Photon tunneling effects give rise to surface waves,amplifying radiative heat transfer in the near-field regime.Recent research has highlighted that the introduction of nanopores into materials creates additional path...Photon tunneling effects give rise to surface waves,amplifying radiative heat transfer in the near-field regime.Recent research has highlighted that the introduction of nanopores into materials creates additional pathways for heat transfer,leading to a substantial enhancement of near-field radiative heat transfer(NFRHT).Being a direct bandgap semiconductor,GaN has high thermal conductivity and stable resistance at high temperatures,and holds significant potential for applications in optoelectronic devices.Indeed,study of NFRHT between nanoporous GaN films is currently lacking,hence the physical mechanism for adding nanopores to GaN films remains to be discussed in the field of NFRHT.In this work,we delve into the NFRHT of GaN nanoporous films in terms of gap distance,GaN film thickness and the vacuum filling ratio.The results demonstrate a 27.2%increase in heat flux for a 10 nm gap when the nanoporous filling ratio is 0.5.Moreover,the spectral heat flux exhibits redshift with increase in the vacuum filling ratio.To be more precise,the peak of spectral heat flux moves fromω=1.31×10^(14)rad·s^(-1)toω=1.23×10^(14)rad·s^(-1)when the vacuum filling ratio changes from f=0.1 to f=0.5;this can be attributed to the excitation of surface phonon polaritons.The introduction of graphene into these configurations can highly enhance the NFRHT,and the spectral heat flux exhibits a blueshift with increase in the vacuum filling ratio,which can be explained by the excitation of surface plasmon polaritons.These findings offer theoretical insights that can guide the extensive utilization of porous structures in thermal control,management and thermal modulation.展开更多
A simple and rapid approach for the electrochemical synthesis of Ag nanoparticles-coated gold nanoporous film (AgGNF) on a gold substrate was reported. The solid gold electrode (SGE) was directly anodized under a high...A simple and rapid approach for the electrochemical synthesis of Ag nanoparticles-coated gold nanoporous film (AgGNF) on a gold substrate was reported. The solid gold electrode (SGE) was directly anodized under a high potential of 5 V, and then reduced to obtain gold nanoporous film (AuNF) by freshly prepared ascorbic acid. The Ag nanoparticles (AgNPs) were grown on the AuNF electrode by potential-step electrodeposition. The resulting AgGNF composites electrodes were characterized by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy and cyclic voltammetry (CV). As-prepared AgGNF electrode was used as a kind of superior sensor for Cr(VI) detection, which exhibited better electrocatalytic behavior than those of AuNF and SGE under identical conditions. Such a designed AgGNF nanocomposites electrode showed outstanding sensitivity (about 0.15 nA/ppb) and favorable reproducibility for Cr(VI) detection. The dependence of reduction current on Cr(VI) concentration is linear from 2 to 370 ppb with a low detection limit of 0.65 ppb. Interferences from other heavy metals ions (Cr3+, Cu2+, Pb2+, As3+ and Hg2+) associated with Cr(VI) analysis could be effectively diminished. The present method proves to be rapid, reliable, sensitive and low-cost.展开更多
Nanoporous BiVO;thin films were deposited using reactive magnetron sputtering in Ar and O;atmosphere, on various substrates, employing pulsed direct-current(DC) power supplies applied to metallic Bi and V targets for ...Nanoporous BiVO;thin films were deposited using reactive magnetron sputtering in Ar and O;atmosphere, on various substrates, employing pulsed direct-current(DC) power supplies applied to metallic Bi and V targets for rapid deposition. The procedure was followed by a post-annealing treatment in air to crystallize the photoactive monoclinic scheelite structure. The influence of total pressure and substrate on the crystal structure, morphology, microstructure, optical and photocatalytic properties of the films was investigated. The crystallization of monoclinic scheelite structure deposited on fused silica substrate starts at 250 ℃ and the films are stable up to 600 ℃. The morphology of the films is rather dense, despite at the high sputtering pressure(>2 Pa), with embedded nanopores. Among the thin films deposited on fused silica, the one deposited at 4.5 Pa exhibits the highest porosity(52%), with the lowest bandgap(2.44 eV) and it shows the highest photocatalytic activity in the degradation of Rhodamine-B(26% after 7 h) under visible light irradiation. The film deposited on the silicon substrate exhibits the highest photoactivity(53% after 7 h). Lack of hypsochromic shift in the UV-Vis temporal absorption spectra shows the dominance of the chromophore cleavage pathway in the photodecomposition.展开更多
