A novel Pd electrocatalyst with flowerlike micro-nanostructures was synthesized by electrochemical deposition on a flexible graphene/polyimide（Gr/PI） composite membrane and characterized by scanning electron microsc...A novel Pd electrocatalyst with flowerlike micro-nanostructures was synthesized by electrochemical deposition on a flexible graphene/polyimide（Gr/PI） composite membrane and characterized by scanning electron microscopy（SEM）,X-ray diffraction（XRD）.The Pd micro-nanoparticles were prepared on a COOH-CNTs/PI membrane as a comparative sample.The XRD and SEM investigations for Pd electrodeposition demonstrate that the particle size of Gr/PI composite membrane is smaller than that of COOH-CNTs/PI membrane,while the uniform and dense distribution of Pd micro-nanoparticles on the Gr/PI composite membrane is greater than that on the COOH-CNTs/PI membrane.The electrocatalytic properties of Pd/Gr/PI and Pd/COOH-CNTs/PI catalysts for the oxidation of formic acid were investigated by cyclic voltammetry（CV） and chronoamperometry（CA）.It is found that the electrocatalytic activity and stability of Pd/Gr/PI are superior to those of Pd/COOH-CNTs/PI catalyst.This is because smaller metal particles and higher dense distribution desirably provide abundant catalytic sites and mean higher catalytic activity.Therefore,the Pd/Gr/PI catalyst has better catalytic performance for formic acid oxidation than the Pd/COOH-CNTs/PI catalyst.展开更多
Indium tin oxide(ITO)thin films were prepared using the technique of rf-sputtering with oblique angle deposition(OAD).The films were as-deposited and thermally treated at 250℃.The combination of substrate inclination...Indium tin oxide(ITO)thin films were prepared using the technique of rf-sputtering with oblique angle deposition(OAD).The films were as-deposited and thermally treated at 250℃.The combination of substrate inclination and annealing was used for modifying morphological and structural properties that lead to changes of the optical properties.The resulting films show morphology of tilted nanocolumn,fissures among columns,and structural changes.The as-deposited films are structurally disordered with an amorphous component and the annealed films are crystallized and more ordered and the film diffractograms correspond to the cubic structure of In2O3.The refractive index could be modified up to 0.3 in as-deposited films and up to 0.15 in annealed films as functions of the inclination angle of the nanocolumns.Similarly,the band gap energy increases up to about 0.4 eV due to the reduction of the microstrain distribution.It is found that the microstrain distribution,which is related to lattice distortions,defects and the presence of fissures in the films,is the main feature that can be engineered through morphological modifications for achieving the adjustment of the optical properties.展开更多
Three thicknesses of TiO2 films, 174, 195, and 229 nm, were deposited onto quartz substrates by sol–gel spin coating method. The as-deposited thin films were characterized by nano-crystallite with different sizes (19...Three thicknesses of TiO2 films, 174, 195, and 229 nm, were deposited onto quartz substrates by sol–gel spin coating method. The as-deposited thin films were characterized by nano-crystallite with different sizes (19–46 nm) and relatively high porous structure. Optical constants were determined and showed the lowest refractive index of 1.66 for the as-prepared films that ever reported till now. Obtained results were discussed through current theoretical ideas.展开更多
Applying negative bias voltages caused significant microstructure changes in arc ion plated CrN films. Nanocrystalline microstructures were obtained by adjusting the negative bias voltage. Structural characterizations...Applying negative bias voltages caused significant microstructure changes in arc ion plated CrN films. Nanocrystalline microstructures were obtained by adjusting the negative bias voltage. Structural characterizations of the films were carried out using X-ray diffractometry (XRD) and high-resolution transmission electron microscopy (HR-TEM). The results indicated that increasing ion bombardment by applying negative bias voltages resulted in the formation of defects in the CrN films, inducing microstructure evolution from micro-columnar to nanocrystalline. The microhardness and residual stresses of the films were also affected. Based on the experimental results, the evolution mechanisms of the film microstructure and properties were discussed by considering ion bombardment effects.展开更多
