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Marappan Sathish

Bio: Marappan Sathish is an academic researcher from Council of Scientific and Industrial Research. The author has contributed to research in topics: Supercapacitor & Graphene. The author has an hindex of 37, co-authored 144 publications receiving 5394 citations. Previous affiliations of Marappan Sathish include Indian Institute of Technology Madras & Academy of Scientific and Innovative Research.


Papers
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TL;DR: In this paper, a nitrogen-doped TiO2 (N−TiO2) nanocatalyst with spherical shape and homogeneous size has been synthesized through a chemical method using TiCl3 as precursor.
Abstract: Nitrogen-doped TiO2 (N−TiO2) nanocatalyst with spherical shape and homogeneous size has been synthesized through a chemical method using TiCl3 as precursor. The light absorption onset shifts from 380 nm on pure TiO2 to the visible region at 550 nm with N−TiO2. A clear decrease in the band gap and the nitrogen 2p states on the top of the valence band on N−TiO2 (compared to TiO2) is deduced from the optical absorption spectroscopy results. The chemical nature of N has been evolved as N−Ti−O in the anatase TiO2 lattice as identified by X-ray photoelectron spectroscopy (XPS). Photocatalytic decomposition of methylene blue has been carried out both in the UV and in the visible region and N−TiO2 shows higher activity than the Degussa P25 TiO2 photocatalyst in the visible region.

881 citations

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TL;DR: In this paper, a symmetric supercapacitor with high specific capacitance and high energy density of 7.8 Wh kg-1 was fabricated by a two-step synthesis via carbonization followed by KOH activation of rice straw at 600 °C in an argon atmosphere.
Abstract: Biomass-derived activated carbon materials were prepared by a two-step synthesis via carbonization followed by KOH activation of rice straw at 600 °C in an argon atmosphere. The formation of disordered micro- and mesopores on carbon by KOH chemical activation and the high specific surface area of ∼1007 m2 g–1 were confirmed by N2 adsorption–desorption. Further, the scanning electron microscopic analysis revealed the formation of disordered pores over the carbon surface, and the transmission electron microscopic analysis confirmed the formation and aggregation of ultrafine carbon nanoparticles of ∼5 nm in size after the carbonization and activation processes. The three-electrode cell in aqueous electrolyte shows high specific capacitance of 332 F g–1, with high specific capacitance retention of 99% after 5000 cycles. The fabricated symmetric supercapacitor device in aqueous 1 M H2SO4 electrolyte showed a high specific capacitance of 156 F g–1, with a high energy density of 7.8 Wh kg–1. The symmetric device...

277 citations

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TL;DR: In this paper, Cadmium sulphide nanoparticles (6-12nm) are prepared by a precipitation process using different zeolite matrices as templates and characterized by UV-Vis, XRD, SEM, TEM and sorptometric techniques.

268 citations

Journal ArticleDOI
TL;DR: The present study reveals the ability of graphene as a low cost cocatalyst instead of expensive noble metals (Pt, Pd), and further shows its capability for the application of self-cleaning coatings with transparency.
Abstract: We develop a simple approach to fabricate graphene-loaded TiO2 thin films on glass substrates by the spin-coating technique. Our graphene-loaded TiO2 films were highly conductive and transparent and showed enhanced photocatalytic activities. More significantly, graphene/TiO2 films displayed superhydrophilicity within a short time even under a white fluorescent light bulb, as compared to a pure TiO2 film. The enhanced photocatalytic activity of graphene/TiO2 films is attributed to its efficient charge separation, owing to electrons injection from the conduction band of TiO2 to graphene. The electroconductivity of the graphene-loaded TiO2 thin film also contributes to the self-cleaning function by its antifouling effect against particulate contaminants. The present study reveals the ability of graphene as a low cost cocatalyst instead of expensive noble metals (Pt, Pd), and further shows its capability for the application of self-cleaning coatings with transparency. The promising characteristics of (inexpen...