Multilayer Nb2O5 nanoporous films were successfully synthesized on Nb surfaces by the control anodization process in ethylene glycol containing 4 vol% HF and 2 vol% H2O2 electrolyte. The nanoporous films are character...Multilayer Nb2O5 nanoporous films were successfully synthesized on Nb surfaces by the control anodization process in ethylene glycol containing 4 vol% HF and 2 vol% H2O2 electrolyte. The nanoporous films are characterized in detail by field-emission scanning electron microscopy（FESEM）, transmission electron microscopy（TEM）, and X-ray diffraction（XRD）. The Nb_2O_5 nanoporous films have a multilayer morphology with the side wall thickness of ～5 nm, irregular pores with a diameter of ～25 nm, and a length of up to 7.39 lm, depending on the anodization time. A mechanism for the multilayer Nb2O5 nanoporous formation was also discussed. These nanoporous materials can be very useful in the fields of solar cells, gas sensors, catalysts, optical filters, and capacitors.展开更多
Ultra-thin membrane with nanoscale through hole has great potential in biomedical applications, where precise controllability of porosity, pore size and film thickness is urgently required. The present work proposed a...Ultra-thin membrane with nanoscale through hole has great potential in biomedical applications, where precise controllability of porosity, pore size and film thickness is urgently required. The present work proposed a cost-effective way to prepare the ultra-thin nanoporous film with a promising controllability. Monodispersed nanoparticle, rather than photoresist, is used as the sacrificial material for this new lift-off process. By releasing the particles, holes can be achieved with predeter-mined characters. A 110 nm-thick nanoporous aluminum film with well-controlled pore＇s diameter was successfully fabricated to validate the technique. The technique has wider process window and better applicability than other nanofabrication methods.展开更多
The crystalline structure and surface morphology of TiO2 semiconductor coating play an important role in the conversion efficiency of dye-sensitized solar cells. In order to obtain TiO2 coating with controllable morph...The crystalline structure and surface morphology of TiO2 semiconductor coating play an important role in the conversion efficiency of dye-sensitized solar cells. In order to obtain TiO2 coating with controllable morphology and high porosity, nanoporous TiO2 films were fabricated on conducting glass （FTO） substrates, Ti thin films （1.5-2 gin） were deposited on conducting glass （FTO） substrates via the DC sputtering method, and then electrochemically anodized in NH4F/ethylene glycol solution. The crystalline structure and surface morphology of the samples were characterized by X-ray diffraction （XRD） and field emission scanning electron microscopy （FESEM）, respectively. The influences of anodizing potential, electrolyte composition, and pH value on the surface morphology of nanoporous TiO2 films were extensively studied. The growth mechanism of nanoporous TiO2 films was discussed by current density variations with anodizing time. The results demonstrate that nanoporous TiO2 films with high porosity and three-dimensional （3D） networks are observed at 30 V, when the NH4F concentration in ethylene glycol solution is 0.3% （mass fraction） and the electrolyte pH value is 5.0.展开更多
