Heterojunction is regarded as a crucial step toward realizing high-performance devices,particularly,forming gradient energy band between heterojunctions benefits self-powered photodetectors.Therefore,in this paper,the...Heterojunction is regarded as a crucial step toward realizing high-performance devices,particularly,forming gradient energy band between heterojunctions benefits self-powered photodetectors.Therefore,in this paper,the synthesis of CsPbI3 nanorods(NRs)and its application as the interfacial layer in high-performance,all-solution-processed self-powered photodetectors are presented.For the bilayer photodetector ITO/ZnO(100 nm)/PbS-TBAI(150 nm)/Au,a responsivity of 3.6 A/W with a specific detectivity of 9.8×10^(12)Jones was obtained under 0.1 mW/cm^(2)white light illumination at zero bias(i.e.in self-powered mode).Meanwhile,the photocurrent was enhanced to an On/Off current ratio of 105 at zero bias with an open circuit voltage of 0.53 V for trilayer photodetector ITO/ZnO(100 nm)/PbSTBAI(150 nm)/CsPbI3(250 nm)/Au,in which the CsPbI3 NRs layer works as the interfacial layer.As a result,a specific detectivity of 4.5×10^(13)Jones with a responsivity of 11.12 A/W was obtained under0.1 mW/cm^(2) white light illumination,as well as the rising/decaying time of 0.57 s/0.41 s with excellent stability and reproducibility upto four weeks in air.The enhanced-performance is ascribed to the mismatch bandgap between PbS-TBAI/CsPbI_(3)interface,which can suppress the carrier recombination and provide efficient transport passages for charge carriers.Thus,it provides a feasible and efficient method for high-performance photodetectors.展开更多
Antimony-based materials are considered as promising anodes for potassium ion batteries due to their high theoretical capacity and low electrode potential. However, the aggregation and bulk expansion of Sb particles i...Antimony-based materials are considered as promising anodes for potassium ion batteries due to their high theoretical capacity and low electrode potential. However, the aggregation and bulk expansion of Sb particles in cycling will cause capacity attenuation and poor rate performance. In this paper, Sb nanoplates were designed to be embedded in flexible porous N-dopped carbon nanofibers(Sb@PCNFs)by a simple electrospinning deposition(ESD) method. In this structural design, Sb nanoplates of high capacity were employed as active materials, N-dopped carbon nanofibers were used to improve conductivity and structural stability. The introduction of pore-forming agent enables the nanofibers to possess porous structure, thus buffering the huge volume change and promoting the transfer of electrolyte/ions.More importantly, the freestanding film can be directly used as a working electrode, reducing the redundancy in the battery and the cost. Benefitting from the favorable structure, the freestanding flexible Sb@PCNFs electrode shows excellent potassium storage performance with a capacity of 314 m Ah/g after 2000 cycles at 500 m A/g. This strategy of employing active material with high capacity in porous and conductive flexible nanofibers represents an effective method of achieving binder-free electrode with good electrochemical performance towards wearable energy storage devices.展开更多
Electroelastic behavior of a cracked piezoelectric ceramics plate subjected to four Cases of combined mechanical-electrical loads is analyzed. The integral transform method is applied to convert the problem involving ...Electroelastic behavior of a cracked piezoelectric ceramics plate subjected to four Cases of combined mechanical-electrical loads is analyzed. The integral transform method is applied to convert the problem involving an impermeable anti-plane crack to dual integral equations. Solving the resulting equations, the explicit analytic expressions for electroelastic field along the crack line and the intensity factors of relevant quantities near the crack tip and the mechanical strain energy release rate we obtained, The known results for an infinite piezoelectric ceramics plane containing an impermeable anti-plane crack are recovered from the present results only if the thickness of the plate h --> infinity.展开更多
