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1.
A. Hinsch S. Behrens M. Berginc H. Bnnemann H. Brandt A. Drewitz F. Einsele D. Faßler D. Gerhard H. Gores R. Haag T. Herzig S. Himmler G. Khelashvili D. Koch G. Nazmutdinova U. Opara‐Krasovec P. Putyra U. Rau R. Sastrawan T. Schauer C. Schreiner S. Sensfuss C. Siegers K. Skupien P. Wachter J. Walter P. Wasserscheid U. Würfel M. Zistler 《Progress in Photovoltaics: Research and Applications》2008,16(6):489-501
In this paper, we report on the outcome of a German network project conducted with 12 partners from universities and research institutes on the material development of dye solar cells (DSC). We give an overview in the field and evaluate the concept of monolithic DSC further with respect to upscaling and producibility on glass substrates. We have developed a manufacturing process for monolithic DSC modules which is entirely based on screen printing. Similar to our previous experience gained in the sealing of standard DSC, the encapsulation of the modules is achieved in a fusing step by soldering of glass frit layers. For use in monolithic DSC, a platinum free, conductive counter electrode layer, showing a charge transfer resistance of RCT < 1·5 Ω cm2, has been realized by firing a graphite/carbon black composite under an inert atmosphere. Glass frit sealed monolithic test cells have been prepared using this platinum‐free material. A solar efficiency of 6% on a 2·0 cm2 active cell area has been achieved in this case. Various types of non‐volatile imidazolium‐based binary ionic liquid electrolytes have been synthesized and optimized with respect to diffusion‐limited currents and charge transfer resistances in DSC. In addition, quasi‐solid‐state electrolytes have been successfully tested by applying inorganic (SiO2) physical gelators. For the use in semi‐transparent DSC modules, a polyol process has been developed which resulted in the preparation of screen printed, transparent catalytic platinum layers showing an extremely low charge transfer resistance (0·25 Ω cm2). Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
2.
Hee‐Dong Kim Ho‐Myoung An Kyoung Heon Kim Su Jin Kim Chi Sun Kim Jaehee Cho E. Fred Schubert Tae Geun Kim 《Advanced functional materials》2014,24(11):1575-1581
A UV light‐emitting diode (LED) is an eco‐friendly optical source with diverse applications. However, currently, the external quantum efficiency (EQE) of AlGaN‐based UV LEDs, particularly in the UV‐C band (<280 nm), is very low (<11%) mainly due to a large optical absorption via p‐GaN contact layers. A direct Ohmic contact to p‐AlGaN layers should be obtained using UV‐transparent conductive electrodes (TCEs) to solve this problem. A universal method is presented here to make such contact using electrical breakdown, with wide‐bandgap materials, to form conductive filaments (CFs), providing a current path between the TCEs and the p‐(Al)GaN layers. The contact resistance between the TCEs and the p‐GaN layers (or p‐AlGaN) is found to be on the order of 10?5 Ω cm2 (or 10?3 Ω cm2), while optical transmittance is maintained up to 95% for AlN‐based TCEs at 250 nm. These findings could be a critical turning point delivering a breakthrough in UV LED technologies. 相似文献
3.
