Preparation of TiO₂ coated Ag nanowire and their application for dye sensitized solar cells (DSSCs)

장인석,( Leonghuijun ),오성근 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.1

To apply for dye-sensitized solar cell, the thermal-stable core-shell structured Ag@TiO₂ was prepared using solvothermal method after functionalization of Ag nanowire via a chemical binder between Ag and TiO₂. Ag nanowire was synthesized with polyvinylpyrrolidone in glycerol through facile microwave assisted alcohol method. The synthesized Ag has a uniform morphology without other shapes and their diameter and length were 40-50 nm and 20-30 μm, respectively. By using surface modification with 2-mercaptoethanol, the surface of Ag nanowire was functionalized with thiol groups. The Ag-TiO₂ composite wire was prepared via solvothermal route at 120℃ and the core-shell structured Ag@TiO₂ nanowire could be acquired by varying the concentration of titanium butoxide as a TiO₂ precursor and the TiO₂ shell having a 20 nm of thickness indicated the anatase crystal structure. The Ag@TiO₂ nanowire exhibited high thermal stability at above 500℃. The high conversion efficiency (5.6%) of fabricated cell with Ag@TiO₂ electrode could be achieved by enhancement of JSC. The core-shell structured Ag@TiO₂ wire could reduce the charge recombination by attribution to electron shortcut for the improvement of electron transfer rate and lifetime.

Ag nanowire-based electrodes for improving the output power of ultraviolet AlGaN-based light-emitting diodes

Park, Jae-Seong,Kim, Jae-Ho,Na, Jin-Young,Kim, Dae-Hyun,Kang, Daesung,Kim, Sun-Kyung,Seong, Tae-Yeon Elsevier 2017 JOURNAL OF ALLOYS AND COMPOUNDS Vol.703 No.-

<P><B>Abstract</B></P> <P>We developed hybrid Ag nanodots (NDs)/Ag nanowires (NWs) electrodes for enhancing the light output power of near ultraviolet (NUV) AlGaN-based light-emitting diodes (LEDs). At 385 nm, 10-nm-thick ITO-only films deposited on p-GaN/sapphire gave a transmittance of 70%, whereas hybrid Ag NDs/Ag NWs film showed a transmittance of 47%. LEDs with ITO-only, Ag NDs/Ag NWs, and activated-Ag NDs/Ag NWs electrodes showed forward-bias voltages of 3.50, 3.65, and 3.57 V, respectively, at 20 mA. The LEDs with the ITO-only, Ag NDs/Ag NWs, and activated-Ag NDs/Ag NWs electrodes produced series resistances of 14.3, 15.2, and 14.5 Ω, respectively. The LEDs with the Ag NDs/Ag NWs and activated-Ag NDs/Ag NWs electrodes yielded 13.1% and 23.7% higher light output powers, respectively, at 20 mA than that produced with the ITO-only electrode. On the basis of the emission images obtained from the LEDs with 10-nm-thick ITO-only, Ag NDs/Ag NWs, and activated-Ag NDs/Ag NWs electrodes, the enhanced light output power is attributed to effective current spreading and current injection.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ag nanowire (NWs) were combined with Ag nanodots (NDs) to form current spreader. </LI> <LI> Ag ND/NW electrode serves as a better current spreader than thin ITO electrode. </LI> <LI> LEDs with Ag ND/NW contact give similar forward voltages to that ITO electrode. </LI> <LI> LEDs with Ag ND/NW electrode show higher output power than that with ITO electrode. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Sensing Properties of Networked Catalyst-metal-codoped Te2O5 Nanowire Sensors

박성훈,선건주,길혜준,이종무,김경국 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.67 No.4

Pt and Ag-codoped Te2O5 nanowires were synthesized by using a two-step process: thermal oxidation of Te powders followed by sputter-deposition of Ag. Multiple-networked sensors were fabricated by using four different types of nanowires: Pt and Ag-codoped Te2O5 nanowires, Ptdoped Te2O5 nanowires, Ag-doped Te2O5 nanowires and pristine Te2O5 nanowires; their acetone gas sensing properties were examined. The Pt and Ag-codoped Te2O5 nanowire sensor exhibited stronger response to acetone gas than the monometal-doped counterparts, as well as the undoped Te2O5 nanowire sensor. The codoped Te2O5 nanowire sensor also showed faster response to acetone gas than the latter. All four sensors showed an optimal operating temperature of 150 C for acetone gas sensing and selectivity for acetone gas over CO, toluene, benzene and LPG gases. The underlying mechanism of the enhanced sensing performance of the Pt and Ag-codoped Te2O5 nanowire sensor is discussed.