11C-labeled C1-C10 partial structure of kulokekahilide-2 (1) was successfully synthesized based on Pd0-mediated rapid C-[11C]methylation using [11C]methyl iodide and pinacol alkenylboronate. The preparation of organob...11C-labeled C1-C10 partial structure of kulokekahilide-2 (1) was successfully synthesized based on Pd0-mediated rapid C-[11C]methylation using [11C]methyl iodide and pinacol alkenylboronate. The preparation of organoboron intermediate via olefin cross-metathesis is also a crucial procedure for the synthesis of 11C-labeling C1-C10 dihy-droxy acid moiety of 1.展开更多
The corrosion behavior of 304L stainless steel(SS)in 3.5wt%NaCl solution after different cavitation erosion(CE)times was mainly evaluated using electrochemical noise and potentiostatic polarization techniques.It was f...The corrosion behavior of 304L stainless steel(SS)in 3.5wt%NaCl solution after different cavitation erosion(CE)times was mainly evaluated using electrochemical noise and potentiostatic polarization techniques.It was found that the antagonism effect resulting in the passivation and depassivation of 304L SS had significant distinctions at different CE periods.The passive behavior was predominant during the incubation period of CE where the metastable pitting initiated at the surface of 304L SS.Over the rising period of CE,the 304L SS experienced a transition from passivation to depassivation,leading to the massive growth of metastable pitting and stable pitting.The depassivation of304L SS was found to be dominant at the stable period of CE where serious localized corrosion occurred.展开更多
Cordierite-based glass-ceramics with non-stoichiometric composition doped with rare earth oxide (REO_2) and heavy metal oxide (M_2O_3) respectively were fabricated from glass powders. After sintering and crystallizati...Cordierite-based glass-ceramics with non-stoichiometric composition doped with rare earth oxide (REO_2) and heavy metal oxide (M_2O_3) respectively were fabricated from glass powders. After sintering and crystallization heat treatment, various physical properties, including compact density and apparent porosity, were examined to evaluate the sintering behavior of cordierite-based glass-ceramics. Results show that the additives both heavy metal oxide and rare earth oxide promote the sintering and lower the phase temperature from μ- to α-cordierite as well as affect the dielectric properties of sintered glass-ceramics. The complete-densification temperature for samples is as low as 900 ℃. The materials have a low dielectric constant (≈5), a low thermal expansion coefficient ((2.80～3.52)×10^(-6) ℃^(-1)) and a low dissipation factor (≤0.2%) and can be co-fired with high conductivity metals such as Au, Cu, Ag/Pd paste at low temperature (below 950 ℃), which makes it to be a promising material for low-temperature co-fired ceramic substrates.展开更多
The novel composite lithium solid polymer electrolytes （SPEs） composed of polyethylene oxide （PEO） matrix and yttrium oxide （Y2O3） nanofillers were prepared by a solution casting method. The crystal morphology o...The novel composite lithium solid polymer electrolytes （SPEs） composed of polyethylene oxide （PEO） matrix and yttrium oxide （Y2O3） nanofillers were prepared by a solution casting method. The crystal morphology of the SPEs was characterized by polarized optical microscope （POM） and wide-angle X-ray diffraction （WAXD）. The induced nucleation and steric hindrance effects of Y2O3 nanofillers result in the increased amount as well as decreased size of PEO spherulites which are closely related to the crystallinity of the SPEs. As the Y2O3 contents increase from 0 wt% to 15 wt%, the crystallinity of the SPEs decreases proportionally. The thermal, mechanical and electrical properties of the SPEs were investigated by thermal gravimetric analysis （TGA）, dynamic mechanical analysis （DMA） and AC impedance method, respectively. The physical properties including thermal, mechanical and electrical performances, depending remarkably on the polymer-filler interactions between PEO and Y2O3 nanoparticles, are improved by different degrees with the increase of Y2O3 contents. The （PEO）21LiI/10 wt%Y2O3 composite SPE exhibits the optimal room-temperature ionic conductivity of 5.95×10-5 Scm-1, which satisfies the requirements of the conventional electrochromic devices.展开更多
