Effect of acidity on the performance of a Ni-based catalyst for hydrogen production through propane steam reforming: K-AlSi_<i>x</i>O_<i>y</i> support with different Si/Al ratios

Do, Jeong Yeon,Kwak, Byeong Sub,Park, No-Kuk,Lee, Tae Jin,Lee, Sang Tae,Jo, Seung Won,Cha, Moon Soon,Jeon, Min-Kyu,Kang, Misook Pergamon Press 2017 International journal of hydrogen energy Vol.42 No.36

<P><B>Abstract</B></P> <P>Propane steam reforming (PSR) for the production of H<SUB>2</SUB> was catalyzed by a NiO/K-AlSi<SUB> <I>x</I> </SUB>O<SUB> <I>y</I> </SUB> catalyst synthesized with various Si/Al ratios (Si/Al = 0, 0.3, 0.5, 0.7, and 1.0). The effect of the Si/Al ratio on the acidity of the NiO/K-AlSi<SUB> <I>x</I> </SUB>O<SUB> <I>y</I> </SUB> catalyst for PSR was investigated. NiO/K-AlSi<SUB> <I>x</I> </SUB>O<SUB> <I>y</I> </SUB> gave a higher H<SUB>2</SUB> selectivity and stability during PSR than NiO/K-SiO<SUB>2</SUB> and NiO/K-Al<SUB>2</SUB>O<SUB>3</SUB>. The NH<SUB>3</SUB>-TPD results showed that the acid quantity and strength of NiO/K-AlSi<SUB> <I>x</I> </SUB>O<SUB> <I>y</I> </SUB> changed significantly depending on the Si/Al ratio. With an increased Si/Al ratio, the densities of both weak and strong acid sites increased. The C<SUB>3</SUB>H<SUB>8</SUB>- and CO-TPD results indicated that desorption amounts increased significantly in all NiO/K-AlSi<SUB> <I>x</I> </SUB>O<SUB> <I>y</I> </SUB> catalysts relative to those of NiO/K-SiO<SUB>2</SUB> and NiO/K-Al<SUB>2</SUB>O<SUB>3</SUB>, and the adsorption amount increased with the Si/Al ratio. PSR results showed that the NiO/K-AlSi<SUB> <I>x</I> </SUB>O<SUB> <I>y</I> </SUB> catalyst exhibited much better stability than the NiO/K-SiO<SUB>2</SUB> and NiO/K-Al<SUB>2</SUB>O<SUB>3</SUB> catalysts. This study confirms the following facts: when the acidity is appropriately adjusted for the catalyst, adsorption of the reaction gas increases, which eventually increases the reaction rate and also inhibits strong sintering between the nickel and the Al<SUB>2</SUB>O<SUB>3</SUB> support. As a result, deterioration of the catalyst can be reduced.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The NiO/K-AlSi<SUB> <I>x</I> </SUB>O<SUB> <I>y</I> </SUB> catalyst was synthesized for the production of H<SUB>2</SUB> from PRS. </LI> <LI> The acid quantity and strength of NiO/K-AlSi<SUB> <I>x</I> </SUB>O<SUB> <I>y</I> </SUB> changed significantly depending on the Si/Al ratio. </LI> <LI> The adsorptions of C<SUB>3</SUB>H<SUB>8</SUB> and CO increased with the Si/Al ratio. </LI> <LI> The NiO/K-AlSi<SUB> <I>x</I> </SUB>O<SUB> <I>y</I> </SUB> catalyst exhibited much better stability during PSR. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Enhanced mixed potential NO_x gas response performance of surface modified and NiO nanoparticles infiltrated solid-state electrochemical-based NiO-YSZ composite sensing electrodes

Balamurugan, C.,Son, Chanjin,Hong, Jaewoon,Song, Sun-Ju Elsevier 2018 Sensors and actuators. B Chemical Vol.262 No.-

