Electrochemical performances of iron-cobalt oxides nanoparticles loaded crumpled graphene for supercapacitor

Lee, Chongmin,Kim, Sun Kyung,Choi, Ji-Hyuk,Chang, Hankwon,Jang, Hee Dong Elsevier 2018 JOURNAL OF ALLOYS AND COMPOUNDS Vol.735 No.-

<P><B>Abstract</B></P> <P>Mixed transition metal oxides (MTMOs) have been explored as attractive electrode materials for supercapacitors owing to their higher electronic conductivity and larger specific capacitance compared with simple transition metal oxides. Among MTMOs, cobalt-based binary metal oxides such as Fe-Co oxides have emerged as alternative electrode materials for supercapacitors because they have the advantages of low cost, natural abundance, and environmental friendliness. Recently, graphene-based Fe-Co oxides composites have become of particular interest for their improved electrochemical performance of supercapacitors due to the synergetic effect of both materials. In this study, we present three-dimensional (3D) crumpled graphene (CGR) decorated with Fe-Co oxides nanoparticles to determine which molar ratio of Fe/Co can exhibit higher electrochemical performance. The Fe-Co oxides/CGR composites were synthesized in different molar ratios of Fe/Co via aerosol spray pyrolysis and post heat treatment. Sizes of Fe-Co oxides nanoparticles ranged from 5 to 10 nm when loaded onto 500 nm CGR. The electrochemical properties of the Fe-Co oxides/CGR composites with different molar ratios of Fe/Co were examined. The Fe-Co oxides/CGR electrodes fabricated at the Fe/Co ratio of 0.1 showed the highest performances in the capacitance and electrical conductivity among those electrodes with different molar ratios of Fe/Co.</P> <P><B>Highlights</B></P> <P> <UL> <LI> 3D Fe-Co oxides/CGR composites were synthesized in different molar ratios of Fe/Co. </LI> <LI> The composites were decorated of oxides nanoparticles on the CGR. </LI> <LI> The highest electrochemical performance was found at the Fe/Co ratio of 0.1. </LI> </UL> </P>

Zn-Fe mixed metal oxides from metal hydroxide precursor: Effect of calcination temperature on phase evolution, porosity, and catalytic acidity

Kim, Bo-Kyung,Lee, Do-Yeon,Gwak, Gyeong-Hyeon,Han, Yang-Su,Oh, Jae-Min Elsevier 2019 Journal of solid state chemistry Vol.269 No.-

<P><B>Abstract</B></P> <P>Mixed metal oxides consisting of Zn and Fe were prepared by calcining ZnFe-mixed metal hydroxide at respective temperature of 400, 500 and 600 °C. According to X-ray diffraction, the calcination resulted in the evolution of wurtzite ZnO partially with ZnFe<SUB>2</SUB>O<SUB>4</SUB> spinel at high temperature. The local structure around Fe and Zn measured by X-ray absorption spectroscopy did not show difference upon temperature, suggesting the intimate association between zinc oxide and iron oxide. The magnetic property of mixed metal oxide was paramagnetic for calcination temperature of 400 and 500 °C; whereas superparamagnetism was observed in 600 °C calcined sample. The specific surface area and pore volume was the highest for mixed metal oxide calcined at 500 °C showing 66.4 m<SUP>2</SUP>/g and 0.908 cm<SUP>3</SUP>/g, respectively. Temperature programmed desorption of ammonia revealed that the ZnFe-mixed metal oxide had majorly strong Lewis acid site compared with previously reported ZnOs. The acid strength was proportional to the calcination temperature, and however, total acidity decreased for 600 °C calcined oxide. Taking into account the phase, porosity and acidity, the ZnFe-mixed metal oxide prepared at 500 °C could be the most advantageous as acid catalysts.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Mixed metal oxides were obtained by calcining metal hydroxides at various temperatures. </LI> <LI> Specific surface area and pore volume were the highest at moderate temperature. </LI> <LI> Acid strength of metal oxides increases upon temperature. </LI> <LI> High calcination temperature negatively affect total acidity of metal oxides. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Structures and catalytic properties of mixed metal oxides are dependent on calcination temperature.</P> <P>[DISPLAY OMISSION]</P>

동해 울릉분지 퇴적물에서 망간산화물과 철산화물 환원율 추정

최유정,김동선,이태희,이창복,Choi, Yu-Jeong,Kim, Dong-Seon,Lee, Tae-Hee,Lee, Chang-Bok 한국해양학회 2009 바다 Vol.14 No.3

