청정 연료인 수소를 생산하기 위해 현재 가장 널리 사용되는 기술인 증기 개질이다. 이 방법으로 생산된 수소는 일산화탄소와 같은 불순물을 함유하고 있어, 이를 연료전지와 같은 응용분야에 사용하기 위해서는 적절한 정제 과정을 반드 시 거쳐야 한다. 최근 효과적인 정제 방법으로 분리막 기술이 각광받고 있다. 본 연구에서는 수소와 일산화탄소 혼합가스에서 수소 분리 및 회수를 위해 바이오가스 고질화용(biogas upgrading) 상용 폴리설폰(polysulfone) 고분자막의 활용 가능성에 대 해서 평가하였다. 먼저, 사용한 상용막의 물리화학적 특성에 대해서 평가하였고, H2/CO를 이용하여 stage-cut, 운전압력과 같 은 다양한 조건에서의 상용막 모듈의 성능 평가를 진행하였다. 마지막으로, 평가 결과를 바탕으로 공정설계를 위한 시뮬레이 션을 진행하였다. 본 연구에서의 상용 분리막 공정의 최대 H2 투과도와 H2/CO 분리계수는 각각 361 GPU와 20.6을 기록하였 다. 또한, CO 제거 효율은 최대 94%를 나타내었으며, 생산 수소 농도는 최대 99.1%를 달성하였다.

본 연구의 목적은 END 금연동기유발 프로그램이 흡연 고등학생의 일산화탄소, 금연자기효능감, 흡연일수, 1일 흡연량에 미치는 효과를 확인하기 위해 실시한 비동등성 대조군 전·후 시차설계를 이용한 유사 실험연구이다. 대상자는 C시에 소재한 고등학생으로 금연에 관심이 있는 흡연학생으로 실험군 27명, 대조군 28명 총 55명이었으며 자료수집은 2018년 7월 12일부터 10월 4일까지였다. 대상자에게 중재한 프로그램은 END 금연동기유발 프로그램으로 주 1회 50분, 총 6주간이었다. 중재결과 실험군은 대조군에 비해 금연 자기효능감(z=110.00, p＜.001), 흡연일수(z=640.00, p＜.001), 1일 흡연량(z=520.50, p＜.016) 이 지지되었다. 따라서 END 금연동기유발 프로그램은 학교 현장에서 흡연 고등학생의 흡연율을 낮추고 금연동기를 유발하여 금연을 유도하기 위한 중재로 본 프로그램의 적용을 제안한다.

We perform density functional theory calculations to study the CO and O2 adsorption chemistry of Pt@X core@shell bimetallic nanoparticles (X = Pd, Rh, Ru, Au, or Ag). To prevent CO-poisoning of Pt nanoparticles, we introduce a Pt@X core-shell nanoparticle model that is composed of exposed surface sites of Pt and facets of X alloying element. We find that Pt@Pd, Pt@Rh, Pt@Ru, and Pt@Ag nanoparticles spatially bind CO and O2, separately, on Pt and X, respectively. Particularly, Pt@Ag nanoparticles show the most well-balanced CO and O2 binding energy values, which are required for facile CO oxidation. On the other hand, the O2 binding energies of Pt@Pd, Pt@Ru, and Pt@Rh nanoparticles are too strong to catalyze further CO oxidation because of the strong oxygen affinity of Pd, Ru, and Rh. The Au shell of Pt@Au nanoparticles preferentially bond CO rather than O2. From a catalysis design perspective, we believe that Pt@Ag is a better-performing Ptbased CO-tolerant CO oxidation catalyst.

Cu-Mn과 Cu-Zn 촉매를 침전제로 다르게 하거나, 금속의 몰비율, 소성온도를 다르게 하여 공침법으로 제조하였고 CO산화반응을 수행하여 혼합산화물 촉매에서 Cu, Mn과 Zn의 영향 및 소성온 도가 미치는 영향을 조사하였다. 촉매의 물리·화학적 특성을 알아보기 위하여 XRD, N2 흡착 및 SEM 의 분석을 수행하였다. Na2CO3로 침전시켜 270℃로 소성하여 제조한 2Cu-1Mn 산화물 촉매가 저온에 서 CO 산화반응 활성이 가장 좋았으며 2Cu-1Mn 산화물 촉매는 43 m2/g으로 가장 높은 비표면적과 촉매 활성을 나타내었다. XRD로 촉매의 결정구조를 분석하였을 때 Cu0.5Mn2.5O4의 결정구조를 갖는 촉 매는 낮은 활성을 보였다. 270℃에서 소성한 촉매가 좋은 활성을 나타냈으며 Pt 촉매와 비교하여도 저 온에서 CO산화반응이 더욱 우수함을 알 수 있었다.

