ACS Catalysis
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2021
·
IF 13.084
Jinqiu Guo,Zongjing Feng,Jun Xu,Jie Zhu,Guanghui Zhang,Yaping Du,Hongbo Zhang,Chunhua Yan
Ethanol transformation with high product selectivity is a great challenge, especially for high weight molecules. Here, we show a combination study of kinetic, thermodynamic, and in situ spectroscopy measurements to probe the selective upgrading of ethanol over lamellar Ce(OH)SO4·xH2O catalysts, with 60–70% Ce3+ preserved during the catalysis. High methyl phenols (MPs) selectivity at ∼80% within condensation products was achieved at ∼50% condensation yield (3.0 kPa C2H5OH, 15 kPa H2, Ar balanced, 693 K, 1 atm, gas hourly space velocity (GHSV) ∼5.4 min–1), with acetaldehyde, acetone, 4-heptanone, and 2-pentanone as the key reaction intermediates. Kinetic measurements with the assistance of isotope labeling proved that MPs generated from the kinetically relevant step (KRS) of C–C bond coupling of enolate nucleophilically attacks surface C2H4O following a Langmuir–Hinshelwood model. Low ethanol and water pressures and high acetaldehyde and hydrogen pressures were proved to be favored for MPs generation rather than dehydration, in which hydrogen could reduce the amount of lattice oxygen and facilitate the preparation of MPs while water and ethanol both compete with acetaldehyde for active sites during catalysis. On the basis of in situ X-ray diffraction (XRD), quasi-in situ X-ray photoelectron spectroscopy (XPS), and Raman characterizations, the Ce(OH)SO4 crystal structure was proved to be maintained along with ethanol activation, and the Ce3+–OH Lewis acid–base pair was proved to be the active species for the selective C–C bond coupling. The KRS assumption was also supported by the apparent activation energy assessment within the reaction network on dehydration, dehydrogenation, aldol condensation, and cyclization and a series of negligible kinetic isotope effects (KIEs). This system can be easily extended to some other systems related to C–C bond coupling and is attracting attention on converting oxygenate platform molecules over lanthanide species.
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JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
·
2021
·
IF 8.067
Guanglu Li,Chang Liu,Zhao Zhang,Baihua Cui,Yanan Chen,Yida Deng,Wenbin Hu
Oxygen evolution and oxygen reduction are considered as essential processes in the energy conversion devices. The progress of cost-effective bifunctional catalysts has become a critical issue to be solved. Here, we report that Co(OH) 2 @N-doped carbon (NC) was facilely synthesized through the impregnation strategy of metal-organic frameworks derived carbon and cobalt ions. N-doped carbon with porous structure and cobalt hydroxide nanosheets play a synergistic effect role, representing excellent catalytic performance toward oxygen evolution and reduction reactions. The obtained Co(OH )2 @NC exhibits remarkable activity in terms of a lower overpotential of 330 mV@10 mA cm −2 for OER and a more positive half-wave potential (E 1/2 = 0.84 V) for ORR in alkaline medium, outperforming IrO 2 and Pt/C. Due to its superior bifunctional catalytic performance, Co(OH) 2 @NC catalyst is applied into a promising air electrode of Zn-air battery. This presented strategy of impregnation synthesis in this work provides a new design direction for practical electrochemical energy devices.
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ACS Applied Materials & Interfaces
·
2020
·
IF 8.758
Xianshu Qiao,Hongjun Kang,Yang Li,Kai Cui,Xin Jia,Henghao Liu,Wei Qin,Max Pupucevski,Gang Wu
We report a highly efficient and stable electrode composed of a porous Fe-doped β-nickel hydroxide nanopyramid array supported on nickel foam (U–Fe-β-Ni(OH)2/NF) for overall water splitting. The unique structure is assembled via a self-templated strategy by utilizing the FeNi oxalate (FeNi–C2O4/NF) nanopyramid as the templates, followed by an anion-exchange reaction at room temperature. Due to the intrinsic activity of Fe-doped β-Ni(OH)2 along with unique porous array structures consisting of two-dimensional (2D) active materials on three-dimensional (3D) conductive substrates, the developed electrode exhibited outstanding electrocatalytic activity for both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in an alkaline medium. The introduced amount of Fe plays a significant role in promoting OER and HER activity compared to the β-Ni(OH)2 electrode. The optimal electrode (U–Fe-β-Ni(OH)2/NF-2) generated a current density of 10 mA cm–2 at low overpotentials of 218 mV for the OER and 121 mV for the HER. The electrode also demonstrated considerably stable performance during the continuous water splitting process. Furthermore, we elucidated the promotion mechanisms of the active Fe-doped β-Ni(OH)2 compound for the OER and HER based on extensive characterization and electrochemical measurements. Hence, this work provides a facile approach to developing low-cost, efficient, and stable hydroxide-based electrodes for bifunctional OER and HER in water splitting.
