With increasingly strict requirements for advanced energy storage devices in electric vehicles (EVs) and stationary energy storage systems (EES), the development of lithium-ion batteries (LIBs) with high power density and safety has become an urgent task. Because the performance of LIBs is determined primarily by the physicochemical characteristics of its electrode material, TiO2, owing to its excellent stability, high safety levels, and environmentally friendly properties, has received significant attention as an alternative material for the replacement of commercial carbon-based anode materials. In particular, self-organized TiO2 micro and nanostructures prepared by anodization have been intensively investigated as promising anode materials. In this review, the mechanism for the formation of anodic TiO2 nanotubes and microcones and the parameters that influence their morphology are described. Furthermore, recent developments in anodic TiO2-based composites as anode electrodes for LIBs to overcome the limitations of low conductivity and specific capacity are summarized.
One-dimensional (1D) piezoelectric nanostructures are attractive candidates for energy generation because of their excellent piezoelectric properties attributed to their high aspect ratios and large surface areas. Vertically grown BaTiO3 nanotube (NT) arrays on conducting substrates are intensively studied because they can be easily synthesized with excellent uniformity and anisotropic orientation. In this study, we demonstrate the synthesis of 1D BaTiO3 NT arrays on a conductive Ti substrate by electrochemical anodization and sequential hydrothermal reactions. Subsequently, we explore the effect of hydrothermal reaction conditions on the piezoelectric energy conversion efficiency of the BaTiO3 NT arrays. Vertically aligned TiO2 NT arrays, which act as the initial template, are converted into BaTiO3 NT arrays using hydrothermal reaction with various concentrations of the Ba source and reaction times. To validate the electrical output performance of the BaTiO3 NT arrays, we measure the electricity generated from each NT array packaged with a conductive metal foil and epoxy under mechanical pushings. The generated output voltage signals from the BaTiO3 NT arrays increase with increasing concentration of the Ba source and reaction time. These results provide a new strategy for fabricating advanced 1D piezoelectric nanostructures by demonstrating the correlation between hydrothermal reaction conditions and piezoelectric output performance.
Transactions of the Korean hydrogen and new energy society
/
v.34
no.5
/
pp.413-420
/
2023
Holmium-doped TiO2 nanotubes (Ho-TNTs) were manufactured through anodization treatment and electrochemical deposition, and optimization experiments were conducted using various Holmium doping concentrations and time as variables. Surface as well as electrochemical characteristics were analyzed to study the prepared photocatalysts. Ho-TNTs were found to exist only in anatase phase through X-ray diffraction analysis. Ho-TNTs with 0.01 wt% 100 seconds shows a photocurrent density of 3.788 mA/cm2 and an effective photo-conversion efficiency (PCE) of 4.30%, which is more efficient than pure TiO2 nanotubes (pure-TNTs) (at bias potential 1.5 V vs. Hg/HgO). The photocatalytic activity of the aforementioned Ho-TNTs for hydrogen production was evaluated with the result of -29.20 µmol/h·cm2.
Seo Young Yoon;Cheol Min Kim;Bitna Bae;Yujin Na;Haksu Jang;Kwi-Il Park
Journal of Powder Materials
/
v.30
no.6
/
pp.521-527
/
2023
Piezoelectric technology, which converts mechanical energy into electrical energy, has recently attracted drawn considerable attention in the industry. Among the many kinds of piezoelectric materials, BaTiO3 nanotube arrays, which have outstanding uniformity and anisotropic orientation compared to nanowire-based arrays, can be fabricated using a simple synthesis process. In this study, we developed a flexible piezoelectric energy harvester (f-PEH) based on a composite film with PVDF-coated BaTiO3 nanotube arrays through sequential anodization and hydrothermal synthesis processes. The f-PEH fabricated using the piezoelectric composite film exhibited excellent piezoelectric performance and high flexibility compared to the previously reported BaTiO3 nanotube array-based energy harvester. These results demonstrate the possibility for widely application with high performance by our advanced f-PEH technique based on BaTiO3 nanotube arrays.
