Nonpolar(11–20) a-plane p-type GaN films were successfully grown on r-plane sapphire substrate with the metal–organic chemical vapor deposition(MOCVD) system. The effects of Mg-doping temperature on the structural a...Nonpolar(11–20) a-plane p-type GaN films were successfully grown on r-plane sapphire substrate with the metal–organic chemical vapor deposition(MOCVD) system. The effects of Mg-doping temperature on the structural and electrical properties of nonpolar p-type GaN films were investigated in detail. It is found that all the surface morphology, crystalline quality, strains, and electrical properties of nonpolar a-plane p-type GaN films are interconnected, and are closely related to the Mg-doping temperature. This means that a proper performance of nonpolar p-type GaN can be expected by optimizing the Mg-doping temperature. In fact, a hole concentration of 1.3×10^(18)cm^(-3), a high Mg activation efficiency of 6.5%,an activation energy of 114 me V for Mg acceptor, and a low anisotropy of 8.3% in crystalline quality were achieved with a growth temperature of 990℃. This approach to optimizing the Mg-doping temperature of the nonpolar a-plane p-type GaN film provides an effective way to fabricate high-efficiency optoelectronic devices in the future.展开更多
Phlogopite-based geopolymer was first prepared successfully under the activation of lye by compression molding at 50 MPa for 1 minute.The geopolymer was endowed with nonpolar surface via brushing modified liquid at ro...Phlogopite-based geopolymer was first prepared successfully under the activation of lye by compression molding at 50 MPa for 1 minute.The geopolymer was endowed with nonpolar surface via brushing modified liquid at room temperature.Swill-cooked dirty oil,whose main component was fatty acid,was used as nonpolar modifier.The raw materials and geopolymer samples were characterized by XRD,FT-IR and SEM.The compression strength of 7-day specimen run up to 36.8 MPa and its surface static water contact angle could reach 132°.The solubility of phlogopite powder directly affected the compressive strength of geopolymers and the evaluation index of mechanical strength of geopolymer based on the solubility of phlogopite powder was proposed.展开更多
Tunnel wash waters characterize all waters that run off after washing procedures of tunnels are performed.These waters represent a wide spectrum of organic and inorganic pollutants,such as polycyclic aromatic hydrocar...Tunnel wash waters characterize all waters that run off after washing procedures of tunnels are performed.These waters represent a wide spectrum of organic and inorganic pollutants,such as polycyclic aromatic hydrocarbons(PAHs)and toxic metals.Removal of such contaminants from water runoff was investigated using laboratory tests after washing procedure was performed on two road tunnels in eastern Norway(Hanekleiv and Bragernes).Due to diverse character of both,treatment media and treated wash waters, the wh...展开更多
Nonpolar （1150） a-plane GaN films are grown by metal-organic chemical vapour deposition （MOCVD） on r-plane （1102） sapphire. The samples are irradiated with neutrons under a dose of 1× 1015 cm-2. The surface...Nonpolar （1150） a-plane GaN films are grown by metal-organic chemical vapour deposition （MOCVD） on r-plane （1102） sapphire. The samples are irradiated with neutrons under a dose of 1× 1015 cm-2. The surface morphology, the crystal defects and the optical properties of the samples before and after irradiation are analysed using atomic force microscopy （AFM）, high resolution X-ray diffraction （HRXRD） and photoluminescence （PL）. The AFM result shows deteriorated sample surface after the irradiation. Careful fitting of the XRD rocking curve is carried out to obtain the Lorentzian weight fraction. Broadening due to Lorentzian type is more obvious in the as-grown sample compared with that of the irradiated sample, indicating that more point defects appear in the irradiated sample. The variations of line width and intensity of the PL band edge emission peak are consistent with the XRD results. The activation energy decreases from 82.5 meV to 29.9 meV after irradiation by neutron.展开更多
