초록 ▼

<1차년도>
○ 금속산화물 나노소재의 표면특성 향상을 위한 모폴로지 제어 기술
- 금속 산화물 반도체 나노로드의 합성 : 마이크로 에멀젼 법
* 마이크로 에멀젼 조건 제어를 통한 ZnO 나노로드 제조 : 비표면적에 비례하는 가스센서 특성
* 도펀트 도핑을 통한 센서 특성 제어 : Al-doped ZnO 나노로드
- 금속 산화물 나노파이버 제조 : 전기 방사법
* 메조포러스 SnO2 나노파이버 제조 및 센서특성 평가
○ 소재 복합화를 통한 응용특성 향상 기술
- 초음파법을 이용한 탄소나노플레

<1차년도>
○ 금속산화물 나노소재의 표면특성 향상을 위한 모폴로지 제어 기술
- 금속 산화물 반도체 나노로드의 합성 : 마이크로 에멀젼 법
* 마이크로 에멀젼 조건 제어를 통한 ZnO 나노로드 제조 : 비표면적에 비례하는 가스센서 특성
* 도펀트 도핑을 통한 센서 특성 제어 : Al-doped ZnO 나노로드
- 금속 산화물 나노파이버 제조 : 전기 방사법
* 메조포러스 SnO2 나노파이버 제조 및 센서특성 평가
○ 소재 복합화를 통한 응용특성 향상 기술
- 초음파법을 이용한 탄소나노플레이크 제조
- 센싱 소재(산화주석)담지를 통한 센서특성 향상
○ 이산화티탄 나노튜브 표면처리 기술
- 이산화티탄 나노튜브 상전이 거동
- 표면처리 기술 개발 : florination, Phaopation
* 상전이를 제한하면서 활성 및 표면특성 광활성 향상
○ 센서 평가 시스템 구축
<2차년도>
○ 나노 구조체 표면 활성 및 기능발현 소재 제조 및 물성 평가
- ZnO 나노로드/나노파이버/나노플레이트 제조 : 수열반응, 전기방사법
* morphology에 따른 표면특성과의 연관성 규명 → 비표면적과 표면결함 등과의 상관성
* Cu-pthalocyanine계 금속착물을 이용한 CuO담지 : 표면결함에 따른 물성 변화 유도
* 가스 센서 특성 평가 : 모폴로지 및 표면특성과의 상관성을 나타냄
- 계면활성제에 따른 In2O3 나노입자의 수열합성 및 morphology 조절
* 입도 및 입형의 변화 관찰 : 비표면적의 변화
* 가스센서 특성과 비표면적 증가 경향성과 일치
○ 나노 복합 소재 제조 및 응용기술 개발
- 탄소 나노복합체의 제조 및 활성 평가
* 고분자 탄소 전구체와 티타네이트 프리커서를 이용 티타네이트 나노튜브가 표면에 담지된 탄
소나노 파이버 제조 : 반응성 및 담지능 향상
- 복합방사 기술을 이용한 무기입자 함유 기능성 섬유 제조 기술
* 이산화티탄을 PET 중합단계에서 복합화하여 방사
* 안정성 및 항균 특성 규명
<3차년도>
○ 기능성 극대화 및 응용 기술을 위한 나노구조체 합성 기술 개발
- 전기 방사법을 이용한 ZnO 나노파이버 제조 : 비표면적 증대 및 가스센서 응답성 향상
- 이온교환 반응을 통한 Li-intercalated titante 나노튜브의 제조 기술 개발 : 비표면적 향상
- 나노비드 및 금속산화물 복합화 기술 개발
- 카본소재 복합화를 통한 고효율 나노소재 개발 : 티타네이트 나노튜브, CdS 복합화 – 비표면적과 수소저장능과의 상관관계 도출
○ 나노세공 및 불순물 담지 도핑 제어 기술 최적화
- 표면처리 기술을 이용한 활성탄소의 표면 활성 향상 및 응용 특성 평가 : 수소저장능 향상
- 금속 담지 ZnO 나노로드의 제조 : 낮은 구동온도에서 78%의 감응도를 지닌 소재 개발
○ 나노소재 응용 실용화 기술 개발
- 고감도 센서 특성 평가 : 센서 소자 특성 평가
- 표면 고활성 응용기술 개발 : 섬유 기능성 향상 응용기술, 수소담지능 향상, 촉매활성 향상 기술 등