Evolution of AgX Nanowires into Ag Derivative Nano/microtubes for Highly Efficient Visible-Light Photocatalysts

Choi, Won San,Byun, Gyo Yeon,Bae, Tae Sung,Lee, Ha-Jin American Chemical Society 2013 ACS APPLIED MATERIALS & INTERFACES Vol.5 No.21

<P>Our study proposes a novel strategy for the synthesis of Ag derivatives (AgX@Ag (X = Cl and Br) or Ag nano/microtubes) using the controlled chemical reduction or electron-beam irradiation of AgX nanowires (NWs), which are formed from the controlled dewetting of a AgX thin film on colloidal particles. The size of the AgX@Ag and Ag nano/microtubes can be controlled using the AgCl NWs as templates and varying the concentration of NaX. By controlling the concentration of NaBr, heterojunction-structured AgCl/AgBr NWs (H-AgCl/AgBr NWs) can be produced from the AgCl NWs due to a partial ion-exchange reaction (low concentration), and the AgBr NWs produced after a complete ion-exchange reaction between Cl- and Br- are further grown into micrometer-sized AgBr wires (high concentration). The resulting AgX NWs can be transformed into corresponding AgX@Ag or Ag nano/microtubes via a controlled chemical or physical method. The AgX derivatives (AgX@Ag nanotubes (NTs) and AgX NWs) are tested as visible-light-induced photocatalysts for decomposition of methyl orange. The AgX@Ag NTs exhibit the best photocatalytic activities due to the advantages of the core@shell structure, allowing multiple reflections of visible light within the interior cavity, providing a well-defined and clean Ag/AgX interface, and preventing direct adsorption of pollutants on AgX because of the shell structure. These advantages allow AgX@Ag NTs to maintain high catalytic performance even after multiple uses. The approach can also be used as a direct method for preparing Ag nano/microtubes with a tailored size and as a new method for incorporating a AgX NW core into a Ag nano/microtube shell. Our approach is useful for synthesizing various types of one-dimensional heterostructured NWs or metal NTs with controlled structures and properties.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2013/aamick.2013.5.issue-21/am4034735/production/images/medium/am-2013-034735_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am4034735'>ACS Electronic Supporting Info</A></P>

NO2 감응을 위한 Ag 금속입자가 기능화된 SnO2 나노선 기반 저온동작 센서

최명식,김민영,안지혜,최승준,이규형 한국마이크로전자및패키징학회 2020 마이크로전자 및 패키징학회지 Vol.27 No.2

In this study, Ag-functionalized SnO2 nanowires are presented for NO2 gas sensitive sensors at low temperatures (50oC). SnO2 nanowires were synthesized using vapor-liquid-solid method, and Ag metal particles were functionalized on the surface of SnO2 nanowires using flame chemical vapor deposition method. As a result of the sensing test about Ag-functionalized SnO2 nanowires based sensor, the response (Rg/Ra) to 10 ppm NO2 was 1.252 at 50oC. We believe that metal-functionalizing is a one of good way to increase the feasibility about semiconductor gas sensor. 본 연구에서는 Ag 금속입자가 기능화된 SnO2 나노선을 제작 및 저온 NO2 가스 센싱 특성을 평가하였다. Vapor–liquid–solid 공법을 이용하여 SnO2 나노선을 합성하였고, flame chemical vapour deposition 공법을 이용하여 Ag 금속입자를 SnO2나노선표면에기능화하였다. 합성된 Ag 금속입자가기능화된 SnO2나노선을이용하여 50oC에서 NO2 10 ppm에대한 가스 센싱 테스트를 진행한 결과, 감응도(Rg/Ra) 1.252를얻었다. 본연구를 통하여, 금속입자가 기능화된나노선을 이용한 저온동작 반도체식 가스센서의 산업 적용을 현실화 할 수 있을 것으로 기대된다.