Kim, Si-Jung;Park, Ji-Man;Bae, Tae-Sung;Park, Eun-Jin
The Journal of Korean Academy of Prosthodontics
/
v.47
no.1
/
pp.39-45
/
2009
Statement of problem: Recently precalcification treatment has been studied to shorten the period of the implant. Purpose: This study was performed to evaluate the effect of precalcification treatment of $TiO_2$ Nanotube formed on Ti-6Al-4V Alloy. Material and methods: Specimens of $20{\times}10{\times}2\;mm$ in dimensions were polished sequentially from #220 to #1000 SiC paper, ultrasonically washed with acetone and distilled water for 5 min, and dried in an oven at $50^{\circ}C$ for 24 hours. The nanotubular layer was processed by electrochemical anodic oxidation in electrolytes containing 0.5 M $Na_2SO_4$ and 1.0 wt% NaF. Anodization was carried out using a regulated DC power supply (Kwangduck FA, Korea) at a potential of 20 V and current density of $30\;㎃/cm_2$ for 2 hours. Specimens were heat-treated at $600^{\circ}C$ for 2 hours to crystallize the amorphous $TiO_2$ nanotubes, and precalcified by soaking in $Na_2HPO_4$ solution for 24 hours and then in saturated $Ca(OH)_2$ solution for 5 hours. To evaluate the bioactivity of the precalcified $TiO_2$ nanotube layer, hydroxyapatite formation was investigated in a Hanks' balanced salts solution with pH 7.4 at $36.5^{\circ}C$ for 2 weeks. Results: Vertically oriented amorphous $TiO_2$ nanotubes of diameters 48.0 - 65.0 ㎚ were fabricated by anodizing treatment at 20 V for 2 hours in an 0.5 M $Na_2SO_4$ and 1.0 NaF solution. $TiO_2$ nanotubes were composed with strong anatase peak with presence of rutile peak after heat treatment at $600^{\circ}C$. The surface reactivity of $TiO_2$ nanotubes in SBF solution was enhanced by precalcification treatment in 0.5 M $Na_2HPO_4$ solution for 24 hours and then in saturated $Ca(OH)_2$ solution for 5 hours. The immersion in Hank's solution for 2 weeks showed that the intensity of $TiO_2$ rutile peak increased but the surface reactivity decreased by heat treatment at $600^{\circ}C$. Conclusion: This study shows that the precalcified treatment of $TiO_2$ Nanotube formed on Ti-6Al-4V Alloy enhances the surface reactivity.
Park, Sung-Hwan;Jung, Suk-Young;Lee, Jae-Yeol;Kim, Gyoo-Cheon;Shin, Sang-Hun
Journal of the Korean Association of Oral and Maxillofacial Surgeons
/
v.34
no.3
/
pp.306-318
/
2008
Anodic spark deposition method(ASD) surface treated titanium implant possesses a considerable osteoconductive potential that promoting a high level of implant osseointegration in normal bone. The purpose of this study was to observe the ASD implant's osseointegration in the osteoporosis-induced animal model. Twenty four rats, 10 weeks of age, were ovarectomized and 5 weeks later divided into two groups : ASD implant group and control implant group. Titanium screw implants (diameter; 2.0 mm, length, 3.5 mm; pitch-height, 0.4 mm) were designed for this study. Experimental implants were ASD treated and no treatment on control implants. ASD implants and control implants were placed in to left tibiae of rats. The rats were sacrificed at different time interval(1, 2, 4 and 8 weeks after implantation) for histopathologic observation and immunohisto-chemistrical observation, with collagen type Ⅰ, fibronectin, integrin ${\alpha}_2{\beta}_1$ and integrin ${\alpha}_5{\beta}_1$ antibodies. The results obtained from this study were as follow: 1. Histopathologic findings, overall tissue response and the pattern of bone formation in both groups were similar. In ASD group, more newly formed bone was seen at 1 week and 2weeks than control group. 2. The levels of type Ⅰ collagen and fibronectin expression were the most abundant at 2weeks and decreased gradually in both groups. Fibronectin and type Ⅰ collagen expression in ASD group were stronger than control group but no significance. 3. The levels of integrin ${\alpha}_2{\beta}_1$ and Integrin ${\alpha}_5{\beta}_1$ expression were most abundant at 2 weeks and decreased gradually in both groups. No significant difference was observed in both groups. From this results, anodic oxidized titanium implants were more advantages in early stage of bone formation than control group, but have no significance in tissue responses and late bone formations. It could be stated that although anodic oxidized titanium implant possesses considerable osteoconductive potential but in osteoporotic bone condition dental implant procedure should performed after improving or treating the osteoporotic bone condition.
