paulraj gnanasekar - Academia.edu (original) (raw)

Papers by paulraj gnanasekar

Research paper thumbnail of Sensitive and label-free shell isolated Ag NPs@Si architecture based SERS active substrate: FDTD analysis and in-situ cellular DNA detection

Applied Surface Science, 2020

Abstract In recent years there has been increasing interest to elicit the molecular dynamics at t... more Abstract In recent years there has been increasing interest to elicit the molecular dynamics at the single-cell level. In this purview, we report the fabrication of SiO2 capped silver nanoparticles (Ag NPs) on silicon (Si) substrate to understand and divulge the fingerprint of cellular DNA by a label-free method. For the in-situ label free identification thin layer of SiO2 deposited on Ag NPs@Si by e-beam evaporation method which forbids the surface degradation of NPs in culture medium. The hot spots generation in the metal-dielectric nano junction assembly from aggregates of identical and non-identical Ag NPs have been evaluated by Finite-Difference Time-Domain simulation method. The coverage of non-identical Ag NPs with a various layer thickness of SiO2 is shown to be the greatest hotspot rather than an identical particle, and appropriate non-identical NPs are validated with experimental evidence at different excitation wavelengths. The SERS efficiency of analyte molecule Rhodamine 6G is evaluated and the enhancement factor of 107 with the low detection limit up to 10−10 M concentration is achieved. The SiO2-Ag NPs@Si substrate could be an ideal platform for the detection of DNA at cellular level.

Research paper thumbnail of Sustained Solar-Powered Electrocatalytic H2 Production by Seawater Splitting Using Two-Dimensional Vanadium Disulfide

Research paper thumbnail of Two‐Dimensional Materials for Renewable Energy Devices

digital Encyclopedia of Applied Physics, 2021

Research paper thumbnail of InGaN-based nanowires development for energy harvesting and conversion applications

Journal of Applied Physics, 2021

Research paper thumbnail of Highly efficient and stable photoelectrochemical hydrogen evolution with 2D-NbS2 /Si nanowire heterojunction

ACS Applied Materials & Interfaces, 2019

Research paper thumbnail of Vertically aligned MoS2 nanosheets on graphene for highly-stable electrocatalytic hydrogen evolution reaction

Nanoscale, 2019

Efficient hydrogen evolution reaction (HER) using two-dimensional layered materials as electrocat... more Efficient hydrogen evolution reaction (HER) using two-dimensional layered materials as electrocatalyst with high-permormance remains a challenging task due to the insufficient edge active sites. In this regard, herein, molybdenum disulphide...

Research paper thumbnail of Promoter-free synthesis of monolayer MoS2 by chemical vapour deposition

CrystEngComm, 2018

Piranha treatment provides an ideal platform for the controlled growth of large-scale monolayer M... more Piranha treatment provides an ideal platform for the controlled growth of large-scale monolayer MoS2 on dielectric and semiconductor substrates for device applications.

Research paper thumbnail of High performance, self-powered photodetectors based on a graphene/silicon Schottky junction diode

Journal of Materials Chemistry C, 2018

In this work, we design and demonstrate a graphene/silicon (Gr/Si) van der Walls (vdW) heterostru... more In this work, we design and demonstrate a graphene/silicon (Gr/Si) van der Walls (vdW) heterostructure for high-performance photodetectors, where graphene acts as an efficient carrier collector and Si as a photon absorption layer. The Gr/Si heterojunction exhibits superior Schottky diode characteristics with a barrier height of 0.76 eV and performs well as a self-powered detector responding to 532 nm at zero bias.

Research paper thumbnail of Hierarchical NbS2/MoS2Carbon Nanofiber Electrode for Highly Efficient and Stable Hydrogen Evolution Reaction at All Ranges of pH

There is an urgent need to develop efficient and nonprecious electrode materials for practical el... more There is an urgent need to develop efficient and nonprecious electrode materials for practical electrocatalyst hydrogen evolution reaction (HER) application to restrain the depletion of fossil fuels. In the present work, we report an efficient and cost-effective electrode with high stability for binder-free water electrolysis under all ranges of pH from 0 to 14. Herein, a two-dimensional (2D) heterostructure of NbS2/MoS2 ultrathin vertical nanosheets was grown on carbon nanofiber with a high aspect ratio by the one-step chemical vapor deposition approach. The resultant hybrid catalyst demonstrates superlative HER performance with a small onset potential (41 mV @ ∼ 0 pH, 22 mV @ ∼ 7 pH and 32 mV @ ∼ 14 pH) and a very low overpotential (0.23 V @ ∼ 0 pH, 0.21 V @ ∼ 7 pH and 0.33 V @ ∼ 14 pH to reach 50 mA/cm2) vs reversible hydrogen electrode (RHE). Besides, the fabricated NbS2/MoS2-CNF displays excellent chronoamperometry stability for more than 50 h in all pH ranges. The proposed heterostructure holds the vital prerequisites for being a significant electrode material owing to multiple HER active edge and planar sulfur sites, excellent barrier-free charge transfer ability toward the electrolyte, and impressive endurance. Overall, the 2D/one-dimensional (1D) hybrid heterostructure appeared to be a precious-metal-free flexible electrode for excellent HER performance under wide ranges of pH for water splitting applications.