Colloidal silica sol is formed by a novel hydrolyzing procedure of tetraethyl orthosilicate(TEOS) catalyzing with NH 3 ·H 2 O in aqueous mediums. Glycerol, combining with the hydrolyzed intermediates of ...Colloidal silica sol is formed by a novel hydrolyzing procedure of tetraethyl orthosilicate(TEOS) catalyzing with NH 3 ·H 2 O in aqueous mediums. Glycerol, combining with the hydrolyzed intermediates of TEOS, controls growing of the silica particles; poly(vinyl vinyl alcohol makes the colloidal silica sol with polymeric structure and spinning, thermal strain makes the gel silica film changed into a nanoporous structure with diameter ranging 50-150 nm. Morphologies of the nanoporous silica film have been characterized; the porosities (%) is 32-64; the average dielectric constant at 1MHz region is 2.0 and 2.1; the thermal conductivity is less than 0.8. Chemical mechanism of the sol gel process is discussed.展开更多
Nanoporous amorphous ZnO films with lamellar structure were electrodetposited on the hydrophilir substrate by utilizing cooperative surface aussembly of anionic sodium dodecyl sulfonate （ SDS ） at a very low concen...Nanoporous amorphous ZnO films with lamellar structure were electrodetposited on the hydrophilir substrate by utilizing cooperative surface aussembly of anionic sodium dodecyl sulfonate （ SDS ） at a very low concentration and inorganic species Zn （ NO3 ）2 under the influence of an electrostatic potential. The deposited films were characterized by X-ray diffraction （XRD） in the range of lou, angle and wide-angle, X-ray photoelectron spectroscopy （ XPS）, scanning electron microscopy （SEM）, and UV-Vis light absorption spectroscopy.The formation mechanism of the films was elementarily discussed.展开更多
The sensing sensitivity of the wavelength interrogated surface plasmon resonance（WISPR） biosensor could be improved by self-assembly of nanoporous thin-film of TiO2 nanoparticles/DNA（TiO2/DNA）n（n is the number of...The sensing sensitivity of the wavelength interrogated surface plasmon resonance（WISPR） biosensor could be improved by self-assembly of nanoporous thin-film of TiO2 nanoparticles/DNA（TiO2/DNA）n（n is the number of bilayer） on wavelength interrogated surface plasmon resonance（WISPR） chips.The growth behavior and surface structure of the nanoporous thin-film were investigated by UV-Vis spectroscopy and scanning electron microscopy,respectively.The home-made WISPR sensor with Krestchmann configuration consisted of a tungsten-halogen lamp as a photon source and a CCD camera as the detector.After the deposition of （DNA/TiO2）n thin film on WISPR chips,the resonance peak of the reflection spectra appeared in air.With the increases of n,the resonance wavelength gradually red shifted,which is consistent with the simulated results.After the optimization of the porous film,the WISPR biosensor was utilized to detect low-molecular-weight analytes,such as biotin.The result demonstrates that the sensitivity of [poly（styrene sulfonate）/polyally lamine hydrochlorides]5（PSS/PAH）5 could be 4 times higher than that of polyelectrolyte multilayer modified WISPR sensor.展开更多
In recent year, nanoporous Si thin films have been widely studied for their potential applications in thermoelectrics, in which high thermoelectric performance can be obtained by combining both the dramatically reduce...In recent year, nanoporous Si thin films have been widely studied for their potential applications in thermoelectrics, in which high thermoelectric performance can be obtained by combining both the dramatically reduced lattice thermal conductivity and bulk-like elec- trical properties. Along this line, a high thermoelectric figure of merit （ZT） is also anticipated for other nanoporous thin films, whose bulk counterparts possess superior electrical properties but also high lattice thermal conductivities. Numerous thermoelectric studies have been carried out on Si-based nanoporous thin fills, whereas cost-effective nitrides and oxides are not systematically studied for similar thermoelectric benefits. In this work, the cross-plane thermal conductivities of nanoporous Ino.lGao.9N thin films with varied porous patterns were measured with the time-domain thermoreflectance techni- que. These alloys are suggested to have better electrical properties than conventional SixGel x alloys; however, a high ZT is hindered by their intrinsically high lattice thermal conductivity, which can be addressed by introdu- cing nanopores to scatter phonons. In contrast to previous studies using dry-etched nanopores