A. Ennaoui M. Br J. Klaer T. Kropp R. Sez‐Araoz M. Ch. Lux‐Steiner 《Progress in Photovoltaics: Research and Applications》2006,14(6):499-511
Recent progress in fabricating Cd‐ and Se‐free wide‐gap chalcopyrite thin‐film solar devices with Zn(S,O) buffer layers prepared by an alternative chemical bath process (CBD) using thiourea as complexing agent is discussed. Zn(S,O) has a larger band gap (Eg = 3·6–3·8 eV) than the conventional buffer material CdS (Eg = 2·4 eV) currently used in chalcopyrite‐based thin films solar cells. Thus, Zn(S,O) is a potential alternative buffer material, which already results in Cd‐free solar cell devices with increased spectral response in the blue wavelength region if low‐gap chalcopyrites are used. Suitable conditions for reproducible deposition of good‐quality Zn(S,O) thin films on wide‐gap CuInS2 (‘CIS’) absorbers have been identified for an alternative, low‐temperature chemical route. The thickness of the different Zn(S,O) buffers and the coverage of the CIS absorber by those layers as well as their surface composition were controlled by scanning electron microscopy, X‐ray photoelectron spectroscopy, and X‐ray excited Auger electron spectroscopy. The minimum thickness required for a complete coverage of the rough CIS absorber by a Zn(S,O) layer deposited by this CBD process was estimated to ∼15 nm. The high transparency of this Zn(S,O) buffer layer in the short‐wavelength region leads to an increase of ∼1 mA/cm2 in the short‐circuit current density of corresponding CIS‐based solar cells. Active area efficiencies exceeding 11·0% (total area: 10·4%) have been achieved for the first time, with an open circuit voltage of 700·4 mV, a fill factor of 65·8% and a short‐circuit current density of 24·5 mA/cm2 (total area: 22·5 mA/cm2). These results are comparable to the performance of CdS buffered reference cells. First integrated series interconnected mini‐modules on 5 × 5 cm2 substrates have been prepared and already reach an efficiency (active area: 17·2 cm2) of above 8%. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
4.
Youpin Gong Xuemin Zhang Guangtong Liu Liqiong Wu Xiumei Geng Mingsheng Long Xiaohui Cao Yufen Guo Weiwei Li Jianbao Xu Mengtao Sun Li Lu Liwei Liu 《Advanced functional materials》2012,22(15):3153-3159
Chemical vapor deposition (CVD) provides a synthesis route for large‐area and high‐quality graphene films. However, layer‐controlled synthesis remains a great challenge on polycrystalline metallic films. Here, a facile and viable synthesis of layer‐controlled and high‐quality graphene films on wafer‐scale Ni surface by the sequentially separated steps of gas carburization, hydrogen exposure, and segregation is developed. The layer numbers of graphene films with large domain sizes are controlled precisely at ambient pressure by modulating the simplified CVD process conditions and hydrogen exposure. The hydrogen exposure assisted with a Ni catalyst plays a critical role in promoting the preferential segregation through removing the carbon layers on the Ni surface and reducing carbon content in the Ni. Excellent electrical and transparent conductive performance, with a room‐temperature mobility of ≈3000 cm2 V?1 s?1 and a sheet resistance as low as ≈100 Ω per square at ≈90% transmittance, of the twisted few‐layer grapheme films grown on the Ni catalyst is demonstrated. 相似文献
5.
With Ni/Au and Pd/Au metal schemes and low temperature processing, we formed low resistance stable Ohmic contacts to p‐type GaN. Our investigation was preceded by conventional cleaning, followed by treatment in boiling HNO3:HCl (1:3). Metallization was by thermally evaporating 30 nm Ni/15 nm Au or 25 nm Pd/15 nm Au. After heat treatment in O2 + N2 at various temperatures, the contacts were subsequently cooled in liquid nitrogen. Cryogenic cooling following heat treatment at 600 ·C decreased the specific contact resistance from 9.84·10?4 Ωcm2 to 2.65·10?4 Ωcm2 for the Ni/Au contacts, while this increased it from 1.80·10?4 Ωcm2 to 3.34·10?4 Ωcm2 for the Pd/Au contacts. The Ni/Au contacts showed slightly higher specific contact resistance than the Pd/Au contacts, although they were more stable than the Pd contacts. X‐ray photoelectron spectroscopy depth profiling showed the Ni contacts to be NiO followed by Au at the interface for the Ni/Au contacts, whereas the Pd/Au contacts exhibited a Pd:Au solid solution. The contacts quenched in liquid nitrogen following sintering were much more uniform under atomic force microscopy examination and gave a 3 times lower contact resistance with the Ni/Au design. Current‐voltage‐temperature analysis revealed that conduction was predominantly by thermionic field emission. 相似文献
6.