Abstract ▼

In recent years, the optical and electronic properties of semiconductor and metal nanoparticles were intensively investigated and their functionality was improved by forming hybrid materials. The combination of semiconductor and metal nanoparticles is particularly interesting for many applications s

In recent years, the optical and electronic properties of semiconductor and metal nanoparticles were intensively investigated and their functionality was improved by forming hybrid materials. The combination of semiconductor and metal nanoparticles is particularly interesting for many applications such as catalyst, optical and sensing materials. Especially, one-dimensional nanostructured materials such as nanowires, nanofibers, nanorods, and nanotubes have received a great attention for their potential applications in numerous areas due to their special properties, which are distinct from conventional bulk materials. The synthesis of nanometer-sized one-dimensional materials has attracted considerable attention because of their great potential for fundamental studies of the role of dimensionality and size in the physical properties as well as for many applications such as transparent electrode in solar cells, gas sensors, hydrogen storage, and photoluminescence devices.
In this work, firstly, we report the synthesis of zinc oxide nanorods with different surface area by using the controlled surfactant-assisted microemulsion method. The alkyl chain length of surfactant would affect aspect ratio of ZnO nanorods. ZnO nanorods synthesized by ethyl benzene acid sodium salt (EBS), which is surfactant with short alkyl chain length, show higher aspect ratio than ones by dodecyl benzene sulfonic acid sodium salt (DBS). These nanorods had diameters in the range of 80–300 nm and length of up to several microns. The Brunauer–Emmett–Teller (BET) surface area of the ZnO nanorods was strongly affected by the morphology of the nanorods. The BET surface area of the nanorods synthesized with EBS was higher than the surface area of the nanorods synthesized with DBS (20.2 and 14.1 ㎡/g for EBS and DBS, respectively). The response of ZnO nanorods to CO in air was strongly affected by surface area, defects and oxygen vacancies. The results demonstrate that the microemulsion synthesis is an easy and useful method to synthesize ZnO nanorods with large aspect ratio, which may enhance their gas sensing properties. In addition, Al-doped ZnO nanorods were also prepared by microemulsion method using the two different surfactants. The AZO nanorods were relatively uniform with an average diameter around 50 nm and length of up to several microns. The CO gas sensing properties of the AZO nanorods were tested at operating temperatures of 200, 300, 350 and 400 ℃. It was found that AZO nanorods based sensor exhibited the highest sensitivity to CO at 350 ℃. In addition, we also studied about the synthesis of copper oxide decorated zinc oxide nanorods and nanoplates by microemulsion and solvothermal method.
Zinc oxide is an n-type semiconductor that has been well known for its applications in pigments, rubber additives, gas sensors, solar cells, varistors, and optical devices. In this aspect, many of the previous investigations on pure and doped zinc oxide prepared by different methods like precipitation, hydrothermal, microemulsion, ultrasonic, sol–gel, solid-state reaction. Zinc oxide nanorods and nanoplates were synthesized by microemulson method. 2, 9, 16, 23-tetranitrophthalocyanine copper (II) (TNCuPc)/zinc oxide nanorod structures were also synthesized by solvothermal method. After calcination of TNCuPc/zinc oxide nanorod structures, copper oxide decorated zinc oxide nanorods and nanoplates were successfully synthesized. The results showed that the copper oxide were successfully grown on the zinc oxide nanorods and nanoplates. The number of oxygen vacancy sites were confirmed from the PL spectra to be reduced in CuO decorated zinc oxide nanorods and nanoplates, which resulted in the decrese of sensing response for CO gas.
On the other hands, the research trends of gas sensing using semiconducting materials can be categorized into two fields. One is focused on the fabrication of the advanced gas sensors and the other is proving the mechanism of gas sensing. The important factors of gas sensing are physical and chemical properties of material. For example, there are several researches regarding modification of structure and electrical affinity which have strong connection with surface area, oxygen vacancy, adsorption-desorption properties and electron transport. To improve these properties, heterogeneous materials, noble metal doped semiconductor, are also investigated very widely, since electron moves fast through the interface of metal and semiconductor compared to the semiconductor only. Although high sensitivity and selectivity of gas sensing, the complicated synthetic procedures such as ionic liquid-assisted, vapor –liquid–solid (VLS) are required, which becomes an negative point in application to industrial fields. In this point of view, we could suggest the simple synthetic method of noble methal doped ZnO nanorod and nanofibers by using photodeposition method.
