Cathodic activation of femtosecond laser textured stainless steel plate for oxygen evolution reaction

Namachivayam Karthik,Seung Tae CHOI(최승태) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.6

Sonochemical fabrication of petal array-like copper/nickel oxide composite foam as a pseudocapacitive material for energy storage

Karthik, Namachivayam,Edison, Thomas Nesakumar Jebakumar Immanuel,Sethuraman, Mathur Gopalakrishnan,Lee, Yong Rok Elsevier BV * North-Holland 2017 Applied Surface Science Vol.396 No.-

<P><B>Abstract</B></P> <P>Copper/nickel oxide composite foam (Cu/Ni) with petal array-like textures were successfully fabricated via a facile sonochemical approach, and its applications as a pseudocapacitive material for energy storage were examined. The nickel foam was immersed into a mixture of copper chloride (CuCl<SUB>2</SUB>) and hydrochloric acid (HCl) and subsequently sonicated for 30min at 60°C. As a result of galvanic replacement, nickel was oxidized while copper was reduced, and the walls of the nickel foam were coated with copper particles. Studies using field emission scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopic analyses confirmed the morphology and chemical structure of the as-obtained Cu/Ni oxide composite foam. The supercapacitive performance of the as-fabricated Cu/Ni oxide composite foam was evaluated in 2M KOH by employing cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy analyses. Cyclic voltammograms revealed that the Cu/Ni oxide composite foam exhibited pseudocapacitive behavior and delivered a high specific capacitance of 1773Fg<SUP>−1</SUP> at a scan rate of 5mVs<SUP>−1</SUP>. This improvement may be attributed to the morphology, surface functionalization with heteroatoms, hydrogen evolution, and high conductivity, along with the low resistance due to short path lengths for electron transportation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A composite Ni foam textured with Cu particles was fabricated by a sonication method. </LI> <LI> The foam can be used as a pseudocapacitive material for energy storage applications. </LI> <LI> The foam has a high specific capacitance of 1773Fg<SUP>−1</SUP> at a scan rate of 5mVs<SUP>−1</SUP>. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Hybrid sol-gel/thiourea binary coating for the mitigation of copper corrosion in neutral medium

Karthik, Namachivayam,Lee, Yong Rok,Sethuraman, Mathur Gopalakrishnan Elsevier 2017 Progress in organic coatings Vol.102 No.2

<P><B>Abstract</B></P> <P>A versatile approach was adopted for mitigation of the corrosion of copper in neutral medium. Initially, a well-known corrosion inhibitor (viz., a thiourea (TU) film) was electrodeposited over the copper surface. Secondly, an environmentally-friendly hybrid sol-gel (Hy) coating consisting of (3-glycidoxypropyl)methyldiethoxysilane (GPTMS) and tetraethyl orthosilicate (TEOS) was immobilized on the thiourea-modified copper surface via an epoxy amine cross-linking reaction to form a binary coating. Thereafter, the individual and combined characteristics of the binary coating were studied via spectroscopic and microscopic analyses. The effectiveness of these binary coatings on mitigation of copper corrosion was scrutinized by electrochemical techniques, viz., electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PP) studies. The results revealed that the binary coating mitigated copper corrosion to a great extent in a complementary and robust manner.</P> <P><B>Highlights</B></P> <P> <UL> <LI> This work explores the formation of thiourea and hybrid sol-gel coatings on copper. </LI> <LI> Thiourea alone protects copper from corrosion only in a limited range. </LI> <LI> Binary coating of hybrid sol-gel and thiourea provide robust copper corrosion mitigation. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Electro-synthesis of sulfur doped nickel cobalt layered double hydroxide for electrocatalytic hydrogen evolution reaction and supercapacitor applications

Karthik, Namachivayam,Edison, Thomas Nesakumar Jebakumar Immanuel,Atchudan, Raji,Xiong, Dangsheng,Lee, Yong Rok Elsevier 2019 Journal of electroanalytical chemistry Vol.833 No.-

