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A Class of Normaloid Weighted Composition Operators on the Fock Space over ℂ
Santhoshkumar, Chandrasekaran,Veluchamy, Thirumalaisamy Department of Mathematics 2021 Kyungpook mathematical journal Vol.61 No.4
Let 𝜙 be an entire self map on ℂ and let 𝜓 be an entire function on ℂ. A weighted composition operator induced by 𝜙 with weight 𝜓 is given by C<sub>𝜓,𝜙</sub>. In this paper we investigate under what conditions the weighted composition operators C<sub>𝜓,𝜙</sub> on the Fock space over ℂ induced by 𝜙 with weight of the form $k_c({\zeta})=e^{{\langle}{\zeta},c{\rangle}-{\frac{{\mid}c{\mid}^2}{2}}}$ is normaloid and essentially normaloid.
Santhoshkumar, P.,Prasanna, K.,Jo, Yong Nam,Sivagami, I. Nirmal,Kang, Suk Hyun,Lee, Chang Woo The Royal Society of Chemistry 2017 Journal of Materials Chemistry A Vol.5 No.32
<▼1><P>In the present work, we have synthesized zero-dimensional (0D) and three-dimensional (3D) iron oxide (α-Fe2O3) sub-micron particles using a one-pot hydrothermal approach.</P></▼1><▼2><P>In the present work, we have synthesized zero-dimensional (0D) and three-dimensional (3D) iron oxide (α-Fe2O3) sub-micron particles using a one-pot hydrothermal approach. Morphological studies reveal that the as-synthesized spherical α-Fe2O3 (SFO) material consists of nanospheres with void spaces. The prepared SFO delivers a high specific surface area of 100.80 m<SUP>2</SUP> g<SUP>−1</SUP> and significantly increases the contact area between the electrode and the electrolyte. The initial galvanostatic specific capacity of the SFO materials was 1306 mA h g<SUP>−1</SUP> at a current density of 100 mA g<SUP>−1</SUP>, which is superior to that of bare cubic α-Fe2O3 (CFO). Moreover, the mesoporous SFO shows a good cycling stability with a capacity retention rate of 91.4% after 100 cycles. These attractive results suggest that the mesoporous SFO shows a good electrochemical performance as a negative electrode material for high-performance Li-ion batteries.</P></▼2>
P. Santhoshkumar,T. Subburaj,K. Karuppasamy,A. Kathalingam,Dhanasekaran Vikraman,박현창,김현석 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.104 No.-
Herein, a red iron oxide @ carbon fiber (RIO@CF) composite is prepared via a simple and effective singlehydrothermal and calcination process. The physico-chemical characteristics of as-prepared electrodeactive materials are examined by X-ray photoelectron spectroscopy, high resolution field emissionscanningelectron microscopy and field emission-tunneling electron microscopy analyses. When usedas the anode material in the Li-ion battery, as-prepared RIO@CF composite have shown a specific capacityof 1138 mAh g 1 after 150 cycles with a capacity retention of 86% at a current density of 100 mA g 1. Moreover, a specific capacity of 825 mAh g 1 is achieved in the first cycle at a current density of about5000 mA g 1. Thus, when compared to the pristine nano-cube-like red iron oxide (RIO) electrode material,the RIO@CF composite electrode exhibits an outstanding cyclic stability and rate capacity. This electrochemicalenhancement facilitates effective lithium ion transport into the RIO@CF composite electrode,thus improving the electrical conductivity. In addition, the application of a homogeneous carbon fibercoating can provide effective contact between the electrode surface and the electrolyte to further benefitthe electrochemical performance.
( Ramasamy Santhoshkumar ),유동진 한국공업화학회 2020 한국공업화학회 연구논문 초록집 Vol.2020 No.-
Building combined materials with a smart nanostructure, by using various transition metal sulfide, metal selenides and oxides carriers as building blocks, economical noble metal-free catalysts for oxygen evolution reaction (OER). We have synthesized a novel ternary composed of Co<sub>3</sub>Se<sub>4</sub>, NiMn<sub>2</sub>S<sub>4</sub>@rGO, via a facile and well-controlled solvo-thermal approach to synthesize Co<sub>3</sub>Se<sub>4</sub>/NiMn<sub>2</sub>S<sub>4</sub>@rGO with super lattice structure and hollow multi-porous architecture. The results revealed that Co<sub>3</sub>Se<sub>4</sub> nanostructure had been successfully epitaxial deposited onto the surface of NiMn<sub>2</sub>S<sub>4</sub>@rGO to form Co<sub>3</sub>Se<sub>4</sub> on NiMn<sub>2</sub>S<sub>4</sub> nanostructures on surface of the rGO. In an alkaline environment, the Co<sub>3</sub>Se<sub>4</sub>/NiMn<sub>2</sub>S<sub>4</sub>@rGO composite exhibits much better electro catalytic activity and durability towards OER than individual Co<sub>3</sub>Se<sub>4</sub>/rGO and NiMn<sub>2</sub>S<sub>4</sub>@rGO catalysts, which facilitate the OER kinetics.