Research paper thumbnail of Sensitive and label-free shell isolated Ag NPs@Si architecture based SERS active substrate: FDTD analysis and in-situ cellular DNA detection

Applied Surface Science, 2020

Abstract In recent years there has been increasing interest to elicit the molecular dynamics at t... more Abstract In recent years there has been increasing interest to elicit the molecular dynamics at the single-cell level. In this purview, we report the fabrication of SiO2 capped silver nanoparticles (Ag NPs) on silicon (Si) substrate to understand and divulge the fingerprint of cellular DNA by a label-free method. For the in-situ label free identification thin layer of SiO2 deposited on Ag NPs@Si by e-beam evaporation method which forbids the surface degradation of NPs in culture medium. The hot spots generation in the metal-dielectric nano junction assembly from aggregates of identical and non-identical Ag NPs have been evaluated by Finite-Difference Time-Domain simulation method. The coverage of non-identical Ag NPs with a various layer thickness of SiO2 is shown to be the greatest hotspot rather than an identical particle, and appropriate non-identical NPs are validated with experimental evidence at different excitation wavelengths. The SERS efficiency of analyte molecule Rhodamine 6G is evaluated and the enhancement factor of 107 with the low detection limit up to 10−10 M concentration is achieved. The SiO2-Ag NPs@Si substrate could be an ideal platform for the detection of DNA at cellular level.

Research paper thumbnail of Sustained Solar-Powered Electrocatalytic H2 Production by Seawater Splitting Using Two-Dimensional Vanadium Disulfide

Research paper thumbnail of Two‐Dimensional Materials for Renewable Energy Devices

digital Encyclopedia of Applied Physics, 2021

Research paper thumbnail of InGaN-based nanowires development for energy harvesting and conversion applications

Journal of Applied Physics, 2021

Research paper thumbnail of Highly efficient and stable photoelectrochemical hydrogen evolution with 2D-NbS2 /Si nanowire heterojunction

ACS Applied Materials & Interfaces, 2019

Research paper thumbnail of Vertically aligned MoS2 nanosheets on graphene for highly-stable electrocatalytic hydrogen evolution reaction

Nanoscale, 2019

Efficient hydrogen evolution reaction (HER) using two-dimensional layered materials as electrocat... more Efficient hydrogen evolution reaction (HER) using two-dimensional layered materials as electrocatalyst with high-permormance remains a challenging task due to the insufficient edge active sites. In this regard, herein, molybdenum disulphide...

Research paper thumbnail of Promoter-free synthesis of monolayer MoS2 by chemical vapour deposition

CrystEngComm, 2018

Piranha treatment provides an ideal platform for the controlled growth of large-scale monolayer M... more Piranha treatment provides an ideal platform for the controlled growth of large-scale monolayer MoS2 on dielectric and semiconductor substrates for device applications.

Research paper thumbnail of High performance, self-powered photodetectors based on a graphene/silicon Schottky junction diode

Journal of Materials Chemistry C, 2018

In this work, we design and demonstrate a graphene/silicon (Gr/Si) van der Walls (vdW) heterostru... more In this work, we design and demonstrate a graphene/silicon (Gr/Si) van der Walls (vdW) heterostructure for high-performance photodetectors, where graphene acts as an efficient carrier collector and Si as a photon absorption layer. The Gr/Si heterojunction exhibits superior Schottky diode characteristics with a barrier height of 0.76 eV and performs well as a self-powered detector responding to 532 nm at zero bias.

Research paper thumbnail of Hierarchical NbS2/MoS2Carbon Nanofiber Electrode for Highly Efficient and Stable Hydrogen Evolution Reaction at All Ranges of pH

There is an urgent need to develop efficient and nonprecious electrode materials for practical el... more There is an urgent need to develop efficient and nonprecious electrode materials for practical electrocatalyst hydrogen evolution reaction (HER) application to restrain the depletion of fossil fuels. In the present work, we report an efficient and cost-effective electrode with high stability for binder-free water electrolysis under all ranges of pH from 0 to 14. Herein, a two-dimensional (2D) heterostructure of NbS2/MoS2 ultrathin vertical nanosheets was grown on carbon nanofiber with a high aspect ratio by the one-step chemical vapor deposition approach. The resultant hybrid catalyst demonstrates superlative HER performance with a small onset potential (41 mV @ ∼ 0 pH, 22 mV @ ∼ 7 pH and 32 mV @ ∼ 14 pH) and a very low overpotential (0.23 V @ ∼ 0 pH, 0.21 V @ ∼ 7 pH and 0.33 V @ ∼ 14 pH to reach 50 mA/cm2) vs reversible hydrogen electrode (RHE). Besides, the fabricated NbS2/MoS2-CNF displays excellent chronoamperometry stability for more than 50 h in all pH ranges. The proposed heterostructure holds the vital prerequisites for being a significant electrode material owing to multiple HER active edge and planar sulfur sites, excellent barrier-free charge transfer ability toward the electrolyte, and impressive endurance. Overall, the 2D/one-dimensional (1D) hybrid heterostructure appeared to be a precious-metal-free flexible electrode for excellent HER performance under wide ranges of pH for water splitting applications.