Kim, Da-Eun;Lee, Yong-Ho;Kim, Dae-Won;Pak, Dae-Won
Journal of the Korean Applied Science and Technology
/
v.34
no.2
/
pp.349-356
/
2017
OH radical generation is one of the common method to evaluate photocatalytic activity. In many of previous studies, only the UV(Ultraviolet) light was applied to test photocatalytic ability of $TiO_2$ nanotubes by studying probe compound(4-Chlorobenzoic acid) concentration change in solution. Also, $TiO_2$ nanotubes were found to show some electrochemical characteristics when the flow of electric current was applied. In this study, the flow of electric current and UV light were applied at the same time to determine whether electrochemical characteristics of $TiO_2$ nanotube plate can give synergetic effect on the photocatalytic activity. $TiO_2$ nanotube was grown on Ti by anodic oxidation to create $TiO_2$ nanotube plate which can be used as a photocatalyst and a electrode that can undergo AOP(Advanced Oxidation Process) for water treatment. Probe compound solution was prepared using 4-chlorobenzoic acid and $H_2O$ as a solvent. NaCl was added to give conductivity to work as electrolyte. As a result, enough level of electric current flow was found to give synergetic photocatalytic effect which can be used for efficient AOP water treatment method.
In the development of new hydrogen absorbing materials for a next generation of metal hydride electrodes for rechargeable batteries, metastable Mg-Ni-based compounds find currently special attention. Amor phous-nanocrystalline $Mg_{63}Ni_{30}Y_7$ and $Mg_{50}Ni_{30}Y_{20}$ alloys were produced by mechanical alloying and melt-spinning and characterized by means of XRD, TEM and DSC. On basis of mechanically alloyed Mg-Ni-Y powders, complex hydride electrodes were fabricated and their electrochemical behaviour in 6M KOH (pH=14,8) was investigated. The electrodes made from $Mg_{63}Ni_{30}Y_7$ powders, which were prepared under use of a SPEX shaker mill, with a major fraction of nanocrystalline phase reveal a higher electrochemical activity far hydrogen reduction and a higher maximum discharge capacity (247 mAh/g) than the electrodes from alloy powder with predominantly amorphous microstructure (216 mAh/g) obtained when using a Retsch planetary ball mill at low temperatures. Those discharge capacities are higher that those fur nanocrystalline $Mg_2Ni$ electrodes. However, the cyclic stability of those alloy powder electrodes was low. Therefore, fundamental stability studies were performed on $Mg_{63}Ni_{30}Y_7$ and $Mg_{50}Ni_{30}Y_{20}$ ribbon samples in the as-quenched state and after cathodic hydrogen charging by means of anodic and cathodic polarisation measurements. Gradual oxidation and dissolution of nickel governs the anodic behaviour before a passive state is attained. A stabilizing effect of higher fractions of yttrium in the alloy on the passivation was detected. During the cathodic hydrogen charging process the alloys exhibit a change in the surface state chemistry, i.e. an enrichment of nickel-species, causing preferential oxidation and dissolution during subsequent anodization. The effect of chemical pre-treatments in 1% HF and in $10\;mg/l\;YCl_3/1%\;H_2O_2$ solution on the surface degradation processes was investigated. A HF treatment can improve their anodic passivation behavior by inhibiting a preferential nickel oxidation-dissolution at low polarisation, whereas a $YCl_3/H_2O_2$ treatment has the opposite effect. Both pre-treatment methods lead to an enhancement of cathodically induced surface degradation processes.
