP82) nanocomposite, synthesized by in-situ single step. The GZnP82 provided a specific capacitance (Cs) of 173.60 F g?1, a specific capacity (Q) of 208.32 C g?1, a specific energy of 34.7220 W h kg?1 and a specific power of 1516.8 W kg?1 at 0.25 A g?1. The GZnP82 exhibits only 28% decay of its initial Cs up to 12500 cycles at 2 A g?1. The GZnP82 is fast in response with the relaxation time (?) of 1.52 s. The capacitance of GZnP82 device obtained from impedance spectroscopy is 1.29 F. The comparison of electrochemical performance of GZnP82 measured from both chronopotentiometry and impedance spectroscopy, with similar reported energy storage materials, apprises that the achieved performances are of similar order; and better than, the reported materials. Most importantly, the addition of Zn(OH)2 has rendered the negative contribution to the GZnP82, as the binary combination of it, the rGO/PANI furnished higher performances than the GZnP82. © 2021, Indian Academy of Sciences.