<P><B>Abstract</B></P> <P>In this work, sulfur doped nickel cobalt layered double hydroxide nanosheet arrays are fabricated on a stainless steel (S-LDH/SS) substrate by simple electrodeposition technique for electrocatalytic hydrogen evolution reaction (HER) and supercapacitor applications. The surface morphology and chemical composition of S-LDH/SS are accessed by field emission electron microscopy (FE-SEM) with energy dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS), respectively. Remarkably, the fabricated S-LDH/SS electrode requires low overpotential of −0.38V vs. RHE to accomplish a current density of −10mAcm<SUP>−2</SUP> with a less Tafel slope of −69mVdec<SUP>−1</SUP> for HER in aqueous KOH. Further, the tailored S-LDH/SS behaves like a battery-type electrode and delivers maximum specific capacity of 344Cg<SUP>−1</SUP> (95.5mAhg<SUP>−1</SUP>) at scan rate of 5mVs<SUP>−1</SUP>, which possess excellent cyclic stability and capacity retention. The S-LDH/SS comprised by two types of active catalytic sites along with anions furnish an excellent conductivity, which improving the mass and ionic transportations. Hopefully, exceptional electrochemical interpretation substantiates that this S-LDH/SS electrode might be a favorable material for the energy conversion and storage applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Sulfur doped nickel cobalt layered double hydroxide nano-arrays were electrodeposited on stainless steel (S-LDH/SS). </LI> <LI> S-LDH/SS displayed good electrochemical performance in KOH. </LI> <LI> S-LDH/SS required low onset and low overpotential for HER. </LI> <LI> S-LDH/SS delivered maximum specific capacity of 344Cg<SUP>−1</SUP> at 5mVs<SUP>−1</SUP>. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

A NEW TYPE OF THE ADDITIVE FUNCTIONAL EQUATIONS ON INTUITIONISTIC FUZZY NORMED SPACES

Arunkumar, Mohan,Bodaghi, Abasalt,Namachivayam, Thirumal,Sathya, Elumalai Korean Mathematical Society 2017 대한수학회논문집 Vol.32 No.4

In this paper, we introduce a new type of additive functional equations and establish the generalized Ulam-Hyers stability for it in intuitionistic fuzzy normed space by using direct and fixed point methods.

Deep-learning performance in identifying and classifying dental implant systems from dental imaging: a systematic review and meta-analysis

Akhilanand Chaurasia,Arunkumar Namachivayam,Revan Birke Koca-Ünsal,이재홍 대한치주과학회 2024 Journal of Periodontal & Implant Science Vol.54 No.1

Deep learning (DL) offers promising performance in computer vision tasks and is highly suitable for dental image recognition and analysis. We evaluated the accuracy of DL algorithms in identifying and classifying dental implant systems (DISs) using dental imaging. In this systematic review and meta-analysis, we explored the MEDLINE/ PubMed, Scopus, Embase, and Google Scholar databases and identified studies published between January 2011 and March 2022. Studies conducted on DL approaches for DIS identification or classification were included, and the accuracy of the DL models was evaluated using panoramic and periapical radiographic images. The quality of the selected studies was assessed using QUADAS-2. This review was registered with PROSPERO (CRDCRD42022309624). From 1,293 identified records, 9 studies were included in this systematic review and meta-analysis. The DL-based implant classification accuracy was no less than 70.75% (95% confidence interval [CI], 65.6%–75.9%) and no higher than 98.19 (95% CI, 97.8%–98.5%). The weighted accuracy was calculated, and the pooled sample size was 46,645, with an overall accuracy of 92.16% (95% CI, 90.8%–93.5%). The risk of bias and applicability concerns were judged as high for most studies, mainly regarding data selection and reference standards. DL models showed high accuracy in identifying and classifying DISs using panoramic and periapical radiographic images. Therefore, DL models are promising prospects for use as decision aids and decision-making tools; however, there are limitations with respect to their application in actual clinical practice.

Direct electro-synthesis of MnO₂ nanoparticles over nickel foam from spent alkaline battery cathode and its supercapacitor performance

Edison, Thomas Nesakumar Jebakumar Immanuel,Atchudan, Raji,Karthik, Namachivayam,Xiong, Dangsheng,Lee, Yong Rok Elsevier 2019 JOURNAL- TAIWAN INSTITUTE OF CHEMICAL ENGINEERS Vol.97 No.-