Shaji, Nitheesha,Santhoshkumar, P.,Nanthagopal, Murugan,Senthil, Chenrayan,Lee, Chang Woo Elsevier 2019 APPLIED SURFACE SCIENCE - Vol.491 No.-
<P><B>Abstract</B></P> <P>The performance of existing lithium-ion batteries (LIBs) is greatly hindered by the low specific capacity of graphite-based anodes (372 mAh g<SUP>−1</SUP>). Therefore, development of suitable anode materials that exhibit higher and stable capacity is necessary to improve performance. Transition metal oxides have attracted tremendous attention as next-generation anode materials for LIBs due to their high theoretical capacity. Herein, we report the synthesis of a porous CaFe<SUB>2</SUB>O<SUB>4</SUB> by a facile and time efficient solution combustion synthesis technique for use in an anode for LIBs. The as-prepared material exhibited improved electrochemical performance with specific discharge capacities of 441 mAh g<SUP>−1</SUP>, 518 mAh g<SUP>−1</SUP>, and 516 mAh g<SUP>−1</SUP> for the initial three cycles. It achieved stability with a deliverable specific discharge capacity of 551 mAh g<SUP>−1</SUP> after 150 cycles at a current density of 200 mA g<SUP>−1</SUP>. The porous CaFe<SUB>2</SUB>O<SUB>4</SUB> exhibits improved cyclic performance and rate capability. These improvements are attributed to the porous nature of active material and, more importantly, the presence of CaO, which effectively alleviates the volume changes by acting as a buffer matrix.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Porous CaFe<SUB>2</SUB>O<SUB>4</SUB> has been synthesized by a facile solution combustion synthesis technique. </LI> <LI> Mixed-metal oxides possessing electrochemically active-inactive constituents are reported. </LI> <LI> The porous CaFe<SUB>2</SUB>O<SUB>4</SUB> as an anode for LIBs exhibited improved electrochemical performances. </LI> <LI> The porous structure and the buffer matrices of CaO are owed for their improved activity. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
조용남,P. Santhoshkumar,K. Prasanna,Kumaran Vediappan,이창우 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.76 No.-
The corrosion and hydrogen evolution reactions of Zn anodes accelerate the self-discharge of a Zn-airbattery. To suppress the corrosion reaction and improve the self-discharge behavior of a Zn-air battery,polyaniline (PANI) is synthesized with different amounts of 0.1 M sulfuric acid and coated on a Zn surface. The PANI-coated materials effectively suppress the corrosion reaction, and the Zn-air cells prepared withPANI-coated Zn materials exhibit enhanced self-discharge behavior. The specific discharge capacity after24 h storage and capacity retention of Zn were 520.2 mA h/g and 74.4%, respectively. Whereas the PANI-coated Zn (100 ml sulfuric acid) shows 565.3 mA h/g of specific discharge capacity after 24 h storage,75.8% corrosion inhibition efficiency and 96.9% capacity retention. Therefore, PANI-coated Zn materialsare effective in suppressing the corrosion reaction and improving self-discharge behaviors in Zn-airbatteries.
Glass ceramic coating on LiNi0.8Co0.1Mn0.1O2 cathode for Li-ion batteries
강형섭,Palanisamy Santhoshkumar,박재우,심규상,MURUGAN NANTHAGOPAL,이창우 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.8
Alleviating the surface degradation of Ni-rich cathode materials is desirable to achieve better electrochemical performance. Herein, we report the surface coating of lithium diborate (Li2O-2B2O3) over the Ni-rich LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode material and the systematic investigation of its electrochemical properties. The structural and morphological properties were characterized through X-ray diffraction (XRD), high resolution field-emission scanning electron microscopy (HR FE-SEM), and high resolution field-emission transmission electron microscopy (HR FE-TEM). As a cathode material for Li-ion batteries, the 1.0 wt% Li2O-2B2O3 coated NCM811 exhibits better electrochemical properties than the bare NCM811 as well as 0.5 and 2wt% coated electrodes at room and elevated temperatures (60 oC). The improved electrochemical performance of 1.0 wt% Li2O-2B2O3 coated NCM811 might be due to the optimal coating amount that promotes better ion and electron movement along with prevention of surface degradation.
조용남,강석현,( P. Santhoshkumar ),조윤철,( S. K. S Saravana Karthikeyan ),이창우 한국공업화학회 2017 한국공업화학회 연구논문 초록집 Vol.2017 No.1
One of promising advanced batteries is a Zn-air battery due to its high specific energy, low cost, high safety, and environmental friendliness. However, the Zn anodes in Zn-air batteries suffer from dendrite formation, shape change, corrosion, and hydrogen evolution reaction (HER). The dendrite formation and shape change could be improved by mechanical recharging system. However, the corrosion and HER are critical issues for both electrical and mechanical rechargeable Zn-air batteries. In this study, we have tried to modify the Zn anodes by alloy or coating for suppressing corrosion, HER, and self-discharge of the Zn-air batteries.