The effect of differently sized Ag catalysts on the fabrication of a silicon nanowire array using Ag-assisted electroless etching

Ai-Huei Chiou,Tse-Chang Chien,Ching-Kuei Su,Jheng-Fong Lin,Chun-Yao Hsu 한국물리학회 2013 Current Applied Physics Vol.13 No.4

A simple and low cost method to generate single-crystalline, well-aligned silicon nanowires (SiNWs) of large area, using Ag-assisted electroless etching, is presented and the effect of differently sized Ag catalysts on the fabrication of SiNWs arrays is investigated. The experimental results show that the size of the Ag catalysts can be controlled by adjusting the pre-deposition time in the AgNO3/HF solution. The optimum pre-deposition time for the fabrication of a SiNWs array is 3 min (about 162.04 38.53 nm Ag catalyst size). Ag catalysts with smaller sizes were formed in a shorter pre-deposition time (0.5 min),which induced the formation of silicon holes. In contrast, a large amount of Ag dendrites were formed on the silicon substrate, after a longer pre-deposition time (4 min). The existence of these Ag dendrites is disadvantageous to the fabrication of SiNWs. Therefore, a proper pre-deposition time for the Ag catalyst is beneficial to the formation of SiNWs. SiNWs were synthesized in the H2O2/HF solution system for different periods of time, using Agassisted electroless etching (pre-deposition of the Ag catalyst for 3 min). The length of the SiNWs increases linearly with immersion time. From TEM, SAED and HRTEM analysis, the axial orientation of the SiNWs is identified to be along the [001] direction, which is the same as that of the initial Si wafer. The use of HF may induce SieHx bonds onto the SiNWarray surface. Overall, the Ag-assisted electroless etching technique has advantages, such as low temperature, operation without the need for high energy and the lack of a need for catalysts or dopants.

Conductive silver nanowires-fenced carbon cloth fibers-supported layered double hydroxide nanosheets as a flexible and binder-free electrode for high-performance asymmetric supercapacitors

Sekhar, S. Chandra,Nagaraju, Goli,Yu, Jae Su Elsevier 2017 Nano energy Vol.36 No.-

<P><B>Abstract</B></P> <P>Silver nanowires (Ag NWs) have attracted particular interest in the development of various electronic and energy storage devices due to their one-dimensional structure, good conductivity, fast charge transportation and direct contact to the current collector. Herein, we have successfully deposited the binder-free nickel-cobalt layered double hydroxide nanosheets on Ag NWs-fenced carbon cloth (NC LDH NSs@Ag@CC) by a facile electrochemical deposition method with a chronoamperometry voltage of −1.0V for 120s. The electrically conductive and superhydrophilic nature of the hybrid nanocomposite electrode led to relatively high areal capacitance (1133.3 mF cm<SUP>−2</SUP> at 1mAcm<SUP>−2</SUP>) and good cycling stability (80.47% after 2000 cycles) compared to the electrode prepared without Ag NWs. Using such hierarchical NC LDH NSs@Ag@CC as a positive electrode, we further fabricated a flexible asymmetric supercapacitor (ASC) with activated carbon coated CC as a negative electrode. The as-assembled ASC exhibited maximum operational potential window of 1.6V, high areal capacitance of 230.2 mF cm<SUP>−2</SUP> and excellent cycling stability of 88.1% with remarkable energy densities at all the charge-discharge conditions (78.8 μWh cm<SUP>−2</SUP> at the power density of 785 μW cm<SUP>−2</SUP> and 40 μWh cm<SUP>−2</SUP> at the high power density of 12.1mWcm<SUP>−2</SUP>, respectively)</P> <P><B>Highlights</B></P> <P> <UL> <LI> Conductive Ag NWs are uniformly decorated on carbon cloth fibers (Ag@CC). </LI> <LI> The highly conductive features and hydrophilicity of Ag@CC induce the dense growth of NC LDH NSs. </LI> <LI> Ag NWs provide the effective pathways for electron transportation during the redox process of NC LDH NSs. </LI> <LI> The areal capacitance of the electrode with Ag NWs is 2.3 times higher than the electrode without Ag NWs. </LI> <LI> The assembled asymmetric supercapacitor delivers high energy and power densities. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Highly Transparent Au-Coated Ag Nanowire Transparent Electrode with Reduction in Haze

