NEW JOURNAL OF CHEMISTRY
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2018
·Vol. 42
·期 18
·14843-14856
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IF 3.201
Manoj Pudukudy,Zahira Yaakob,Qingming Jia,Mohd Sobri Takriff
The catalytic decomposition of methane is a strategic process to produce COx-free hydrogen and carbon nanomaterials. In this work, for the first time, highly porous ceria was prepared by a urea-assisted solid state combustion method and used as a support for the preparation of a set of platinum-promoted nickel catalysts. The amount of Pt varied from 0.05% to 0.2% while retaining 20% nickel in the catalysts. The prepared catalysts were completely characterized for their structural, textural and redox properties, and their catalytic performance was tested for undiluted methane decomposition. A fine surface dispersion of nickel oxide over ceria was observed in the prepared catalysts. No peaks related to Pt were observed in the catalysts, indicating its good surface dispersion. An enhancement was observed in the properties of the Ni/CeO2 catalyst after the addition of Pt as a promoter. The crystallinity of NiO was not altered by the addition of Pt, whereas the specific surface area of the catalysts was increased with the incremental addition of Pt. Furthermore, the reduction temperature of nickel oxide was shifted to low temperature in the Pt-promoted catalysts due to the hydrogen spillover effect. The surface composition and chemical states of the Pt-promoted Ni/CeO2 catalysts were further studied using XPS. The Pt-promoted Ni/CeO2 catalysts exhibited high catalytic efficiency for methane decomposition due to their improved catalytic properties. The addition of Pt increased the hydrogen yield, and a significant increase in the hydrogen yield was observed for the incremental amount of Pt in the catalysts. Moreover, by increasing the reaction temperature from 650 °C to 750 °C, the hydrogen yield increased significantly. A maximum hydrogen yield of 65% was observed for the 0.2% Pt@Ni/CeO2 catalyst at 750 °C. The enhanced activity and stability of the catalysts were attributed to the synergistic effects of Ni and Pt due to their fine surface dispersion over ceria with a proper metal–support interaction. Multiwalled carbon nanotubes with different diameters were deposited over the catalysts. The carbon nanotubes deposited over the Ni/CeO2 catalyst were found to be more homogeneous than the Pt-promoted catalysts. Moreover, a wide hollow channel was observed in the carbon nanotubes deposited over the Pt-promoted catalyst.
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ACS Sustainable Chemistry & Engineering
·
2018
·
IF 6.14
Yan Xu,Linjie Xie,Di Li,Rong Yang,Deli Jiang,Min Chen
The exploration of earth-abundant and high-efficiency electrocatalysts for water oxidation is of great significance for sustainable energy conversion. Co–Mo-based bimetallic oxides are considered as promising candidates for the oxygen evolution reaction (OER) due to their high intrinsic activity and low cost. In this work, we reported an interfacial engineering design of CoMoO4 nanoplate arrays wrapped with Ni(OH)2 nanosheets supported on Ni foam for high-performance OER. Remarkably, benefiting from the hierarchical heterostructure arrays with strong interfacial interaction, enlarged surface areas, and more active sites, the optimized CoMoO4-Ni(OH)2 electrocatalyst manifests the excellent OER catalytic performance with a low overpotential of 349 mV at the current density of 100 mA cm–2, a long-term stability, and high (nearly 100%) Faradaic efficiency, which is superior to those of most previously reported Co–Mo-based bimetallic oxides electrocatalysts. Therefore, this interfacial engineering demonstrates an effective strategy for designing and fabricating high-performance electrocatalysts for OER reaction.
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JOURNAL OF ALLOYS AND COMPOUNDS
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2018
·
IF 3.779
Jing Li,Huilian Hao,Jianjun Wang,Wenyao Li,Wenzhong Shen
Nitrogen-enriched graphene coupled with nickel hydroxide nanosheets (Ni(OH) 2 /NG) hydrogel is successfully synthesized through a facile one-pot hydrothermal method . Comprehensive investigations reveal that the nitrogen atoms are successfully inserted into graphene and that the nickel hydroxide nanosheets (∼30–50 nm) are anchored on NG homogeneously. With the enhanced electroactivity caused by nitrogen doping and the synergy effect from Ni(OH) 2 nanosheets and NG, the Ni(OH) 2 /NG hydrogel electrode displays much better electrochemical properties than two individual electrodes. It features a specific capacitance as high as 896 F g −1 at 0.5 A g −1 and even 504 F g −1 at 12 A g −1 showing a high rate capability (56.3% retention with 24 times higher current density). An asymmetric supercapacitor device on the basic of Ni(OH) 2 /NG hydrogel and activated carbon (AC) was assembled and delivered a high energy density of 28.7 W h kg −1 at the power energy density of 0.36 kW kg −1 . Such results indicate that the Ni(OH) 2 /NG hydrogel could be considered as a promising candidate for electrochemical supercapacitors .