Ulrich P. Muecke Daniel Beckel Andr Bernard Anja Bieberle‐Hütter Silvio Graf Anna Infortuna Patrik Müller Jennifer L. M. Rupp Julian Schneider Ludwig J. Gauckler 《Advanced functional materials》2008,18(20):3158-3168
Miniaturized solid oxide fuel cells are fabricated on a photostructurable glass ceramic substrate (Foturan) by thin film and micromachining techniques. The anode is a sputtered platinum film and the cathode is made of a spray pyrolysis (SP)‐deposited lanthanum strontium cobalt iron oxide (LSCF), a sputtered platinum film and platinum paste. A single‐layer of yttria‐stabilized zirconia (YSZ) made by pulsed laser deposition (PLD) and a bilayer of PLD–YSZ and SP–YSZ are used as electrolytes. The total thickness of all layers is less than 1 µm and the cell is a free‐standing membrane with a diameter up to 200 µm. The electrolyte resistance and the sum of polarization resistances of the anode and cathode are measured between 400 and 600 °C by impedance spectroscopy and direct current (DC) techniques. The contribution of the electrolyte resistance to the total cell resistance is negligible for all cells. The area‐specific polarization resistance of the electrodes decreases for different cathode materials in the order of Pt paste > sputtered Pt > LSCF. The open circuit voltages (OCVs) of the single‐layer electrolyte cells ranges from 0.91 to 0.56 V at 550 °C. No electronic leakage in the PLD–YSZ electrolyte is found by in‐plane and cross‐plane electrical conductivity measurements and the low OCV is attributed to gas leakage through pinholes in the columnar microstructure of the electrolyte. By using a bilayer electrolyte of PLD–YSZ and SP–YSZ, an OCV of 1.06 V is obtained and the maximum power density reaches 152 mW cm−2 at 550 °C. 相似文献
7.
Moon Hee Kang Ajeet Rohatgi Junegie Hong Brian Rounsaville Vijaykumar Upadhyaya Abasifreke Ebong Arnab Das 《Progress in Photovoltaics: Research and Applications》2013,21(3):351-358
Screen‐printed metal contact formation through a carbon containing antireflection coating was investigated for silicon solar cells by fabricating conventional carbon‐free SiNx and carbon‐rich SiCxNy film. An appreciable difference was found in the average shunt resistance (Rsh), which was about an order of magnitude higher for SiCxNy‐coated solar cells relative to the counterpart SiNx‐coated solar cells. Series resistance (Rs) and fill factor (FF) were comparable for both antireflection coatings but the starting efficiency of SiCxNy‐coated cell was ~0·2% lower because of slightly inferior surface passivation. However, SiCxNy‐coated solar cells showed less degradation under lower illumination (<1000 W/m2) compared with the SiNx‐coated cells due to reduced FF degradation under low illumination. Theoretical calculations in this paper support that this is a direct result of high Rsh. Detailed photovoltaic system and cost modeling is performed to quantify the enhanced energy production and the reduced levelized cost of electricity due to higher shunt resistance of the SiCxNy‐coated cells. It is shown that Rsh value below 30 Ω (7000 Ω cm2 for 239 cm2 cell) can lead to appreciable loss in energy production in regions of low solar insolation. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
8.
A method is presented for the calculation of the specific contact resistance and noise of contacts on thin layers. The contribution to the contact resistance and noise of the interface between the contact and the layer is determined from experimental results. Using the developed method on thin CuxS layers with a sheet resistance of 42.5 Ω values for the specific contact resistance of 4 × 10?2 Omega; cm2 and 2.5 Ω cm2 were observed for two different contact technologies. 相似文献
9.