To get a better understanding of the influence of rare-earth element doping,CaCu3Ti4O12（CCTO） samples with a partial substitution of Ca with Eu with different compensation mechanisms were designed and prepared by so...To get a better understanding of the influence of rare-earth element doping,CaCu3Ti4O12（CCTO） samples with a partial substitution of Ca with Eu with different compensation mechanisms were designed and prepared by solid-state reaction.All the ceramics were single phase,while the dielectric constants and thermally activated energy values for dielectric relaxation in Eu-doped ceramics were both lower than those of CCTO.Ca（0.875）Eu（0.1）Cu3Ti4O12（CECT1）exhibited a slight decrease in both the permittivity and electric resistance of grain boundaries compared with CCTO,while Ca（0.85）Eu（0.1）Cu3Ti4O12（CECT2） underwent a sharp decrease in permittivity associated with an abnormally large resistance.The different dielectric behavior indicates that the dielectric properties of CCTO are sensitive to the valence states of cations and defects.The variation of permittivity is related to the localization of carriers,which,according to the XPS results,should be caused by the presence of oxygen vacancies.The formation of defect complexes between cations and oxygen vacancies leads to the increase in resistance and prevents the hopping between Cu^＋ and Cu^2＋,which is an important source of the polarization in grain boundaries.展开更多
Indium-doped ZnO(ZnO:In) films are deposited on quartz substrates by rf magnetron sputtering. The effects of post-annealing on structural, electrical, optical and Raman properties are investigated by x-ray diffraction...Indium-doped ZnO(ZnO:In) films are deposited on quartz substrates by rf magnetron sputtering. The effects of post-annealing on structural, electrical, optical and Raman properties are investigated by x-ray diffraction,Raman scattering, Hall measurement and first-principles calculation. The results indicate that all of the ZnO:In films have excellent crystallinity with a preferred ZnO(002) orientation. It is found that the incorporation of In can dramatically increase the intensity of the 274 cm^(-1) Raman mode. However, both post-annealing treatment and increasing O_2 partial pressure in the process of preparing thin films can reduce the intensity of the 274 cm^(-1) mode or even eliminate it, and relax compressive stress of the ZnO:In film judged by analyzing the shifts of the(002) Bragg peaks and E_2(high) mode. Finally, the origin of the 274 cm^(-1) mode is inferred to be the vibration of Zn interstitial(Zni) defects, which play a crucial role in the high electron concentration and low resistivity of ZnO:In films annealed in an appropriate temperature range(450–600℃).展开更多
Fifty hours of mechanical activation of mixed oxides at room temperature did not trigger the formation of Nd BaPbO 3 (BPO) in the existence of excessive PbO, but decreased the synthesis temperature of the BPO. The c...Fifty hours of mechanical activation of mixed oxides at room temperature did not trigger the formation of Nd BaPbO 3 (BPO) in the existence of excessive PbO, but decreased the synthesis temperature of the BPO. The crystalline of the activation derived perovskite BPO phase was further established when the activated mixture was subjected to calcination at 650 ℃. The perovskite phase was sintered to a density of 98% of theoretical value at 980 ℃ for 2 h. The sintered BPO with 0.1% Nd doped exhibits a resistivity of 2×10 -4 Ω·cm and an excellent PTC effect at Curie temperature of 750 ℃ .展开更多
The title compound N-（2-（1-butyl-3-phenylureido）-1H-indol-3-yl）-N-（4-chloro-phenyl）-benzamide （C32H29ClN4O2, Mr = 537.04） was synthesized by a sequential Ugi four com-ponent condensation （4CC）/aza-Wittig/car...The title compound N-（2-（1-butyl-3-phenylureido）-1H-indol-3-yl）-N-（4-chloro-phenyl）-benzamide （C32H29ClN4O2, Mr = 537.04） was synthesized by a sequential Ugi four com-ponent condensation （4CC）/aza-Wittig/carbodiimide-mediated cyclization, and the structure was characterized by NMR, IR, MS, elemental analysis and X-ray single-crystal diffraction analysis. The crystal belongs to orthorhombic, space group P212121 with a = 11.3663（9）, b = 13.3248（10）, c = 18.7887（15） A, V = 2845.6（4）A^3, Z = 4, Dc=1.254 mg/m^3,μ = 0.170 mm^-1, F（000） = 1128, the final R = 0.0538 and wR = 0.1187. X-ray analysis reveals that the new five-membered ring （C（ 14）-C（ 15）-N（2）-C（ 16）-C（21 ）） and the benzene ring （C（16）-C（21 ）） are nearly coplanar.展开更多