We report on the NO gas sensing properties of Al-doped zinc oxide-carbon nanotube (ZnO-CNT) wire-like layered composites fabricated by coaxially coating Al-doped ZnO thin films on randomly oriented single-walled carbon nanotubes. We were able to wrap thin ZnO layers around the CNTs using the pulsed laser deposition method, forming wire-like nanostructures of ZnO-CNT. Microstructural observations revealed an ultrathin wire-like structure with a diameter of several tens of nm. Gas sensors based on ZnO-CNT wire-like layered composites were found to exhibit a novel sensing capability that originated from the genuine characteristics of the composites. Specifically, it was observed by measured gas sensing characteristics that the gas sensors based on ZnO-CNT layered composites showed a very high sensitivity of above 1,500% for NO gas in dry air at an optimal operating temperature of 200˚C; the sensors also showed a low NO gas detection limit at a sub-ppm level in dry air. The enhanced gas sensing properties of the ZnO-CNT wire-like layered composites are ascribed to a catalytic effect of Al elements on the surface reaction and an increase in the effective surface reaction area of the active ZnO layer due to the coating of CNT templates with a higher surface-to-volume ratio structure. These results suggest that ZnO-CNT composites made of ultrathin Al-doped ZnO layers uniformly coated around carbon nanotubes can be promising materials for use in practical high-performance NO gas sensors.

Semiconducting metal oxides have been frequently used as gas sensing materials. While zinc oxide is a popular material for such applications, structures such as nanowires, nanorods and nanotubes, due to their large surface area, are natural candidates for use as gas sensors of higher sensitivity. The compound ZnO has been studied, due to its chemical and thermal stability, for use as an n-type semiconducting gas sensor. ZnO has a large exciton binding energy and a large bandgap energy at room temperature. Also, ZnO is sensitive to toxic and combustible gases. The NO gas properties of zinc oxide-single wall carbon nanotube (ZnO-SWCNT) composites were investigated. Fabrication includes the deposition of porous SWCNTs on thermally oxidized SiO2 substrates followed by sputter deposition of Zn and thermal oxidation at 400˚C in oxygen. The Zn films were controlled to 50 nm thicknesses. The effects of microstructure and gas sensing properties were studied for process optimization through comparison of ZnO-SWCNT composites with ZnO film. The basic sensor response behavior to 10 ppm NO gas were checked at different operation temperatures in the range of 150-300˚C. The highest sensor responses were observed at 300˚C in ZnO film and 250˚C in ZnO-SWCNT composites. The ZnO-SWCNT composite sensor showed a sensor response (~1300%) five times higher than that of pure ZnO thin film sensors at an operation temperature of 250˚C.

We investigated the carbon monoxide (CO) gas-sensing properties of nanostructured Al-doped zinc oxide thin films deposited on self-assembled Au nanodots (ZnO/Au thin films). The Al-doped ZnO thin film was deposited onto the structure by rf sputtering, resulting in a gas-sensing element comprising a ZnO-based active layer with an embedded Pt/Ti electrode covered by the self-assembled Au nanodots. Prior to the growth of the active ZnO layer, the Au nanodots were formed via annealing a thin Au layer with a thickness of 2 nm at a moderate temperature of 500˚C. It was found that the ZnO/Au nanostructured thin film gas sensors showed a high maximum sensitivity to CO gas at 250˚C and a low CO detection limit of 5 ppm in dry air. Furthermore, the ZnO/Au thin film CO gas sensors exhibited fast response and recovery behaviors. The observed excellent CO gas-sensing properties of the nanostructured ZnO/Au thin films can be ascribed to the Au nanodots, acting as both a nucleation layer for the formation of the ZnO nanostructure and a catalyst in the CO surface reaction. These results suggest that the ZnO thin films deposited on self-assembled Au nanodots are promising for practical high-performance CO gas sensors.