O. Schultz S. W. Glunz S. Riepe G. P. Willeke 《Progress in Photovoltaics: Research and Applications》2006,14(8):711-719
Measurements of the dislocation density are compared with locally resolved measurements of carrier lifetime for p‐type multicrystalline silicon. A correlation between dislocation density and carrier recombination was found: high carrier lifetimes (>100 µs) were only measured in areas with low dislocation density (<105 cm−2), in areas of high dislocation density (>106 cm−2) relatively low lifetimes (<20 µs) were observed. In order to remove mobile impurities from the silicon, a phosphorus diffusion gettering process was applied. An increase of the carrier lifetime by about a factor of three was observed in lowly dislocated regions whereas in highly dislocated areas no gettering efficiency was observed. To test the effectiveness of the gettering in a solar cell manufacturing process, five different multicrystalline silicon materials from four manufacturers were phosphorus gettered. Base resistivity varied between 0·5 and 5 Ω cm for the boron‐ and gallium‐doped p‐type wafers which were used in this study. The high‐efficiency solar cell structure, which has led to the highest conversion efficiencies of multicrystalline silicon solar cells to date, was used to fabricate numerous solar cells with aperture areas of 1 and 4 cm2. Efficiencies in the 20% range were achieved for all materials with an average value of 18%. Best efficiencies for 1 cm2 (20·3%) and 4 cm2 (19·8%) cells were achieved on 0·6 and 1·5 Ω cm, respectively. This proves that multicrystalline silicon of very different material specification can yield very high efficiencies if an appropriate cell process is applied. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
10.
M.G. Debije M.P. deHaas J.M. Warman M. Fontana N. Stutzmann M. Kristiansen W.R. Caseri P. Smith S. Hoffmann T.I. Slling 《Advanced functional materials》2004,14(4):323-328
Charge‐carrier mobilities of various self‐assembled platinum complexes were measured by time‐resolved microwave conductivity techniques in the temperature range –80 to +100 °C. Eight compounds were investigated in the present study, including the original Magnus' green salt ([Pt(NH3)4][PtCl4]) and derivatives with the general structure [Pt(NH2R)4][PtCl4], where R denotes an alkyl side chain. In one instance, the chlorines were substituted with bromines. For these complexes, which all consist of a linear backbone of platinum atoms with Pt–Pt distances, d, varying from 3.1 to ≥ 3.6 Å, a strong, inverse correlation was found between d and the one‐dimensional charge‐carrier mobility, Σμ1D. The highest value of Σμ1D at room temperature was observed for R = (S)‐3,7‐dimethyloctyl (dmoc) with Σμ1D ≥ 0.06 cm2 V–1 s–1. Almost all materials exhibited a charge‐carrier mobility that was relatively independent of the temperature over the range studied. One exceptional compound (R = (R)‐2‐ethylhexyl) showed a pronounced negative temperature dependence of the charge‐carrier mobility; upon decreasing the temperature from +100 °C to –80 °C the charge‐carrier mobility increased by a factor of about ten. 相似文献
11.
R. Sastrawan J. Beier U. Belledin S. Hemming A. Hinsch R. Kern C. Vetter F. M. Petrat A. Prodi‐Schwab P. Lechner W. Hoffmann 《Progress in Photovoltaics: Research and Applications》2006,14(8):697-709
A new interdigital design for large area dye solar modules is developed for an area of 30×30 cm2. This design requires fewer holes in the glass substrate for electrolyte filling, than the conventional strip design. A complete manufacturing process of this module—ranging from screen printed layers to semi‐automated colouring and electrolyte filling—in a laboratory‐scale baseline is illustrated. As primary sealing method, a durable glass frit sealing is used. It is shown, that the lead (Pb) content present in many glass frit powders contaminates the catalytic platinum electrode during the sintering process, resulting in a lowering of the fill factor. A screen printable lead‐free glass frit paste is developed, which solves this problem. Long term stability tests are presented on 2·5 cm2 dye solar cells, which have been completely sealed with glass frit. In consecutively performed accelerated ageing tests under 85°C in the dark (about 1400 h) and continuous illumination with visible light (1 sun, about 1700 h), a 2·5 cm2 dye solar cell with an electrolyte based on propylmethylimidazolium iodide showed an overall degradation of less than 5% in conversion efficiency. In a subsequently performed thermal cycling test (−40°C to +85°C, 50 cycles) a 2·5 cm2 dye solar cell with the same electrolyte composition also showed only a slight degradation of less than 5% in conversion efficiency. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
12.