with amorphous poreedges, the measured nanoporous thin films of this work are directly grown on a patterned sapphire substrate to minimize the structural damage by dry etching. This removes the uncertainty in the phonon transport analysis due to amorphous pore edges. Based on the measurement results, remarkable phonon size effects can be found for a thin film with periodic 300-nm-diameter pores of different patterns. This indicates that a significant amount of heat inside these alloys is still carried by phonons with -300 nm or longer mean flee paths. Our studies provide important guidance for ZT enhancement in alloys of nitrides and similar oxides.展开更多
The synthesis of ZnO architecture on a fluorine-doped SnO(FTO) conducting glass pre-coated with nanoporous TiOfilm has been achieved by a one-step hydrothermal method at a temperature of 70℃.The effect of the reactio...The synthesis of ZnO architecture on a fluorine-doped SnO(FTO) conducting glass pre-coated with nanoporous TiOfilm has been achieved by a one-step hydrothermal method at a temperature of 70℃.The effect of the reaction time on the morphology of the ZnO architecture has been investigated,and a possible growth mechanism for the formation of the ZnO architecture is discussed in detail.The morphology and phase structures of the as-obtained composite films have been investigated by field-emission scanning electron microscopy(FE-SEM) and X-ray diffraction(XRD).The results show that the growth time greatly affects the morphology of the obtained ZnO architecture.The photoelectrochemical performances of as-prepared composite films are measured by assembling them into dye sensitized solar cells(DSSCs).The DSSC based on the as-prepared composite film (2 h) has obtained the best power conversion efficiency of 1.845%.展开更多
The laser-generated surface acoustic wave（SAW） technique is an accurate,fast and nondestructive solution to determine the mechanical properties of ultra thin films.SAWs are dispersive during the wave propagation on ...The laser-generated surface acoustic wave（SAW） technique is an accurate,fast and nondestructive solution to determine the mechanical properties of ultra thin films.SAWs are dispersive during the wave propagation on the layered structure.The Young＇s moduli of thin films can be obtained by matching the experimentally and theoretically calculated dispersive SAW curves.A short ultraviolet laser pulse is employed to generate the broad spectral range of the dispersive SAWs.The frequency range of dispersive SAWs in this study reaches 180 MHz,which is adequate for the SAW technique applied for the investigated samples.In this work,the Young＇s moduli of a series of nanoporous Black Diamond^（TM） low dielectric constant（low-k） films deposited on a Si（100） substrate are characterized successfully by the SAW technique.展开更多
Nano porous polymer film with a hexagonal colum nar(Coln)structure was fabricated by templated hydroge n-bonding discotic liquid crystals containing methacrylate functional group.The supramolecular hydrogen-bonded com...Nano porous polymer film with a hexagonal colum nar(Coln)structure was fabricated by templated hydroge n-bonding discotic liquid crystals containing methacrylate functional group.The supramolecular hydrogen-bonded complex T3Ph-L is composed of a 1,3/5-tris(1Hbenzo[d]imidazol-2-yl)benzene(T3Ph)core molecule as the hydrogen-bonding acceptor and 3,4,5-tris((11-(methacryloyloxy)undecyl)oxy)benzoic acid(L)peripheral molecules as donors.And the Colh structure is always retained after self-assembly,photo-crosslinking,and removal of the template T3Ph.The nanoporous polymer film can retain the Colh phase even under the dry condition,which indicates more possibilities for practical applicati ons.After chemical modificati on of the inner wall of the nano pores,the nan oporous polymer film with pores of about 1 nm selectively adsorbs ionic dyes,and the adsorption process is spontaneous and exothermic in nature.Homeotropic alignment can be obtained when the blend complex was sandwiched between two modified glasses after annealing by slow cooling,which shows that the nanoporous polymer film has potential in applications such as nanofiltration.展开更多