The anisotropic strain of a nonpolar （1120） a-plane GaN epilayer on an r-plane （1102） sapphire substrate, grown by low-pressure metal-organic vapour deposition is investigated by Raman spectroscopy. The room-tempe...The anisotropic strain of a nonpolar （1120） a-plane GaN epilayer on an r-plane （1102） sapphire substrate, grown by low-pressure metal-organic vapour deposition is investigated by Raman spectroscopy. The room-temperature Raman scattering spectra of nonpolar a-plane GaN are measured in surface and edge backscattering geometries. The lattice is contracted in both the c- and the m-axis directions, and the stress in the m-axis direction is larger than that in the c-axis direction. On the surface of this sample, a number of cracks appear only along the m-axis, which is confirmed by the scanning electron micrograph. Atomic force microscopy images reveal a significant decrease in the root-mean-square roughness and the density of submicron pits after the stress relief.展开更多
We report on the growth of the high-quality GaN grain on a r-plane sapphire substrate by using a self-organized SiN interlayer as a selective growth mask. Transmission electron microscopy, scanning electron microscopy...We report on the growth of the high-quality GaN grain on a r-plane sapphire substrate by using a self-organized SiN interlayer as a selective growth mask. Transmission electron microscopy, scanning electron microscopy, and Raman spectroscopy are used to reveal the effect of SiN on the overgrown a-plane GaN growth. The SiN layer effectively terminates the propagation of the threading dislocation and basal plane stacking faults during a-plane GaN regrowth through the interlayer, resulting in the window region shrinking from a rectangle to a ＂black hole＂. Furthermore, strong yellow luminescence （YL） in the nonpolar plane and very weak YL in the semipolar plane on the GaN grain is revealed by cathodoluminescence, suggesting that C-involved defects are responsible for the YL.展开更多
A novel groove-type channel enhancement-mode AlGaN/GaN MIS high electron mobility transistor（GTCE-HEMT）with a combined polar and nonpolar AlGaN/GaN heterostucture is presented. The device simulation shows a threshol...A novel groove-type channel enhancement-mode AlGaN/GaN MIS high electron mobility transistor（GTCE-HEMT）with a combined polar and nonpolar AlGaN/GaN heterostucture is presented. The device simulation shows a threshold voltage of 1.24 V, peak transconductance of 182 m S/mm, and subthreshold slope of 85 m V/dec, which are obtained by adjusting the device parameters. Interestingly, it is possible to control the threshold voltage accurately without precisely controlling the etching depth in fabrication by adopting this structure. Besides, the breakdown voltage（VB） is significantly increased by 78% in comparison with the value of the conventional MIS-HEMT. Moreover, the fabrication process of the novel device is entirely compatible with that of the conventional depletion-mode（D-mode） polar AlGaN/GaN HEMT. It presents a promising way to realize the switch application and the E/D-mode logic circuits.展开更多
We report on the growth and fabrication of nonpolar a-plane light emitting diodes with an in-situ SiNx interlayer grown between the undoped a-plane GaN buffer and Si-doped GaN layer. X-ray diffraction shows that the c...We report on the growth and fabrication of nonpolar a-plane light emitting diodes with an in-situ SiNx interlayer grown between the undoped a-plane GaN buffer and Si-doped GaN layer. X-ray diffraction shows that the crystalline quality of the GaN buffer layer is greatly improved with the introduction of the SiNx interlayer. The electrical properties are also improved. For example, electron mobility and sheet resistance are reduced from high resistance to 31.6 cm2/（V· s） and 460 Ω/respectively. Owing to the significant effect of the SiNx interlayer, a-plane LEDs are realized. Electrolurninescence of a nonpolar a-plane light-emitting diode with a wavelength of 488nm is demonstrated. The emission peak remains constant when the injection current increases to over 20 mA.展开更多