Finally, ZnO nanofibers and hollow nanofibers were synthesized by electrospinning method in order to investigate the relationship between the gas sensing ability and morphology or oxygen vacancy. The eletrospinning method is the very simple method for the syntheses of various morphological ZnO nanofibers. Among the various structures, 1D nanofiber structure has unique selectivity and sensitivity for gas sensing because of high surface to volume ratio, large porosity, and the occurrence of abundant vacancy sites. Comparing the physico-chemical properties for two type of nanofibers, hollow nanofiber and common nanofiber, synthesized in different synthetic conditions, it was found that Gas sensing ability was closely related with oxygen vacancy in N-type semiconductor ZnO nanostructured material. In this work, Synthetic method of ZnO nanofibers and hollow nanofiber using zinc acetate with PAN polymer composite by electrospinning and ZnO hollow nanofiber formation mechanism were explained in detail. The synthesized ZnO nanofibers and hollow nanofibers were characterized by scanning electron microscopy (SEM), transmitted electron microscopy (TEM), energy dispersive spectroscopy (EDS), x-ray diffraction (XRD), photoluminescence (PL), thermal gravimetric analysis (TG-DTA), and x-ray photoelectron spectroscopy (XPS). And their gas sensitivity was investigated using CO gas 10 ppm. It is worth to note that calcination of zinc acetate with PAN polymer at 500℃ above makes a form of ZnO hollow structured nanofiber. Its gas sensitivity is enhanced compare to uncalcined one because of hollow structure and abundant of oxygen vacancy. In special, the ZnO hollow nanofibers was observed to show the high response of about 80% to CO gas.
As the purpose of other application, nanostructured titanates were also prepared by alkaline hydrothermal processing in order to study applicability of TiO₂ based nanotubes to gas sensing materials, hydrogen storage materials, and so on. The titanates were transformed to the anatase particles at low concentrations of acid, whereas the rutile rods were produced from the titanates at high concentrations of acid. These changes were more retarded in the titanate nanofiber product than in titanate nanotubes product, which could be attributed to the stability and high crystallinity of the titanate nanofiber product prepared at a high hydrothermal temperature. The photocatalytic activities of the acid treated nanostructured titanates for MB degradation and gaseous CH₃CHO oxidation were strongly dependent on the presence of the anatase crystalline phase. On the other hand, core-shell type hybrid nanofibers, with the titanate nanotubes on the surface of carbon fibers, were successfully fabricated by carbonizaion and post base-treatment of the electorspinned PET-TiO₂ composite nanofibers.
In this work, we synthesized core–shell-structured CNF-TiNTs by electrospinning/carbonization and subsequent alkaline hydrothermal treatment.
First, TiO₂-embedded PAN nanofibers were prepared by electrospinning. Second, TiO₂-embedded PAN nanofibers were carbonized under N2 flow, which reduced the TiO₂ nanoparticles and PAN nanofibers to TiN and CNFs, respectively, and TiN-embedded CNFs are formed. Finally, the TiN nanoparticles in CNF are dissolved, transferred to the solution, and then transformed into TiNTs on the CNF surface as a result of the alkaline hydrothermal treatment. The formation of TiNTs on the CNF surface was observed by SEM, HR-TEM, XRD, and XPS analysis. Core–shell-structured CNF-TiNT exhibited efficient photocatalytic activities for CH₃CHO oxidation. As previously reported, TiO₂-embedded CNFs could be a facile alternative environmental remediation materials for practical application and have potential applications in many fields, such as air or water purification, hydrogen production from water splitting, fuel cells, and hydrogen adsorption. This study suggests that the alkaline hydrothermal treatment of TiOx- or TiO₂- embedded CNFs is a useful method to improve their adsorption and photocatalytic activities.