We investigated the NO gas sensing characteristics of ZnO-carbon nanotube (ZnO-CNT) layered composites fabricated by coaxial coating of single-walled CNTs with a thin layer of 1 wt% Al-doped ZnO using rf magnetron sputtering deposition. Morphological studies clearly revealed that the ZnO appeared to form beadshaped crystalline nanoparticles with an average diameter as small as 30 nm, attaching to the surface of the nanotubes. It was found that the NO gas sensing properties of the ZnO-CNT layered composites were dramatically improved over Al-doped ZnO thin films. It is reasoned from these observations that an increase in the surface-to-volume ratio associated with the numerous ZnO “nanobeads” on the surface of the CNTs results in the enhancement of the NO gas sensing properties. The ZnO-CNT layered composite sensors exhibited a maximum sensitivity of 13.7 to 2 ppm NO gas at a temperature of 200˚C and a low NO gas detection limit of 0.2 ppm in dry air.

We investigated the effects of Co doping on the NO gas sensing characteristics of ZnO-carbon nanotube (ZnO-CNT) layered composites fabricated by coaxial coating of single-walled CNTs with ZnO using pulsed laser deposition. Structural examinations clearly confirmed a distinct nanostructure of the CNTs coated with ZnO nanoparticles of an average diameter as small as 10 nm and showed little influence of doping 1 at.% Co into ZnO on the morphology of the ZnO-CNT composites. It was found from the gas sensing measurements that 1 at.% Co doping into ZnO gave rise to a significant improvement in the response of the ZnO-CNT composite sensor to NO gas exposure. In particular, the Co-doped ZnO-CNT composite sensor shows a highly sensitive and fast response to NO gas at relatively low temperatures and even at low NO concentrations. The observed significant improvement of the NO gas sensing properties is attributed to an increase in the specific surface area and the role as a catalyst of the doped Co elements. These results suggest that Co-doped ZnOCNT composites are suitable for use as practical high-performance NO gas sensors.

The NO gas sensing properties of ZnO-carbon nanotube (ZnO-CNT) composites fabricated by the coaxial coating of single-walled CNTs with ZnO were investigated using pulsed laser deposition. Upon examination, the morphology and crystallinity of the ZnO-CNT composites showed that CNTs were uniformly coated with polycrystalline ZnO with a grain size as small as 5-10 nm. Gas sensing measurements clearly indicated a remarkable enhancement of the sensitivity of ZnO-CNT composites for NO gas compared to that of ZnO films while maintaining the strong sensing stability of the composites, properties that CNT-based sensing materials do not have. The enhanced gas sensing properties of the ZnO-CNT composites are attributed to an increase in the surface adsorption area of the ZnO layer via the coating by CNTs of a high surface-to-volume ratio structure. These results suggest that the ZnO-CNT composite is a promising template for novel solid-state semiconducting gas sensors.

동아시아에서 일산화탄소의 지역적 배경 농도 수준을 분석하기 위해, 1991년부터 2004년까지 장기간 중국 Waliguan(WLG), 몽골이아의 Ulaan Uul(UUM), 한국의 태안반도(TAP), 일본의 Ryori(RYO)에서 관측한 일산화탄소 농도를 분석하였다. 연평균 일산화탄소 농도는 WLG(135±22ppb), UUM(155±26ppb), RYO(171±36ppb), TAP(233±41ppb) 순서로 높은 농도를 보이고 있었다. WLG를 제외하고 전체적으로 봄철에 높고 여름철에 낮은 계절 변동의 특징은 동아시아 다른 지점들에서도 공통적으로 나타나고 있다. TAP는 WLG, UUM, RYO와 비교하여 전체 계절에 높은 일산화탄소 농도를 보이고 있으며 히스토그램에서 넓은 농도 분포를 보이는데 동아시아 대륙, 특히 중국의 가까운 풍하측에 위치하고 있어 광역적 대기 오염의 영향이 크기 때문이다. TAP는 중국 동부 지역을 경유하는 RPC가 봄, 가을, 겨울에서 높은 농도를 나타내었고, 여름철에는 저위도 북태평양으로부터의 OBG에 의해 낮은 일산화탄소 농도를 갖고 있는 해양성 기단의 영향을 받고 있다. NOAA 위성 영상과 GEOS-CHEM 모델 시뮬레이션은 중국 남동부 연안으로부터 황해를 거쳐 한반도와 동해로 확산하고 있는 광역적 대기오염 이동 사례를 확인하고 있다.

There appeared enhancements of the conversion of methane by adding a small amount of CO in the aromatization reaction of methane using the Mo-zeolite catalyst. In case of adding CO2, CO2 changed to CO first, and then the conversion reaction occurred. It was observed by using isotopes as reactants that CO is related to the aromatization reaction of methane.