We report a method to synthesize both organicinorganic CH3NH3PbBr3 and all-inorganic CsPbBr3 perovskite nanocrystals in nonpolar solvent at high temperature. The cesium oleate and CH3NH3Br （MABr） are prepared and th...We report a method to synthesize both organicinorganic CH3NH3PbBr3 and all-inorganic CsPbBr3 perovskite nanocrystals in nonpolar solvent at high temperature. The cesium oleate and CH3NH3Br （MABr） are prepared and then injected into the nonpolar solvent of octadecene including oleic acid, oleylamine, and lead halide. In the synthesis of organic-inorganic perovskites of CHaNH3PbBr3, the frequently-used polar solvent of dimetbylformamide or other polar solvents are not used. The prepared CsPbBr3 nanocrystals are spherical nanoparticles with the diameter of 250 nm. The CHaNH3PbBr3 perovskites are micro-scale hexagonal nanoplatelets. The colloidal perovskites exhibit high-efficient fluorescence and excellent stability.展开更多
Nonpolar components from ginseng of different ages were extracted and analysed using a GC-MS technique to determine their chemical compositions. In total, 23 ingredients, mostly aliphatic compounds, were identified. T...Nonpolar components from ginseng of different ages were extracted and analysed using a GC-MS technique to determine their chemical compositions. In total, 23 ingredients, mostly aliphatic compounds, were identified. The compounds extracted included 10,12-octadecadiynoic acid (12.81% - 36.43%), falcarinol (4.95% - 36.79%), n-hexadecanoic acid (0.60% - 9.70%), 9,12-octadecadienoic acid, ethyl ester (0.33% - 5.63%), 5,7-dodecadiyn-1,12-diol (0.97% - 3.85%), (Z)-9-octadecenamide (2.66% - 5.38%) and (Z,Z)-9,12-octadecadienoic acid (0.46% - 5.27%). The two major diyne compositions, falcarinol (8) and 10,12-octadecadiynoic acid (12), were the predominant components (over 50%) of the nonpolar extract of older ginseng. Moreover, the 10,12-octadecadiynoic acid obviously accumulated as the ginseng grew. Sitosterol, a universal metabolite in higher plants, makes up 55.80% of the content of 6-year-old ginseng, but markedly decreases in older ginseng. There was not much difference between the extracts of 8, 10, 12 and 16-year ginsengs, but the extracts of 6-year-old ginseng were distinctive.展开更多
Covalent organic frameworks(COFs)with polar linkages have been employed as metal-free catalysts for the oxygen reduction reaction(ORR).However,it is still a big challenge to precisely design or locate the catalytic si...Covalent organic frameworks(COFs)with polar linkages have been employed as metal-free catalysts for the oxygen reduction reaction(ORR).However,it is still a big challenge to precisely design or locate the catalytic sites for such kinds of COFs because their polar linkages always make some catalytic activity.In addition,the polar linkages are facile to bind with O_(2) and oxygen-contained intermediates in the catalytic process,severely weakening the long-term stability of these COFs.In this work,we demonstrated the single metalfree catalytic sites based on the pyridine-cored COFs with nonpolar linkages(C=C bonds)to catalyze the ORR.The nonpolar linkages excluded their potential roles as catalytic sites and also circumvented the possible decomposition in the process of catalysis.By modulating the pyridine N with positive charges,the catalytic performance can be previously improved,because of the enhanced Lewis acidity of the carbon atoms next to the pyridine N,and thus favorable for the electrons transfer to the catalytic sites.The newly-synthesized charged COF showed high activity of a half-wave potential of 0.74 V with a mass activity of 4.34 A g^(-1),which was 50 mV more positive and 1.63 times higher than those of the neutral COF.And the nonpolar linkages made the COFs display better long-term stability than other metal-free COFs.The theoretical calculation revealed that the ionization of pyridine promoted the formation of the intermediate OOH*,and thus improved the catalytic activity.This work gives us a new insight into designing single sites based on COFs.展开更多