동해 울릉분지에서 망간산화물과 철산화물의 유기물 분해 기여율을 정량화하기 위하여 6개의 박스형 시추퇴적물을 채집하였다. 수심이 2,000 m 이상인 울릉분지 표층퇴적물에서 유기탄소 함량은 2.6% 가량으로 육상기원 유기물 유입이 많은 흑해와 용승 해역인 칠레 주변해역들과 비슷했다. 울릉분지에 위치한 정점들에서 망간산화물 함량은 퇴적물 최상부에서 2% 이상으로 매우 높았고, 철산화물 함량은 울릉분지 표층 $1{\sim}4cm$ 내외에서 2% 가량의 최고값을 나타냈다. 그러나 대륙사면 정점들에서 망간산화물과 철산화물 함량은 분지처럼 높은 값을 보이지 않았다. 동해 울릉분지에서 2% 이상으로 높은 망간산화물 함량은 높은 유기탄소 함량과 사면보다 비교적 느린 퇴적속도 때문이거나 망간 이온이 저탁류를 통해 사면에서 분지로 이동한 것으로 예상된다. 망간산화물 환원율은 $0.3{\sim}0.57\;mmol\;m^{-2}\;day^{-1}$의 범위를 보였고, 철산화물 환원율은 $0.10{\sim}0.24\;mmol\;m^{-2}\;day^{-1}$의 범위를 나타냈다. 울릉분지에서 금속산화물은 유기물 분해에 $13{\sim}26%$ 정도를 차지하였으며, 이는 칠레 용승 해역과 유사하고, 덴마크 연안보다 낮은 값이다. In order to determine organic carbon oxidation by manganese and iron oxides, six core sediments were obtained in slope and basin sediments of Ulleung Basin in East Sea. The basin sediments show high organic carbon contents (>2%) at the water depths deeper than 2,000 m; this is rare for deep-sea sediments, except for those of the Black Sea and Chilean upwelling regions. In the Ullleung Basin, the surface sediments were extremely enriched by Manganese oxides with more than 2%. Maximum contents of Fe oxides were found at the depth of $1{\sim}4cm$ in basin sediments. However, the high level of Mn and Fe oxides was not observed in slope sediment. Surface manganese enrichments (>2%) in Ulleung Basin may be explained by two possible mechanisms: high organic carbon contents and optimum sedimentation rates and sufficient supply of dissolved Manganese from slope to the deep basin. Reduction rates of iron and manganese oxides ranged from 0.10 to $0.24\;mmol\;m^{-2}day^{-1}$ and from 0.30 to $0.57\;mmol\;m^{-2}day^{-1}$, respectively. In Ulleung Basin sediments, $13{\sim}26%$ of organic carbon oxidation may be linked to the reduction of iron and manganese oxides. Reduction rates of metal oxides were comparable to those of Chilean upwelling regions, and lower than those of Danish coastal sediments.

Effects of Complex Oxides on Charpy Impact Properties of Heat Affected Zones of Two API X70 Linepipe Steels

Shin, Sang Yong,Oh, Kyungshik,Kang, Ki Bong,Lee, Sunghak The Iron and Steel Institute of Japan 2009 ISIJ international Vol.49 No.8

<P>This study is concerned with effects of oxides on Charpy impact properties of heat affected zone (HAZ) of API X70 linepipe steels. Various oxides were formed by adding alloying elements of Ti, Al, and Mg to the API X70 steels, and effects of these oxides on HAZ microstructures and Charpy impact properties were investigated. Oxides present in the steels were sized about 2 μm, and had characteristics of complex oxides composed of various elements. The steel containing more Al, Ti, and Mg showed higher volume fraction of oxides than the conventional steel. After the HAZ simulation test, the oxide-containing steel HAZs were composed mainly of acicular ferrite, together with small amount of bainite, whereas the conventional steel HAZ were composed mainly of bainite with a small amount of acicular ferrite. This formation of acicular ferrite in the oxide-containing steel HAZs was associated with the active nucleation of acicular ferrite at oxides, thereby leading to the great (five times or more) improvement of Charpy impact properties of the HAZs over the conventional steel HAZs.</P>

SIMULTANEOUSLY CATALYTIC REMOVAL OF NOx AND SOOT ON RARE EARTH ELEMENT OXIDE LOADED WITH POTASSIUM AND TRANSITION NANOSIZED METAL OXIDES

ZHI JIANG,HAIRONG ZHANG,ZHONGPENG WANG,MINGXIA CHEN,WENFENG SHANGGUAN 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2008 NANO Vol.3 No.4