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CARBON
·
2014
·
IF 6.16
Chao Ding,Weili Wei,Hanjun Sun,Jinhua Ding,Jinsong Ren,Xiaogang Qu
A reduced graphene oxide (rGO) supported chiral-modified Ni catalyst was synthesized, characterized and employed for asymmetric hydrogenation. The prepared hybrid catalyst could produce each enantiomer with d - or l -tartaric acid as chiral modifier and exhibited a high TOF (20160 h −1 ) and enantioselectivity (enantiomeric excess, 98.5%) for asymmetric hydrogenation of methyl acetoacetate. The high catalytic activity and enantioselectivity were mainly attributed to the unique properties of the support rGO, as it had a large specific surface area to sustain and stabilize Ni particles and its high charge carrier mobility could enable the readily transfer of electrons in the reaction process. Besides, the catalyst could also gain an enhanced reactant sorption with the support of rGO, thus achieved a greatly catalysis enhancement. The ferromagnetism of Ni made the catalyst easier for separation and reuse. The catalytic and recycling performance of the prepared chiral Ni catalyst demonstrated that rGO was indeed a promising support to improve activity, enantioselectivity and durability of catalysts, and the prepared catalysts were promising reusable heterogeneous catalysts for asymmetric hydrogenation.
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ELECTROCHIMICA ACTA
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2015
·
IF 4.504
Mingshu Xiao,Yanping Tian,Yuhua Yan,Kai Feng,Yuqing Miao
In order to lower the energy barrier and improve the energy efficiency for hydrogen production by splitting water, highly efficient OER catalysts are required. Here, we report the electrodeposition of Ni(OH) 2 /NiOOH in the presence of urea showing the improved electrocatalysis for the hydrogen production in KOH electrolyte. By potential scanning, the Ni(OH) 2 colloid in alkali solution was transformed into the deposited Ni(OH) 2 /NiOOH. The presence of urea facilitates to deposit Ni(OH) 2 /NiOOH with higher electron transfer than the absence of urea, leading to a higher electrocatalytic OER. As supporting electrolyte , KOH exhibits better performance on the electrodeposition of Ni(OH) 2 /NiOOH and their OER electrocatalysis than NaOH. The work shows the potential application using cheap, non-precious metal-based electrocatalysts to overcome the well-known bottlenecks limiting power density of hydrogen fuel cell and energy efficiency of splitting water.
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CATALYSIS TODAY
·
2015
·
IF 3.893
Liangguang Chen,Huiwen Li,Junying Fu,Changlin Miao,Pengmei Lv,Zhenhong Yuan
A series of Ni/HZSM-5 catalysts with different Ni loading and Si/Al ratios were prepared by incipient wetness impregnation. The physicochemical properties of the catalysts were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N 2 -adsorption, temperature-programmed desorption of ammonia (NH 3 -TPD), and thermogravimetric (TG) analysis. Moreover, their catalytic performance was investigated for the hydroprocessing of long-chain unsaturated fatty acid methyl esters (FAMEs) to renewable alkane fuels using a high-pressure fixed bed reactor system with a facility for online analysis. The different Ni loading and Si/Al ratios of the catalysts, as well as the influence of reaction conditions such as temperature, pressure, H 2 /oil molar ratio, and liquid hourly space velocity (LHSV), were studied in detail. The NiO aggregates dispersed on the surface of the support clearly increased the acidity after H 2 reduction, thus significantly affecting the catalytic performance. Temperature and pressure played crucial roles in the conversion of FAMEs and selectivity for gasoline or jet or diesel alkane. Hydroprocessing over 10 wt% Ni/HZSM-5 (Si/Al = 25) at 280 °C, a H 2 pressure of 0.8 MPa, an LHSV of 4 h −1 , and with a highly purified H 2 /oil molar ratio of 15 led to a high selectivity of 88.2% for C 5 –C 18 liquid alkanes, which includes 8% of gasoline alkane, 32.5% of jet alkane and 47.7% of diesel alkane, along with appropriate isomerization selectivity of 27.0%, while the conversion of FAME reached 85.1%. To demonstrate the potential of this catalyst for practical applications, its stability in the hydroprocessing of FAMEs was also investigated. The conversion of FAMEs decreased to 30.1% over 10 wt% Ni/HZSM-5 (Si/Al = 25) after operation for 80 h. Catalyst deactivation was predominantly caused by the deposition of carbon which causes blockage of the pores for FAMEs as evidence from TG analysis.