Kim, Joung Soo;Yi, Yong-Sun;Kwon, Oh Chul;Kim, Hong Pyo
Corrosion Science and Technology
/
v.6
no.6
/
pp.316-321
/
2007
The effect of annealing on the pitting corrosion resistance of anodized Al-Mg alloy (AA5052) processed by equal-channel angular pressing (ECAP) was investigated by electrochemical techniques in a solution containing 0.2 mol/L of $AlCl_3$ and also by surface analysis. The Al-Mg alloy was annealed at a fixed temperature between 473 and 573 K for 120 min in air after ECAP. Anodizing was conducted for 40 min at $100-400A/m^2$ at 293 K in a solution containing 1.53 mol/L of $H_2SO_4$ and 0.0185 mol/L of $Al_2(SO_4)_3$. The internal stress generated in anodic oxide films during anodization was measured with a strain gauge to clarify the effect of ECAP on the pitting corrosion resistance of anodized Al-Mg alloy. The time required to initiate the pitting corrosion of anodized Al-Mg alloy was shorter in samples subjected to ECAP, indicating that ECAP decreased the pitting corrosion resistance. However, the pitting corrosion resistance was greatly improved by annealing after ECAP. The time required to initiate pitting corrosion increased with increasing annealing temperature. The strain gauge attached to Al-Mg alloy revealed that the internal stress present in the anodic oxide films was compressive stress, and that the stress was larger with ECAP than without. The compressive internal stress gradually decreased with increasing annealing temperature. Scanning electron microscopy showed that cracks occurred in the anodic oxide film on Al-Mg alloy during initial corrosion and that the cracks were larger with ECAP than without. The ECAP process of severe plastic deformation produces large internal stresses in the Al-Mg alloy; the stresses remain in the anodic oxide films, increasingthe likelihood of cracks. It is assumed that the pitting corrosion is promoted by these cracks as a result of the higher internal stress resulting from ECAP. The improvement in the pitting corrosion resistance of anodized AlMg alloy as a result of annealing appears to be attributable to a decrease in the internal stresses in anodic oxide films
The effect of annealing on the pitting corrosion resistance of anodized Al-Mg alloy (AA5052) processed by equal-channel angular pressing (ECAP) was investigated by electrochemical techniques in a solution containing 0.2 mol/L of $AlCl_3$ and also by surface analysis. The Al-Mg alloy was annealed at a fixed temperature between 473 and 573 K for 120 min in air after ECAP. Anodizing was conducted for 40 min at $100-400A/m^2$ at 293 K in a solution containing 1.53 mol/L of $H_2SO_4$ and 0.0185 mol/L of $Al_2(SO_4)_3$. The internal stress generated in anodic oxide films during anodization was measured with a strain gauge to clarify the effect of ECAP on the pitting corrosion resistance of anodized Al-Mg alloy. The time required to initiate the pitting corrosion of anodized Al-Mg alloy was shorter in samples subjected to ECAP, indicating that ECAP decreased the pitting corrosion resistance. However, the pitting corrosion resistance was greatly improved by annealing after ECAP. The time required to initiate pitting corrosion increased with increasing annealing temperature. The strain gauge attached to Al-Mg alloy revealed that the internal stress present in the anodic oxide films was compressive stress, and that the stress was larger with ECAP than without. The compressive internal stress gradually decreased with increasing annealing temperature. Scanning electron microscopy showed that cracks occurred in the anodic oxide film on Al-Mg alloy during initial corrosion and that the cracks were larger with ECAP than without. The ECAP process of severe plastic deformation produces large internal stresses in the Al-Mg alloy; the stresses remain in the anodic oxide films, increasingthe likelihood of cracks. It is assumed that the pitting corrosion is promoted by these cracks as a result of the higher internal stress resulting from ECAP. The improvement in the pitting corrosion resistance of anodized AlMg alloy as a result of annealing appears to be attributable to a decrease in the internal stresses in anodic oxide films
본 웹사이트에 게시된 이메일 주소가 전자우편 수집 프로그램이나
그 밖의 기술적 장치를 이용하여 무단으로 수집되는 것을 거부하며,
이를 위반시 정보통신망법에 의해 형사 처벌됨을 유념하시기 바랍니다.
[게시일 2004년 10월 1일]
이용약관
제 1 장 총칙
제 1 조 (목적)
이 이용약관은 KoreaScience 홈페이지(이하 “당 사이트”)에서 제공하는 인터넷 서비스(이하 '서비스')의 가입조건 및 이용에 관한 제반 사항과 기타 필요한 사항을 구체적으로 규정함을 목적으로 합니다.
제 2 조 (용어의 정의)
① "이용자"라 함은 당 사이트에 접속하여 이 약관에 따라 당 사이트가 제공하는 서비스를 받는 회원 및 비회원을
말합니다.
② "회원"이라 함은 서비스를 이용하기 위하여 당 사이트에 개인정보를 제공하여 아이디(ID)와 비밀번호를 부여
받은 자를 말합니다.