211 citations

Journal ArticleDOI
TL;DR: In this article, the synthesis of Cu2S particles as the core wrapped-up with thin layer of TiO2-shell for improved surface and interface control of photo-excitons for H2 production.
Abstract: This study focuses on the synthesis of Cu2S particles as the core wrapped-up with thin layer of TiO2-shell for improved surface and interface control of photo-excitons for H2 production. Chemical states of metal Cu+, Ti4+ ions were confirmed by X-ray Photo-electron and Electron Paramagnetic Resonance (g-factor of 2.03) Spectroscopy. Transmission Electron Microscopic images revealed the hexagonal shape of Cu2S wrapped-up with TiO2 having the shell thickness varying from 12.0 to 16.7 nm. Time resolved transient photoluminescence decay spectra confirmed that three folds prolonged life-time of excitons generated on Cu2S@TiO2 core-shell than pristine Cu2S. The batch photo-ractor used to evaluate the performance of photocatalysts in an aqueous solution containing Na2S/Na2SO4 promoted oxidation reaction for H+ generation. The control over shell thickness directly influenced the optical and surface-interface properties, resulting in the enhanced H2 production of 41.6 mmol h−1 g−1 of catalyst for an optimized catalyst with UV–vis light to H2 production efficiency of 10.3%. The same catalyst also exhibited excellent stability for un-interrupted H2 production upto 30 h, along with good results on recyclability and reusable efficiency. Scale-up operation performed to recover H2 from sulphide wastewater in tank photo-reactor triggered H2 gas 16.1 mmol h−1 g−1 of catalyst.

197 citations


Cited by
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TL;DR: Approaches to Modifying the Electronic Band Structure for Visible-Light Harvesting and its Applications d0 Metal Oxide Photocatalysts 6518 4.4.1.
Abstract: 2.3. Evaluation of Photocatalytic Water Splitting 6507 2.3.1. Photocatalytic Activity 6507 2.3.2. Photocatalytic Stability 6507 3. UV-Active Photocatalysts for Water Splitting 6507 3.1. d0 Metal Oxide Photocatalyts 6507 3.1.1. Ti-, Zr-Based Oxides 6507 3.1.2. Nb-, Ta-Based Oxides 6514 3.1.3. W-, Mo-Based Oxides 6517 3.1.4. Other d0 Metal Oxides 6518 3.2. d10 Metal Oxide Photocatalyts 6518 3.3. f0 Metal Oxide Photocatalysts 6518 3.4. Nonoxide Photocatalysts 6518 4. Approaches to Modifying the Electronic Band Structure for Visible-Light Harvesting 6519

6,332 citations

01 Nov 2000
TL;DR: In this paper, the authors compared the power density characteristics of ultracapacitors and batteries with respect to the same charge/discharge efficiency, and showed that the battery can achieve energy densities of 10 Wh/kg or higher with a power density of 1.2 kW/kg.
Abstract: The science and technology of ultracapacitors are reviewed for a number of electrode materials, including carbon, mixed metal oxides, and conducting polymers. More work has been done using microporous carbons than with the other materials and most of the commercially available devices use carbon electrodes and an organic electrolytes. The energy density of these devices is 3¯5 Wh/kg with a power density of 300¯500 W/kg for high efficiency (90¯95%) charge/discharges. Projections of future developments using carbon indicate that energy densities of 10 Wh/kg or higher are likely with power densities of 1¯2 kW/kg. A key problem in the fabrication of these advanced devices is the bonding of the thin electrodes to a current collector such the contact resistance is less than 0.1 cm2. Special attention is given in the paper to comparing the power density characteristics of ultracapacitors and batteries. The comparisons should be made at the same charge/discharge efficiency.

2,437 citations

Journal ArticleDOI
TL;DR: This review for the first time summarizes all the developed earth-abundant cocatalysts for photocatalytic H2- and O2-production half reactions as well as overall water splitting.
Abstract: Photocatalytic water splitting represents a promising strategy for clean, low-cost, and environmental-friendly production of H2 by utilizing solar energy. There are three crucial steps for the photocatalytic water splitting reaction: solar light harvesting, charge separation and transportation, and the catalytic H2 and O2 evolution reactions. While significant achievement has been made in optimizing the first two steps in the photocatalytic process, much less efforts have been put into improving the efficiency of the third step, which demands the utilization of cocatalysts. To date, cocatalysts based on rare and expensive noble metals are still required for achieving reasonable activity in most semiconductor-based photocatalytic systems, which seriously restricts their large-scale application. Therefore, seeking cheap, earth-abundant and high-performance cocatalysts is indispensable to achieve cost-effective and highly efficient photocatalytic water splitting. This review for the first time summarizes all the developed earth-abundant cocatalysts for photocatalytic H2- and O2-production half reactions as well as overall water splitting. The roles and functional mechanism of the cocatalysts are discussed in detail. Finally, this review is concluded with a summary, and remarks on some challenges and perspectives in this emerging area of research.

1,990 citations