Physiological changes in the photosynthesis, respiration and cell division of Chlamydomonas reinhardtii, a freshwater green alga, in response to adenine nucleotides were investigated. In advance of this investigation,...Physiological changes in the photosynthesis, respiration and cell division of Chlamydomonas reinhardtii, a freshwater green alga, in response to adenine nucleotides were investigated. In advance of this investigation, two adenine nucleotides, di(2'-O-methyl)-cyclic bis(3'-5')diadenylic acid (1) and its N-benzoyl-protected analog 2 were synthesized from the commercially available adenosine phosphoramidite. The respective analogs significantly promoted the cell division (cell number) of C. reinhardtii strains 137c mt+ and BR mt+. Moreover, they significantly enhanced the O2 evolution (photosynthesis) and O2 uptake (respiration) of both strains. c-di-AMP analogs seem to play an effective role as a physiological activator in planta.展开更多
It is urgent to develop novel energy storage and conversion systems to address the pressing issues of the energy crisis and environmental pollution,including alkaline water electrolysis,alkaline fuel cells and metal-a...It is urgent to develop novel energy storage and conversion systems to address the pressing issues of the energy crisis and environmental pollution,including alkaline water electrolysis,alkaline fuel cells and metal-air batteries.However,these systems are hampered by the sluggish kinetics of the oxygen evolution reaction(OER)or oxygen reduction reaction(ORR).One of the most effective strategies to overcome this challenge is the development of efficient and stable catalysts for both ORR and OER,which typically consist of Pt,Ir,or other precious metals.Unfortunately,most precious metal catalysts are limited to single catalytic activity(either ORR or OER)and are constrained by the high cost and scarcity of noble metals.Perovskite oxides offer significant promise as efficient bifunctional ORR/OER catalysts due to their high catalytic activity,versatile composition,low cost,and high stability in alkaline environments.The general preparation methods of perovskite-type oxides are summarized in this work.Then recent mechanistic studies on the ORR and OER of perovskite oxides are also discussed,particularly highlighting the theoretical and experimental methods employed to facilitate these studies.Further strategies for improving the catalytic performance of perovskite oxides are discussed from five perspectives.The perspective of challenges and future directions for the development of perovskite oxides in ORR and OER applications are finally presented.展开更多
Solar-blind imaging has attracted considerable interest in both military and civilian applications,spurring the development of high-performance deep-ultraviolet photodetector arrays(PDAs) with wide-bandgap semiconduct...Solar-blind imaging has attracted considerable interest in both military and civilian applications,spurring the development of high-performance deep-ultraviolet photodetector arrays(PDAs) with wide-bandgap semiconductor materials.Herein,we present a novel method to enhance the performance of solar-blind PDAs(SBPDs) using β-Ga_(2)O_(3) films obtained by the phase transition of heterogeneous epitaxial sub-stable ε-Ga_(2)O_(3),achieved through high-temperature rapid annealing.Metal-semiconductor-metaltype SBPDs based on phase-transformed β-Ga_(2)O_(3) films exhibited superior performance,including an ultrahigh responsivity of 459.38 A/W,detectivity of 10^(14)–10^(15) Jones,external quantum efficiency of 10^(4)%–10^(5)%,rejection ratio(R_(254)/R_(365)) of 10^(5)–10^(6),photo-to-dark current ratio of 10^(4)–10^(6),fast response speed of 1.01 s/0.06 s,and favorable stability.Notably,the ultrahigh responsivity of β-Ga_(2)O_(3)-film-based devices was approximately 222-fold higher than that of ε-Ga_(2)O_(3) film-based devices.The assembled 4×5 β-Ga_(2)O_(3) film-based PDAs exhibited favorable uniformity,repeatability,and high spatial resolution for solarblind imaging.Our study offers a promising approach for the development of high-performance β-Ga_(2)O_(3)-based PDAs for solarblind ultraviolet imaging with potential applications in both military and civilian fields.展开更多