Nano/microcrystalline composite diamond films were deposited on the holes of WC-6%Co drawing dies by a two-step procedure using alternative carbon sources, i.e., methane for the microcrystalline diamond（MCD） layer a...Nano/microcrystalline composite diamond films were deposited on the holes of WC-6%Co drawing dies by a two-step procedure using alternative carbon sources, i.e., methane for the microcrystalline diamond（MCD） layer and acetone for the nanocrystalline diamond（NCD） layer. Moreover, the monolayer methane-MCD and acetone-NCD coated drawing dies were fabricated as comparisons. The adhesion and wear rates of the diamond coated drawing dies were also tested by an inner hole polishing apparatus. Compared with mono-layer diamond coated drawing die, the composite diamond coated one exhibits better comprehensive performance, including higher adhesive strength and better wear resistance than the NCD one, and smoother surface（Ra=65.3 nm） than the MCD one（Ra=95.6 nm） after polishing at the same time. Compared with the NCD coated drawing die, the working lifetime of the composite diamond coated one is increased by nearly 20 times.展开更多
Anodized composite films containing Si C nanoparticles were synthesized on Ti6Al4 V alloy by anodic oxidation procedure in C4O6H4Na2 electrolyte. Scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS) ...Anodized composite films containing Si C nanoparticles were synthesized on Ti6Al4 V alloy by anodic oxidation procedure in C4O6H4Na2 electrolyte. Scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS) and X-ray photoelectron spectroscopy(XPS) were employed to characterize the morphology and composition of the films fabricated in the electrolytes with and without addition of Si C nanoparticles. Results show that Si C particles can be successfully incorporated into the oxide film during the anodizing process and preferentially concentrate within internal cavities and micro-cracks. The ball-on-disk sliding tests indicate that Si C-containing oxide films register much lower wear rate than the oxide films without Si C under dry sliding condition. Si C particles are likely to melt and then are oxidized by frictional heat during sliding tests. Potentiodynamic polarization behavior reveals that the anodized alloy with Si C nanoparticles results in a reduction in passive current density to about 1.54×10-8 A/cm2, which is more than two times lower than that of the Ti O2 film(3.73×10-8 A/cm2). The synthesized composite film has good anti-wear and anti-corrosion properties and the growth mechanism of nanocomposite film is also discussed.展开更多
In this work, a development of a method of a thin insulating film vertical edge visualization of metal-insulator-metal （MIM） memory cells with atomic force microscopy （AFM） using a modified Omicron UHV AFM/STM mic...In this work, a development of a method of a thin insulating film vertical edge visualization of metal-insulator-metal （MIM） memory cells with atomic force microscopy （AFM） using a modified Omicron UHV AFM/STM microscope was performed. This included a development of a technique of the AFM visualization of segments of a vertical edge of thin insulator SiO2 film structures on a conductive substrate, a comparison of AFM topography and current profilograms for the edge profiles, and an Omicron microscope custom upgrade. The latter allowed us to perform the AFM probe positioning to any specific area of the sample in the scanning plane by two coordinates with an order of precision of 1 micrometer. The method is illustrated with the experimental results of AFM investigations of the special MIM structures with comb-type topology, and of the cells of functioning memory matrices with 20 nm thin silicon dioxide film open edge perimeter and TiN lower electrode, including topography/current profilograms. As a conclusion, our ongoing work on the AFM visualization of a complete perimeter of a SiO2 open edge of memory cells with a special new topology with a goal to visualize conductive phase nanoparticles during switching processes is briefly overviewed.展开更多