<P><B>Abstract</B></P> <P>We have designed the solid-state electrochemical mixed potential type NiO and yttrium-stabilized zirconia (YSZ) composite based sensing electrode for selective detection of NO<SUB>x</SUB> at elevated temperatures. The planner NiO-YSZ composite sensing electrode could detect NO<SUB>x</SUB> even at 400 °C, with acceptable response/recovery rates. The change in emf values of the sensor varied linearly with NO<SUB>x</SUB> concentrations on a logarithmic scale in the range of 5–100 ppm. The response characteristic of the sensor was improved by modifying the surface with different vol% of pore former. As a result, obtained porous electrodes showed better response characteristics concerning speed and response owing to higher porosity. To improve response kinetics of porous NiO-YSZ electrode, NiO nanoparticles are infiltrated into an optimized NiO-YSZ sensing electrode surface by controlled urea/cation infiltration method. The experimental results demonstrated that NiO nanoparticles infiltrated NiO-YSZ sensor electrode reveal remarkably high emf response to NO<SUB>x</SUB> compared that of planar electrode, suggesting that NiO nanoparticles introduction can significantly enhance catalytic activity and electrochemical performance of NiO-YSZ electrode. Finally, the porosity effect of electrode subtracts (YSZ) with NO<SUB>x</SUB> gases response and recovery kinetics was examined under the optimum operating temperature at 400 °C. The sensing mechanism based on the mixed potential for the surface modified NiO-YSZ composite sensing electrode was discussed based on the obtained result of sensing characterizations.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The detailed NO<SUB>x</SUB> gas sensing characteristics of NiO-YSZ based three different types of mixed potential sensing electrodes for the comparatively low operating temperature of 400 °C. </LI> <LI> Optimized NiO-YSZ electrode surface was modified by the addition of different vol% of pore former, it showed better response characteristics concerning speed and response. </LI> <LI> The NiO nanoparticles infiltrated NiO-YSZ sensing electrode shows a remarkably high emf variation to 100 ppm NO<SUB>x</SUB>, and it can detect a level as low as 3 ppm. </LI> <LI> The porosity effect of electrode subtracts (YSZ) with NO<SUB>x</SUB> gases response and recovery kinetics was also examined under the optimum operating temperature at 400 °C. </LI> </UL> </P>

P-i-n 페로브스카이트 태양전지 응용을 위한 2PACz을 이용한 NiO의 개질

이선민 ( Seon-min Lee ),김석순 ( Seok-soon Kim ) 한국공업화학회 2024 공업화학 Vol.35 No.2

NiO와 페로브스카이트 사이의 전하 이동과 계면특성을 개선하기 위해, 솔-젤로 제조된 NiO를 [2-(9H-carbazol-9-yl)ethyl] phosphonic acid (2PACz)으로 개질한다. 2PACz의 인산기(head group)는 NiO 표면의 수산화기(-OH)와 응축 반응을 통해 결합되며, 더 깊은 가전자대가 형성되면서 페로브스카이트 층의 가전자대와 에너지밴드가 더 잘 일치하게 되어 생성된 전하의 재결합이 억제되고 에너지 손실이 감소하게 된다. 더불어, 페로브스카이트의 표면 및 페로브스카이트/정공 전달층 계면에 핀홀이 없는 고질의 페로브스카이트 필름이 형성된다. 결과적으로, 13.69%의 효율을 나타내는 NiO 기반 소자와 비교했을 때, 최적의 2PACz으로 개질된 NiO 기반 소자는 17.08%의 높은 효율을 보여주며, 공기 조건에서 더 뛰어난 안정성을 보여준다. To improve charge transfer and surface contact between NiO and perovskite, sol-gel derived NiO is modified with [2-(9H-carbazol-9-yl)ethyl] phosphonic acid (2PACz) in p-i-n structured perovskite solar cells (PeSCs). The phosphonic acid head group in the 2PACz can bind to the hydroxyl groups on the surface of NiO by a condensation reaction, which results in a better-matched energy level with the valence band of perovskite layers, reducing nonradiative recombination and energy loss. Furthermore, the formation of pin-hole free perovskite films is observed in the 2PACz modified NiO system. Consequently, the combination of sol-gel processed NiO with optimal 2PACz exhibits a higher efficiency of 17.08% and superior stability under ambient air conditions without any encapsulation, compared to a bare NiO based device showing 13.69%.

