전기방사법으로 제조한 W:BiVO4 나노섬유의 형상 제어 및 니켈 촉매의 기능화를 통한 물분해용 광촉매에 관한 연구

학위논문(석사) - 한국과학기술원 : 신소재공학과, 2014.2, [ vi, 55 p. ]The rising human demand for developing clean and renewable energy has been promotive of photochemical/photoelectrochemical water splitting as a pathway to convert solar energy into chemical energy. Nanostructured catalysts are widely regarded as an opportunity to improve light harvesting and conversion efficiency for water splitting. For the water oxidation catalyst, 1D nanostructured tungsten doped bismuth vanadate nanofibers (W:BiVO4 NFs) with high specific surface area (SBET = 13.656 m2/g) were successfully prepared by facile electrospinning method. Nickel nanoparticles (Ni NPs) with diameter of 5-10 nm as co-catalysts for lowering the activation barrier of water redox reactions and assisting in charge separation near the co-catalyst and semiconductor interface were synthesized by the polyol method. Ni NPs decorated W:BiVO4 nanofibers (Ni/W:BiVO4 NFs) were characterized using X-ray diffraction analysis (XRD), X-ray photoelectron spectroscopy (XPS), Scanning electron microscope (SEM) and Transmission electron microscopy (TEM). The results proved that the elongated W:BiVO4 NFs in longitudinal direction had many small grains with monoclinic scheelite structure and bimodal pore distribution. The surface of W:BiVO4 NFs was covered in patches with the Ni NPs mostly comprised of the Ni metal phase. Photocatalytic activity of the prepared samples was measured by oxygen evolution test with sacrificial electron scavenger (AgNO3) and photo-absorption property of them was measured by diffuse-reflectance spectra. In the final analysis, the photocatalytic activity in water oxidation reactions was significantly improved by introducing Ni NPs on W:BiVO4 NFs in comparison with that of W:BiVO4 bulk or pristine W:BiVO4 NFs. In the results of the absorption properties and band gap calculation, Ni/W:BiVO4 NFs make a loss to harvesting photon energies. However, this negative effect is explicitlyexplicitly explicitlyexplicitlyexplicitlyexplicitlyexplicitlyexplicitly overcompensat...한국과학기술원 : 신소재공학과

Perovskite metal oxide nanofibers as air electrode for lithium air batteries, and fabrication method thereof

리튬-공기 전지용 촉매로서 나노섬유 형상의 페롭스카이트 금속산화물이 사용된 공기 전극 및 그 제조방법이 개시된다. 리튬-공기 전지용 공기 전극은, 일반식 A(1-x)A'xB(1-y)B'yO3 (x=0.0~1.0, y=0.0~1.0)의 페롭스카이트(perovskite) 구조를 갖는 금속산화물 나노섬유 촉매를 포함할 수 있다. 이때, 상기 금속산화물 나노섬유 촉매는, 다공성 기공을 포함하고, 다결정성 나노섬유 형상을 갖는 것을 특징으로 할 수 있다

단일층의 WS2 나노판과 탄소 나노섬유의 결착을 통한 리튬 이온 전지의 음극과 수소 발생 촉매로서 뛰어난 전기화학적 성능

Transition metal dichalcogenides (TMDs) such as WS2 have drawn tremendous attention due to their fascinating physicochemical properties when they are single-layered or few-layered. Such attention can be ascribed to an interesting phenomenon that a reduction in the dimensionality leads to a variety of exotic characteristics which differ from those of their bulk material counterparts. Unfortunately, their poor intrinsic conductivities hamper their use in energy storage and conversion applications. In this regard, it is an efficient strategy to make a composite, combining single-layered TMDs with highly conductive materials. In this study, we report that single layers of WS2 nanoplates can be uniformly embedded in nitrogen-doped carbon nanofibers (WS2@NCNFs), and also can be anchored to hollow nitrogen-doped carbon nanofibers (WS2@HNCNFs) via electrospinning. These rationally designed materials were electrochemically tested as anode materials for lithium ion batteries and electrocatalysts for hydrogen evolution. The distinctive design of the materials enables outstanding electrochemical performances

METAL OXIDE NANOFIBERS FUNCTIONALIZED BY BINARY NANOPARTICLE CATALYSTS, CATALYST FOR AIR ELECTRODE OF LITHIUM-AIR BATTERY USING THE SAME AND MANUFACTURING METHOD THEREOF

리튬-공기전지의 공기극용 촉매, 이를 이용한 리튬-공기전지 및 그 제조 방법이 제공된다. 이종의 금속간화합물, 금속/금속, 금속/금속산화물, 또는 금속산화물/금속산화물 나노입자 촉매가 나노섬유의 표면에 결착되어 제조된 나노섬유 촉매 및 그 제조 방법이 제공되고, 제조된 나노섬유 촉매를 사용하는 리튬-공기전지 및 리튬-공기전지의 공기극과, 그 제조 방법이 제공된다

Effect of Dispersion Solvent on Properties of Fluorinated Polymer Reinforced Composite Membrane for Fuel Cell by Solution Coating Method

최근 화석연료기반에서 친환경 수소 기반의 청정에너지원으로 전환되는 세계적 흐름에 따라, 수소연료전지의 고성능저가격 핵심 소재 기술 개발에 많은 관심이 이루어지고 있다. 그 가운데 연료전지의 전해질로 사용되는 강화복합막의기술 도입은 과불소계 술폰산 이오노머(Perfluorosulfonic acid, PFSA) 양의 감소 및 막 두께 감소를 통한 가격 저감 및셀 저항 감소, 치수 안정성 개선 그리고 계면 안정성에 대한 확보가 가능하여 최종적으로 연료전지 성능 향상과 가격절감이 동시에 가능하다. 본 연구에서는 연료전지용 불소계 전해질 강화복합막 코팅 공정에서 이오노머 분산용매에 따라 막 형성 및 물성 변화와 연료전지 성능에 미치는 영향에 대해 연구하였다.22Nkc