JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY
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2015
·Vol. 78
·期 2
·293-298
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IF 1.532
Cui Hongtao,Ma Wenle,Wang Li,Xue Junying
Abstract
In this work, α-Co(OH) 2 monolayer nanosheets were prepared by an intercalation agent-free route utilizing a precipitation reaction between epoxide and aqueous complexes of cobalt ions ([Co(H 2 O) 6 ] 2+ ). The protonation and the following ring-opening reaction of epoxide promoted the hydrolysis of [Co(H 2 O) 6 ] 2+ , leading to the formation of α-Co(OH) 2 nanosheets. The obtained nanosheets were then exfoliated to monolayer nanosheets in formamide under ultrasonic vibration. A possible exfoliation mechanism is proposed for the exfoliating process of α-Co(OH) 2 nanosheets. The water molecules incorporated in the layered structure of α-Co(OH) 2 are considered to be the key medium for the layer exfoliation. It seems that the water molecules coordinated with the cobalt ions weakened the interlayer interaction. Therefore, the extraction of water molecules by formamide readily broke the interlayer connection in α-Co(OH) 2 , resulting in the exfoliation of nanosheets. Graphical Abstract α-Co(OH) 2 monolayer nanosheets were prepared by an intercalation agent-free route utilizing a precipitation reaction between epoxide and aqueous complexes of cobalt ions ([Co(H 2 O) 6 ] 2+ ).
研究领域:
材料科学
·
化学
✓ 已验证
产品关联
DOI
高影响因子
ENERGY & FUELS
·
2021
·
IF 3.605
Hairong Tang,Yong He,Peixi Liu,Jiaming Shao,Fawei Lin,Zhihua Wang
Zeolitic-imidazolate framework precursors (ZIF-67) were synthesized in an inorganic solution with triethylamine as a deprotonating agent for N2O decomposition, and the catalytic activities of the pyrolysis products under different conditions were investigated. Among them, the Co/CoOx@carbon catalyst pyrolyzed at 650 °C in a N2 atmosphere (Co-650N) exhibited excellent low-temperature catalytic activity and stability, achieving 50% decomposition efficiency at 305 °C and ∼100% at 400 °C, which benefitted from its large specific surface area, great reduction performance, abundant cobalt active sites, and surface oxygen species. Further, utilizing temperature-programmed desorption (TPD) and in situ diffused reflectance infrared Fourier transform spectroscopy (DRIFTS) results, it was found that N2O molecules preferentially combined with oxygen species bound to cobalt sites. The absorbed N2O was decomposed into N2 and oxygen species, and the latter was subsequently transferred to carbon frameworks. Interestingly, the amorphous graphitic carbon frameworks played an important role in transferring/storing active oxygen and regenerating cobalt sites. Moreover, Co-650N exhibited better resistance to SO2, and the efficiency could be recovered via heating and finally stabilized at 100%. Finally, the mechanisms of N2O decomposition and sulfur poisoning-reactivation on Co/CoOx@carbon catalysts were proposed for the first time.
研究领域:
催化化学
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环境科学
·
材料科学
✓ 已验证
DOI
高影响因子
ACS Sustainable Chemistry & Engineering
·
2024
·
IF 7.1
Jitong Deng,Yanan Zhang,Hongjing Han,Yongjun Zhang,Haiying Wang,Xuzhong Gong,Yanguang Chen
The chemical looping conversion of CH4 has been one of the most promising technologies for achieving the “two-carbon” strategy. Fe2O3 oxygen carrier cannot maintain the excellent release performance of lattice oxygen at high temperature due to the sintering and carbon deposition. Therefore, quaternary La1–xSrxFe1–y CoyO3 perovskite was selected as the transfer support of oxygen ions. By using the MOF precursor method, ternary La0.8Sr0.2FeO3 was prepared via the introduction of metal Sr into the binary LaFeO3. The adsorption energy of CH4 on the La0.8Sr0.2FeO3 was the lowest (−0.054 eV), compared with separate Fe2O3 and LaFeO3, and the adsorption energy of free H at the adjacent Fe site was the lowest (1.650 eV). Furthermore, the La1–xSrxFe1–yCoyO3 perovskite was successfully synthesized by the doping of Co into the ternary La0.8Sr0.2FeO3. La0.8Sr0.2Fe0.8Co0.2O3 was chosen to composite Fe2O3 oxygen carrier. As m(Fe2O3):m(La0.8Sr0.2Fe0.8Co0.2O3) = 1:1, the lattice oxygen conversion rate was less than 47% and the selectivity of CO2 reached 99.5% through the synergistic effect of lattice oxygen and oxygen vacancies. Fe2O3–La0.8Sr0.2Fe0.8Co0.2O3 increased the lattice oxygen conversion by 17.6%, compared with Fe2O3–La0.8Sr0.2FeO3. After the CH4 chemical looping conversion cycles five times, Fe2O3–La0.8Sr0.2Fe0.8Co0.2O3 still had favorable structural stability and oxidation performance, and the lattice oxygen conversion rate still reached >95%.