Ru–NiO<i>x</i> nanohybrids on TiO₂ support prepared by impregnation-reduction method for efficient hydrogenation of lactose to lactitol

Mishra, Dinesh Kumar,Dabbawala, Aasif A.,Truong, Cong Chien,Alhassan, Saeed M.,Jegal, Jonggeon,Hwang, Jin Soo Elsevier 2018 Journal of industrial and engineering chemistry Vol.68 No.-

<P><B>Abstract</B></P> <P>Lactose is a reducing disaccharide consisting of two different monosaccharides such as galactose and glucose. The hydrogenation of lactose to lactitol is a formidable challenge because it is a complex process and several side products are formed. In this work, we synthesized Ru–Ni bimetallic nanohybrids as efficient catalysts for selective lactose hydrogenation to give selective lactitol. Ru–Ni bimetallic nanohybrids with Ru–NiO<I> <SUB>x</SUB> </I> (<I>x</I> =1, 5, and 10wt%) are prepared by impregnating Ru and Ni salts precursors with TiO<SUB>2</SUB> used as support material. Ru–Ni bimetallic nanohybrids (represented as 5Ru–5NiO/TiO<SUB>2</SUB>) catalyst is found to exhibit the remarkably high selectivity of lactitol (99.4%) and turnover frequency i.e. (374h<SUP>−1</SUP>). In contrast, monometallic Ru/TiO<SUB>2</SUB> catalyst shows poor performance with (TOF=251h<SUP>−1</SUP>). The detailed characterizations confirmed a strong interaction between Ru and NiO species, demonstrating a synergistic effect on the improvement on lactitol selectivity. The impregnation-reduction method for the preparation of bimetallic Ru–NiO/TiO<SUB>2</SUB> catalyst promoted Ru nanoparticles dispersed on NiO and intensified the interaction between Ru and NiO species. Ru–NiO/TiO<SUB>2</SUB> efficiently catalyzed the hydrogenation of lactose to lactitol with high yield/selectivity at almost complete conversion of lactose at 120°C and 55bar of hydrogen (H<SUB>2</SUB>) pressure. Moreover, Ru–NiO/TiO<SUB>2</SUB> catalyst could also be easily recovered and reused up to four runs without notable change in original activity.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Highly active supported Ru–Ni bimetallic catalysts with NiO are prepared. </LI> <LI> Bimetallic Ru–5NiO/TiO<SUB>2</SUB> catalyst shows high selectivity to lactitol (99.4%). </LI> <LI> Optimization and kinetics studies of lactose hydrogenation. </LI> <LI> Bimetallic Ru–5NiO/TiO<SUB>2</SUB> catalyst is reused up to several consecutive times. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

AgNWs networks for high-performing transparent heaters by using NiO window layer

Patel, Malkeshkumar,Chauhan, Khushbu R.,Kim, Joondong,Kim, Jong-Woong,Lim, Donggun Elsevier 2017 Sensors and actuators. A, Physical Vol.267 No.-

<P><B>Abstract</B></P> <P>We demonstrate the high-performing silver nanowire (AgNW) networks for transparent heaters by using a NiO window layer. The colorless polyimide (cPI) was used as a substrate in order to configure the transparent heater of NiO/AgNWs/cPI, having over 77% transmittance at a wavelength of 550nm. AgNWs networks were formed on the cPI substrate and the NiO layer was reactively sputtered onto AgNWs at a room temperature. Due to the NiO capping layer onto AgNWs, the electrical and optical properties of AgNW networks were preserved. An extremely high-performing AgNWs-based transparent heater was achieved by utilizing NiO protective. The NiO window layer provides an excellent atmospheric isolation for partially-embedded silver nanowires and makes the heater operation to be stable at high temperatures of 185.5°C with a relatively small bias of 7V. The excellent performances are attributed to the Schottky barrier formed between the NiO window and AgNW networks. The efficient exploitation of capping layers, such as NiO in this study will boost the viability of AgNW-based heaters and electronic devices for commercial applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> High-performing transparent heater was formed by AgNWs and NiO layer. </LI> <LI> NiO layer efficiently protected AgNWs from deformation. </LI> <LI> NiO functional window effectively controlled the electrical and thermal properties. </LI> <LI> 200°C was reached by applying 7V for stable operation. </LI> </UL> </P>

리튬-황 전지용 프리스탠딩 플렉서블 S/CNT/NiO 전극의 제조 및 전기화학적 특성

신윤정 ( Yun Jung Shin ),이원열 ( Won Yeol Lee ),김태윤 ( Tae Yun Kim ),문승근 ( Seung-guen Moon ),김은미 ( En Mei Jin ),정상문 ( Sang Mun Jeong ) 한국화학공학회 2022 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.60 No.2