基金partially funded by the project of State Key Laboratory of Transducer Technology(SKT1404)the project of the Key Laboratory of Photoelectronic Imaging Technology and System(2017OEIOF02)Beijing Institute of Technology,Ministry of Education of Chinathe project of the Key R&D projects of the Ministry of Science and Technology(SQ2019YFB220038)。
文摘Heterojunction is regarded as a crucial step toward realizing high-performance devices,particularly,forming gradient energy band between heterojunctions benefits self-powered photodetectors.Therefore,in this paper,the synthesis of CsPbI3 nanorods(NRs)and its application as the interfacial layer in high-performance,all-solution-processed self-powered photodetectors are presented.For the bilayer photodetector ITO/ZnO(100 nm)/PbS-TBAI(150 nm)/Au,a responsivity of 3.6 A/W with a specific detectivity of 9.8×10^(12)Jones was obtained under 0.1 mW/cm^(2)white light illumination at zero bias(i.e.in self-powered mode).Meanwhile,the photocurrent was enhanced to an On/Off current ratio of 105 at zero bias with an open circuit voltage of 0.53 V for trilayer photodetector ITO/ZnO(100 nm)/PbSTBAI(150 nm)/CsPbI3(250 nm)/Au,in which the CsPbI3 NRs layer works as the interfacial layer.As a result,a specific detectivity of 4.5×10^(13)Jones with a responsivity of 11.12 A/W was obtained under0.1 mW/cm^(2) white light illumination,as well as the rising/decaying time of 0.57 s/0.41 s with excellent stability and reproducibility upto four weeks in air.The enhanced-performance is ascribed to the mismatch bandgap between PbS-TBAI/CsPbI_(3)interface,which can suppress the carrier recombination and provide efficient transport passages for charge carriers.Thus,it provides a feasible and efficient method for high-performance photodetectors.
基金the financial support from the National Natural Science Foundation of China (Nos. 51872071, 52172173)Anhui Provincial Natural Science Foundation for Distinguished Young Scholar(No. 2108085J25)Natural Science Research Projects of Universities in Anhui Province (No. KJ2020A0021)。
文摘Antimony-based materials are considered as promising anodes for potassium ion batteries due to their high theoretical capacity and low electrode potential. However, the aggregation and bulk expansion of Sb particles in cycling will cause capacity attenuation and poor rate performance. In this paper, Sb nanoplates were designed to be embedded in flexible porous N-dopped carbon nanofibers(Sb@PCNFs)by a simple electrospinning deposition(ESD) method. In this structural design, Sb nanoplates of high capacity were employed as active materials, N-dopped carbon nanofibers were used to improve conductivity and structural stability. The introduction of pore-forming agent enables the nanofibers to possess porous structure, thus buffering the huge volume change and promoting the transfer of electrolyte/ions.More importantly, the freestanding film can be directly used as a working electrode, reducing the redundancy in the battery and the cost. Benefitting from the favorable structure, the freestanding flexible Sb@PCNFs electrode shows excellent potassium storage performance with a capacity of 314 m Ah/g after 2000 cycles at 500 m A/g. This strategy of employing active material with high capacity in porous and conductive flexible nanofibers represents an effective method of achieving binder-free electrode with good electrochemical performance towards wearable energy storage devices.
文摘Electroelastic behavior of a cracked piezoelectric ceramics plate subjected to four Cases of combined mechanical-electrical loads is analyzed. The integral transform method is applied to convert the problem involving an impermeable anti-plane crack to dual integral equations. Solving the resulting equations, the explicit analytic expressions for electroelastic field along the crack line and the intensity factors of relevant quantities near the crack tip and the mechanical strain energy release rate we obtained, The known results for an infinite piezoelectric ceramics plane containing an impermeable anti-plane crack are recovered from the present results only if the thickness of the plate h --> infinity.