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Nanoscale
·
2014
·Vol. 6
·期 13
·7424-7429
·
IF 6.739
Beibei Zhan,Changbing Liu,Huaping Chen,Huaxia Shi,Lianhui Wang,Peng Chen,Wei Huang,Xiaochen Dong
Three-dimensional graphene foam (3DGF) is a superior sensing material because of its high conductivity, large specific surface area and wide electrochemical potential windows. In this work, hexagonal Ni(OH)2 nanosheets are deposited on the surface of chemical vapor deposition-grown 3DGF through a facial hydrothermal process without any auxiliary reagents. The morphology and structure of the composite are characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM), Raman spectroscopy, and X-ray diffraction (XRD). Based on the Ni(OH)2/3DGF composite, a free-standing electrochemical electrode is fabricated. Being employed as a nonenzymatic glucose detection electrochemical electrode, it exhibits a high sensitivity (∼2.65 mA mM−1 cm−2), low detection limit (0.34 μM) and excellent selectivity with a linear response from 1 μM to 1.17 mM. The excellent sensing properties of the Ni(OH)2/3DGF electrode may be attributed to the synergistic effect of the high electrocatalytic activity of Ni(OH)2 nanosheets and the high conductivity and large surface area of 3DGF.
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MATERIALS LETTERS
·
2014
·
IF 2.269
Jing-He Yang,Chao Wang,Duo Yang,Xingyun Li,Peng Shang,Yamin Li,Ding Ma
The boron-doped α-Ni(OH) 2 nanoflowers (B-α-Ni(OH) 2 ) with high specific surface area (400 m 2 g −1 ) were synthesized by the one pot liquid-phase method using P123 (EO 20 PO 70 EO 20 ) as template and NaBH 4 as alkali and boron sources. The size of the B-α-Ni(OH) 2 nanoflowers is about 300 nm and there are many porous. The 50 nm nanoplates are the basic structure units of nanoflowers and thickness of the nanosheets is approximately 5 nm. The content of B is about 15% among the Ni, B, O elements and boron exists mainly in the form of BO 2 − , which was confirmed by XPS characterization. B-α-Ni(OH) 2 nanoflowers exhibit a high specific capacitance of ~2296 F g −1 at a charge and discharge current density of 3 A g −1 with excellent cycling ability. The high specific capacitance and remarkable rate capability are promising for applications of B-α-Ni(OH) 2 nanostructures as advanced electrochemical capacitor materials with both high energy and cycling ability.
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ULTRASONICS SONOCHEMISTRY
·
2014
·
IF 3.816
Deming Zhao,Yiya Zheng,Min Li,Shams Ali Baig,Donglei Wu,Xinhua Xu
In this study, nickle/iron (Ni/Fe) nanoparticles were synthesized by liquid phase reductive method in the presence of 20 kHz ultrasonic irradiation to improve nanoparticles’ disparity and avoid agglomeration. The characterized results showed that this method has obviously modified most of the particles in term of sizes and specific surface areas. Meanwhile, the improved nanoscale Ni/Fe particles were employed for the reductive dechlorination of 2,4-dichlorophenol (2,4-DCP) as a function of some influential factors (Ni content, Ni/Fe nanoparticles dosage, reaction temperature and initial pH values) and degradation path. Experimental results showed that 2,4-DCP was first adsorbed by Ni/Fe nanoparticles, then quickly reduced to o -chlorophenol ( o -CP), p -chlorophenol ( p -CP), and finally to phenol (P). The application of ultrasonic irradiation for Ni/Fe nanoparticles synthesis was found to significantly enhance the removal efficiency of 2,4-DCP. Consequently, the phenol production rates increased from 68% (in the absence of ultrasonic irradiation) to 87% (in the presence of ultrasonic irradiation) within 180 min. Nearly 96% of 2,4-DCP was removed after 300 min reaction with these optimized conditions: Ni content over Fe 0 3 wt%, initial 2,4-DCP concentration 20 mg L −1 , Ni/Fe dosage 3 g L −1 , initial pH value 3.0, and reaction temperature 25 °C. The degradation of 2,4-DCP followed pseudo-first-order kinetics reaction and the apparent pseudo-first-order kinetics constant was 0.0737 min −1 . This study suggested that the presence of ultrasonic irradiation in the synthesis of nanoscale Ni/Fe particles could be a promising technique to enhance nanoparticle’s disparity and avoid agglomeration.