<P><B>Abstract</B></P> <P>This work reports the recovery of manganese ions from spent primary alkaline battery (PAB) cathode, subsequent anodic electro-synthesis of MnO<SUB>2</SUB> nanoparticles on Ni foam (MnO<SUB>2</SUB> NPs/Ni foam) for supercapacitors. The as-fabricated MnO<SUB>2</SUB> NPs/Ni foam is characterized by common optical and surface analytical techniques. The X-ray diffraction (XRD) of MnO<SUB>2</SUB> NPs/Ni foam matches well with γ-MnO<SUB>2</SUB> NPs pattern and hence the synthesized MnO<SUB>2</SUB> NPs mainly exist in γ-phase. The synthesized MnO<SUB>2</SUB> NPs are mostly in spherical cluster shape with an average size of 15 nm, inferred from the scanning electron microscopic (SEM) images. The X-ray photoelectron spectroscopy (XPS) result reveals that, synthesized MnO<SUB>2</SUB> NPs embraces with two different oxidation states such as 4<SUP>+</SUP> (MnO<SUB>2</SUB>) and 3<SUP>+</SUP> (MnOOH). The MnO<SUB>2</SUB> NPs/Ni foam delivers a maximum specific capacity of 549 F/g at the scan rate of 5 mV/s in three electrodes aqueous K<SUB>2</SUB>SO<SUB>4</SUB> system. Further, the two electrode asymmetric supercapacitor device is constructed with MnO<SUB>2</SUB> NPs/Ni foam as a positive and commercial graphene nanoplatelets coated Ni foam (GNP/Ni foam) as a negative electrode. The assembled supercapacitor device yields a maximum specific capacitance of 105 F/g at 5 mV/s, which achieves a maximum energy density of 14.7 Wh/kg at the power density of 748.9 W/kg between 0 and 1.5 V of working potential. This effort may pave the way for recovery and utilization of spent PAB cathode materials for energy storage devices.</P> <P><B>Highlights</B></P> <P> <UL> <LI> This work presents simple method for the recovery and utilization of Mn<SUP>2+</SUP> from spent alkaline battery cathode. </LI> <LI> The average size of the MnO<SUB>2</SUB> NPs was about 15 nm with spherical cluster shape. </LI> <LI> The electro-synthesized MnO<SUB>2</SUB> NPs revealed good electrochemical performance in K<SUB>2</SUB>SO<SUB>4</SUB>. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

One-pot dual product synthesis of hierarchical Co₃O₄@N-rGO for supercapacitors, N-GDs for label-free detection of metal ion and bio-imaging applications

Atchudan, Raji,Edison, Thomas Nesakumar Jebakumar Immanuel,Chakradhar, Dasagrandhi,Karthik, Namachivayam,Perumal, Suguna,Lee, Yong Rok Elsevier 2018 CERAMICS INTERNATIONAL Vol.44 No.3

<P><B>Abstract</B></P> <P>Cobalt oxide nanoparticles@nitrogen-doped reduced graphene oxide (Co<SUB>3</SUB>O<SUB>4</SUB>@N-rGO) composite and nitrogen-doped graphene dots (N-GDs) were synthesized by a one-pot simple hydrothermal method. The average sizes of the synthesized bare cobalt oxide nanoparticles (Co<SUB>3</SUB>O<SUB>4</SUB> NPs) and Co<SUB>3</SUB>O<SUB>4</SUB> NPs in the Co<SUB>3</SUB>O<SUB>4</SUB>@N-rGO composite were around 22 and 24nm, respectively with an interlayer distance of 0.21nm, as calculated using the XRD patterns. The Co<SUB>3</SUB>O<SUB>4</SUB>@N-rGO electrode exhibits superior capacitive performance with a high capability of about 450Fg<SUP>−1</SUP> at a current density of 1Ag<SUP>−1</SUP> and has excellent cyclic stability, even after 1000 cycles of GCD at a current density of 4Ag<SUP>−1</SUP>. The obtained N-GDs exhibited high sensitivity and selectivity towards Fe<SUP>2+</SUP> and Fe<SUP>3+</SUP>, the limit of detection was as low as 1.1 and 1.0μM, respectively, representing high sensitivity to Fe<SUP>2+</SUP> and Fe<SUP>3+</SUP>. Besides, the N-GDs was applied for bio-imaging. We found that N-GDs were suitable candidates for differential staining applications in yeast cells with good cell permeability and localization with negligible cytotoxicity. Hence, N-GDs may find dual utility as probes for the detection of cellular pools of metal ions (Fe<SUP>3+</SUP>/Fe<SUP>2+</SUP>) and also for early detection of opportunistic yeast infections in biological samples.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Dual product of Co<SUB>3</SUB>O<SUB>4</SUB>@N-rGO and fluorescent N-GDs by one-pot hydrothermal method. </LI> <LI> The Co<SUB>3</SUB>O<SUB>4</SUB>@N-rGO delivered a high C<SUB>s</SUB> of 450 F g<SUP>−1</SUP> at current density of 1 A g<SUP>−1</SUP>. </LI> <LI> First time, the byproducted N-GDs was used for label-free detection of Fe<SUP>3+</SUP>/Fe<SUP>2+</SUP>. </LI> <LI> N-GDs were used as a fluorescent probe for bio-imaging with good biocompatibility. </LI> <LI> N-GDs would offer a great potential for clinical applications in the near future. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Concurrent synthesis of nitrogen-doped carbon dots for cell imaging and ZnO@nitrogen-doped carbon sheets for photocatalytic degradation of methylene blue

Atchudan, Raji,Edison, Thomas Nesakumar Jebakumar Immanuel,Perumal, Suguna,Karthik, Namachivayam,Karthikeyan, Dhanapalan,Shanmugam, Mani,Lee, Yong Rok Elsevier 2018 Journal of photochemistry and photobiology Chemist Vol.350 No.-