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COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2020
·
IF 3.99
Bin Yan,Ji Lan,Yueshan Li,Yinjie Peng,Lingying Shi,Rong Ran
In this paper, hexagonal Ni(OH) 2 nanosheets were prepared by hydrothermal method with nickel chloride hexahydrate as matrix and ammonia as precipitant. The lateral size of Ni(OH) 2 nanosheets was about 100–250 nm. The structure of the Ni(OH) 2 sheets was characterized by XRD , SEM , IR, TGA etc. Pickering emulsion was prepared by using Ni(OH) 2 nanosheets as stabilizer and dichloromethane (DCM) as oil phase. Furthermore, the stability factors of Pickering emulsion and the adsorption of Congo red (CR) on interface particle layer were studied. The adsorption equilibrium of CR was analyzed by Langmuir adsorption model and Freundlich adsorption model, and the adsorption process was researched by pseudo-first-order kinetics and pseudo-second-order kinetics. Compared with Ni(OH) 2 in the water phase, the Ni(OH) 2 in interface particle layer exhibited a much higher adsorption capacity and a faster deposition rate . The adsorption mechanism of CR can be mainly attributed to electrostatic interaction between the positively charged interface particle layer and the anionic CR molecules. It can be expected that as a promising adsorbent for CR removal in water treatment, the Ni(OH) 2 sheets in Pickering interface layer can provide a new strategy for dye adsorption.
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JOURNAL OF ENVIRONMENTAL MANAGEMENT
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2020
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IF 5.647
Shuo Li,Jia Liu,Tianwei Tan,Jiapei Nie,Huili Zhang
To reduce the emission of greenhouse gases, the substitution of fossil fuel by renewable energy sources is increasingly important. Matching energy supply and demand is however required, even more so if intermittent renewable energy sources are employed. Thermal energy storage then offers significant advantages. Thermo-chemical energy storage systems, using reversible reactions, have a high reaction enthalpy that exceeds the storage capacities of sensible and latent heat modes. Magnesium hydroxide is a candidate TCES material for such a system at temperature around 300 °C, and adaptable when doping Mg(OH) 2 with metal salts. Both pure Mg(OH) 2 and its composites with 1, 3, 6 and 10 wt% LiNO 3 are studied. The present work validates this TCES process and develops reaction rate equations needed for its design. The LiNO 3- doping significantly reduces the onset temperature of dehydration. For pure Mg(OH) 2 , the temperature is 325 °C. It is reduced to 289 °C when 1 wt% LiNO 3 is present, and further reduced to 269 °C at a dosage of 10 wt% LiNO 3 . Whereas the dehydration of pure Mg(OH) 2 is slow, with a rate constant k of 1.72 10 −5 s −1 at 300 °C, adding increasing amounts of LiNO 3 progressively increases the reaction rate constant to ~10 −2 s −1 at 300 °C when 10 wt% LiNO 3 is present. The kinetic expressions enable to predict the conversion yield and amount of heat stored or released for any desired temperature and selected duration of the heat-induced dehydration. LiNO 3- doped Mg(OH) 2 have a high potential in TCES applications when the heat source is available at temperatures between 250 and 400 °C, since the equilibrium temperature and the extent of de-hydration Mg(OH) 2 can be tuned to the required temperature range by adding different wt% of LiNO 3 .