Nonpolar m-plane AlGaN offers the advantage of polarization-free multiple quantum wells(MQWs)for ultraviolet(UV)emission and can be achieved on the sidewalls of selective area grown GaN nanowires.We reveal that the gr...Nonpolar m-plane AlGaN offers the advantage of polarization-free multiple quantum wells(MQWs)for ultraviolet(UV)emission and can be achieved on the sidewalls of selective area grown GaN nanowires.We reveal that the growth of AlGaN on GaN nanowires by metal organic chemical vapor deposition(MOCVD)is driven by vapor-phase diffusion,and consequently puts a limit on the pitch of nanowire array due to shadowing effect.An insight into the difficulty of achieving metal-polar AlGaN nanowire by selective area growth(SAG)in MOCVD is also provided and can be attributed to the strong tendency to form pyramidal structure due to a very small growth rate of{1011}semipolar planes compared to(0001)c-plane.The nonpolar m-plane sidewalls of GaN nanowires obtained via SAG provides an excellent platform for growth of nonpolar AlGaN MQWs.UV emission from mplane Al_(x)Ga_(1−x)N/Al_(y)Ga_(1−y)N MQWs grown on sidewalls of dislocation-free GaN nanowire is demonstrated in the wavelength range of 318–343 nm.展开更多
The fundamental relationship between microstructure,constituent,processing and performances of separating materials is really a vital issue.Traditional preparation methods for separation membranes are complex,time-con...The fundamental relationship between microstructure,constituent,processing and performances of separating materials is really a vital issue.Traditional preparation methods for separation membranes are complex,time-consuming and easy to be fouled.Also,the durability of conventional coatings on membrane is poor.By combination of bioinspiration from mussel adhesive and fish scales’underwater superoleophobicity,we propose a general route to prepare organic-inorganic hybrid coatings,while no complex apparatus is needed.Specifically,based on the biomimetic adhesion of polydopamine(PDA),we used it as a binder to adhere TiO_(2)nanoparticles and built rough microstructure on fabric.In this way,we obtained TiO_(2)-PDA treated fabric with special wettability.These TiO_(2)-PDA treated samples owned superamphiphilicity in air,underwater superoleophobicity(underwater oil contact angles(OCAs)>150°),underoil superhydrophobicity(underoil water contact angles(WCAs)>150°),excellent multiresistance;and can separate polar/nonpolar liquid mixture effectively.It also owned superaerophobicity underwater(underwater bubble contact angles(BCAs)>150°).The proposed TiO_(2)-PDA coatings are highly expected to be employed for real situation of water pollution remediation,self-cleaning,oil extraction and harsh chemical engineering issues.展开更多
基金Project supported by the National Key Research and Development Program of China (Grant Nos.2021YFB3601000 and 2021YFB3601002)the National Natural Science Foundation of China (Grant Nos.62074077,61921005,61974062,62204121,and 61904082)+1 种基金Leading-edge Technology Program of Jiangsu Natural Science Foundation (Grant No.BE2021008-2)the China Postdoctoral Science Foundation (Grant No.2020M671441)。
文摘Nonpolar(11–20) a-plane p-type GaN films were successfully grown on r-plane sapphire substrate with the metal–organic chemical vapor deposition(MOCVD) system. The effects of Mg-doping temperature on the structural and electrical properties of nonpolar p-type GaN films were investigated in detail. It is found that all the surface morphology, crystalline quality, strains, and electrical properties of nonpolar a-plane p-type GaN films are interconnected, and are closely related to the Mg-doping temperature. This means that a proper performance of nonpolar p-type GaN can be expected by optimizing the Mg-doping temperature. In fact, a hole concentration of 1.3×10^(18)cm^(-3), a high Mg activation efficiency of 6.5%,an activation energy of 114 me V for Mg acceptor, and a low anisotropy of 8.3% in crystalline quality were achieved with a growth temperature of 990℃. This approach to optimizing the Mg-doping temperature of the nonpolar a-plane p-type GaN film provides an effective way to fabricate high-efficiency optoelectronic devices in the future.
