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Ultrathin 2D trifunctional NiCoFe /Ni nanosheet electrocatalyst for efficient water-splitting
( Tufa Lemma ),강소현,이재범 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.1
The hydrogen energy has facilitation of storage, transfer and high energy density. Also when the energy combustion, the remaining is water. Currently, hydrogen production method usually use fuel energy. However to develop more eco-friendly method, solar energy will be used in this paper for energy source. First process is incidence of photon makes electron-hole pair. Then interface reaction of electrode and electrolyte occurs through charge transfer. To enhance solar-to-hydrogen conversion efficiency, the control about structure, surface and interface of electrode. In this paper, the control of surface will be focused. The way of hydrogen use is water-splitting which makes water to break to oxygen(OER) and hydrogen(HER). In this system, OER is more important part. To get higher OER makes to get higher STH conversion efficiency, for that the surface of electrode has less overpotential, high stability and high activity.
Tufa, Lemma Teshome,Oh, Sangjin,Tran, Van Tan,Kim, Jeonghyo,Jeong, Ki-Jae,Park, Tae Jung,Kim, Hwa-Jung,Lee, Jaebeom Elsevier 2018 ELECTROCHIMICA ACTA Vol.290 No.-
<P><B>Abstract</B></P> <P>A glassy carbon electrode (GCE) is modified with a nanotriplex [<I>i.e.,</I> three nanolayers consisting of graphene quantum dot (GQD)-coated Fe<SUB>3</SUB>O<SUB>4</SUB>@Ag core-shell nanostructure (Fe<SUB>3</SUB>O<SUB>4</SUB>@Ag/GQD)]. The nanotriplex is a sensitive electrochemical biosensor platform for detecting <I>Mycobacterium tuberculosis</I> antigen (culture filtrate protein; CFP-10). Gold nanoparticles (AuNPs) conjugated to an anti-CFP-10 antibody are used as a label for signal amplification. The nanotriplex-based sensing platform attains synergetic electrochemical performance by the three different roles of three nanomaterials: Fe<SUB>3</SUB>O<SUB>4</SUB> increases the surface to volume ratio; Ag enhances electrical conductivity; and GQD for loading more of the anti-CFP-10 antibody onto the electrode. The electron transfer kinetics at the surface of the electrode is simulated by means of the Butler–Volmer model. A sandwich-type immunoassay results by immobilizing the first antibody on the Fe<SUB>3</SUB>O<SUB>4</SUB>@Ag/GQD-modified GCE and by incubating this system with the antigen and then with AuNPs conjugated with the second anti-CFP-10 antibody (Ab<SUB>2</SUB>−AuNPs). The AuNPs are quantified by exposing the immunocomplex to a potential of 1.3 V for 40 s and scanning by differential pulse voltammetry. The immunosensor shows a wide linear range (0.005–500 μg/mL) with a limit of detection (signal/noise = 3) reaching 0.33 ng/mL. The results suggest that the reliable and robust performance with high selectivity and simple operation may be extended to detection of other biomarkers of pathogenic bacteria.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The nanotriplex particles (Fe<SUB>3</SUB>O<SUB>4</SUB>@Ag/GQD) were prepared with different reagents by stepwise functionalization. </LI> <LI> An electrochemical biosensor was developed for detection of a <I>Mtb</I> antigen CFP-10 using a GCE modified with a nanotriplex. </LI> <LI> The nanotriplex-based sensing platform showed synergetic electrochemical performance by means of three nanomaterials. </LI> <LI> The immunosensor showed high selectivity and a wide linear range with a LOD (S/N = 3) reaching 0.33 ng/mL. </LI> </UL> </P>
Magnetic field effect of Ag@Fe3O4 nanoassembly in oxygen reduction reaction
( Tufa Lemma ),이재범 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.1
Lorentz or Kelvin force generated by externally applied magnetic field may introduce additional convection of electrolyte near the working electrode and consequently caused magnetocurrent (IM), which can be attributed to magneto-hydrodynamic (MHD) flow and extra electrochemical reaction. Then, the reduction current was carefully monitored in the presence of a magnetic field (B, up to 380 mT), resulting in extraordinarily enhancing 23% of reduction current of [Fe(CN)6]3-owing to additional magnetic field from 3D magnetoplasmonic nanoassembly. The computational simulation was also performed, in which the variances of the MHD flow (correlated with the Lorentz force, FL) and nonuniform magnetic fields.
