RSC Advances
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2017
·Vol. 7
·期 4
·1947-1955
·
IF 3.108
Xin Ran,Long Yang,Qing Qu,Shunling Li,Ying Chen,Limei Zuo,Lei Li
In this work, ultrasmall Pd–Pt bimetallic nanoclusters with a uniform size of 2.0 nm monodispersed on β-cyclodextrin functionalized reduced graphene oxide (β-CD-RGO) were successfully prepared in aqueous solution at room temperature within 30 min without the need for any organic solvent or high temperature. The integration of β-CD and RGO was responsible for the formation of the monodispersed 2.0 nm Pd–Pt bimetallic nanoclusters. Inspired by the monodisperse, ultrasmall, and pristine properties of the Pd–Pt clusters, the Pd–Pt@β-CD-RGO nanohybrid displayed enhanced activity for methanol and ethanol oxidation in alkaline media in comparison with the commercial Pd/C catalysts. This facile and simple method is of significance for the preparation of bimetallic nanocatalysts with high catalytic activity on suitable supporting materials.
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ELECTROCHIMICA ACTA
·
2016
·
IF 4.803
Baocang Liu,Lili Huo,Geng Zhang,Jun Zhang
A novel hollow mesoporous TiN/N-graphene (N-G) hybrid architecture (@M-TiN/N-G) composed of N-doped graphene wrapped mesoporous TiN nanoparticle shells was constructed for the first time. It can be used as an efficient support for creating a highly efficient ternary @M-TiN/N-G/Pt electrocatalyst with superior catalytic activity and stability for methanol oxidation reaction (MOR) and oxygen reduction reaction (ORR) through decorating well-dispersed Pt nanoparticles on @M-TiN/N-G surface. By optimizing the content of N-G in catalysts, the @M-TiN/N-G/Pt catalysts display superior catalytic activity and stability toward MOR and ORR to traditional Pt/C and graphene-free Pt/TiN and @M-TiN/Pt catalysts. The various characterization results reveal that the outstanding electrocatalytic performance of @M-TiN/N-G/Pt catalyst roots in its large surface area, high porosity, strong interaction among Pt, TiN, and N-G, excellent electron transfer property facilitated by N-doped graphene, and small size of Pt and TiN nanocrystals. The synthetic approach may be available for constructing other graphene based hollow metal nitrides, carbides, and phosphides for various electrocatalytic applications.
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Analytical Methods
·
2016
·Vol. 8
·期 9
·2097-2105
·
IF 1.915
Junrong Li,Liang Lv,Guannan Zhang,Xiaodong Zhou,Aiguo Shen,Jiming Hu
We herein present a simple and surfactant-free synthetic strategy for the preparation of core–shell Fructus Broussonetia-like Au@Ag@Pt nanoparticles (FBNPs) via a combination of galvanic replacement and reagent reduction, in which a chitosan (CS)-mediated epitaxial growth of Pt multi-branches occurs on cresyl violet labeled Au core–Ag shell nanoparticles (NPs) at room temperature. The as-prepared novel nanostructures exhibit an enzyme mimetic activity due to the formation of a Fructus Broussonetia-shaped Pt shell, the absence of surfactants and the positively charged CS molecules intertwined within the outermost Pt NPs. Relying on the high sensitivity of resonance-enhanced Raman scattering and the highly efficient intrinsic peroxidase-like activity of FBNPs, H2O2 was detected with a wide detection window from 10 pM to 100 μM when utilizing 3,3′,5,5′-tetramethylbenzidine (TMB) as the substrate. Based on the H2O2–TMB catalytic oxidation system a simple, sensitive, selective and universal platform has been extended for the detection of all peroxidase-related analytes. For example, glucose at a concentration range of 1 nM to 200 μM was detected in the presence of glucose oxidase with a limit of detection of 1 nM.