Improving the electrical and mechanical behavior of electrically conductive paint by partial replacement of silver by carbon black 总被引:2,自引:0,他引:2
Partial replacement of silver particles by carbon black (low cost) in electrically conductive paint was found to decrease
the electrical resistivity and increase the scratch resistance of the resulting thick film, which is for use in electrical
interconnections. An effective carbon black content is 0.055 of the total filler volume. By using a total solid volume fraction
of 0.1969 and a silane-propanol (1:1 by weight) solution as the vehicle, a paint that gives a thick film with resistivity
2 × 10−3 Ω·cm has been attained. 相似文献
13.
H. Plagwitz M. Nerding N. Ott H. P. Strunk R. Brendel 《Progress in Photovoltaics: Research and Applications》2004,12(1):47-54
We have passivated boron‐doped, low‐resistivity crystalline silicon wafers on both sides by a layer of intrinsic, amorphous silicon (a‐Si:H). Local aluminum contacts were subsequently evaporated through a shadow mask. Annealing at 210°C in air dissolved the a‐Si:H underneath the Al layer and reduces the contact resistivity from above 1 Ω cm2 to 14·9 m Ω cm2. The average surface recombination velocity is 124 cm/s for the annealed samples with 6% metallization fraction. In contrast to the metallized regions, no structural change is observed in the non‐metallized regions of the annealed a‐Si:H film, which has a recombination velocity of 48 cm/s before and after annealing. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
14.
Fe,Cu‐Coordinated ZIF‐Derived Carbon Framework for Efficient Oxygen Reduction Reaction and Zinc–Air Batteries
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Zhihao Wang Huihui Jin Tian Meng Ke Liao Wenqian Meng Jinlong Yang Daping He Yuli Xiong Shichun Mu 《Advanced functional materials》2018,28(39)
Zeolitic imidazole frameworks (ZIFs) offer rich platforms for rational design and construction of high‐performance nonprecious‐metal oxygen reduction reaction (ORR) catalysts owing to their flexibility, hierarchical porous structures, and high surface area. Herein, an Fe, Cu‐coordinated ZIF‐derived carbon framework (Cu@Fe‐N‐C) with a well‐defined morphology of truncated rhombic dodecahedron is facilely prepared by introducing Fe2+ and Cu2+ during the growth of ZIF‐8, followed by pyrolysis. The obtained Cu@Fe‐N‐C, with bimetallic active sites, large surface area, high nitrogen doping level, and conductive carbon frameworks, exhibits excellent ORR performance. It displays 50 mV higher half‐wave potential (0.892 V) than that of Pt catalysts in an alkaline medium and comparable performance to Pt catalysts in an acidic medium. In addition, it also has excellent durability and methanol resistance ability in both acidic and alkaline solutions, which makes it one of the best Pt‐free catalysts reported to date for ORR. Impressively, when being employed as a cathode catalyst in zinc–air batteries, Cu@Fe‐N‐C presents a higher peak power density of 92 mW cm?2 than that of Pt/C (74 mW cm?2) as well as excellent durability. 相似文献
15.
Hwe Jae Lee Soon Jae Yu Hajime Asahi Shun-Ichi Gonda Young Hwan Kim Jin Koo Rhee S. J. Noh 《Journal of Electronic Materials》1998,27(7):829-832
Ohmic contacts with low resistance are fabricated on n-GaN films using Al/Ti bilayer metallization. GaN films used are 0.3
μm thick layers with carrier concentrations of 1 × 1019 cm−3 grown on the c-plane sapphire by ion-removed electron cyclotron resonance molecular beam epitaxy. The lowest value for the
specific contact resistivity (ρc) of 1.2×10−8 Ω·cm2 was obtained with furnace annealing at 500°C for 60 min. This result shows the effectiveness of high carrier concentration
GaN layers and the low temperature annealing for the realization of low resistance ohmic contacts. Sputtering Auger electron
spectroscopy analysis reveals that Al diffuses into Ti layer and comes into contact with the GaN surface. 相似文献
16.