Sol-gel-derived nanoporous ZnO film has been successfully deposited on glass substrate at 200 °C and subsequently annealed at different temperatures of 300, 400 and 600 °C. Atomic force micrographs demonstra...Sol-gel-derived nanoporous ZnO film has been successfully deposited on glass substrate at 200 °C and subsequently annealed at different temperatures of 300, 400 and 600 °C. Atomic force micrographs demonstrated that the film was crack-free, and that granular nanoparticles were homogenously distributed on the film surface. The average grain size of the nanoparticles and RMS roughness of the scanned surface area was 10 nm and 13.6 nm, respectively, which is due to the high porosity of the film. Photoluminescence （PL） spectra of the nanoporous ZnO film at room temperature show a diffused band, which might be due to an increased amount of oxygen va- cancies on the lattice surface. The observed results of the nanoporous ZnO film indicates a promising application in the development of electrochemical biosensors due to the porosity of film enhancing the higher loading of biomacromolecules （enzyme and proteins）.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No.52106099)the Natural Science Foundation of Shandong Province (Grant No.ZR2022YQ57)the Taishan Scholars Program。
文摘Photon tunneling effects give rise to surface waves,amplifying radiative heat transfer in the near-field regime.Recent research has highlighted that the introduction of nanopores into materials creates additional pathways for heat transfer,leading to a substantial enhancement of near-field radiative heat transfer(NFRHT).Being a direct bandgap semiconductor,GaN has high thermal conductivity and stable resistance at high temperatures,and holds significant potential for applications in optoelectronic devices.Indeed,study of NFRHT between nanoporous GaN films is currently lacking,hence the physical mechanism for adding nanopores to GaN films remains to be discussed in the field of NFRHT.In this work,we delve into the NFRHT of GaN nanoporous films in terms of gap distance,GaN film thickness and the vacuum filling ratio.The results demonstrate a 27.2%increase in heat flux for a 10 nm gap when the nanoporous filling ratio is 0.5.Moreover,the spectral heat flux exhibits redshift with increase in the vacuum filling ratio.To be more precise,the peak of spectral heat flux moves fromω=1.31×10^(14)rad·s^(-1)toω=1.23×10^(14)rad·s^(-1)when the vacuum filling ratio changes from f=0.1 to f=0.5;this can be attributed to the excitation of surface phonon polaritons.The introduction of graphene into these configurations can highly enhance the NFRHT,and the spectral heat flux exhibits a blueshift with increase in the vacuum filling ratio,which can be explained by the excitation of surface plasmon polaritons.These findings offer theoretical insights that can guide the extensive utilization of porous structures in thermal control,management and thermal modulation.
基金supported by the National Natural Science Foundation of China (21005014)the Foundation of Donghua University (113-10-0044029)
文摘A simple and rapid approach for the electrochemical synthesis of Ag nanoparticles-coated gold nanoporous film (AgGNF) on a gold substrate was reported. The solid gold electrode (SGE) was directly anodized under a high potential of 5 V, and then reduced to obtain gold nanoporous film (AuNF) by freshly prepared ascorbic acid. The Ag nanoparticles (AgNPs) were grown on the AuNF electrode by potential-step electrodeposition. The resulting AgGNF composites electrodes were characterized by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy and cyclic voltammetry (CV). As-prepared AgGNF electrode was used as a kind of superior sensor for Cr(VI) detection, which exhibited better electrocatalytic behavior than those of AuNF and SGE under identical conditions. Such a designed AgGNF nanocomposites electrode showed outstanding sensitivity (about 0.15 nA/ppb) and favorable reproducibility for Cr(VI) detection. The dependence of reduction current on Cr(VI) concentration is linear from 2 to 370 ppb with a low detection limit of 0.65 ppb. Interferences from other heavy metals ions (Cr3+, Cu2+, Pb2+, As3+ and Hg2+) associated with Cr(VI) analysis could be effectively diminished. The present method proves to be rapid, reliable, sensitive and low-cost.