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RSC Advances
·
2021
·Vol. 11
·期 53
·33626-33636
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IF 3.361
Leliang Wu,Yiting Lin,Yimin Zhang,Peng Wang,Mingjun Ding,Minghua Nie,Caixia Yan,Shiyao Chen
Alkaline substances could activate peroxymonosulfate (PMS) for the removal of organic pollutants, but relatively high alkali consumption is generally required, which can cause too high pH of the solution after the reaction and lead to secondary pollution. Within this study, PMS activated by a relatively low dosage of Ca(OH)2 (1 mM) exhibited excellent efficiency in the removal of bisphenol S (BPS). The pH of the solution declined to almost neutral (pH = 8.2) during the reaction period and conformed to the direct emission standards (pH = 6–9). In a typical case, BPS was completely degraded within 240 min and followed the kinetics of pseudo-first-order. The degradation efficiency of BPS depended on the operating parameters, such as the Ca(OH)2, PMS and BPS dosages, initial solution pH, reaction temperature, co-existing anions, humic acid (HA), and water matrices. Quenching experiments were performed to verify that singlet oxygen (1O2) and superoxide radicals (O2˙−) were the predominant ROS. Degradation of BPS has been significantly accelerated as the temperature increased. Furthermore, degradation of BPS could be maintained at a high level across a broad range of pH values (5.3–11.15). The SO4−, NO3− did not significantly impact the degradation of BPS, however, both HCO3− and HA inhibited oxidation of BPS by the Ca(OH)2/PMS system, and Cl− had a dual-edged sword effect on BPS degradation. In addition, based on the 4 identified intermediates, 3 pathways of BPS degradation were proposed. The degradation of BPS was lower in domestic wastewater compared to other naturals waters and ultrapure; nevertheless, up to 75.86%, 77.94% and 81.48% of BPS was degraded in domestic wastewater, Yaohu Lake water and Poyang Lake water, respectively. Finally, phenolic chemicals and antibiotics, including bisphenol A, norfloxacin, lomefloxacin hydrochloride, and sulfadiazine could also be efficiently removed via the Ca(OH)2/PMS system.
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JOURNAL OF ALLOYS AND COMPOUNDS
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2019
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IF 4.175
Chengbo Wei,Chuan Liu,Linna Gao,Yanfang Sun,Qingyun Liu,Xiao Zhang,Jinxue Guo
Integrating heterogeneous hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) electrocatalysts into compatible composite catalysts with specific interfaces and structures holds great promise for the development of efficient bifunctional catalysts for overall water splitting. Herein, heterogeneous MoS 2 -Ni(OH) 2 catalyst supported by Ni foam (MoS 2 @Ni(OH) 2 /NF) is developed, in which the Ni(OH) 2 nanorod array is grafted with MoS 2 nanosheets . The hierarchical 1D/2D structures benefit not only the exposure of catalytic site but also the facilitated charge transfer. The heterointerfaces allow the synergism of electric structure modulation for improved catalytic activity and kinetics towards HER, OER, and overall water splitting. MoS 2 @Ni(OH) 2 /NF achieves a current density of 10 mA cm −2 at low overpotentials of 134 and 233 mV for HER and OER in 1 M KOH, respectively. Moreover, a cell voltage as low as 1.46 V is obtained to afford 10 mA cm −2 in a tow-electrode electrolyzer using MoS 2 @Ni(OH) 2 /NF as bifunctional catalysts, assuring it superior to most of the reported noble-metal-free bifunctional electrocatalysts. Such heterogeneous design of composite catalyst should shed light on the exploration of functional materials for energy applications.
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APPLIED CATALYSIS A-GENERAL
·
2015
·
IF 3.942
Cen Tang,Yanxia Jin,Jiqing Lu,Xiaonian Li,Guanqun Xie,Mengfei Luo
A series of Mg catalysts supported on SiO 2 were prepared by an incipient wetness impregnation method and tested for gas phase dehydrochlorination of 1,1,2-trichloroethane. It was found that these catalysts were very active and selective for the reaction. The catalytic performance depended on the Mg loading rather than the Mg precursors as the catalysts using Mg(NO 3 ) 2 ·6H 2 O and MgCl 2 ·6H 2 O as the precursors showed the similar performance. A catalyst containing 10 wt.% of Mg showed the best performance with a steady state TCE conversion of 92% and cis -dichloroethene selectivity of 91%. Moreover, characterizations of the catalysts revealed the formation of Cl-containing Mg species on the surface during the reaction. The analyses of the compositions of the stable catalysts under working conditions indicated a Cl/Mg ratio of 1, suggesting that Mg(OH)Cl could be the active sites for the reaction.