Mohamed M. Hilali Kenta Nakayashiki Abasifreke Ebong Ajeet Rohatgi 《Progress in Photovoltaics: Research and Applications》2006,14(2):135-144
High‐efficiency 4 cm2 screen‐printed (SP) textured cells were fabricated on 100 Ω/sq emitters using a rapid single‐step belt furnace firing process. The high contact quality resulted in a low series resistance of 0·79 Ωcm2, high shunt resistance of 48 836 Ωcm2, a low junction leakage current of 18·5 nA/cm2 (n2 = 2) yielding a high fill factor (FF) of 0·784 on 100 Ω/sq emitter. A low resistivity (0·6 Ωcm) FZ Si was used for the base to enhance the contribution of the high sheet‐resistance emitter without appreciably sacrificing the bulk lifetime. This resulted in a 19% efficient (confirmed at NREL) SP 4 cm2 cell on textured FZ silicon with SP contacts and single‐layer antireflection coating. This is apparently higher in performance than any other previously reported cell using standard screen‐printing approaches (i.e., single‐step firing and grid metallization). Detailed cell characterization and device modeling were performed to extract all the important device parameters of this 19% SP Si cell and provide guidelines for achieving 20% SP Si cells. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
17.
Hierarchical Free‐Standing Carbon‐Nanotube Paper Electrodes with Ultrahigh Sulfur‐Loading for Lithium–Sulfur Batteries
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Jia‐Qi Huang Xin‐Yan Liu Dai‐Wei Wang Xin‐Bing Cheng Qiang Zhang 《Advanced functional materials》2014,24(39):6105-6112
The rational combination of conductive nanocarbon with sulfur leads to the formation of composite cathodes that can take full advantage of each building block; this is an effective way to construct cathode materials for lithium–sulfur (Li–S) batteries with high energy density. Generally, the areal sulfur‐loading amount is less than 2.0 mg cm?2, resulting in a low areal capacity far below the acceptable value for practical applications. In this contribution, a hierarchical free‐standing carbon nanotube (CNT)‐S paper electrode with an ultrahigh sulfur‐loading of 6.3 mg cm?2 is fabricated using a facile bottom–up strategy. In the CNT–S paper electrode, short multi‐walled CNTs are employed as the short‐range electrical conductive framework for sulfur accommodation, while the super‐long CNTs serve as both the long‐range conductive network and the intercrossed mechanical scaffold. An initial discharge capacity of 6.2 mA·h cm?2 (995 mA·h g?1), a 60% utilization of sulfur, and a slow cyclic fading rate of 0.20%/cycle within the initial 150 cycles at a low current density of 0.05 C are achieved. The areal capacity can be further increased to 15.1 mA·h cm?2 by stacking three CNT–S paper electrodes—resulting in an areal sulfur‐loading of 17.3 mg cm?2—for the cathode of a Li–S cell. The as‐obtained free‐standing paper electrode are of low cost and provide high energy density, making them promising for flexible electronic devices based on Li–S batteries. 相似文献
18.