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ELECTROCHIMICA ACTA
·
2016
·
IF 4.803
Kang Fu,Yang Wang,Linchang Mao,Junhong Jin,Shenglin Yang,Guang Li
Graphene-porous carbon nanofiber (G-PCNF) and Graphene-carbon nanofiber (G-CNF) hybrid materials were prepared by the one-pot modified Hummers method followed by thermal annealing as the unique Pt nanoparticles supports for oxygen reduction reaction (ORR). Particularly, 1D PCNF and CNF can be spacers for 2D graphene (G) to make full utilization of the high intrinsic surface area of graphene and the Pt nanoparticles can be uniformly deposited on the hybrid supports, resulting in excellent activity for ORR. The newly developed Pt/G-PCNF and Pt/G-CNF catalysts exhibit higher activity compared to the Pt/G catalyst. The electrochemical activity and durability of Pt/G-PCNF as well as the commercial catalyst Pt/C (JM20) were also researched. The ORR results show that the onset potential of Pt/G-PCNF is 38 mV higher than JM20 and the mass activity (at 0.8 V) is twice higher than JM20. Pt/G-PCNF also demonstrates better stability, maintaining 50.4% of its electrochemical active surface area (ECSA) after accelerated durability testing (ADT) whereas JM20 only retain 17.0%. Furthermore, the half-wave potential of Pt/G-PCNF loses about only 9 mV, significantly superior to the 154 mV half-wave potential loss for JM20. These results indicate that G-PCNF can be a promising candidate as highly promising class of catalyst supports for the improvement of electrochemical activity of proton exchange membrane fuel cells (PEMFCs).
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RSC Advances
·
2015
·Vol. 5
·期 114
·94456-94461
·
IF 3.84
Zhen Zhang,Yanzhou Jiang,Maoqiang Chi,Zezhou Yang,Ce Wang,Xiaofeng Lu
Herein, we report the fabrication of polyacrylonitrile (PAN) nanofibers supported Pd–Pt alloy nanoparticles (PAN/Pd–Pt) through a simple and reliable approach by combining an electrospinning technique and in situ reduction process. The resulting PAN/Pd–Pt membranes are composed of a well-defined fiber-like structure with uniform sizes. Pd–Pt alloy nanoparticles are well dispersed on the surface of PAN nanofibers and the composition of alloy nanoparticles can be regulated through adjusting the feed molar ratio of Na2PdCl4 and K2PtCl4. The obtained products are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) measurements. The as-prepared PAN/Pd–Pt composite exhibits a remarkable catalytic performance towards the hydrogen generation from the hydrolysis of ammonia borane (NH3BH3, AB). By tuning the composition of the alloy nanoparticles of the nanocatalyst, a turnover frequency (TOF) of 51.9 mol H2 min−1 (mol Pd–Pt alloy)−1 was achieved, much higher than Pd and Pt-based nanocatalysts. In addition, the as-prepared PAN/Pd–Pt composite nanofibers show good recycling stability, as the catalyst can be easily separated from the suspension system. The electrospun nanofiber membrane supported noble metal nanoalloy catalysts shows high potential to find applications for the development of hydrogen generation for clean energy.
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CRYSTENGCOMM
·
2013
·Vol. 16
·期 12
·2384-2394
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IF 3.879
Zhifeng Jiang,Jianjun Zhu,Dong Liu,Wei Wei,Jimin Xie,Min Chen
Considering that the reduction of particle size can increase the number of active sites, particle size is accepted to be the key factor in the design of photocatalysts. However, serious agglomeration of nanosized particles may cause not only a decreased surface area but also increase grain boundary recombination. Forming a hollow nano-hemisphere in single crystals with reactive sites could be a good method to overcome this drawback. In this work, we report the synthesis of novel anatase TiO2 hollow nano-hemispheres by using a mixture of CH3COO− and F− as size and morphology controlling co-agents that prevent aggregation and increase the number of active sites. Furthermore, bimetallic Ag/Pt nanoparticles (NPs) are uniformly loaded on both interior and exterior of the nano-hemispheres in situ. The Ag/Pt@TiO2 NPs with improved visible-light-harvesting ability, high charge–hole mobility, and low electron–hole recombination exhibited improved photocatalytic performance in the degradation of rhodamine B/ciprofloxacin (RhB/CIP) and hydrogen generation. The results presented here give a promising way toward the development of delicate bimetal@semiconductor composites for board applications in photocatalysis.