ZnO thin films were prepared by electrophoretic deposition on stainless steel wire sieve, using zinc acetate as a precursor. The film was sintered and characterised by Scanning Electron Microscopy （SEM）, X-Ray Diffr...ZnO thin films were prepared by electrophoretic deposition on stainless steel wire sieve, using zinc acetate as a precursor. The film was sintered and characterised by Scanning Electron Microscopy （SEM）, X-Ray Diffraction （XRD） and chemisorption of oxygen. A culture bacterial consortium composed by gram negative rod-shaped microbes was prepared in a liquid agar in a flask. It was transported by air through a reactor equipped with a UV lamp with 3 and 5 sieves of a stainless steel wire coated with ZnO film. It was exposed in continuous in five experiments to photocatalytic advanced oxidation. The experiments showed a total efficiency for colony forming unit reduction of a maximum of 99.66% for a residence time of 20 seconds with 5 stainless steel wire where exposed in continuous to UV. Also they were evaluated at 7.5 seconds, observing that the contribution of residence time and amount of catalytic for the CFU reduction was quite similar. Variance analysis showed that the efficiency was significant with the no parametric Kruskal-Wallis test with P 〈 0.05. This technology could be used to clean indoor air of closed environments such as hospitals, crowded buildings or public transportation systems where airborne bacteria has been documented.展开更多
Peptoids(or poly-N-substituted glycines)are a promising class of bioinspired sequence-defined polymers due to their highly efficient synthesis,high chemical stability,enzyme hydrolysis resistance,and biocompatibility....Peptoids(or poly-N-substituted glycines)are a promising class of bioinspired sequence-defined polymers due to their highly efficient synthesis,high chemical stability,enzyme hydrolysis resistance,and biocompatibility.By tuning the side chain chemistry of peptoids,it allows for precise control over sequences and achieving a large side-chain diversity.Due to these unique features,in the last several years,many amphiphilic peptoids were designed as highly tunable building blocks for the preparation of biomimetic nanomaterials with well-defined hierarchical structures and desired functionalities.Herein,we provide an overview of the recent achievements in this area by dividing them into the following three aspects.First,mica-and silica-templated peptoid selfassembly are summarized.The presence of inorganic substrates provides the guarantee of investigating their selfassembly mechanisms and interactions between peptoids and substrates using nanoscale characterization techniques,particularly in situ atomic force microscopy(AFM)and AFMbased dynamic force spectroscopy(AFM-DFS).Second,solution-phase self-assembly of peptoids into nanotubes and nanosheets is presented,as well as their self-repair properties.Third,the applications of peptoid-based nanomaterials are outlined,including the construction of catalytic nanomaterials as a template and cytosolic delivery as cargoes.展开更多
基金Project(51372106)supported by the National Natural Science Foundation of China
文摘A novel Pd electrocatalyst with flowerlike micro-nanostructures was synthesized by electrochemical deposition on a flexible graphene/polyimide（Gr/PI） composite membrane and characterized by scanning electron microscopy（SEM）,X-ray diffraction（XRD）.The Pd micro-nanoparticles were prepared on a COOH-CNTs/PI membrane as a comparative sample.The XRD and SEM investigations for Pd electrodeposition demonstrate that the particle size of Gr/PI composite membrane is smaller than that of COOH-CNTs/PI membrane,while the uniform and dense distribution of Pd micro-nanoparticles on the Gr/PI composite membrane is greater than that on the COOH-CNTs/PI membrane.The electrocatalytic properties of Pd/Gr/PI and Pd/COOH-CNTs/PI catalysts for the oxidation of formic acid were investigated by cyclic voltammetry（CV） and chronoamperometry（CA）.It is found that the electrocatalytic activity and stability of Pd/Gr/PI are superior to those of Pd/COOH-CNTs/PI catalyst.This is because smaller metal particles and higher dense distribution desirably provide abundant catalytic sites and mean higher catalytic activity.Therefore,the Pd/Gr/PI catalyst has better catalytic performance for formic acid oxidation than the Pd/COOH-CNTs/PI catalyst.