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Journal of Energy Chemistry
·
2015
·
IF 2.352
Feifei Sun,Yue An,Lecheng Lei,Fuying Wu,Jingke Zhu,Xingwang Zhang
Hydrogenation of carbazole and N-ethylcarbazole over Raney-Ni catalyst were realized in the temperature range of 393–503 K. 4[H] adduct dominated the hydrogenation products and the formation of 2[H] adduct was the rate-limiting step during the period, in which the conversion of carbazole was less than 40%. The hydrogenation process followed pseudo-first-order kinetics and the hydrogenation activation energies of carbazole and N-ethylcarbazole were 90 kJ/mol and 115 kJ/mol, respectively. The reaction starting position as well as the pathway of the hydrogenation of (N-ethyl)carbazole were investigated by comparing the kinetic characteristics of hydrogen uptake of carbazole and N-ethylcarbazole. The results showed that the reaction was a stepwise hydrogenation process and the first H 2 was added to the C1 = C10 double bond in the hydrogenation.
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APPLIED SURFACE SCIENCE
·
2015
·
IF 2.711
Yixuan Song,Tingting Qiang,Ming Ye,Qiuyang Ma,Zhen Fang
Design an effective absorbent that has high surface area, and perfect recyclable is imperative for pollution elimination. Herein, we report a facile two-step strategy to fabricate magnetically separable 3-dimensional (3D) hierarchical carbon-coated nickel (Ni@C) nanocomposites by calcinating nickel based metal organic framework (Ni 3 (OH) 2 (C 8 H 4 O 4 ) 2 (H 2 O) 4 ). SEM and TEM images illuminate that the nanocomposites were constructed by 8 nm nickel nanoparticle encapsulated in 3D flake like carbon. The specific surface area of the obtained nanocomposites is up to 120.38 m 2 g −1 . Room temperature magnetic measurement indicates the nanocomposites show soft magnetism property, which endows the nanocomposites with an ideal fast magnetic separable property. The maximum adsorption capacity of the nanocomposites for rhodamine B is 84.5 mg g −1 . Furthermore, the nanocomposites also exhibit a high adsorption capacity for heavy metal ions. The adsorbent can be very easily separated from the solution by using a common magnet without exterior energy. The as-prepared Ni@C nanocomposites can apply in waste water treatment on a large-scale as a new adsorbent with high efficiency and excellent recyclability.
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ACS Applied Materials & Interfaces
·
2017
·
IF 7.504
Xinzuo Fang,Long Jiao,Rui Zhang,Hai-Long Jiang
The sluggish kinetics of oxygen evolution reaction (OER) hampers the H2 production by H2O electrolysis, and it is very important for the development of highly efficient and low-priced OER catalysts. Herein, a representative metalloporphyrinic MOF, PCN-600-Ni, integrated with graphene oxide (GO), serves as an ideal precursor and template to afford bimetallic iron–nickel phosphide/reduced graphene oxide composite (denoted as Fe–Ni–P/rGO-T; T represents pyrolysis temperature) via pyrolysis and subsequent phosphidation process. Thanks to the highly porous structure, the synergetic effect of Fe and Ni elements in bimetallic phosphide, and the good conductivity endowed by rGO, the optimized Fe–Ni–P/rGO-400 exhibits remarkable OER activity in 1 M KOH solution, affording an extremely low overpotential of 240 mV at 10 mA/cm2, which is far superior to the commercial IrO2 and among the best in all non-noble metal-based electrocatalysts.
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