基金the supports of this study by the Iran National Science Foundation (No. 98001285)Pays de Montbéliard Agglomération (France) for the support of this work。
文摘Nanoporous BiVO;thin films were deposited using reactive magnetron sputtering in Ar and O;atmosphere, on various substrates, employing pulsed direct-current(DC) power supplies applied to metallic Bi and V targets for rapid deposition. The procedure was followed by a post-annealing treatment in air to crystallize the photoactive monoclinic scheelite structure. The influence of total pressure and substrate on the crystal structure, morphology, microstructure, optical and photocatalytic properties of the films was investigated. The crystallization of monoclinic scheelite structure deposited on fused silica substrate starts at 250 ℃ and the films are stable up to 600 ℃. The morphology of the films is rather dense, despite at the high sputtering pressure(>2 Pa), with embedded nanopores. Among the thin films deposited on fused silica, the one deposited at 4.5 Pa exhibits the highest porosity(52%), with the lowest bandgap(2.44 eV) and it shows the highest photocatalytic activity in the degradation of Rhodamine-B(26% after 7 h) under visible light irradiation. The film deposited on the silicon substrate exhibits the highest photoactivity(53% after 7 h). Lack of hypsochromic shift in the UV-Vis temporal absorption spectra shows the dominance of the chromophore cleavage pathway in the photodecomposition.
基金financially supported by the National Natural Science Foundation of China (Nos. 50902115 and 51104121)
文摘Multilayer Nb2O5 nanoporous films were successfully synthesized on Nb surfaces by the control anodization process in ethylene glycol containing 4 vol% HF and 2 vol% H2O2 electrolyte. The nanoporous films are characterized in detail by field-emission scanning electron microscopy（FESEM）, transmission electron microscopy（TEM）, and X-ray diffraction（XRD）. The Nb_2O_5 nanoporous films have a multilayer morphology with the side wall thickness of ～5 nm, irregular pores with a diameter of ～25 nm, and a length of up to 7.39 lm, depending on the anodization time. A mechanism for the multilayer Nb2O5 nanoporous formation was also discussed. These nanoporous materials can be very useful in the fields of solar cells, gas sensors, catalysts, optical filters, and capacitors.
基金the National Natural Science Foundation of China (Grant Nos. 60606014 and 90607004)
文摘Ultra-thin membrane with nanoscale through hole has great potential in biomedical applications, where precise controllability of porosity, pore size and film thickness is urgently required. The present work proposed a cost-effective way to prepare the ultra-thin nanoporous film with a promising controllability. Monodispersed nanoparticle, rather than photoresist, is used as the sacrificial material for this new lift-off process. By releasing the particles, holes can be achieved with predeter-mined characters. A 110 nm-thick nanoporous aluminum film with well-controlled pore＇s diameter was successfully fabricated to validate the technique. The technique has wider process window and better applicability than other nanofabrication methods.
基金Projects(21171027,50872014) supported by the National Natural Science Foundation of ChinaProject(K1001020-11)supported by the Science and Technology Key Project of Changsha City,China
文摘The crystalline structure and surface morphology of TiO2 semiconductor coating play an important role in the conversion efficiency of dye-sensitized solar cells. In order to obtain TiO2 coating with controllable morphology and high porosity, nanoporous TiO2 films were fabricated on conducting glass （FTO） substrates, Ti thin films （1.5-2 gin） were deposited on conducting glass （FTO） substrates via the DC sputtering method, and then electrochemically anodized in NH4F/ethylene glycol solution. The crystalline structure and surface morphology of the samples were characterized by X-ray diffraction （XRD） and field emission scanning electron microscopy （FESEM）, respectively. The influences of anodizing potential, electrolyte composition, and pH value on the surface morphology of nanoporous TiO2 films were extensively studied. The growth mechanism of nanoporous TiO2 films was discussed by current density variations with anodizing time. The results demonstrate that nanoporous TiO2 films with high porosity and three-dimensional （3D） networks are observed at 30 V, when the NH4F concentration in ethylene glycol solution is 0.3% （mass fraction） and the electrolyte pH value is 5.0.
