JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2021
·Vol. 32
·期 20
·24939-24952
·
IF 2.478
Guo Xiaoying,Zhang Weifeng,Wu Shan,Sun Chaozhong,Hu Changzheng,Liu Laijun,Fang Liang,Luo Nengneng
In this study, Ba 4 RCo 0.5 Nb 9.5 O 30 (R = La, Nd, Sm, Eu) (BRCN) ceramics were synthesized using a high-temperature solid-state reaction. The XRD refinement results show that ceramic samples are tetragonal tungsten bronze (TTB). As the radius of rare-earth ions decreases, the unit cell volume of BRCN ceramics decreases, and the radius difference between Ba 2+ and R ions increase, which results in BO 6 octahedral distortion and the Raman peaks shift to high frequency. In addition, as the radius of rare-earth ions decreases, the ionic displacements increase and thus the dielectric constant peak temperature goes up. The high-temperature impedance results show that there exists n-type electronic conduction in the samples. The remanent polarization of the P–E curve at low frequencies increases from 0.470 to 1.038 μC cm −2 as the rare-earth ion radius decreases.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2021
·
IF 5.316
Weiwei Zhang,Shengsong Du,Baosong Li,Tianyong Mei,Yicheng Miao,Hongqiang Chu,Jiajia Wang
In the present work, TiN nanoparticle reinforced Ni-Co alloy coatings have been synthesized by pulse current electrodeposition under the assistance of magnetic and ultrasonic agitation. Various analytical techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), atomic force microscope (AFM), X-ray photoelectron spectroscopy (XPS) were used to explore the effects of current densities and agitation modes on the coating composition, morphology and structure of the electrodeposits. The corrosion resistance of the composite coating was examined by electrochemical impedance spectroscopy (EIS) in 3.5 wt% NaCl solution. The electrodeposits prepared under magnetic stirring exhibit nodular-protrusion morphology. The ultrasonic-assisted electrodeposited Ni-Co/TiN coatings are flatter, finer, and denser compared to that of magnetic stirring. The agitation mode affects the Co and TiN content in the composite coatings. The preferred orientation was (111) texture, which was gradually changed to (200) plane as the current density increased. The crystallite size was 14–17 nm, 11–14 nm for the magnetic and ultrasonic-assisted electrodeposited Ni-Co/TiN coatings, respectively. The roughness of the samples prepared under ultrasonic agitation was lower than that of magnetic stirring. EIS measurements show that the composite coating prepared at 6 A dm −2 under ultrasonic assistance exhibits the best corrosion resistance with maximum R ct during the whole immersion period. The ultrasonic-assisted electrodeposited Ni-Co/TiN coating has a denser structure and better corrosion resistance than that prepared under mechanical stirring.
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JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2023
·
IF 3.9
Lu Liu,Xiao Li Zhu,Xiang Ming Chen
In the present work, the strategy of multielements co-substitution for BiFeO 3 ceramics was adopted to enhance the ferroelectricity and magnetoelectric coupling effect where the effective radius of rare-earth ions was equivalent to that of Sm 3+ . Differing from the case of Sm-substituted BiFeO 3 ceramics, the symmetry of the present ceramics changed from R3c to Pbnm directly without the formation of Pna 2 1 with increasing RE-substitution content. The ferroelectricity was significantly improved, and the saturated polarization−electric field ( P - E ) hysteresis loop with P r = 37.63 μC/cm 2 was obtained in Bi 0.95 (La 0.20 Nd 0.20 Sm 0.20 Gd 0.20 Lu 0.20 ) 0.05 FeO 3 ceramics. The leakage current was reduced by almost six orders of magnitude in multielements co-substituted BiFeO 3 ceramics, which was much lower than that of BiFeO 3 end-member. Moreover, the magnetoelectric coupling coefficient α ME of 0.96 mV/cm Oe was achieved in Bi 0.86 (La 0.20 Nd 0.20 Sm 0.20 Gd 0.20 Lu 0.20 ) 0.14 FeO 3 ceramics, which was larger than that of Sm-substituted BiFeO 3 ceramics. The strategy of multielements co-substitution might provide a new approach to improving ferroelectricity and magnetoelectric coupling effect in BiFeO 3 ceramics, which could be physically interpreted as the results of the reduced leakage current and increased local polarization configuration caused by the multiple elements substitution.
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ENERGY & FUELS
·
2022
·
IF 4.654
Weijun Zhang,Fen Li,Zhinan Fu,Sheng Dai,Fenghongkang Pan,Jinxia Li,Lihui Zhou
The appearance of mixed-metal MOF materials with abundant metal active sites, high porosity, large surface area, and, particularly, the synergistic effect between different metals which show prominent catalytic activity for oxygen evolution reaction (OER) has motivated profound research. Most of the related reports focus on the hydrothermal methods to prepare the mixed-metal MOFs containing metal ions such as Co, Ni, and Cr, etc. In this work, we proposed a facile impregnation method through an ion-exchange process to fabricate Fe-doped Co-BDC nanosheets (Fe@Co-BDC NSs) that represented significant enhancement for electrocatalytic OER. The tuning mechanism of the ion-exchange method was investigated by the morphology change and electronic structure of Fe@Co-BDC NSs, which should be important for an efficient OER catalyst. The optimized Fe@Co-BDC NSs (5 mM, 60 min) exhibited a significantly lower overpotential of 307 mV with a smaller Tafel slope of 34.1 mV·dec–1, as compared with the pure Co-BDC NSs.