文摘11C-labeled C1-C10 partial structure of kulokekahilide-2 (1) was successfully synthesized based on Pd0-mediated rapid C-[11C]methylation using [11C]methyl iodide and pinacol alkenylboronate. The preparation of organoboron intermediate via olefin cross-metathesis is also a crucial procedure for the synthesis of 11C-labeling C1-C10 dihy-droxy acid moiety of 1.
基金financially supported of the National Natural Science Foundation of China (Nos.52101105 and 51975263)。
文摘The corrosion behavior of 304L stainless steel(SS)in 3.5wt%NaCl solution after different cavitation erosion(CE)times was mainly evaluated using electrochemical noise and potentiostatic polarization techniques.It was found that the antagonism effect resulting in the passivation and depassivation of 304L SS had significant distinctions at different CE periods.The passive behavior was predominant during the incubation period of CE where the metastable pitting initiated at the surface of 304L SS.Over the rising period of CE,the 304L SS experienced a transition from passivation to depassivation,leading to the massive growth of metastable pitting and stable pitting.The depassivation of304L SS was found to be dominant at the stable period of CE where serious localized corrosion occurred.
文摘Cordierite-based glass-ceramics with non-stoichiometric composition doped with rare earth oxide (REO_2) and heavy metal oxide (M_2O_3) respectively were fabricated from glass powders. After sintering and crystallization heat treatment, various physical properties, including compact density and apparent porosity, were examined to evaluate the sintering behavior of cordierite-based glass-ceramics. Results show that the additives both heavy metal oxide and rare earth oxide promote the sintering and lower the phase temperature from μ- to α-cordierite as well as affect the dielectric properties of sintered glass-ceramics. The complete-densification temperature for samples is as low as 900 ℃. The materials have a low dielectric constant (≈5), a low thermal expansion coefficient ((2.80～3.52)×10^(-6) ℃^(-1)) and a low dissipation factor (≤0.2%) and can be co-fired with high conductivity metals such as Au, Cu, Ag/Pd paste at low temperature (below 950 ℃), which makes it to be a promising material for low-temperature co-fired ceramic substrates.
基金Funded by the National Natural Science Foundation of China (No. 51003082)the Key Project of Science and Technology Research of Ministry of Education (No. 208089)+2 种基金the Educational Commission of Hubei Province (No.Q20101606)the Young Outstanding Talent Foundation of Hubei Province (No.2008CDB261)the Natural Science Foundation of Hubei Province (No. 2007ABA075)
文摘The novel composite lithium solid polymer electrolytes （SPEs） composed of polyethylene oxide （PEO） matrix and yttrium oxide （Y2O3） nanofillers were prepared by a solution casting method. The crystal morphology of the SPEs was characterized by polarized optical microscope （POM） and wide-angle X-ray diffraction （WAXD）. The induced nucleation and steric hindrance effects of Y2O3 nanofillers result in the increased amount as well as decreased size of PEO spherulites which are closely related to the crystallinity of the SPEs. As the Y2O3 contents increase from 0 wt% to 15 wt%, the crystallinity of the SPEs decreases proportionally. The thermal, mechanical and electrical properties of the SPEs were investigated by thermal gravimetric analysis （TGA）, dynamic mechanical analysis （DMA） and AC impedance method, respectively. The physical properties including thermal, mechanical and electrical performances, depending remarkably on the polymer-filler interactions between PEO and Y2O3 nanoparticles, are improved by different degrees with the increase of Y2O3 contents. The （PEO）21LiI/10 wt%Y2O3 composite SPE exhibits the optimal room-temperature ionic conductivity of 5.95×10-5 Scm-1, which satisfies the requirements of the conventional electrochromic devices.