Controlled Growth of MoS2 Nanosheets on 2D N‐Doped Graphdiyne Nanolayers for Highly Associated Effects on Water Reduction
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Huidi Yu Yurui Xue Lan Hui Chao Zhang Yingjie Zhao Zhibo Li Yuliang Li 《Advanced functional materials》2018,28(19)
The first utilization of nitrogen‐doped graphdiyne (NGDY) as an efficient catalytic promoter for hydrogen evolution reaction (HER) is reported. X‐ray powder diffraction and X‐ray photoelectron spectroscopy studies indicate the presence of strong interactions between NGDY and MoS2, which should effectively facilitate the charge transport behavior and improvement of the HER kinetics. The creative hybridization of MoS2 and NGDY endows such heterostructure with structural and compositional advantages for boosting the catalytic activity (low overpotential of 186 mV at 10 mA cm?2 and Tafel slope of 63 mV dec?1) and extraordinary stability (higher than all reported MoS2‐based materials and even better than that of commercial Pt and almost all benchmarked electrocatalysts). All of the results not only demonstrate that NGDY can be used as an effective catalytic promoter for hydrogen production, but also provide new strategy for fabricating efficient water‐splitting electrodes. 相似文献
19.
Hydrophilic Nanotube Supported Graphene–Water Dispersible Carbon Superstructure with Excellent Conductivity
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Vasilios Georgakilas Athanasios Demeslis Evangelos Ntararas Antonios Kouloumpis Konstantinos Dimos Dimitrios Gournis Mikuláš Kocman Michal Otyepka Radek Zbořil 《Advanced functional materials》2015,25(10):1481-1487
In this work, it is shown that the hydrophilic functionalized multiwall carbon nanotubes (MWCNs) can stabilize a large amount of pristine graphene nanosheets in pure water without the assistance of surfactants, ionic liquids, or hydrophilic polymers. Role of stabilizer is conveyed by highly hydrophilic carbon nanotubes, functionalized by dihydroxy phenyl groups, affording a stable dispersion at concentrations as high as 15 mg mL?1. Such multidimensional (2D/1D) graphene/MWCN hybrid is found to be dispersible also in other polar organic solvents such as ethanol, isopropanol, N,N‐dimethylformamide, ethylene glycol, and their mixtures. High‐resolution transmission microscopy and atomic force microscopy (AFM) including a liquid mode AFM manifest several types of interaction including trapping of multiwalled carbon nanotubes between the graphene sheets or the modification of graphene edges. Molecular dynamic simulations show that formation of an assembly is kinetically controlled. Importantly, the hybrid can be deposited on the paper by drop casting or dispersed in water‐soluble polymers resulting in record values of electrical conductivity (sheet resistance up to Rs ≈ 25 Ω sq?1 for free hybrid material and Rs ≈ 1300 Ω sq?1 for a polyvinilalcohol/hybrid composite film). Thus, these novel water dispersible carbon superstructures reveal a high application potential as conductive inks for inkjet printing or as highly conductive polymers. 相似文献
20.
Pt Nanoparticles Sensitized Ordered Mesoporous WO3 Semiconductor: Gas Sensing Performance and Mechanism Study
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Junhao Ma Yuan Ren Xinran Zhou Liangliang Liu Yongheng Zhu Xiaowei Cheng Pengcheng Xu Xinxin Li Yonghui Deng Dongyuan Zhao 《Advanced functional materials》2018,28(6)
In this study, a straightforward coassembly strategy is demonstrated to synthesize Pt sensitized mesoporous WO3 with crystalline framework through the simultaneous coassembly of amphiphilic poly(ethylene oxide)‐b‐polystyrene, hydrophobic platinum precursors, and hydrophilic tungsten precursors. The obtained WO3/Pt nanocomposites possess large pore size (≈13 nm), high surface area (128 m2 g?1), large pore volume (0.32 cm3 g?1), and Pt nanoparticles (≈4 nm) in situ homogeneously distributed in mesopores, and they exhibit excellent catalytic sensing response to CO of low concentration at low working temperature with good sensitivity, ultrashort response‐recovery time (16 s/1 s), and high selectivity. In‐depth study reveals that besides the contribution from the fast diffusion of gaseous molecules and rich interfaces in mesoporous WO3/Pt nanocomposites, the partially oxidized Pt nanoparticles that chemically and electronically sensitize the crystalline WO3 matrix, dramatically enhance the sensitivity and selectivity. 相似文献