③ "회원 아이디(ID)"라 함은 회원의 식별 및 서비스 이용을 위하여 자신이 선정한 문자 및 숫자의 조합을
말합니다.
④ "비밀번호(패스워드)"라 함은 회원이 자신의 비밀보호를 위하여 선정한 문자 및 숫자의 조합을 말합니다.
제 3 조 (이용약관의 효력 및 변경)
① 이 약관은 당 사이트에 게시하거나 기타의 방법으로 회원에게 공지함으로써 효력이 발생합니다.
② 당 사이트는 이 약관을 개정할 경우에 적용일자 및 개정사유를 명시하여 현행 약관과 함께 당 사이트의
초기화면에 그 적용일자 7일 이전부터 적용일자 전일까지 공지합니다. 다만, 회원에게 불리하게 약관내용을
변경하는 경우에는 최소한 30일 이상의 사전 유예기간을 두고 공지합니다. 이 경우 당 사이트는 개정 전
내용과 개정 후 내용을 명확하게 비교하여 이용자가 알기 쉽도록 표시합니다.
제 4 조(약관 외 준칙)
① 이 약관은 당 사이트가 제공하는 서비스에 관한 이용안내와 함께 적용됩니다.
② 이 약관에 명시되지 아니한 사항은 관계법령의 규정이 적용됩니다.
제 2 장 이용계약의 체결
제 5 조 (이용계약의 성립 등)
① 이용계약은 이용고객이 당 사이트가 정한 약관에 「동의합니다」를 선택하고, 당 사이트가 정한
온라인신청양식을 작성하여 서비스 이용을 신청한 후, 당 사이트가 이를 승낙함으로써 성립합니다.
② 제1항의 승낙은 당 사이트가 제공하는 과학기술정보검색, 맞춤정보, 서지정보 등 다른 서비스의 이용승낙을
포함합니다.
제 6 조 (회원가입)
서비스를 이용하고자 하는 고객은 당 사이트에서 정한 회원가입양식에 개인정보를 기재하여 가입을 하여야 합니다.
제 7 조 (개인정보의 보호 및 사용)
당 사이트는 관계법령이 정하는 바에 따라 회원 등록정보를 포함한 회원의 개인정보를 보호하기 위해 노력합니다. 회원 개인정보의 보호 및 사용에 대해서는 관련법령 및 당 사이트의 개인정보 보호정책이 적용됩니다.
제 8 조 (이용 신청의 승낙과 제한)
① 당 사이트는 제6조의 규정에 의한 이용신청고객에 대하여 서비스 이용을 승낙합니다.
② 당 사이트는 아래사항에 해당하는 경우에 대해서 승낙하지 아니 합니다.
- 이용계약 신청서의 내용을 허위로 기재한 경우
- 기타 규정한 제반사항을 위반하며 신청하는 경우
제 9 조 (회원 ID 부여 및 변경 등)
① 당 사이트는 이용고객에 대하여 약관에 정하는 바에 따라 자신이 선정한 회원 ID를 부여합니다.
② 회원 ID는 원칙적으로 변경이 불가하며 부득이한 사유로 인하여 변경 하고자 하는 경우에는 해당 ID를
해지하고 재가입해야 합니다.
③ 기타 회원 개인정보 관리 및 변경 등에 관한 사항은 서비스별 안내에 정하는 바에 의합니다.
제 3 장 계약 당사자의 의무
제 10 조 (KISTI의 의무)
① 당 사이트는 이용고객이 희망한 서비스 제공 개시일에 특별한 사정이 없는 한 서비스를 이용할 수 있도록
하여야 합니다.
② 당 사이트는 개인정보 보호를 위해 보안시스템을 구축하며 개인정보 보호정책을 공시하고 준수합니다.
③ 당 사이트는 회원으로부터 제기되는 의견이나 불만이 정당하다고 객관적으로 인정될 경우에는 적절한 절차를
거쳐 즉시 처리하여야 합니다. 다만, 즉시 처리가 곤란한 경우는 회원에게 그 사유와 처리일정을 통보하여야
합니다.
제 11 조 (회원의 의무)
① 이용자는 회원가입 신청 또는 회원정보 변경 시 실명으로 모든 사항을 사실에 근거하여 작성하여야 하며,
허위 또는 타인의 정보를 등록할 경우 일체의 권리를 주장할 수 없습니다.
