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Abstract: Novel morphology of amorphous/nanocrystalline (nanomorph) silicon has been obtained by plasma enhanced CVD using template porous alumina substrate. The growing heterogeneous Si layer is composed of nanocrystalline and amorphous distinct areas, conformal to the tipped/ribbed alumina template. Raman spectroscopy and XRD data evidence the plasma-assisted preferential growth of nanocrystalline Si bunches forming the honeycomb net and presumably amorphous Si:H areas between them. [Copyright &y& Elsevier]

Cu/C films were prepared at ambient temperature under a Cu(hfac)2-Ar-H2 atmosphere in order to obtain metallized polymer by using electron cyclotron resonance metal organic chemical vapor deposition(ECR-MOCVD) coupled with a direct current (DC) bias system. DC bias selectively attracts the positively charged copper ions and then makes them deposit on the polymer substrate. Structural analysis of the films by ECR showed that fine copper grains were embedded in an amorphous polymer matrix. The electrical properties of the films were closely related to the process parameters such as microwave power, magnet current, H2/Ar mole ratio and periodic negative voltage. The increase in H2 contents, microwave power, magnet current and the negative voltage brought on copper-rich film formation with low electrical resistance. On the other hand carbon-rich films with low sheet electrical resistance were prepared with lower values for process parameters described above. Formation of Cu/C films depends strongly on the periodic negative pattern of DC bias and the electrical sheet resistance of the films was controlled in the 108–100 ohm/sq range by process parameters of the ECR-MOCVD system. [ABSTRACT FROM AUTHOR]

In this paper, we discuss the surface modification of spinel LiMn2O4 cathodes by MnO2 particles via a simple precipitation method at room temperature, without any heat treatment. Nanosized MnO2 particles with an amorphous structure were formed and distributed evenly on the parent cathode, without severe agglomeration. Electrochemical measurements at ambient temperature revealed that the MnO2-coated LiMn2O4 electrode exhibited superior rate capability as compared to the pristine LiMn2O4 electrode. Based on the capacity at low currents, the surface-modified electrode delivered 62% capacity, whereas the pristine LiMn2O4 electrode maintained 8% capacity during fast discharging for 3 min at 20 C-rate. Surface coating with nano-MnO2 enhanced the electrochemical properties such as storage characteristics, particularly at elevated temperatures. X-ray photoelectron spectroscopy data showed that the improved performance of the coated electrode was mainly because of the suppressed side reaction between the cathode and the electrolyte. [ABSTRACT FROM AUTHOR]

Four different kinds of diamond-like carbon (DLC) coating morphologies on the surface of silicon films were prepared directly on a copper foil by using radio frequency plasma-enhanced chemical vapor deposition at 200 °C. A thin double layer film consisting of DLC (60 nm) and silicon film (250 nm) was fabricated for use as the anode material of lithium secondary batteries, and its electrochemical performance was also examined with special attention being paid to the surface coverage of the DLC film. The full coverage of silicon by the DLC film resulted in poor capacity due to the ensuing low reactivity with the lithium ions. On the other hand, the partial coating of the DLC film on the silicon film not only reduced the capacity fading, but also increased the discharge capacity during the charge/discharge cycles. These results indicated that the good dispersion of the DLC coating, obtained by using a smaller coating sector on the silicon film, improved the integrity of the electrode structure, thus giving higher capacities and reduced capacity fading. [ABSTRACT FROM AUTHOR]

Multiwalled carbon nanotubes were grown from acetylene and hydrogen gas mixture directly on stainless steel plates by rf powered PECVD and then electric double layer capacitors were fabricated from them without any further treatment. It was found that suitable pretreatment of stainless steel substrates was required for the satisfactory growth of carbon nanotubes on them. In this study substrates were polished, etched in HF solution and then treated with hydrogen plasma before the growth of carbon nanotubes. SEM shows that the surface of the substrate became smooth after polishing. It was severely etched to reveal grains of stainless steel after dipping in HF solution. With hydrogen plasma treatment the grains become more rounded in shape and grew in size. When the grains size was tens of nanometers, carbon nanotubes were grown. Exposing substrates to the hydrogen plasma for 10 min or longer caused the grains to grow larger and the growth of carbon nanotubes became poorer. Carbon nanotubes grown in this study were mutiwalled and curly in shape. Capacitors made from the carbon nanotubes showed initial specific capacitance in the range of 80–100 F/g. [ABSTRACT FROM AUTHOR]