基金supported by the National Natural Science Foundations of China(Grant Nos.21271084 and11264024)the Open Project of State Key Laboratory of Superhard Materials(No.201608)
文摘To get a better understanding of the influence of rare-earth element doping,CaCu3Ti4O12（CCTO） samples with a partial substitution of Ca with Eu with different compensation mechanisms were designed and prepared by solid-state reaction.All the ceramics were single phase,while the dielectric constants and thermally activated energy values for dielectric relaxation in Eu-doped ceramics were both lower than those of CCTO.Ca（0.875）Eu（0.1）Cu3Ti4O12（CECT1）exhibited a slight decrease in both the permittivity and electric resistance of grain boundaries compared with CCTO,while Ca（0.85）Eu（0.1）Cu3Ti4O12（CECT2） underwent a sharp decrease in permittivity associated with an abnormally large resistance.The different dielectric behavior indicates that the dielectric properties of CCTO are sensitive to the valence states of cations and defects.The variation of permittivity is related to the localization of carriers,which,according to the XPS results,should be caused by the presence of oxygen vacancies.The formation of defect complexes between cations and oxygen vacancies leads to the increase in resistance and prevents the hopping between Cu^＋ and Cu^2＋,which is an important source of the polarization in grain boundaries.
基金the National Natural Science Foundation of China under Grant Nos 51472038 and 51502030the Natural Science Foundation of Chongqing City under Grant Nos CSTC2016jcyjA and 2018jcyjA2923+1 种基金the Education Commission of Chongqing under Grant Nos KJ1500319,1501112 and KJ1600314the PhD Scientific Research Fund under Grant No 16XlB002
文摘Indium-doped ZnO(ZnO:In) films are deposited on quartz substrates by rf magnetron sputtering. The effects of post-annealing on structural, electrical, optical and Raman properties are investigated by x-ray diffraction,Raman scattering, Hall measurement and first-principles calculation. The results indicate that all of the ZnO:In films have excellent crystallinity with a preferred ZnO(002) orientation. It is found that the incorporation of In can dramatically increase the intensity of the 274 cm^(-1) Raman mode. However, both post-annealing treatment and increasing O_2 partial pressure in the process of preparing thin films can reduce the intensity of the 274 cm^(-1) mode or even eliminate it, and relax compressive stress of the ZnO:In film judged by analyzing the shifts of the(002) Bragg peaks and E_2(high) mode. Finally, the origin of the 274 cm^(-1) mode is inferred to be the vibration of Zn interstitial(Zni) defects, which play a crucial role in the high electron concentration and low resistivity of ZnO:In films annealed in an appropriate temperature range(450–600℃).
文摘Fifty hours of mechanical activation of mixed oxides at room temperature did not trigger the formation of Nd BaPbO 3 (BPO) in the existence of excessive PbO, but decreased the synthesis temperature of the BPO. The crystalline of the activation derived perovskite BPO phase was further established when the activated mixture was subjected to calcination at 650 ℃. The perovskite phase was sintered to a density of 98% of theoretical value at 980 ℃ for 2 h. The sintered BPO with 0.1% Nd doped exhibits a resistivity of 2×10 -4 Ω·cm and an excellent PTC effect at Curie temperature of 750 ℃ .
基金supported by Educational Commission of Hubei Province (No. Q20122509)the National NaturalScience Foundation of China (No. 21172085)the Doctoral Starting up Foundation of Hubei University of Arts and Science
文摘The title compound N-（2-（1-butyl-3-phenylureido）-1H-indol-3-yl）-N-（4-chloro-phenyl）-benzamide （C32H29ClN4O2, Mr = 537.04） was synthesized by a sequential Ugi four com-ponent condensation （4CC）/aza-Wittig/carbodiimide-mediated cyclization, and the structure was characterized by NMR, IR, MS, elemental analysis and X-ray single-crystal diffraction analysis. The crystal belongs to orthorhombic, space group P212121 with a = 11.3663（9）, b = 13.3248（10）, c = 18.7887（15） A, V = 2845.6（4）A^3, Z = 4, Dc=1.254 mg/m^3,μ = 0.170 mm^-1, F（000） = 1128, the final R = 0.0538 and wR = 0.1187. X-ray analysis reveals that the new five-membered ring （C（ 14）-C（ 15）-N（2）-C（ 16）-C（21 ）） and the benzene ring （C（16）-C（21 ）） are nearly coplanar.