文摘Colloidal silica sol is formed by a novel hydrolyzing procedure of tetraethyl orthosilicate(TEOS) catalyzing with NH 3 ·H 2 O in aqueous mediums. Glycerol, combining with the hydrolyzed intermediates of TEOS, controls growing of the silica particles; poly(vinyl vinyl alcohol makes the colloidal silica sol with polymeric structure and spinning, thermal strain makes the gel silica film changed into a nanoporous structure with diameter ranging 50-150 nm. Morphologies of the nanoporous silica film have been characterized; the porosities (%) is 32-64; the average dielectric constant at 1MHz region is 2.0 and 2.1; the thermal conductivity is less than 0.8. Chemical mechanism of the sol gel process is discussed.
基金Founded by National Science Foundation of Tianjin ( No.33802311)
文摘Nanoporous amorphous ZnO films with lamellar structure were electrodetposited on the hydrophilir substrate by utilizing cooperative surface aussembly of anionic sodium dodecyl sulfonate （ SDS ） at a very low concentration and inorganic species Zn （ NO3 ）2 under the influence of an electrostatic potential. The deposited films were characterized by X-ray diffraction （XRD） in the range of lou, angle and wide-angle, X-ray photoelectron spectroscopy （ XPS）, scanning electron microscopy （SEM）, and UV-Vis light absorption spectroscopy.The formation mechanism of the films was elementarily discussed.
基金Supported by the National Natural Science Foundation of China（Nos.91123029, 61077066, 61340032）, the National High Technology Research and Development Program of China（No.2012AA063302） and the Natural Science Foundation of Shandong Province, China（No.ZR2012CM029）.
文摘The sensing sensitivity of the wavelength interrogated surface plasmon resonance（WISPR） biosensor could be improved by self-assembly of nanoporous thin-film of TiO2 nanoparticles/DNA（TiO2/DNA）n（n is the number of bilayer） on wavelength interrogated surface plasmon resonance（WISPR） chips.The growth behavior and surface structure of the nanoporous thin-film were investigated by UV-Vis spectroscopy and scanning electron microscopy,respectively.The home-made WISPR sensor with Krestchmann configuration consisted of a tungsten-halogen lamp as a photon source and a CCD camera as the detector.After the deposition of （DNA/TiO2）n thin film on WISPR chips,the resonance peak of the reflection spectra appeared in air.With the increases of n,the resonance wavelength gradually red shifted,which is consistent with the simulated results.After the optimization of the porous film,the WISPR biosensor was utilized to detect low-molecular-weight analytes,such as biotin.The result demonstrates that the sensitivity of [poly（styrene sulfonate）/polyally lamine hydrochlorides]5（PSS/PAH）5 could be 4 times higher than that of polyelectrolyte multilayer modified WISPR sensor.
文摘In recent year, nanoporous Si thin films have been widely studied for their potential applications in thermoelectrics, in which high thermoelectric performance can be obtained by combining both the dramatically reduced lattice thermal conductivity and bulk-like elec- trical properties. Along this line, a high thermoelectric figure of merit （ZT） is also anticipated for other nanoporous thin films, whose bulk counterparts possess superior electrical properties but also high lattice thermal conductivities. Numerous thermoelectric studies have been carried out on Si-based nanoporous thin fills, whereas cost-effective nitrides and oxides are not systematically studied for similar thermoelectric benefits. In this work, the cross-plane thermal conductivities of nanoporous Ino.lGao.9N thin films with varied porous patterns were measured with the time-domain thermoreflectance techni- que. These alloys are suggested to have better electrical properties than conventional SixGel x alloys; however, a high ZT is hindered by their intrinsically high lattice thermal conductivity, which can be addressed by introdu- cing nanopores to scatter phonons. In contrast to previous studies using dry-etched nanopores with amorphous poreedges, the measured nanoporous thin films of this work are directly grown on a patterned sapphire substrate to minimize the structural damage by dry etching. This removes the uncertainty in the phonon transport analysis due to amorphous pore edges. Based on the measurement results, remarkable phonon size effects can be found for a thin film with periodic 300-nm-diameter pores of different patterns. This indicates that a significant amount of heat inside these alloys is still carried by phonons with -300 nm or longer mean flee paths. Our studies provide important guidance for ZT enhancement in alloys of nitrides and similar oxides.