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CARBON
·
2014
·
IF 6.16
Shengchun Yang,Pengtao Qiu,Guang Yang
Shape controlled synthesis of Pt nanoparticles is of great significance for the development of electrochemical catalysts with high performance. In this study, we found that the reduced graphene oxide can induce the growth of 2-dimentional single crystal Pt nanosheets with a thickness of about 9.8 nm in a KNO 3 –LiNO 3 eutectic mixture molten salt medium without using any organic solvent , capping agents or structure-directing agents. A series of investigations to understand the formation mechanism indicated that the aggregation and sintering of the isolated nanoparticles along the surface of reduced graphene oxide was responsible for the formation Pt nanosheets. The electrochemical tests indicated that the as-prepared hybrid material exhibited an enhanced activity and durability toward the methanol oxidation compared with the commercial used Pt/C catalysts.
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Chemistry-An Asian Journal
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2015
·Vol. 10
·期 7
·1561-1570
·
IF 4.587
Yanyan Wang,Wanhong He,Liren Wang,Junjiao Yang,Xu Xiang,Bing Zhang,Feng Li
Graphical Support your local catalysts : Supported platinum nanocatalysts were synthesized by an alcohol reduction method towards cinnamaldehyde hydrogenation. The findings showed that high activity and selectivity towards the C=O bond were achieved on the small-sized Pt nanoparticles. The synergy of Pt valence and hydroxyl moieties contribute to the high selectivity. The hydrogenation of α,β-unsaturated aldehydes to allylic alcohols or saturated aldehydes provides a typical example to study the catalytic effect on structure-sensitive reactions. In this work, supported platinum nanocatalysts over hydrotalcite were synthesized by an alcohol reduction method. The Pt catalyst prepared by the reduction with a polyol (ethylene glycol) outperforms those prepared with ethanol and methanol in the hydrogenation of cinnamaldehyde. The selectivity towards the C=O bond is the highest over the former, although its mean size of Pt particles is the smallest. The hydroxyl groups on hydrotalcite could act as an internally accessible promoter to enhance the selectivity towards the C=O bond. The optimal Pt catalyst showed a high activity with an initial turnover frequency (TOF) of 2.314 s −1 . This work unveils the synergic effect of metal valence and in situ promoter on the chemoselective hydrogenation, which could open up a new direction in designing hydrogenation catalysts.
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ELECTROCHIMICA ACTA
·
2014
·
IF 4.086
Yingqiang Huang,Haoliang Huang,Qiongzhi Gao,Cuifen Gan,Yingju Liu,Yueping Fang
The two-dimensional sandwich-like Pt/Mn 3 O 4 /reduced-graphene-oxide (RGO) nanocomposites are successfully fabricated through a spontaneous and electroless approach, where Mn 3 O 4 is rationally utilized as a green reducing agent in the synthesis of Pt nanoparticles and also a superior metal oxide support for the growth of Pt nanoparticles. By using X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy to characterize the catalysts, Pt nanoparticles are found to highly disperse on the Mn 3 O 4 /RGO surface. Electrochemical measurements indicate that the Pt/Mn 3 O 4 /RGO nanocomposites not only possess remarkably excellent long-time stability and electrocatalytic activity toward methanol oxidation, but also reduce the overpotential of methanol oxidation significantly, as compared to the Pt/RGO and the conventional Pt/C catalyst, which could be ascribed to the unique sandwich-like structure and the synergetic interaction formed between Pt, Mn 3 O 4 and RGO . Therefore, the present approach provides some new clues for further development of two-dimensional sandwich-like electrocatalysts for fuel cells.