研究领域:
材料科学
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能源工程
✓ 已验证
产品关联
DOI
高影响因子
PROCESS SAFETY AND ENVIRONMENTAL PROTECTION
·
2024
·
IF 6.9
Dawei Lan,Huiwen Zhu,Jianwen Zhang,Fan Wang,Yueying Zheng,Zeyu Guo,Gang Yang,Mengxia Xu,Tao Wu
Metal-organic frameworks (MOFs) is a promising material that can be used in many fields, including environmental remediation. In this work, a novel adsorbent was successfully prepared by doping the Co element into the framework of UiO-66 with an in-situ oil bath synthesis. This modification ensured that the materials retained relatively good crystallinity. The Co-doping process had a major impact on the particle size and morphology of the original MOFs. The CoUiO-2 exhibited larger surface area and pore size than pristine UiO-66. Accordingly, the maximum adsorption amount of malachite green (MG) on CoUiO-2 (628.93 mg/g) was significantly larger compared with UiO-66 (343.64 mg/g), which was due to more active adsorption sites. In addition, the CoUiO-2 also showed a superior adsorption capacity on rhodamine B (RhB) (1106.22 mg/g). The adsorption process was well described by both the pseudo-second order and Langmuir models, indicating it was dominated by chemisorption and the adsorbent had a homogeneous surface area for adsorption. Therefore, the CoUiO-2 material could be a promising adsorbent for wastewater treatment . This work can provide an important insight into the modification of MOF materials and identify further opportunities to promote the adsorption performance in environmental remediation.
研究领域:
环境科学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Environmental Chemical Engineering
·
2023
·
IF 7.7
Chen Cai,Jiayin Chen,Wei Fu,Shuying Ning,Hao Zhou,Muhammad Kashif,Yaxin Su
The Ce-modified OMS-2 catalyst (Ce x -OMS-2) was synthesized by the hydrothermal synthesis method, after which its catalytic efficacy in the selective reduction of NO by CO was assessed. The experiments showed that Ce 0.08 -OMS-2 was capable of 100% NO conversion between 175 and 300 °C when 0.05%NO, 0.1%CO, 5%O 2 and N 2 were used as equilibrium gases, and the N 2 selectivity peaked at 93.2% at 175 °C. Additionally, Ce 0.08 -OMS-2 exhibits good sulfur resistance in the presence of 0.02% SO 2 and maintains more than 88% NO conversion at 175–275 °C. By using BET, XPS, H 2 -TPR, NH 3 -TPD, and In situ DRIFTS to characterize the catalysts, the effects of doping the active metal Ce on the physicochemical characteristics of OMS-2 catalysts were under investigation. In conclusion, the improvement of the low-temperature activity of the Ce x -OMS-2 catalyst is facilitated by lower agglomeration and crystallinity , larger specific surface area, smaller average pore size, enhanced surface oxygen vacancies, increased Mn 4+ concentration, and richer Brønsted acid. Reaction gas adsorbed species and intermediates on the catalyst surface were dynamically captured during In situ DRIFTS experiments. The CO-SCR reaction of the catalyst was found to follow the E-R mechanism below 200 ℃ and the L-H mechanism at 200–350 ℃.
研究领域:
环境科学
·
催化化学
✓ 已验证
DOI
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2024
·
IF 8.1
Shiyong Xu,Mei Li,Ziyu Li,Meijuan Ding,Yijun Wang,Zhiliang Jin
NS-CQDs were synthesized by a hydrothermal method using high-sulfur lignite as the carbon source. Modification of Ni-MOF and Co/Zr-MOF using NS-CQDs to explore the performance of composite photocatalysts for hydrogen production . It was found that NS-CQDs significantly enhanced the hydrogen precipitation performance of the composite photocatalysts compared with the MOFs catalysts alone, and the highest hydrogen precipitation rate of the novel composite photocatalyst 5%NS-CQDs/NCZ2 reached 3662.68 μmol g −1 h −1 . It can be inferred from the conduction band and valence band positions of Ni-MOF, Co/Zr-MOF and NS-CQDs that a double S-type heterojunction is formed. The presence of thiophene and pyrrole nitrogen in NS-CQDs can promote electron transport , reduce the rate of electron-hole pair complexation, and improve the hydrogen evolution activity of the 5%NS-CQDs/NCZ2.