② 당 사이트가 관계법령 및 개인정보 보호정책에 의거하여 그 책임을 지는 경우를 제외하고 회원에게 부여된
ID의 비밀번호 관리소홀, 부정사용에 의하여 발생하는 모든 결과에 대한 책임은 회원에게 있습니다.
③ 회원은 당 사이트 및 제 3자의 지적 재산권을 침해해서는 안 됩니다.
제 4 장 서비스의 이용
제 12 조 (서비스 이용 시간)
① 서비스 이용은 당 사이트의 업무상 또는 기술상 특별한 지장이 없는 한 연중무휴, 1일 24시간 운영을
원칙으로 합니다. 단, 당 사이트는 시스템 정기점검, 증설 및 교체를 위해 당 사이트가 정한 날이나 시간에
서비스를 일시 중단할 수 있으며, 예정되어 있는 작업으로 인한 서비스 일시중단은 당 사이트 홈페이지를
통해 사전에 공지합니다.
② 당 사이트는 서비스를 특정범위로 분할하여 각 범위별로 이용가능시간을 별도로 지정할 수 있습니다. 다만
이 경우 그 내용을 공지합니다.
제 13 조 (홈페이지 저작권)
① NDSL에서 제공하는 모든 저작물의 저작권은 원저작자에게 있으며, KISTI는 복제/배포/전송권을 확보하고
있습니다.
② NDSL에서 제공하는 콘텐츠를 상업적 및 기타 영리목적으로 복제/배포/전송할 경우 사전에 KISTI의 허락을
받아야 합니다.
③ NDSL에서 제공하는 콘텐츠를 보도, 비평, 교육, 연구 등을 위하여 정당한 범위 안에서 공정한 관행에
합치되게 인용할 수 있습니다.
④ NDSL에서 제공하는 콘텐츠를 무단 복제, 전송, 배포 기타 저작권법에 위반되는 방법으로 이용할 경우
저작권법 제136조에 따라 5년 이하의 징역 또는 5천만 원 이하의 벌금에 처해질 수 있습니다.
제 14 조 (유료서비스)
① 당 사이트 및 협력기관이 정한 유료서비스(원문복사 등)는 별도로 정해진 바에 따르며, 변경사항은 시행 전에
당 사이트 홈페이지를 통하여 회원에게 공지합니다.
② 유료서비스를 이용하려는 회원은 정해진 요금체계에 따라 요금을 납부해야 합니다.
제 5 장 계약 해지 및 이용 제한
제 15 조 (계약 해지)
회원이 이용계약을 해지하고자 하는 때에는 [가입해지] 메뉴를 이용해 직접 해지해야 합니다.
제 16 조 (서비스 이용제한)
① 당 사이트는 회원이 서비스 이용내용에 있어서 본 약관 제 11조 내용을 위반하거나, 다음 각 호에 해당하는
경우 서비스 이용을 제한할 수 있습니다.
- 2년 이상 서비스를 이용한 적이 없는 경우
- 기타 정상적인 서비스 운영에 방해가 될 경우
② 상기 이용제한 규정에 따라 서비스를 이용하는 회원에게 서비스 이용에 대하여 별도 공지 없이 서비스 이용의
일시정지, 이용계약 해지 할 수 있습니다.
제 17 조 (전자우편주소 수집 금지)
회원은 전자우편주소 추출기 등을 이용하여 전자우편주소를 수집 또는 제3자에게 제공할 수 없습니다.
제 6 장 손해배상 및 기타사항
제 18 조 (손해배상)
당 사이트는 무료로 제공되는 서비스와 관련하여 회원에게 어떠한 손해가 발생하더라도 당 사이트가 고의 또는 과실로 인한 손해발생을 제외하고는 이에 대하여 책임을 부담하지 아니합니다.
제 19 조 (관할 법원)
서비스 이용으로 발생한 분쟁에 대해 소송이 제기되는 경우 민사 소송법상의 관할 법원에 제기합니다.
[부 칙]
1. (시행일) 이 약관은 2016년 9월 5일부터 적용되며, 종전 약관은 본 약관으로 대체되며, 개정된 약관의 적용일 이전 가입자도 개정된 약관의 적용을 받습니다.