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CHINESE JOURNAL OF CATALYSIS
·
2015
·
IF 1.964
Junrui Li,Xiaohong Li,Yue Ding,Peng Wu
Pt nanoparticles entrapped in ordered mesoporous CMK-3 carbons with p6mm symmetry were prepared using a facile impregnation method, and the resulting materials were characterized using X-ray diffraction spectroscopy, N 2 adsorption-desorption, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. The Pt nanoparticles were highly dispersed in the CMK-3 with 43.7% dispersion. The Pt/CMK-3 catalyst was an effective catalyst for the liquid-phase hydrogenation of nitrobenzene and its derivatives under the experimental conditions studied here. The Pt/CMK-3 catalyst was more active than commercial Pt/C catalyst in most cases. A highest turnover frequency of 43.8 s −1 was measured when the Pt/CMK-3 catalyst was applied for the hydrogenation of 2-methyl-nitrobenzene in ethanol under optimal conditions. It is worthy of note that the Pt/CMK-3 catalyst could be recycled easily, and could be reused at least fourteen times without any loss in activity or selectivity for the hydrogenation of nitrobenzene in ethanol.
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SOLID STATE SCIENCES
·
2017
·
IF 1.811
Chi Him A. Tsang,D.Y.C. Leung
Fabrication of electrocatalyst for direct glucose fuel cell (DGFC) operation involves destructive preparation methods with the use of stabilizer like binder, which may cause activity depreciation. Binder-free electrocatalytic electrode becomes a possible solution to the above problem. Binder-free bimetallic Pd-Pt loaded graphene aerogel on nickel foam plates with different Pd/Pt ratios (1:2.32, 1:1.62, and 1:0.98) are successfully fabricated through a green one-step mild reduction process producing a Pd-Pt/GO/nickel form plate (NFP) composite. Anode with the binder-free electrocatalysts exhibit a strong activity in a batch type DGFC unit under room temperature. The effects of glucose and KOH concentrations, and the Pd/Pt ratios of the electrocatalyst on the DGFC performance are also studied. Maximum power density output of 1.25 mW cm −2 is recorded with 0.5 M glucose/3 M KOH as the anodic fuel, and Pd 1 Pt 0.98 /GA/NFP as catalyst, which is the highest obtained so far among other types of electrocatalyst.
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DALTON TRANSACTIONS
·
2017
·Vol. 46
·期 22
·7210-7218
·
IF 4.029
Wenhui Liu,Qi Wang,Yan Zheng,Shubin Wang,Yan Yan,Yanzhao Yang
In this study, a method of one-step separation and recycling of high purity Pd(II) and Pt(IV) using an ionic liquid, 1-butyl-3-benzimidazolium bromate ([HBBIm]Br), was investigated. The effects of [HBBIm]Br concentration, initial metal concentration, and loading capacity of [HBBIm]Br were examined in detail. It was observed that [HBBIm]Br was a very effective extractant for selectively extracting Pd(II) and precipitating Pt(IV). Through selectively extracting Pd(II) and precipitating Pt(IV), each metal with high purity was separately obtained from mixed Pd(II) and Pt(IV) multi-metal solution. The method of one-step separation of Pd(II) and Pt(IV) is simple and convenient. The anion exchange mechanism between [HBBIm]Br and Pt(IV) was proven through Job's method and FTIR and 1H NMR spectroscopies. The coordination mechanism between [HBBIm]Br and Pd(II) was demonstrated via single X-ray diffraction and was found to be robust and distinct, as supported by the ab initio quantum-chemical studies. The crystals of the [PdBr2 ·2BBIm] complex were formed first. Moreover, the influence of the concentrations of hydrochloric acid, sodium chloride, and sodium nitrate on the precipitation of Pt(IV) and extraction of Pd(II) was studied herein. It was found that only the concentration of H+ could inhibit the separation of Pt(IV) because H+ could attract the anion PtCl62−; thus, the exchange (anion exchange mechanism) between the anions PtCl62− and Br− was prevented. However, both the concentration of H+ and Cl− can obviously inhibit the extraction of Pd(II) because H+ and Cl− are the reaction products and increasing their concentration can inhibit the progress of the reaction (coordination mechanism).
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