基金supported by the Project No.CB/2012/178748 CONACYT/México
文摘Indium tin oxide(ITO)thin films were prepared using the technique of rf-sputtering with oblique angle deposition(OAD).The films were as-deposited and thermally treated at 250℃.The combination of substrate inclination and annealing was used for modifying morphological and structural properties that lead to changes of the optical properties.The resulting films show morphology of tilted nanocolumn,fissures among columns,and structural changes.The as-deposited films are structurally disordered with an amorphous component and the annealed films are crystallized and more ordered and the film diffractograms correspond to the cubic structure of In2O3.The refractive index could be modified up to 0.3 in as-deposited films and up to 0.15 in annealed films as functions of the inclination angle of the nanocolumns.Similarly,the band gap energy increases up to about 0.4 eV due to the reduction of the microstrain distribution.It is found that the microstrain distribution,which is related to lattice distortions,defects and the presence of fissures in the films,is the main feature that can be engineered through morphological modifications for achieving the adjustment of the optical properties.
文摘Three thicknesses of TiO2 films, 174, 195, and 229 nm, were deposited onto quartz substrates by sol–gel spin coating method. The as-deposited thin films were characterized by nano-crystallite with different sizes (19–46 nm) and relatively high porous structure. Optical constants were determined and showed the lowest refractive index of 1.66 for the as-prepared films that ever reported till now. Obtained results were discussed through current theoretical ideas.
基金Project(2010-0001-226) supported by the National Core Research Center (NCRC) Program through the National Research Foundation of Korea funded by the Ministry of Education, Science and TechnologyProject supported by the Fundamental R&D Program for Core Technology of Materials funded by the Ministry of Knowledge Economy, Korea
文摘Applying negative bias voltages caused significant microstructure changes in arc ion plated CrN films. Nanocrystalline microstructures were obtained by adjusting the negative bias voltage. Structural characterizations of the films were carried out using X-ray diffractometry (XRD) and high-resolution transmission electron microscopy (HR-TEM). The results indicated that increasing ion bombardment by applying negative bias voltages resulted in the formation of defects in the CrN films, inducing microstructure evolution from micro-columnar to nanocrystalline. The microhardness and residual stresses of the films were also affected. Based on the experimental results, the evolution mechanisms of the film microstructure and properties were discussed by considering ion bombardment effects.
基金Project(51275302) supported by the National Natural Science Foundation of China
文摘Nano/microcrystalline composite diamond films were deposited on the holes of WC-6%Co drawing dies by a two-step procedure using alternative carbon sources, i.e., methane for the microcrystalline diamond（MCD） layer and acetone for the nanocrystalline diamond（NCD） layer. Moreover, the monolayer methane-MCD and acetone-NCD coated drawing dies were fabricated as comparisons. The adhesion and wear rates of the diamond coated drawing dies were also tested by an inner hole polishing apparatus. Compared with mono-layer diamond coated drawing die, the composite diamond coated one exhibits better comprehensive performance, including higher adhesive strength and better wear resistance than the NCD one, and smoother surface（Ra=65.3 nm） than the MCD one（Ra=95.6 nm） after polishing at the same time. Compared with the NCD coated drawing die, the working lifetime of the composite diamond coated one is increased by nearly 20 times.
基金Project(51271012)supported by the National Natural Science Foundation of China
文摘Anodized composite films containing Si C nanoparticles were synthesized on Ti6Al4 V alloy by anodic oxidation procedure in C4O6H4Na2 electrolyte. Scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS) and X-ray photoelectron spectroscopy(XPS) were employed to characterize the morphology and composition of the films fabricated in the electrolytes with and without addition of Si C nanoparticles. Results show that Si C particles can be successfully incorporated into the oxide film during the anodizing process and preferentially concentrate within internal cavities and micro-cracks. The ball-on-disk sliding tests indicate that Si C-containing oxide films register much lower wear rate than the oxide films without Si C under dry sliding condition. Si C particles are likely to melt and then are oxidized by frictional heat during sliding tests. Potentiodynamic polarization behavior reveals that the anodized alloy with Si C nanoparticles results in a reduction in passive current density to about 1.54×10-8 A/cm2, which is more than two times lower than that of the Ti O2 film(3.73×10-8 A/cm2). The synthesized composite film has good anti-wear and anti-corrosion properties and the growth mechanism of nanocomposite film is also discussed.