수열합성을 통해 합성한 다공성 NiO는 리튬 폴리설파이드의 용출을 억제하기 위하여 리튬-황 전지의 전극에 사용되었다. 리튬-황 전지의 전극은 경제적이고 간단한 진공 여과 방법을 이용하여 집전체와 바인더가 없는 프리스탠딩 플렉서블 전극으로 제작되었다. 다공성 NiO를 첨가한 S/CNT/NiO 전극은 순수 S/CNT 전극에 비해 125 mA h g^-1 증가한 877 mA h g^-1 (0.2 C)의 초기 방전용량과 200 사이클 후 84% (S/CNT: 66%)의 우수한 용량 유지율을 나타내었다. 이는 방전 과정 중에서 NiO와 리튬 폴리설파이드의 강한 화학적 결합에 의하여 리튬 폴리설파이드의 전해질로 용출되는 것을 억제하여 나타난 결과이다. 또한 S/CNT/NiO 전극의 유연성 테스트를 위해 1.6 × 4 ㎠의 파우치셀로 제작하여 폴딩한 상태와 하지 않은 상태에서 모두 620 mA h g^-1의 안정적인 사이클 특성을 나타내었다. Porous NiO synthesized via hydrothermal synthesis was used in the electrodes of lithium-sulfur batteries to inhibit the elution of lithium polysulfide. The electrode of the lithium-sulfur battery was manufactured as a freestanding flexible electrode using an economical and simple vacuum filtration method without a current collector and a binder. The porous NiO-added S/CNT/NiO electrode exhibited a high initial discharge capacity of 877 mA h g^-1 (0.2 C), which was 125 mA h g^-1 higher than that of S/CNT, and also showed excellent retention of 84% (S/CNT: 66%). This is the result of suppressing the dissolution of lithium polysulfide into the electrolyte by the strong chemical bond between NiO and lithium polysulfide during the charging and discharging process. In addition, for the flexibility test of the S/CNT/NiO electrode, the 1.6 × 4 ㎠ pouch cell was prepared and exhibited stable cycle characteristics of 620 mA h g^-1 in both the unfolded and folded state.

Pulsed Wire Evaporation(PWE) Method으로 제조된 나노 NiO 분말의 SOFC 연료극 기능성층으로의 적용

김혜원,김동주,박석주,임탁형,이승복,신동렬,윤순길,송락현 한국수소및신에너지학회 2009 한국수소 및 신에너지학회논문집 Vol.20 No.6

In present work, NiO/YSZ anode functional layer was prepared by nano NiO powder and 8YSZ powder. The nano NiO powders were made by Pulsed wire evaporation (PWE) method. Nano NiO- YSZ functional layer was sintered at the temperature of 900-1400℃. The prepared functional layer was characterized by scanning electron microscopy (SEM) and electrochemical impedance spectroscopy. The nano NiO- YSZ anode functional layer sintered at 1300℃ shows the lowest polarization resistance. Nano NiO- YSZ anode functional layer shows about two times smaller polarization resistance than the anode functional layer made by commercial NiO-YSZ powders. Based on these experimental results, it is concluded that the nano NiO-YSZ cermet is suitable as a anode functional layer operated at 800℃.

Structural and Stoichiometry Change in NiO with a Thin IrO2 Layer

S. Yoon,E. Cho,C. Kim,S. Seo,J. Lee,R. Jung,D. Kim,H. Cheong,M. Bastjan,B. Schulz,M. Ruubhausen 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.6

An IrO2 layer has been proposed as the material for minimizing dispersion of several memory switching parameters of resistance-change random access memory devices using NiO. We present Raman scattering and ellipsometry measurements on NiO lms with and without an IrO2 layer. Our Raman measurements on the NiO films show that the addition of an IrO2 layer enhances the local crystalline quality, which is completely consistent with previous results. Moreover, we found an IrO2 layer to be associated with the changing stoichiometry in the NiO film. This can also be related to an abrupt change in the optical transition near 2.7 eV with IrO2, which is known to re ect the NiO stoichiometry. An IrO2 layer has been proposed as the material for minimizing dispersion of several memory switching parameters of resistance-change random access memory devices using NiO. We present Raman scattering and ellipsometry measurements on NiO lms with and without an IrO2 layer. Our Raman measurements on the NiO films show that the addition of an IrO2 layer enhances the local crystalline quality, which is completely consistent with previous results. Moreover, we found an IrO2 layer to be associated with the changing stoichiometry in the NiO film. This can also be related to an abrupt change in the optical transition near 2.7 eV with IrO2, which is known to re ect the NiO stoichiometry.