基金Funded by the National Natural Science Foundation of China(Nos.2018033022,2017036019)the Open Funds of Engineering Research Center of Nano-Geo Materials of Ministry of Education,China University of Geosciences(No.NGM2017KF001)+1 种基金the Fundamental Research Funds for the Central Universities(No.185206011)the Open Funds of the State Key Laboratory of Refractories and Metallurgy(Wuhan University of Science and Technology)(No.G201806)。
文摘Phlogopite-based geopolymer was first prepared successfully under the activation of lye by compression molding at 50 MPa for 1 minute.The geopolymer was endowed with nonpolar surface via brushing modified liquid at room temperature.Swill-cooked dirty oil,whose main component was fatty acid,was used as nonpolar modifier.The raw materials and geopolymer samples were characterized by XRD,FT-IR and SEM.The compression strength of 7-day specimen run up to 36.8 MPa and its surface static water contact angle could reach 132°.The solubility of phlogopite powder directly affected the compressive strength of geopolymers and the evaluation index of mechanical strength of geopolymer based on the solubility of phlogopite powder was proposed.
文摘Tunnel wash waters characterize all waters that run off after washing procedures of tunnels are performed.These waters represent a wide spectrum of organic and inorganic pollutants,such as polycyclic aromatic hydrocarbons(PAHs)and toxic metals.Removal of such contaminants from water runoff was investigated using laboratory tests after washing procedure was performed on two road tunnels in eastern Norway(Hanekleiv and Bragernes).Due to diverse character of both,treatment media and treated wash waters, the wh...
基金supported by the National Key Science and Technology Special Project,China (Grant No.2008ZX01002-002)the Major Program and State Key Program of the National Natural Science Foundation of China (Grant Nos.60890191 and 60736033)the Fundamental Research Funds for the Central Universities,China (Grant No.JY10000904009)
文摘Nonpolar （1150） a-plane GaN films are grown by metal-organic chemical vapour deposition （MOCVD） on r-plane （1102） sapphire. The samples are irradiated with neutrons under a dose of 1× 1015 cm-2. The surface morphology, the crystal defects and the optical properties of the samples before and after irradiation are analysed using atomic force microscopy （AFM）, high resolution X-ray diffraction （HRXRD） and photoluminescence （PL）. The AFM result shows deteriorated sample surface after the irradiation. Careful fitting of the XRD rocking curve is carried out to obtain the Lorentzian weight fraction. Broadening due to Lorentzian type is more obvious in the as-grown sample compared with that of the irradiated sample, indicating that more point defects appear in the irradiated sample. The variations of line width and intensity of the PL band edge emission peak are consistent with the XRD results. The activation energy decreases from 82.5 meV to 29.9 meV after irradiation by neutron.
基金supported by the National Key Science and Technology Special Project, China (Grant No. 2008ZX01002-002)the Major Program and State Key Program of National Natural Science Foundation of China (Grant Nos. 60890191 and 60736033)the Fundamental Research Funds for the Central Universities, China (Grant No. JY10000904009)
文摘The anisotropic strain of a nonpolar （1120） a-plane GaN epilayer on an r-plane （1102） sapphire substrate, grown by low-pressure metal-organic vapour deposition is investigated by Raman spectroscopy. The room-temperature Raman scattering spectra of nonpolar a-plane GaN are measured in surface and edge backscattering geometries. The lattice is contracted in both the c- and the m-axis directions, and the stress in the m-axis direction is larger than that in the c-axis direction. On the surface of this sample, a number of cracks appear only along the m-axis, which is confirmed by the scanning electron micrograph. Atomic force microscopy images reveal a significant decrease in the root-mean-square roughness and the density of submicron pits after the stress relief.
基金Project supported by the Fundamental Research Funds for the Central Universities,China (Grant No. K50511250002)the National Key Science and Technology Special Project,China (Grant No. 2008ZX01002-002)the National Natural Science Foundation of China (Grant Nos. 60736033,60976068,and 61076097)
文摘We report on the growth of the high-quality GaN grain on a r-plane sapphire substrate by using a self-organized SiN interlayer as a selective growth mask. Transmission electron microscopy, scanning electron microscopy, and Raman spectroscopy are used to reveal the effect of SiN on the overgrown a-plane GaN growth. The SiN layer effectively terminates the propagation of the threading dislocation and basal plane stacking faults during a-plane GaN regrowth through the interlayer, resulting in the window region shrinking from a rectangle to a ＂black hole＂. Furthermore, strong yellow luminescence （YL） in the nonpolar plane and very weak YL in the semipolar plane on the GaN grain is revealed by cathodoluminescence, suggesting that C-involved defects are responsible for the YL.