2LN-9 Electrochemical Characterization and Magnetoplasmonic Electrochemical Biosensor
( Tufa Lemma ),이재범 한국공업화학회 2017 한국공업화학회 연구논문 초록집 Vol.2017 No.1
Development in understanding the physicochemical properties of nanoparticles (NPs) is essential for rational and optimized applications. Electrochemical technique is one of the powerful tools for characterization of NPs. Here, an electrochemical biosensor was developed for detection of mycobacterium tuberculosis (Mtb) antigen (CFP-10) using Fe3O4@Ag/GQD modified glassy carbon electrode (GCE) as a sensing platform and gold nanoparticles (AuNPs) as a label for signal amplification. A sandwich type immunoassay was prepared by immobilizing antibody 1 (Ab1), and AuNPs functionalized with antibody 2 (Ab2-AuNPs) on Fe3O4@Ag/GQD modified GCE. The immunosensor showed a wide linear range (0.005 - 500 μg/mL) with a limit of detection (LOD, S/N = 3) reaching 0.33 ng/mL. The result showed good performance with a high selectivity, and simple operation, can be easily extended to other pathogenic bacteria detection.
Thermobattery based on CNT Coated Carbon Textile and Thermoelectric Electrolyte
배경민,Hee Doo Yang,TUFA LEMMA TESHOME,강태준 한국정밀공학회 2015 International Journal of Precision Engineering and Vol.16 No.7
In this work, we report a thermobattery that can efficiently harvest low-grade waste heat. The thermobattery utilizes temperature dependence of ferri/ferrocyanide (Fe(CN)6 3-/Fe(CN)6 4-) redox potential and employs the porous carbon textile electrode that is coated with single-walled carbon nanotube (SWNT). Simple and scalable dipping and drying process was applied to prepare the SWNT coated textile electrodes (SWNT-CT). The SWNT coating not only decreases the sheet conductance of the textile remarkably but also provides the number of available reaction sites for thermogalvanic conversion, resulting in improving electrical outputs. The capability for power generation in the thermobattery was quantitatively investigated by measuring potential versus current curves. Discharge behavior of the thermobattery was also discussed to provide an understanding of the internal resistances that limit output electrical power.
A tubing shaped, flexible thermal energy harvester based on a carbon nanotube sheet electrode
Yang, H.D.,Tufa, L.T.,Bae, K.M.,Kang, T.J. Pergamon Press ; Elsevier Science Ltd 2015 Carbon Vol.86 No.-
A tubing-shaped, flexible electrochemical thermal energy harvester (thermocell), which can be wound around various types of waste heat sources, was fabricated. The thermocell utilizes the temperature dependence of the ferri/ferrocyanide (Fe(CN)<SUB>6</SUB><SUP>3-</SUP>/Fe(CN)<SUB>6</SUB><SUP>4-</SUP>) redox potential, providing a thermoelectric coefficient of ~1.4mV/K. A highly porous carbon nanotube (CNT) sheet, which is wrapped onto a thin platinum (Pt) wire, was used as an electrode for the redox reaction. The electrode performance was examined by comparing the output powers from the thermocells using a bare Pt wire and CNT sheet wound electrodes. The CNT sheet electrode showed a higher output power from 8.5 to 15.6μW, and the short-circuit current density (j<SUB>sc</SUB>) was increased ~1.8 times compared to that of the Pt wire electrode. The performance of the CNT sheet based thermocell was examined according to the winding number of the CNT sheet, the temperature difference between the two electrodes and the operating temperature. The series connection of the thermocells, to demonstrate the voltage and power scaling, was also examined with an understanding of the primary internal resistance that limits the output electrical power.
Tran, Van Tan,Kim, Jeonghyo,Tufa, Lemma Teshome,Oh, Sangjin,Kwon, Junyoung,Lee, Jaebeom American Chemical Society 2018 ANALYTICAL CHEMISTRY - Vol.90 No.1
<P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancham/2018/ancham.2018.90.issue-1/acs.analchem.7b04255/production/images/medium/ac-2017-04255v_0009.gif'></P>