SnO₂ (<i>n</i>)-NiO (<i>p</i>) composite nanowebs: Gas sensing properties and sensing mechanisms

Kim, Jae-Hun,Lee, Jae-Hyoung,Mirzaei, Ali,Kim, Hyoun Woo,Kim, Sang Sub Elsevier Sequoia 2018 Sensors and actuators. B Chemical Vol.258 No.-

<P><B>Abstract</B></P> <P>Aiming to optimize SnO<SUB>2</SUB>-NiO nanocomposite sensors for detection of hazardous gases, a series of xSnO<SUB>2</SUB>-(1-x) NiO composite nanowebs with different compositions (x=0.1, 0.3, 0.5, 0.7, and 0.9) were synthesized using an electrospinning process. The formation of long and continuous SnO<SUB>2</SUB>-NiO nanowebs was verified. Depending on the composition, xSnO<SUB>2</SUB>-(1-x) NiO composite nanowebs‎ showed either <I>n</I>-type (SnO<SUB>2</SUB>-rich composition) or <I>p</I>-type (NiO-rich composition) gas-sensing behavior. The best sensing performance was obtained for the nanowebs of 0.5SnO<SUB>2</SUB>-0.5NiO. The presence of plenty of <I>p</I>-<I>n</I> heterojunctions along with the high oxygen adsorption property of NiO were the main reasons for the high response to the NO<SUB>2</SUB> and C<SUB>6</SUB>H<SUB>6</SUB> gases at this optimized composition.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We optimized SnO<SUB>2</SUB>-NiO nanocomposite sensors for detection of hazardous gases. </LI> <LI> Depending on the composition, SnO<SUB>2</SUB>-NiO composite nanowebs showed either <I>n</I>-type or <I>p</I>-type behavior. </LI> <LI> The <I>p</I>-<I>n</I> junctions, NiO with high oxygen adsorption capability, and crystallographic defects generated by possible substitution of Ni<SUP>+2</SUP> in Sn<SUP>+4</SUP> were the main reasons for the efficient sensing. </LI> </UL> </P>

Enhanced H₂S Sensing Performance of a <i>p</i>-type Semiconducting PdO-NiO Nanoscale Heteromixture

Balamurugan, C.,Jeong, Y.J.,Lee, D.W. Elsevier BV * North-Holland 2017 Applied Surface Science Vol.420 No.-

<P><B>Abstract</B></P> <P>Semiconducting nanocrystalline nickel oxide (NiO) and PdO-doped NiO heteromixture (2, 5 and 10 wt%) have been synthesized via a metal-citrate complex method. The obtained materials were further characterized using TG/DTA, FT-IR, UV-vis, XRD, XPS, BET/BJH, SEM and TEM analyses to determine their structural and morphological properties. The results indicated that the spherical, uniform PdO nanoparticles were densely deposited on the NiO surface mainly in diameters of 10–15nm. Moreover, the existence of various defect states was also analyzed with the help of photoluminescence (PL) spectroscopy. The gas response characteristics of synthesized materials were evaluated in the presence and absence of toxic gases such as hydrogen sulfide (H<SUB>2</SUB>S), carbon monoxide (CO), liquid petroleum gas (LPG), and ethanol (C<SUB>2</SUB>H<SUB>5</SUB>OH). The experimental results revealed that the sensitivity and selectivity of the NiO-based sensor material are dependent on the weight% of PdO loading in the NiO nanopowder. Among the investigated compound, the 5wt% PdO-doped NiO sensor material showed excellent sensitivity and selectivity to 100ppm H<SUB>2</SUB>S with a fast response/recovery characteristics of 6s and 10s, respectively. Furthermore, the 5wt% PdO-doped NiO based sensor showed a linear relationship between the different concentrations of H<SUB>2</SUB>S gas and a significantly higher response to H<SUB>2</SUB>S even at the low concentration of 20ppm (43%) at 60°C. The dominant H<SUB>2</SUB>S gas sensing mechanisms in the NiO and 5wt% PdO-doped NiO nanomaterials are systematically discussed based on the obtained characterization results.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We report detailed H<SUB>2</SUB>S gas sensing behaviour of NiO-PdO nanoscale heteromixtures prepared by the simple metal-citrate complex process. </LI> <LI> Materials obtained in the way are generally more homogenous, have higher surface area and finer particle size. </LI> <LI> 5wt % PdO-doped materials shows excellent sensitivity, selectivity and a fast response time upon repeated H2S exposure at 60°C. </LI> </UL> </P>