The simultaneous catalytic removal of NOx and soot over the rare earth element (REE) oxide-based mixture oxides loaded with potassium and transition nanosized metal oxide (designated as M/K/REE oxide) was investigated by using temperature-programmed reaction (TPR). The influence of the type of REE oxides together with the type and amount of transitional metal oxides on the catalytic removal activity was discussed. K/Nd2O3 was found to be the most active oxide among the REE oxides to simultaneous remove the NOx and soot under lean conditions. Chromium oxide was more active than the other transition metal oxides on enhancing the activity of soot oxidation of Nd2O3 loaded with potassium. The optimum loading level of chromium was about 10 wt%, with ignition temperature at about 237°C and the conversion ratio NO → N2 about 24.1%. The Mn-loading on K/Nd2O3 resulted in the biggest conversion efficiency of NO to N2 at about 30.2%. The increasing catalytic reaction of NOx–soot activities is attributed to the formation of complex crystalline phase in the catalyst together with the improving contacting between catalysts and soot.

Effects of acicular ferrite on charpy impact properties in heat affected zones of oxide-containing API X80 linepipe steels

Sung, H.K.,Shin, S.Y.,Cha, W.,Oh, K.,Lee, S.,Kim, N.J. Elsevier Sequoia 2011 Materials science & engineering. properties, micro Vol.528 No.9

This study was concerned with effects of acicular ferrite on Charpy impact properties in heat affected zones (HAZs) of two API X80 linepipe steels containing oxides. In the one steel, Mg and O<SUB>2</SUB> were additionally added to form a larger amount of oxides than the other steel, which was a conventional X80 steel containing a considerable amount of Al and Ti. Various HAZ microstructures were obtained by conducting HAZ simulation tests under different heat inputs of 35kJcm<SUP>-1</SUP> and 60kJcm<SUP>-1</SUP>. Oxides present in the API X80 linepipe steels were complex oxides whose average size was 1-2μm, and the number of oxides increased with increasing amount of Mg and O<SUB>2</SUB>. The volume fraction of acicular ferrite present in the steel HAZs increased with increasing number of oxides, and decreased with increasing heat input. When the volume fraction of acicular in the HAZ was higher than 20%, Charpy impact energy at -20<SUP>o</SUP>C was higher than 100J as the ductile fracture mode was dominant. Particularly in the steel HAZs having a larger amount of oxides, Charpy impact properties were excellent because oxides worked as nucleation sites of acicular ferrite during welding. Charpy impact properties of the HAZs could be well correlated with the volume fraction of acicular ferrite and number of oxides under different heat input conditions.

철기 유물 부식 산화물 처리제의 제조

양은희(Yang, Eun Hee),한원식(Han Won-Sik),최광선(Choi Kwang-Sun),홍태기(Hong Tae-Kee) 한국전시산업융합연구원 2017 한국과학예술융합학회 Vol.30 No.-

금속은 우리 인류 문화 발전에 많은 영향을 준 재료이며, 과거에서부터 현재까지 우리 생활에 밀접한 연관이 있는 재료이다. 선사시대부터 사용해온 금속의 종류는 다양하며 우리나라의 출토 금속 유물 중 철기유물이 가장 큰 비중을 차지하고 있다. 출토 유물에서 전승 유물에 이르기까지 철기 유물들의 존재를 가장 크게 위협하는 것이 부식 진행 과정이며, 부식된 산화물을 제거하기 위해서는 현재 물리적인 제거 방법이 가장 많이 사용되고 있다. 본 논문은 부식 산화물을 제거하는 작업에 대한 내용으로 철기 유물 자체의 모재는 보호하면서 부식 산화물만을 처리하는 화학적 부식 산화물 제거제에 대하여 연구하고자 하였다. 철기 유물의 부식 산화물에 대한 보다 안전하고 효과적인 제거를 위해, 새로운 산성, 알칼리성, 중성의 산화물 제거제를 제조하고, 이의 조성을 다양하게 변화하면서 철기 유물의 부식 산화물 제거 가능성과 최적화된 조성을 찾는 것에 목표를 두고 실행하였으며 근대유물에 적용하여 그 가능성까지를 검토하였다. 연구결과는 다음과 같다. 첫째, 산성 처리 용액의 경우 철 시편 표면에 산화된 부식물은 일부만이 제거되는 결과를 나타내었다. 둘째, 알칼리성과 중성 처리 용액의 경우 검은색의 부식물이 남은 상태였으나 이는 처리 시간과 처리 용액의 양을 증가시키면 이들도 제거되는 결과를 나타내었다. 셋째, 이 세 종류 용액은 처리 시에 모두 모재 자체에 손상을 주지 않았으며 용액의 농도와 처리 시간의 조절만으로도 유물에 따른 상황 대처가 가능하여 모재나 안정화 부식층을 보호하면서 불안정한 산화물층만을 제거할 수 있는 결과를 나타내었다. Metal is a material that has exerted a lot of influence on the development of human cultures, and has closely connected with our life from the past to the present. Types of metal we have used from the prehistoric times are varied, and iron relics take the largest percentage of metal relics excavated in our country. The biggest threat to the existence of iron relics ranging from excavated relics to the ones that are transmitted is the process of corrosion, and physical removal has been used the most for removing corroded oxides. For details for removal of corrosion oxides, this thesis aimed to research on the chemical corrosion oxides remover that protects parent material of iron relics but treats corrosion oxides only. For safe and effective removal of corrosion oxides of iron relics, this study was conducted aiming at finding the possibility of and optimized composition for removal of iron relics corrosion oxides by manufacturing new acid, alkaline and neutral oxides removers and changing their composition variously, exploring the possibility by applying the agents to modern relics. The results of this study are as follows: First, the acid solution removed only some part of corrosive substance oxidized on the surface of metal specimen. Second, the application of each of alkaline and neutral solution resulted in remaining black-colored corrosive substance, but it was removed when the quantity of the solution and the duration of application are increased. Third, All the three solutions did not cause any damage to parent material in the course of application, and showed the result that they are capable of removing unstable oxide layer while protecting parent material and stable corrosive layer as the solutions would be able to deal with situation by a relic only through the control of concentration of solution and duration of application.