研究领域:
材料科学
·
能源化学
✓ 已验证
产品关联
DOI
高影响因子
Materials Today Nano
·
2021
·
IF 8.109
B. Yi,H. Zhao,L. Cao,X. Si,Y. Jiang,P. Cheng,Y. Zuo,Y. Zhang,L. Su,Y. Wang,C.-K. Tsung,L.-Y. Chou,J. Xie
Mixed-metal metal-organic frameworks (MM-MOFs) contain more than one type of metal node, which can improve or even introduce new features compared with the single metal frameworks. Traditionally, most of the MM-MOFs are synthesized by solution method which requires all the metal ions to form stable coordination with the ligand in a single framework and therefore limits the choice of the metal ions. In this work, Pt-doped Zn-MOF-74 (PtZn-MOF-74) has been prepared through a mechanochemical conversion approach from Pt-doped ZnO (Pt–ZnO) directly. The absence of a large quantity of solvent limits the solvation and diffusion of growth species during the mechanochemical conversion and therefore prevented the agglomeration of Pt dopants in PtZn-MOF-74. CO oxidation was used to evaluate the catalytic performance of the prepared MM-MOFs. Compared with inert Zn-MOF-74, PtZn-MOF-74 with unsaturated coordinated Pt at elevated temperature can act as the active sites to catalyze CO oxidation reaction. This study provides a novel design strategy for the synthesis of MM-MOFs with extended functionalities.
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Huihui Deng,Baozhen Li,Wenchun Zheng,Qin Sun,Mengjia Zhu,Jun Zuo,Yu Tang,Lizhi Wu,Li Tan
Propane dehydrogenation is one of the most promising routes for propylene production due to its single reactant, product and high economic efficiency. For Co-based catalysts, the state of Co species is one of the important factors affecting the performance of propane dehydrogenation. Here, we designed zeolite Silicalite-1 (S-1) with different silanol nests content as support to investigate the effect of silanol nests content to form Td-Co(II) species. It is found that the content of silanol nests in the S-1 supports have a linear correlation with the formation of T d -Co(II) species and corresponding PDH catalytic activity through the study of the catalyst structure-performance relationship. And the silanol nests of S-1 could be fully coordinated with 0.5 wt% Co content over 0.5Co/S-1-1-HTS in the form of T d -Co(II) species to maximize the Co atomic utilization. Correspondingly, 0.5Co/S-1-1-HTS shows the most excellent catalytic activity and stability, with C 3 H 6 generation rate of 3014 mmol C 3 H 6 g Co −1 h −1 and deactivation rate of 0.07 h −1 at 550 °C.
研究领域:
化学工程
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催化科学
✓ 已验证
产品关联
DOI
高影响因子
Materials Science and Engineering B-Advanced Functional Solid-State Materials
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2025
·
IF 4.6
Feng Hu,Jing Li,Xiaoling Peng,Shan Tao,Jingcai Xu,Bo Hong,Xinqing Wang
In this study, the novel Co/C/LaFeO 3 composites were synthesized by in-situ growth of LaFeO 3 on Co/C derived from ZIF-67. The electromagnetic wave (EMW) absorption performance of the Co/C/LaFeO 3 composites was investigated with varying proportions of Co/C and LaFeO 3 . When the weight ration of Co/C to LaFeO 3 was 2:1, the Co/C/LaFeO 3 composites exhibited a remarkable minimum reflection loss (RL min ) of −57.8 dB and demonstrated an effectively absorbing broadband (EAB, RL min ≤ -10 dB) of 5.12 GHz at 1.7 mm. Benefiting from the combined impact of Co nanoparticles, carbon layer, and LaFeO 3 , diverse interfaces and conductive networks were formed, and optimized impedance matching was obtained. In addition, the incorporation of LaFeO 3 significantly enriched the electromagnetic loss mechanisms, ultimately enhancing the comprehensive EMW absorption efficiency of the Co/C/LaFeO 3 composites. This research serves as an essential guide for designing and synthesizing MOF-derived carbon composites with significant EMW absorption capacities.