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ACS Omega
·
2019
·
IF 2.584
Bo Lin,Aiyong Wang,Yanglong Guo,Yuanqing Ding,Yun Guo,Li Wang,Wangcheng Zhan,Feng Gao
Co-, Ni-, and Zn-containing MOFs are prepared and then pyrolyzed to generate materials for ambient temperature NO adsorption. Materials containing Co are much more efficient for NO adsorption than those containing Ni and Zn; therefore, Co is identified as the active phase. The best performing material studied here achieves 100% low concentration (10 ppm) NO adsorption for more than 15 h under a weight hourly space velocity of 120 000 mL g–1 h–1. Powder X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared, and Raman spectroscopies, along with scanning electron microscopy and TEM, are used to probe the physicochemical properties of the materials, particularly the Co active phase, and chemistries involved in NO adsorption–desorption. NO adsorbs on oxygen-covered Co nanoparticle surfaces in the form of nitrates and desorbs as NO at higher temperatures as a result of surface nitrate decomposition. NO storage capacity decreases gradually upon repeated NO adsorption–desorption cycles, likely because of Co3O4 formation during these processes.
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PubMed
高影响因子
ENERGY & FUELS
·
2020
·
IF 3.421
Wei Zhao,Shanshan Ruan,Siyu Qian,Beibei Feng,Chengcheng Ao,Lei Wang,Fuyi Liu,Lidong Zhang
Catalytic combustion has become a promising technology to address the accelerating volatile organic compounds (VOCs) emissions. In this work, cobalt modified ZSM-5 zeolite catalysts (3–18 wt % Co) were prepared to investigate the combustion of n-butane (one typical model component of VOCs). The performances of catalysts were evaluated by conducting experiments in a flow tube reactor. XRD, BET, FT-IR, and XPS were also utilized to characterize their physicochemical properties. A significant enhancement of the catalytic activity was demonstrated in terms of the cobalt supported over ZSM-5, with an optimal cobalt loading of 7 wt %. The excellent catalytic activity of 7 wt % Co-ZSM-5 is mainly attributed to a higher concentration of active surface Co3+ species. Furthermore, DFT calculations indicated that the role of Co can enhance the activity by decreasing the activation barriers for C–H bond cleavage. In addition, the primary reaction mechanism of n-butane combustion on Co-ZSM-5 was also revealed.
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IONICS
·
2020
·Vol. 27
·期 1
·351-360
·
IF 2.394
Wang Jia,Rui Jiayi,Yin Jingzhou,Zhou Guolang,Zhu Lili,Wang Hao,Zhao Pusu,Zhang Lili
Two-dimensional Mg-substituted cobalt hydroxides (Co x Mg y (OH) z ) with different crystal phases were synthesized via a facile reaction of magnesium (Mg) powder and cobalt aqueous solution. The phases of Co x Mg y (OH) z (amorphous phase and β phase) were controlled by adjusting the cobalt salt precursors. The obtained hybrid amorphous Co x Mg y (OH) z (a-Co x Mg y (OH) z ) showed excellent specific capacitance (662.2 F g −1 , 1 A g −1 ) than β phase Co x Mg y (OH) z (β-Co x Mg y (OH) z ) and pure Co(OH) 2 (p-Co(OH) 2 ). Additionally, the hybrid supercapacitor assembled with a-Co x Mg y (OH) z and the activated carbon showed high specific capacitance (77.8 F g −1 , 1 A g −1 ) and ultrahigh cycling stability with 99.7% retention of the first capacitance at 10 A g −1 after 5000 cycles.
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RSC Advances
·
2015
·Vol. 5
·期 85
·69263-69267
·
IF 3.84
Zhaokun Yang,Dongjian Shi,Xiaodong Zhang,Huanhuan Liu,Mingqing Chen,Shirong Liu
Polyacrylamide (PAM) hydrogel photonic crystals with an inverse opal structure were elaborated using a modified vertical deposition approach involving a co-deposition motif. Free-standing inverse opal hydrogel (IOH) films of different thicknesses that could be peeled from the support were first fabricated. A three-dimensional ordered structure without over-layers could easily be acquired by the co-deposition approach. Moreover, the bi-continuous structure was not affected by the increase in film thickness. All these IOH films showed a fascinating pH response property after hydrolysis, and the color change corresponding to the shift of the Bragg diffraction peak of the acquired hydrogel photonic crystal films could be easily distinguished by the naked eye. Three types of IOH films with different thicknesses showed similar pH response properties. The co-deposition approach is found to be suitable for the construction of thicker IOH film without over-layers.