基金Project supported by the National Basic Research Program of China(No.2007CB936300)the Research Foundation for Advanced Talents of Jiangsu University,China(No.10JDG 142)
文摘The synthesis of ZnO architecture on a fluorine-doped SnO(FTO) conducting glass pre-coated with nanoporous TiOfilm has been achieved by a one-step hydrothermal method at a temperature of 70℃.The effect of the reaction time on the morphology of the ZnO architecture has been investigated,and a possible growth mechanism for the formation of the ZnO architecture is discussed in detail.The morphology and phase structures of the as-obtained composite films have been investigated by field-emission scanning electron microscopy(FE-SEM) and X-ray diffraction(XRD).The results show that the growth time greatly affects the morphology of the obtained ZnO architecture.The photoelectrochemical performances of as-prepared composite films are measured by assembling them into dye sensitized solar cells(DSSCs).The DSSC based on the as-prepared composite film (2 h) has obtained the best power conversion efficiency of 1.845%.
基金Project supported by the National Natural Science Fotmdation of China(No.60876072)the New Century Excellent Talents in University,China(No.NCET-08-0389).
文摘The laser-generated surface acoustic wave（SAW） technique is an accurate,fast and nondestructive solution to determine the mechanical properties of ultra thin films.SAWs are dispersive during the wave propagation on the layered structure.The Young＇s moduli of thin films can be obtained by matching the experimentally and theoretically calculated dispersive SAW curves.A short ultraviolet laser pulse is employed to generate the broad spectral range of the dispersive SAWs.The frequency range of dispersive SAWs in this study reaches 180 MHz,which is adequate for the SAW technique applied for the investigated samples.In this work,the Young＇s moduli of a series of nanoporous Black Diamond^（TM） low dielectric constant（low-k） films deposited on a Si（100） substrate are characterized successfully by the SAW technique.
基金the National Key R&D Program of China(No.2018YFB0703702)the National Natural Science Foundation of China(No.51725301).
文摘Nano porous polymer film with a hexagonal colum nar(Coln)structure was fabricated by templated hydroge n-bonding discotic liquid crystals containing methacrylate functional group.The supramolecular hydrogen-bonded complex T3Ph-L is composed of a 1,3/5-tris(1Hbenzo[d]imidazol-2-yl)benzene(T3Ph)core molecule as the hydrogen-bonding acceptor and 3,4,5-tris((11-(methacryloyloxy)undecyl)oxy)benzoic acid(L)peripheral molecules as donors.And the Colh structure is always retained after self-assembly,photo-crosslinking,and removal of the template T3Ph.The nanoporous polymer film can retain the Colh phase even under the dry condition,which indicates more possibilities for practical applicati ons.After chemical modificati on of the inner wall of the nano pores,the nan oporous polymer film with pores of about 1 nm selectively adsorbs ionic dyes,and the adsorption process is spontaneous and exothermic in nature.Homeotropic alignment can be obtained when the blend complex was sandwiched between two modified glasses after annealing by slow cooling,which shows that the nanoporous polymer film has potential in applications such as nanofiltration.
文摘Sol-gel-derived nanoporous ZnO film has been successfully deposited on glass substrate at 200 °C and subsequently annealed at different temperatures of 300, 400 and 600 °C. Atomic force micrographs demonstrated that the film was crack-free, and that granular nanoparticles were homogenously distributed on the film surface. The average grain size of the nanoparticles and RMS roughness of the scanned surface area was 10 nm and 13.6 nm, respectively, which is due to the high porosity of the film. Photoluminescence （PL） spectra of the nanoporous ZnO film at room temperature show a diffused band, which might be due to an increased amount of oxygen va- cancies on the lattice surface. The observed results of the nanoporous ZnO film indicates a promising application in the development of electrochemical biosensors due to the porosity of film enhancing the higher loading of biomacromolecules （enzyme and proteins）.