CrOx/TiO2 촉매의 결정성과 TCE 산화반응 활성

김문현 ( Moon Hyeon Kim ),이효상 ( Hyo Sang Lee ) 한국환경과학회 2014 한국환경과학회지 Vol.23 No.5

itania-supported chromium oxides with different loadings have been embarked in catalytic oxidation of trichloroethylene (TCE) to inquire association of the formation of crystalline Cr2O3 with catalytic performances. A better activity in the oxidative TCE decomposition at chosen temperatures was represented when chromium oxides (CrOx) had been dispersed on pure anatase-type TiO2 (DT51D) rather than on phase-mixed and sulfur-contained ones such as P25 and DT51. The extent of TCE oxidation at temperatures below 350oC was a strong function of CrOx content in CrOx/DT51D TiO2, and a noticeable point was that the catalyst has two optimal CrOx loadings in which the lowest T50 and T90 values were measured for the TCE oxidation. This behavior in the activity with respect to CrOx amounts could be associated with the formation of crystalline Cr2O3 on the support surface, that is less active for the oxidation reaction, and an easier mobility of the surface oxygen existing in noncrystalline CrOx species with higher oxidation states, such as Cr2O8 and CrO3.

Effect of Palladium and Nickel on the Temperature Programmed Reduction of Metal Oxides and Metal Oxide Layers

Kim, Jong Pal 한국화학공학회 2004 Korean Journal of Chemical Engineering Vol.21 No.2

A new binary oxide support was suggested as being useful in many commercial reactions. Our study was focused on the reduction effect of metal oxide layer on alumina during reaction. Hence temperature programmed reduction of both bulk metal oxide and metal oxide layer on alumina was studied first and the effect of palladium and nickel on the reduction of the oxide support was also investigated. Vanadium oxide was mainly studied and niobium oxide, tantalum oxide, titanium oxide and zirconium oxide were also compared. Some metal oxides were reduced in a hydrogen stream at elevated temperature. In these cases both the bulk metal oxide and metal oxide layer were reduced. A tiny amount of palladium or nickel affected the reduction by decreasing the reduction temperature. The decrease of the reduction temperature was explained by means of increased adsorption of hydrogen on the transition metal and ability of the metal to spillover of the hydrogen to the oxides.

Effect of Palladium and Nickel on the Temperature Programmed Reduction of Metal Oxides and Metal Oxide Layers

김종팔 한국화학공학회 2004 Korean Journal of Chemical Engineering Vol.21 No.2

A new binary oxide support was suggested as being useful in many commercial reactions. Our study wasfocused on the reduction effect of metal oxide layer on alumina during reaction. Hence temperature programmedreduction of both bulk metal oxide and metal oxide layer on alumina was studied first and the effect of palladium andnickel on the reduction of the oxide support was also investigated. Vanadium oxide was mainly studied and niobiumoxide, tantalum oxide, titanium oxide and zirconium oxide were also compared. Some metal oxides were reduced ina hydrogen stream at elevated temperature. In these cases both the bulk metal oxide and metal oxide layer werereduced. A tiny amount of palladium or nickel afected the reduction by decreasing the reduction temperature. Thedecrease of the reduction temperature was explained by means of increased adsorption of hydrogen on the transitionmetal and ability of the metal to spillover of the hydrogen to the oxides.