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高影响因子
International Journal of Electrochemical Science
·
2023
·
IF 1.5
Muhammad Sumair Sultan,Waqar Uddin,Salma Hamza,Abdullah K. Alanazi
Replacement of expensive state-of-art catalysts by cost-effective transition metal/composites is not only ease production of oxygen from water by electrochemical technique but also a step for the betterment of the green environment. In this regard, a composite of nickel and cobalt doped molybdenum disulfide (CoNiMoS 2 ) electrochemical catalyst was synthesized by a hydrothermal method which was found efficient for oxygen evolution reaction (OER) in an alkaline medium with an overpotential of 1.477 mV at a current density of 1.0 mA.cm −2 . Morphology of catalysts were analyzed through SEM & TEM. The brief explanation is that the pristine MoS 2 and NiMoS 2 were appeared flower-like petal nano-sheets whereas CoMoS 2 & CoNiMoS 2 seemed as a cubic structures. XRD & X-ray patterns has confirms crystallinity and composition of elements in composites. With the help of linear swept voltammetry (LSV) and electrochemical impedance spectroscopy (EIS), the polarization curves and charge transference resistance of catalysts were examined respectively.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2014
·
IF 2.93
Qizhao Wang,Guoxia Yun,Yan Bai,Ning An,Yutao Chen,Rongfang Wang,Ziqiang Lei,Wenfeng Shangguan
TiO 2 photocatalysts loaded CuS and NiS as co-catalyst were prepared by hydrothermal approach and characterized by XRD , UV–visible DRS , BET, XPS, SEM and TEM. When TiO 2 was loaded MS as co-catalyst, it showed higher photocatalytic activities for splitting water into hydrogen in methanol aqueous solution under 500 W Xe lamp. Among the photocatalysts with various compositions , the maximum evolution of H 2 obtained from 5 wt% CuS – 5 wt% NiS – TiO 2 sample was about 800 μmol h −1 , which was increased up to about twenty-eight times than that of TiO 2 alone. It was proven that CuS, NiS can act as effective dual co-catalysts to enhance the photocatalytic H 2 production activity of TiO 2 .
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JOURNAL OF LUMINESCENCE
·
2019
·
IF 2.961
Olga Giraldo Giraldo,Mingzhi Fei,Rongfei Wei,Liming Teng,Zhigang Zheng,Hai Guo
Bi 3+ /Eu 3+ -doped SiO 2 –Al 2 O 3 –CaO–B 2 O 3 –La 2 O 3 –K 2 O glasses were fabricated and the luminescent properties, energy transfer as well as thermal stability were systematically investigated. Under 333 nm light excitation, bluish-green luminescence centered at 480 nm is observed in the obtained Bi 3+ -doped glass. By co-doped with Eu 3+ , highly efficient energy transfer process happens from Bi 3+ to Eu 3+ via a quadrupole-quadrupole interaction. The energy transfer efficiency can reach 86% and the concentration of Eu 3+ is not quenched in here. With increasing Eu 3+ concentration, tunable luminescence from bluish-green via white to orange-red is realized. Significantly, pure white light emission with CIE coordinates (0.348, 0.333) is obtained when excited by 333 nm light. Temperature-dependent emission spectra present superior color stability in operating temperature lower than 423 K for the prepared glasses. These results indicate that these glasses are potential white light emitting materials for organic-resin-free W-LEDs.
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APPLIED CATALYSIS B-ENVIRONMENTAL
·
2019
·
IF 14.229
Xiangdong Kong,Yan Liu,Pai Li,Jingwen Ke,Zhongyu Liu,Fawad Ahmad,Wensheng Yan,Zhenyu Li,Zhigang Geng,Jie Zeng
As CO 2 coordination with the metal sites in molecular catalysts represents an effective means to CO 2 activation, it is important to develop molecular catalysts with high ability of CO 2 coordination to enhance their catalytic performance in CO 2 electroreduction. Herein, we investigated the coordinate activation of CO 2 with Co-based molecular catalysts by manipulating their ligand structures. During CO 2 electroreduction, the current density of Co-salophen for CO was −16.0 mA cm −2 at −0.75 V versus reversible hydrogen electrode ( vs RHE), which was 7.6 times of that (−2.1 mA cm −2 ) of Co-salen. In addition, the Faradaic efficiency (FE) of Co-salophen for CO reached 75 % at −0.70 V vs RHE, whereas the FE of Co-salen for CO production was 19 %. In-situ experiments and mechanistic studies revealed that both Co-salophen and Co-salen adopted a side-on coordination of CO 2 with Co sites. Moreover, the bonding between CO 2 and Co sites was strengthened in Co-salophen, resulting in the enhanced activity of Co-salophen.
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