<P><B>Abstract</B></P> <P>The hybrid composite of ZnO nanoparticles decorated nitrogen-doped graphitic carbon sheets (ZnO@N-C) alongside nitrogen-doped carbon dots (N-CDs) were synthesized by the direct hydrothermal method of peach fruit juice and ZnO nanoparticles (ZnO NPs). The synthesized ZnO@N-C hybrid composite and N-CDs were thoroughly characterized by various physicochemical techniques including powder X-ray diffraction (PXRD), attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, field emission scanning electron microscopy (FESEM) with energy-dispersive X-ray (EDX) spectroscopy, high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, ultraviolet-visible (UV-vis) spectroscopy, and fluorescence spectroscopy. The ZnO NPs were dispersed in the graphitic carbon structure with an average size of 25±5nm. The chemical composition of C, O, N, and Zn within the ZnO@N-C hybrid composite exhibits enough graphitization. Methylene blue (MB)-degradation was estimated utilizing the ZnO@N-C hybrid composite, a maximum degradation efficiency of >95% was achieved in a neutral aqueous medium within 60min under UV-light irradiation. This maximum efficiency allows estimating the contribution of the heterogeneous and homogeneity of ZnO@N-C hybrid composite which is responsible for the MB-degradation. Moreover, the economic natural biosource or bio-waste was employed for the synthesis of ZnO@N-C hybrid composite and displays an excellent photocatalytic degradation under UV-light irradiation which is an alternate for other carbon-based metal oxides. In addition, the resulting N-CDs were utilized as a fluorescence probe for cellular imaging, owing to their tremendous properties such as bright fluorescence with high quantum yield, excellent water solubility, and good biocompatibility. The N-CDs displays a multicolour fluorescence based on their changing of excitation wavelength and these multicolour fluorescence emissions offered a multicolour cellular imaging which could be applicable for real biological system in the near future.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Concurrent green synthesis of N-CDs and ZnO@N-C hybrid by a hydrothermal method. </LI> <LI> N-CDs used as a multicolour fluorescent probe for cell imaging without passivation. </LI> <LI> ZnO@N-C utilized for the degradation of MB with a high rate constant of 0.0456min<SUP>−1</SUP>. </LI> <LI> This green synthesized material could offer eco-friendly environmental applications. </LI> <LI> Moreover, new avenue to synthesize metal oxide grafted carbon sheets was provided. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Ultrasonic synthesis, characterization and energy applications of Ni–B alloy nanorods

Edison, Thomas Nesakumar Jebakumar Immanuel,Atchudan, Raji,Karthik, Namachivayam,Sethuraman, Mathur Gopalakrishnan,Lee, Yong Rok Elsevier 2017 Journal of the Taiwan Institute of Chemical Engine Vol.80 No.-

<P><B>Abstract</B></P> <P>Alloy nanostructures had received much attention for their applications in energy, catalysis, and optics. This paper described a facile ultrasonic approach for the synthesis of Ni–B alloy nanorods (Ni–B NRs). The crystallinity, chemical state, surface area and surface morphology of Ni–B NRs were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N<SUB>2</SUB> adsorption–desorption isotherms and high-resolution transmission electron microscopy (HR–TEM) analyses, respectively. The electrocatalytic behavior of Ni–B NRs toward the oxygen evolution reaction (OER) was studied by linear sweep voltammetry (LSV) and Tafel polarization methods in 0.1 M aqueous KOH. The LSV results of Ni–B NRs showed very low OER onset potential of 1.44 V<SUB>RHE</SUB> with an overpotential of 212 mV<SUB>RHE</SUB>. The Ni–B NRs attained 10 mA/cm<SUP>2</SUP> of current density at a very low potential of 1.61 V<SUB>RHE</SUB> than bare SS (1.87 V<SUB>RHE</SUB>) and bare Pt (2.50 V<SUB>RHE</SUB>). Further, Ni–B NRs showed a low Tafel slope of 45 mV/dec when compared to other standard materials, revealed the fast OER kinetics. The calculated specific capacitance of synthesized Ni–B NRs was 581 F/g, from the results of cyclic voltammetry at a scan rate of 2 mV/s. The electrocatalytic and supercapacitor studies exposed that the synthesized Ni–B NRs can be used as an electrocatalyst for OER as well as pseudocapacitor for commercial electric vehicles.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Amorphous Ni–B alloy nanorods (Ni–B NRs) are synthesized by ultrasonic method. </LI> <LI> Ni–B NRs shows excellent electrocatalytic activity toward OER than Ru and Ir. </LI> <LI> Ni–B NRs exhibit good pseudocapacitor behavior in aqueous KOH. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>