Kim, Taegeon,Canlier, Ali,Cho, Changsoon,Rozyyev, Vepa,Lee, Jung-Yong,Han, Seung Min American Chemical Society 2014 ACS APPLIED MATERIALS & INTERFACES Vol.6 No.16

<P>Ag nanowire transparent electrode has excellent transmittance and sheet resistance, yet its optical haze still needs to be improved in order for it to be suitable for display applications. Ag nanowires are known to have high haze because of the geometry of the nanowire and the high light scattering characteristic of the Ag. In this study, a Au-coated Ag nanowire structure was proposed to reduce the haze, where a thin layer of Au was coated on the surface of the Ag nanowires using a mild [Au(en)<SUB>2</SUB>]Cl<SUB>3</SUB> galvanic displacement reaction. The mild galvanic exchange allowed for a thin layer of Au coating on the Ag nanowires with minimal truncation of the nanowire, where the average length and the diameter were 13.0 μm and 60 nm, respectively. The Au-coated Ag nanowires were suspended in methanol and then electrostatically sprayed on a flexible polycarbonate substrate that revealed a clear reduction in haze with a 2–4% increase in total transmittance, sheet resistance ranges of 80–90%, and 8.8–36.8 Ohm/sq. Finite difference time domain simulations were conducted for Au-coated Ag nanowires that indicated a significant reduction in the average scattering from 1 to 0.69 for Au layer thicknesses of 0–10 nm.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2014/aamick.2014.6.issue-16/am502632t/production/images/medium/am-2014-02632t_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am502632t'>ACS Electronic Supporting Info</A></P>

Ag nanowire/ZnO nanobush hybrid structures for improved photocatalytic activity

Thanh Hoai Ta, Qui,Park, Sungho,Noh, Jin-Seo Academic Press 2017 Journal of Colloid and Interface Science Vol. No.

<P><B>Abstract</B></P> <P>Reverse-engineered Ag nanowire/ZnO nanobush hybrid structures have been synthesized for the first time by a combination of polyol method and low-temperature solution method. Through the elaborate control of Ag-to-ZnO weight ratio, vertically aligned ZnO nanobushes grew on the surface of well-faceted Ag nanowires. The Ag/ZnO hybrid nanostructures showed the crystal features of both Ag nanowires and wurtzite ZnO nanostructures. They exhibited strong UV absorption, whereas their photoluminescence spectra were much weaker than pure ZnO nanostructures due to the inhibited carrier recombination. The photocatalytic activity of Ag/ZnO hybrid nanostructures was greatly improved compared to pure ZnO nanostructures. Furthermore, they showed good cyclic performance and easy recovery from the test solution, demonstrating the possibility of their practical use.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Synthesis of size-controlled Ag nanowires via a seed-mediated growth method

전광훈,전석진 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.7

Seed-mediated growth has attracted much attention due to the wide range of controllability in size and shape, improved reproducibility, and capability to form bimetallic structures. Especially, seed-mediated growth of Ag has been extensively studied due to the excellent electrical, thermal, optical, and catalytic properties of Ag, but it has been conducted mainly for isotropic seeds such as nanocubes, and relatively little attention has been given to anisotropic seeds such as nanowires. We studied the seed-mediated growth of Ag nanowires for their size control, exploring the effect of hydrochloric acid (HCl), capping agents, and seeds to find the experimental condition for heterogeneous nucleation. By the optimized condition, the length and diameter were grown up to nearly 7 and 12 times, respectively, by those of seeds. Interestingly, for the condition that causes homogeneous nucleation, Ag particles of various shapes, including nanocubes, nanowires, and micro rods, were synthesized. The size-controlled Ag nanowires and Ag particles of various shapes obtained in this work are expected to be applied for the study of low resistance electrodes and the size- and shape-dependent properties of metal nanomaterials.