基金supported by the National Science and Technology Major Project,China(Grant No.2013ZX02308-002)the National Natural Science Foundation of China(Grant Nos.11435010,61474086,and 61404099)
文摘A novel groove-type channel enhancement-mode AlGaN/GaN MIS high electron mobility transistor（GTCE-HEMT）with a combined polar and nonpolar AlGaN/GaN heterostucture is presented. The device simulation shows a threshold voltage of 1.24 V, peak transconductance of 182 m S/mm, and subthreshold slope of 85 m V/dec, which are obtained by adjusting the device parameters. Interestingly, it is possible to control the threshold voltage accurately without precisely controlling the etching depth in fabrication by adopting this structure. Besides, the breakdown voltage（VB） is significantly increased by 78% in comparison with the value of the conventional MIS-HEMT. Moreover, the fabrication process of the novel device is entirely compatible with that of the conventional depletion-mode（D-mode） polar AlGaN/GaN HEMT. It presents a promising way to realize the switch application and the E/D-mode logic circuits.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.60676032,60776041,60976009 and U0834001)the National Basic Research program of China(Grant No.2007CB307004)
文摘We report on the growth and fabrication of nonpolar a-plane light emitting diodes with an in-situ SiNx interlayer grown between the undoped a-plane GaN buffer and Si-doped GaN layer. X-ray diffraction shows that the crystalline quality of the GaN buffer layer is greatly improved with the introduction of the SiNx interlayer. The electrical properties are also improved. For example, electron mobility and sheet resistance are reduced from high resistance to 31.6 cm2/（V· s） and 460 Ω/respectively. Owing to the significant effect of the SiNx interlayer, a-plane LEDs are realized. Electrolurninescence of a nonpolar a-plane light-emitting diode with a wavelength of 488nm is demonstrated. The emission peak remains constant when the injection current increases to over 20 mA.
基金Supported by the National Natural Science Foundation of China(11374236,11674254)
文摘We report a method to synthesize both organicinorganic CH3NH3PbBr3 and all-inorganic CsPbBr3 perovskite nanocrystals in nonpolar solvent at high temperature. The cesium oleate and CH3NH3Br （MABr） are prepared and then injected into the nonpolar solvent of octadecene including oleic acid, oleylamine, and lead halide. In the synthesis of organic-inorganic perovskites of CHaNH3PbBr3, the frequently-used polar solvent of dimetbylformamide or other polar solvents are not used. The prepared CsPbBr3 nanocrystals are spherical nanoparticles with the diameter of 250 nm. The CHaNH3PbBr3 perovskites are micro-scale hexagonal nanoplatelets. The colloidal perovskites exhibit high-efficient fluorescence and excellent stability.
文摘Nonpolar components from ginseng of different ages were extracted and analysed using a GC-MS technique to determine their chemical compositions. In total, 23 ingredients, mostly aliphatic compounds, were identified. The compounds extracted included 10,12-octadecadiynoic acid (12.81% - 36.43%), falcarinol (4.95% - 36.79%), n-hexadecanoic acid (0.60% - 9.70%), 9,12-octadecadienoic acid, ethyl ester (0.33% - 5.63%), 5,7-dodecadiyn-1,12-diol (0.97% - 3.85%), (Z)-9-octadecenamide (2.66% - 5.38%) and (Z,Z)-9,12-octadecadienoic acid (0.46% - 5.27%). The two major diyne compositions, falcarinol (8) and 10,12-octadecadiynoic acid (12), were the predominant components (over 50%) of the nonpolar extract of older ginseng. Moreover, the 10,12-octadecadiynoic acid obviously accumulated as the ginseng grew. Sitosterol, a universal metabolite in higher plants, makes up 55.80% of the content of 6-year-old ginseng, but markedly decreases in older ginseng. There was not much difference between the extracts of 8, 10, 12 and 16-year ginsengs, but the extracts of 6-year-old ginseng were distinctive.