In this study, we developed a cost-effective method to enhance the electro-catalytic activity and conductivity of graphene-based counter electrodes (CEs) by diminishing the oxygen content in graphene nanoplatelets (GNPs) through dry plasma reduction (DPR). As a result, the efficiency of dye-sensitized solar cells (DSCs) based on GNPs with an average surface area of 750m²/g treated by DPR was enhanced by 15% over that of devices with pristine graphene oxide electrodes. The next step in the design strategy for improving DSC performance suggested the immobilization of platinum nanoparticles (PtNPs) on the electrode surface through DPR. DSCs based on the newly developed CEs had an increase in efficiency by 50.3% over that of the Pt-free device, and by 10.4% over the efficiency of state-of-the-art DSCs. The introduction of PtNPs on the surface of a CE through DPR along with removal of the oxygen functional groups from the surface of the GNP electrode reduces the charge-transfer resistance at the electrolyte/CE interface and the diffusion impedance of triiodide ions. PtNPs hybridization on the surface of CE facilitates the electron conductivity in the PtNPs/CE structure by creating a conductive network in the sp³ phase for charge carriers delocalized in a sp² matrix. [ABSTRACT FROM AUTHOR]

The effect of interface morphology on electrochromic characteristics was examined for an electrochromic device (ECD). Micro-patterned fluorine-doped tin oxide (FTO) films were fabricated using a photolithography process. Prussian blue (PB) films were then deposited on the patterned FTO films. The surface areas of both PB films and FTO films were increased by patterning. ECDs were assembled using patterned PB/FTO films as the electrochromic electrode, bare FTO films as the counter electrode, and an electrolyte containing LiClO4 salt. The increased effective surface area of the patterned PB/FTO electrode boosted the mobility of ions at the interphase between the electrolyte and PB electrode, and the electron transfer between PB films and FTO films. As a result, electrochromic properties such as transmittance and response time were significantly improved by employing the patterned FTO films as the transparent conductive oxide layer of the electrochromic electrode. [ABSTRACT FROM AUTHOR]

The adsorption equilibria and transport properties of toluene and p ‐xylene on a Eurosil 100‐30‐C 18 column were measured from a chromatographic response in a reversed‐phase HPLC. Moment method was applied to the effluent peaks obtained from various temperatures and eluent compositions. The adsorption equilibrium constants were obtained from the first moment analysis. On the other hand, the transport properties such as the axial dispersion coefficient and effective diffusivity were obtained from the second moment analysis. The simulated results of the simulated moving bed process using the parameters obtained from the moment analysis agreed well with the experimental results. And the separation of toluene/ p ‐xylene mixture could be successfully separated by the simulated moving bed process. [ABSTRACT FROM AUTHOR]

The research of superhydrophobic materials has attracted many researchers’ attention due to its application value and prospects. In order to expand the serviceable range, people have investigated various superhydrophobic materials. The simple and easy preparation method has become the focus for superhydrophobic materials. In this paper, we present a program for preparing a rough surface on an aluminum foil, which possesses excellent hydrophobic properties after the treatment with low surface energy materials at high vacuum. The resulting contact angle is larger than 160°, and the droplet cannot freeze on the surface above −10 °C. Meanwhile, the modified aluminum foil with the thickness of less than can be used as an ideal flexible applied material for superhydrophobicity/anti-icing. [ABSTRACT FROM AUTHOR]

Hydrogen spillover mechanism of metal-supported covalent-organic frameworks COF-105 is investigated by means of the density functional theory, and the effects of metal catalysts M4 (Pt4, Pd4, and Ni4) on the whole spillover process are systematically analyzed. These three metal catalysts exhibit several similar phenomena: (i) they prefer to deposit on the tetra (4-dihydroxyborylphenyl) silane (TBPS) cluster with surface-contacted configuration; (ii) only the H atoms at the bridge site can migrate to 2,3,6,7,10,11-hexahydroxy triphenylene (HHTP) and TBPS surfaces, and the migration process is an endothermic reaction and not stable; (iii) the introduction of M4 catalyst can greatly reduce the diffusion energy barrier of H atoms, which makes it easier for the H atoms to diffuse on the substrate surface. Differently, all of the H2 molecules spontaneously dissociate into H atoms onto Pt4 and Pd4 clusters. However, the adsorbed H2 molecules on Ni4 cluster show two types of adsorption states: one activated state with stretched H–H bond length of 0.88 Å via the Kubas interaction and five dissociated states with separated hydrogen atoms. Among all the M4 catalysts, the orders of the binding energy of M4 deposited on the substrate and average chemisorption energy per H2 molecule are Pt4>Ni4>Pd4. On the contrary, the orders of the migration and diffusion barriers of H atoms are Pt4