文摘In this work, a development of a method of a thin insulating film vertical edge visualization of metal-insulator-metal （MIM） memory cells with atomic force microscopy （AFM） using a modified Omicron UHV AFM/STM microscope was performed. This included a development of a technique of the AFM visualization of segments of a vertical edge of thin insulator SiO2 film structures on a conductive substrate, a comparison of AFM topography and current profilograms for the edge profiles, and an Omicron microscope custom upgrade. The latter allowed us to perform the AFM probe positioning to any specific area of the sample in the scanning plane by two coordinates with an order of precision of 1 micrometer. The method is illustrated with the experimental results of AFM investigations of the special MIM structures with comb-type topology, and of the cells of functioning memory matrices with 20 nm thin silicon dioxide film open edge perimeter and TiN lower electrode, including topography/current profilograms. As a conclusion, our ongoing work on the AFM visualization of a complete perimeter of a SiO2 open edge of memory cells with a special new topology with a goal to visualize conductive phase nanoparticles during switching processes is briefly overviewed.
文摘ZnO thin films were prepared by electrophoretic deposition on stainless steel wire sieve, using zinc acetate as a precursor. The film was sintered and characterised by Scanning Electron Microscopy （SEM）, X-Ray Diffraction （XRD） and chemisorption of oxygen. A culture bacterial consortium composed by gram negative rod-shaped microbes was prepared in a liquid agar in a flask. It was transported by air through a reactor equipped with a UV lamp with 3 and 5 sieves of a stainless steel wire coated with ZnO film. It was exposed in continuous in five experiments to photocatalytic advanced oxidation. The experiments showed a total efficiency for colony forming unit reduction of a maximum of 99.66% for a residence time of 20 seconds with 5 stainless steel wire where exposed in continuous to UV. Also they were evaluated at 7.5 seconds, observing that the contribution of residence time and amount of catalytic for the CFU reduction was quite similar. Variance analysis showed that the efficiency was significant with the no parametric Kruskal-Wallis test with P 〈 0.05. This technology could be used to clean indoor air of closed environments such as hospitals, crowded buildings or public transportation systems where airborne bacteria has been documented.
基金supported by the Startup Research Fund of Dongguan University of Technology(KCYKYQD2017015)the US Department of Energy,Office of Science,Office of Basic Energy Sciences,as part of the Energy Frontier Research Centers program:CSSAS—The Center for the Science of Synthesis Across Scales(DESC0019288)。
文摘Peptoids(or poly-N-substituted glycines)are a promising class of bioinspired sequence-defined polymers due to their highly efficient synthesis,high chemical stability,enzyme hydrolysis resistance,and biocompatibility.By tuning the side chain chemistry of peptoids,it allows for precise control over sequences and achieving a large side-chain diversity.Due to these unique features,in the last several years,many amphiphilic peptoids were designed as highly tunable building blocks for the preparation of biomimetic nanomaterials with well-defined hierarchical structures and desired functionalities.Herein,we provide an overview of the recent achievements in this area by dividing them into the following three aspects.First,mica-and silica-templated peptoid selfassembly are summarized.The presence of inorganic substrates provides the guarantee of investigating their selfassembly mechanisms and interactions between peptoids and substrates using nanoscale characterization techniques,particularly in situ atomic force microscopy(AFM)and AFMbased dynamic force spectroscopy(AFM-DFS).Second,solution-phase self-assembly of peptoids into nanotubes and nanosheets is presented,as well as their self-repair properties.Third,the applications of peptoid-based nanomaterials are outlined,including the construction of catalytic nanomaterials as a template and cytosolic delivery as cargoes.