基金financially supported by the Science and Technology Commission of Shanghai Municipality(20JC1414900)the National Natural Science Foundation of China(22271188,22075178,22005189)the China Postdoctoral Science Foundation(2023M742244)。
文摘Covalent organic frameworks(COFs)with polar linkages have been employed as metal-free catalysts for the oxygen reduction reaction(ORR).However,it is still a big challenge to precisely design or locate the catalytic sites for such kinds of COFs because their polar linkages always make some catalytic activity.In addition,the polar linkages are facile to bind with O_(2) and oxygen-contained intermediates in the catalytic process,severely weakening the long-term stability of these COFs.In this work,we demonstrated the single metalfree catalytic sites based on the pyridine-cored COFs with nonpolar linkages(C=C bonds)to catalyze the ORR.The nonpolar linkages excluded their potential roles as catalytic sites and also circumvented the possible decomposition in the process of catalysis.By modulating the pyridine N with positive charges,the catalytic performance can be previously improved,because of the enhanced Lewis acidity of the carbon atoms next to the pyridine N,and thus favorable for the electrons transfer to the catalytic sites.The newly-synthesized charged COF showed high activity of a half-wave potential of 0.74 V with a mass activity of 4.34 A g^(-1),which was 50 mV more positive and 1.63 times higher than those of the neutral COF.And the nonpolar linkages made the COFs display better long-term stability than other metal-free COFs.The theoretical calculation revealed that the ionization of pyridine promoted the formation of the intermediate OOH*,and thus improved the catalytic activity.This work gives us a new insight into designing single sites based on COFs.
基金the ACT node of the NCRIS-enabled Australian National Fabrication Facility(ANFF-ACT).
文摘Nonpolar m-plane AlGaN offers the advantage of polarization-free multiple quantum wells(MQWs)for ultraviolet(UV)emission and can be achieved on the sidewalls of selective area grown GaN nanowires.We reveal that the growth of AlGaN on GaN nanowires by metal organic chemical vapor deposition(MOCVD)is driven by vapor-phase diffusion,and consequently puts a limit on the pitch of nanowire array due to shadowing effect.An insight into the difficulty of achieving metal-polar AlGaN nanowire by selective area growth(SAG)in MOCVD is also provided and can be attributed to the strong tendency to form pyramidal structure due to a very small growth rate of{1011}semipolar planes compared to(0001)c-plane.The nonpolar m-plane sidewalls of GaN nanowires obtained via SAG provides an excellent platform for growth of nonpolar AlGaN MQWs.UV emission from mplane Al_(x)Ga_(1−x)N/Al_(y)Ga_(1−y)N MQWs grown on sidewalls of dislocation-free GaN nanowire is demonstrated in the wavelength range of 318–343 nm.
基金supported by the National Natural Science Foundation of China(Grant No.51705138).
文摘The fundamental relationship between microstructure,constituent,processing and performances of separating materials is really a vital issue.Traditional preparation methods for separation membranes are complex,time-consuming and easy to be fouled.Also,the durability of conventional coatings on membrane is poor.By combination of bioinspiration from mussel adhesive and fish scales’underwater superoleophobicity,we propose a general route to prepare organic-inorganic hybrid coatings,while no complex apparatus is needed.Specifically,based on the biomimetic adhesion of polydopamine(PDA),we used it as a binder to adhere TiO_(2)nanoparticles and built rough microstructure on fabric.In this way,we obtained TiO_(2)-PDA treated fabric with special wettability.These TiO_(2)-PDA treated samples owned superamphiphilicity in air,underwater superoleophobicity(underwater oil contact angles(OCAs)>150°),underoil superhydrophobicity(underoil water contact angles(WCAs)>150°),excellent multiresistance;and can separate polar/nonpolar liquid mixture effectively.It also owned superaerophobicity underwater(underwater bubble contact angles(BCAs)>150°).The proposed TiO_(2)-PDA coatings are highly expected to be employed for real situation of water pollution remediation,self-cleaning,oil extraction and harsh chemical engineering issues.