文摘Physiological changes in the photosynthesis, respiration and cell division of Chlamydomonas reinhardtii, a freshwater green alga, in response to adenine nucleotides were investigated. In advance of this investigation, two adenine nucleotides, di(2'-O-methyl)-cyclic bis(3'-5')diadenylic acid (1) and its N-benzoyl-protected analog 2 were synthesized from the commercially available adenosine phosphoramidite. The respective analogs significantly promoted the cell division (cell number) of C. reinhardtii strains 137c mt+ and BR mt+. Moreover, they significantly enhanced the O2 evolution (photosynthesis) and O2 uptake (respiration) of both strains. c-di-AMP analogs seem to play an effective role as a physiological activator in planta.
基金the Natural Science Foundation of Shanghai Municipality General Project(No.24ZR1430400).
文摘It is urgent to develop novel energy storage and conversion systems to address the pressing issues of the energy crisis and environmental pollution,including alkaline water electrolysis,alkaline fuel cells and metal-air batteries.However,these systems are hampered by the sluggish kinetics of the oxygen evolution reaction(OER)or oxygen reduction reaction(ORR).One of the most effective strategies to overcome this challenge is the development of efficient and stable catalysts for both ORR and OER,which typically consist of Pt,Ir,or other precious metals.Unfortunately,most precious metal catalysts are limited to single catalytic activity(either ORR or OER)and are constrained by the high cost and scarcity of noble metals.Perovskite oxides offer significant promise as efficient bifunctional ORR/OER catalysts due to their high catalytic activity,versatile composition,low cost,and high stability in alkaline environments.The general preparation methods of perovskite-type oxides are summarized in this work.Then recent mechanistic studies on the ORR and OER of perovskite oxides are also discussed,particularly highlighting the theoretical and experimental methods employed to facilitate these studies.Further strategies for improving the catalytic performance of perovskite oxides are discussed from five perspectives.The perspective of challenges and future directions for the development of perovskite oxides in ORR and OER applications are finally presented.
基金supported by the National Natural Science Foundation of China(Grant Nos.11904041 and 12104077)the Natural Science Foundation of Chongqing(Grant Nos.cstc2020jcyj-msxmX0557,cstc2019jcyj-msxmX0237,cstc2020jcyj-msxmX0533,and CSTB2022BSXM-JCX0090)+1 种基金the Science and Technology Research Project of Chongqing Education Committee(Grant Nos.KJQN202100540,KJQN202000511,and KJQN202100501)the College Students Innovation and Entrepreneurship Training Program of Chongqing City(Grant No.S202210637052)。
文摘Solar-blind imaging has attracted considerable interest in both military and civilian applications,spurring the development of high-performance deep-ultraviolet photodetector arrays(PDAs) with wide-bandgap semiconductor materials.Herein,we present a novel method to enhance the performance of solar-blind PDAs(SBPDs) using β-Ga_(2)O_(3) films obtained by the phase transition of heterogeneous epitaxial sub-stable ε-Ga_(2)O_(3),achieved through high-temperature rapid annealing.Metal-semiconductor-metaltype SBPDs based on phase-transformed β-Ga_(2)O_(3) films exhibited superior performance,including an ultrahigh responsivity of 459.38 A/W,detectivity of 10^(14)–10^(15) Jones,external quantum efficiency of 10^(4)%–10^(5)%,rejection ratio(R_(254)/R_(365)) of 10^(5)–10^(6),photo-to-dark current ratio of 10^(4)–10^(6),fast response speed of 1.01 s/0.06 s,and favorable stability.Notably,the ultrahigh responsivity of β-Ga_(2)O_(3)-film-based devices was approximately 222-fold higher than that of ε-Ga_(2)O_(3) film-based devices.The assembled 4×5 β-Ga_(2)O_(3) film-based PDAs exhibited favorable uniformity,repeatability,and high spatial resolution for solarblind imaging.Our study offers a promising approach for the development of high-performance β-Ga_(2)O_(3)-based PDAs for solarblind ultraviolet imaging with potential applications in both military and civilian fields.