研究领域:
材料科学
·
电磁学
✓ 已验证
产品关联
DOI
高影响因子
Molecular Catalysis
·
2024
·
IF 3.9
Wen-Xia Zhang,Xi Zhao,Lin-Ya Xu,Shuang Xia,Yu-Fen Zhou,Chong-Lai Chen,Hai-Hua He,Meng-Fei Luo,Jian Chen
The surface Pt species and adsorbed oxygen on the Pt/ZrO 2 catalyst were successfully modulated by altering the preparation methods, resulting in distinct catalytic behaviors for CO, n-heptane, and toluene oxidation. The Pt/ZrO 2 catalyst was initially prepared via wetness impregnation and subsequently reduced in an H 2 atmosphere to obtain the Pt/ZrO 2 -R catalyst. In contrast, the Pt/ZrO 2 -E catalyst was synthesized using ethanol solvent (also serving as a reducing agent) instead of water during wetness impregnation. Moreover, the pre-prepared Pt nanoparticles were loaded onto the ZrO 2 surface using polyvinylpyrrolidine (as a protective and structure directing agent) dissolved in ethanol solvent to fabricate the Pt/ZrO 2 -EP catalyst. Among these catalysts, the Pt/ZrO 2 -R exhibits superior catalytic activity towards CO oxidation due to its abundant metallic Pt species. It is found that activity of Pt/ZrO 2 catalyst for n-heptane oxidation is positively correlated with its surface adsorbed oxygen concentration, thus the highest activity is achieved over the Pt/ZrO 2 -EP catalyst possessing a higher concentration of surface adsorbed oxygen species. Unlike CO and n-heptane oxidation, toluene oxidation activity is affected by multiple factors, it is primarily promoted by synergistic catalysis between metallic Pt species (Pt 0 ) and surface adsorbed oxygen species over the Pt/ZrO 2 -EP catalyst. Our preliminary findings underscore that precise modulation of sensitive active sites on surfaces plays a critical role in specific catalytic reactions.
研究领域:
催化化学
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材料科学
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环境科学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2013
·
IF 5.825
Qiying Liu,Yuwei Bie,Songbai Qiu,Qi Zhang,Jani Sainio,Tiejun Wang,Longlong Ma,Juha Lehtonen
Co/MgO, Co/SiO 2 and Co/Hβ catalysts were prepared by incipient wetness impregnation. The formation of MgO-CoO solid solution and MgCo 2 O 4 spinel in Co/MgO resulted in high dispersions of Co on MgO even at the low calcined temperatures and the high Co loadings. The second impregnation of Co on Co/MgO enhanced Co cations in surface/subsurface of catalysts, which led to the enlarged metallic Co particle sizes by H 2 reduction. Comparatively, the highly dispersion of Co was only observed on SiO 2 and Hβ at the low Co loadings owing to the Co δ + species of strong interactions with these supports. The solid solution/spinel and the strongly interacted Co δ + species induced the Co cations reduced at higher temperatures with obtaining the small Co particle sizes. These cases also significantly decreased the basicities of Co/MgO depending on calcined temperature and Co loadings, and increased the acidic sites of Co/SiO 2 and Co/Hβ with obtaining enhanced acidities, respectively. During hydrogenolysis processing, the basic sites of Co/MgO triggers the splitting of acyl C O bond of methyl heptanoate to form heptanal and methanol, followed by further hydrogenation of heptanal to 1-heptanol. While the acidic Co/SiO 2 and Co/Hβ induce the cracking of ether C O bond to heptanoic acid and CH 4 . Heptanoic acid intermediate is then converted into C 6 and C 7 alkanes by the parallel decarbonylation and HDO pathways, respectively. The activity and product distribution could be facilely mediated by the synergistic catalysis of metal and acid/base. Under optimal conditions, the maximal 1-heptanol and summed C 6 /C 7 alkanes yields of 55% and 89% were observed over Co/MgO and Co/SiO 2 with desire Co loadings, respectively, indicating the promising applications of these catalysts in hydrogenolysis of vegetable oils.
研究领域:
催化化学
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能源材料科学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2020
·
IF 6.182
Hongming Zhang,Lu Zhang,Ismael A. Rodríguez-Pérez,Wenkang Miao,Kangli Chen,Wenfeng Wang,Yuan Li,Shumin Han
Sodium borohydride (NaBH 4 ) is widely identified as a promising hydrogen storage material, therefore, developing a catalyst with high efficiency for hydrogen production is an important subject for development and utilization of hydrogen energy. Meanwhile the hydrolytic mechanism of NaBH 4 needs further study which is helpful for hydrolysis researches. In this study, an efficient catalyst comprising of carbon nanospheres (CNSs) supporting ultrafine bimetallic Pt-Co nanoparticles (CNSs@Pt 0.1 Co 0.9 ) has been successfully synthesized for hydrogen evolution from NaBH 4 hydrolysis. The growth of the Pt-Co nanoparticles on the surface of CNSs is regulated by adjustment of solvent during the preparation. The as-prepared CNSs@Pt 0.1 Co 0.9 catalyst exhibits an outstanding performance in the kinetic and thermodynamic tests with the highest hydrogen generation rate (HGR) of 8943 mL H2 ·min −1 ·g M –1 , initial turnover frequency (TOF) value of 280.1 moL H2 ·min −1 ·mol Pt –1 , and a low activation energy ( E a ) of 38.0 kJ·mol −1 . The hydrolytic mechanism has been surveyed simultaneously by the isotopic tracer method through the mass spectrometric analysis. The catalyst retains extremely high catalytic activity value and the hydrogen generation conversion is still 100% even after five cycles in the catalytic performance tests.
研究领域:
材料科学
·
催化化学
·
能源化学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）