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ACS Applied Materials & Interfaces
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2013
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IF 5.008
Chaoran Li,Zanyong Zhuang,Feng Huang,Zhicheng Wu,Yangping Hong,Zhang Lin
Treatment of wastewater containing low-concentration yet highly-expensive rare earth elements (REEs) is one of the vital issues in the REEs separation and refining industry. In this work, the interaction and related mechanism between self-supported flowerlike nano-Mg(OH)2 and low-concentration REEs wastewater were investigated. More than 99% REEs were successfully taken up by nano-Mg(OH)2. Further analysis revealed that the REEs could be collected on the surface of Mg(OH)2 as metal hydroxide nanoparticles (<5 nm). An ion-exchange model was proposed as a critical factor for both guaranteeing the reaction speed and maintaining the self-supported structure of the materials. In addition, a method was developed to further separate the immobilized REEs and the residual magnesium hydroxide by varying the solution pH. In a pilot-scale experiment, the REEs from practical wastewater were immobilized effectively at a high flow rate. We anticipate this work can provide a good example for the recycling of valuable REEs in practical industrial applications.
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高影响因子
NEW JOURNAL OF CHEMISTRY
·
2015
·Vol. 39
·期 11
·8999-9005
·
IF 3.086
Yingda Du,Ming Xing,Zhiman Li,Wei Guo
Along with the rapid development of modern medicine, the creation and evaluation of nanoparticulate contrast agents have attracted considerable attention of scientists worldwide. Herein, we designed and synthesized a metabolizable nano-sized contrast agent based on rod-like PEGylated gadolinium hydroxide (defined as PEG-Gd(OH)3) via a facile and economic route. Due to the high amount of gadolinium in these nanorods, these well-prepared PEG-Gd(OH)3 could provide more enhanced contrast than clinical iodine-based agents under the usual voltages in computed tomography (CT) imaging. Different from other small molecule-based contrast agents, our PEG-Gd(OH)3 exhibited an obvious liver-targeted property based on our in vivo experiments, indicating their expected usage in the detection of hepatic metastases. Long-term toxicity and possible metabolic pathway demonstrated that these nanorods exhibit overall safety and could not cause gadolinium-associated nephrogenic systemic fibrosis (NSF). With its high biocompatibility and superior contrast efficacy, PEG-Gd(OH)3 could bring more opportunities to a new generation of nanoparticulate CT contrast agents in biomedicine.
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Nanoscale
·
2014
·Vol. 7
·期 5
·1963-1969
·
IF 6.739
Pei Hu,Dongfang Hou,Yanwei Wen,Bin Shan,Chaoji Chen,Yunhui Huang,Xianluo Hu
Novel three-dimensional (3D) hierarchical Nb3O7(OH) nanostructures with a sheaf-like nanoarchitecture were fabricated for the first time by a hydrothermal process. Interestingly, the nanosheafs are composed of nanorods with an average diameter of about 25 nm. The as-prepared 3D hierarchical nanostructures possess a high surface area of 77 m2 g−1 with pore diameters of ca. 4.2–12.5 nm. A possible growth mechanism based on the combined Ostwald ripening and self-assembly process was proposed. It is found that both the valence-band top and the conduction-band bottom consist of O 2p and Nb 4d orbitals. Importantly, the 3D hierarchical Nb3O7(OH) nanostructures exhibit enhanced photocatalytic activity for the degradation of Rhodamine B (RhB) under UV-visible light, which is attributed to the unusual hierarchical structure, high surface area, and hybridization of energy bands.
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CRYSTENGCOMM
·
2017
·Vol. 19
·期 38
·5780-5786
·
IF 3.474
Kun Ding,Xiao Zhang,Juping Li,Ping Yang,Xin Cheng
Ultrathin α-Co(OH)2 nanosheets (NSs) were hydrothermally synthesized without using surfactants and templates. Interestingly, the ultrathin α-Co(OH)2 NSs evolved from graphene-like NSs to hexagonal nanoplates (NPs) and then transformed into a needle-like Co(CO3)0.5(OH)·0.11H2O phase with increasing reaction temperature and time. The phase and morphology evolution depended strongly on the CO32− ions in the solution. We ruled out the possibility that CO32− originated from the adsorption of CO2 in air and proposed the possible phase transition mechanism from α-Co(OH)2 to Co(CO3)0.5(OH)·0.11H2O, which was due to the decomposition of hexamethylenetetramine driven by dynamics and thermodynamics. The morphology evolution could be regarded as the dissolution–recrystallization–redissolution–recrystallization of α-Co(OH)2. The electrochemical behavior tests demonstrated that the ultrathin α-Co(OH)2 electrode exhibited an excellent specific capacitance of 833.4 F g−1 at 5 A g−1; however, the specific capacitance of the needle-like Co(CO3)0.5(OH)·0.11H2O electrode was 247.2 F g−1 at the same current density. This excellent electrochemical property is attributed to the crystalline phase and ultrathin nature of the materials.
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