The crossmodal interaction of different senses,which is an important basis for learning and memory in the human brain,is highly desired to be mimicked at the device level for developing neuromorphic crossmodal percept...The crossmodal interaction of different senses,which is an important basis for learning and memory in the human brain,is highly desired to be mimicked at the device level for developing neuromorphic crossmodal perception,but related researches are scarce.Here,we demonstrate an optoelectronic synapse for vision-olfactory crossmodal perception based on MXene/violet phosphorus(VP)van der Waals heterojunctions.Benefiting from the efficient separation and transport of photogenerated carriers facilitated by conductive MXene,the photoelectric responsivity of VP is dramatically enhanced by 7 orders of magnitude,reaching up to 7.7 A W^(−1).Excited by ultraviolet light,multiple synaptic functions,including excitatory postsynaptic currents,pairedpulse facilitation,short/long-term plasticity and“learning-experience”behavior,were demonstrated with a low power consumption.Furthermore,the proposed optoelectronic synapse exhibits distinct synaptic behaviors in different gas environments,enabling it to simulate the interaction of visual and olfactory information for crossmodal perception.This work demonstrates the great potential of VP in optoelectronics and provides a promising platform for applications such as virtual reality and neurorobotics.展开更多
Developing effective strategies to improve the initial Coulombic efficiency(ICE)and cycling stability of hard carbon(HC)anodes for sodium-ion batteries is the key to promoting the commercial application of HC.In this ...Developing effective strategies to improve the initial Coulombic efficiency(ICE)and cycling stability of hard carbon(HC)anodes for sodium-ion batteries is the key to promoting the commercial application of HC.In this paper,homotype heterojunctions are designed on HC to induce the generation of stable solid electrolyte interfaces,which can effectively increase the ICE of HC from 64.7%to 81.1%.The results show that using a simple surface engineering strategy to construct a homotypic amorphous Al_(2)O_(3) layer on the HC could shield the active sites,and further inhibit electrolyte decomposition and side effects occurrence.Particularly,due to the suppression of continuous decomposition of NaPF 6 in ester-based electrolytes,the accumulation of NaF could be reduced,leading to the formation of thinner and denser solid electrolyte interface films and a decrease in the interface resistance.The HC anode can not only improve the ICE but elevate its sodium storage performance based on this homotype heterojunction composed of HC and Al_(2)O_(3).The optimized HC anode exhibits an outstanding reversible capacity of 321.5mAhg^(−1) at 50mAg^(−1).The cycling stability is also improved effectively,and the capacity retention rate is 86.9%after 2000 cycles at 1Ag^(−1) while that of the untreated HC is only 52.6%.More importantly,the improved sodium storage behaviors are explained by electrochemical kinetic analysis.展开更多
We report the scalable fabrication of CdS/ZnS 1D/2D heterojunctions under ambient air conditions(i.e.,room temperature and atmospheric pressure)in which ZnS nanoparticles are anchored on the surface of CdS nanosheets....We report the scalable fabrication of CdS/ZnS 1D/2D heterojunctions under ambient air conditions(i.e.,room temperature and atmospheric pressure)in which ZnS nanoparticles are anchored on the surface of CdS nanosheets.The as-formed heterojunctions exhibit a significantly enhanced photocatalytic H_(2) evolution rate of 14.02 mmol h^(-1) g^(-1) when irradiated with visible light,which is~10 and 85 times higher than those of pristine CdS nanosheets and CdS nanoparticles,respectively,and superior to most of the CdS-based photocatalysts reported to date.Furthermore,they provide robust photocatalytic performance with demonstratable stability over 58 h,indicating their potential for practical applications.The formation of 1D/2D heterojunctions not only provides improved exposed active sites that respond to illumination but also provides a rapid pathway to generate photogenerated carriers for efficient separation and transfer through the matrix of single-crystalline CdS nanosheets.In addition,first-principles simulations demonstrate that the existence of rich Zn vacancies increases the energy level of the ZnS valence band maximum to construct type-II and Z-scheme mixed heterojunctions,which plays a critical role in suppressing the recombination of carriers with limited photocorrosion of CdS to enhance photocatalytic behavior.展开更多
An in-depth understanding of the photoconductivity and photocarrier density at the interface is of great significance for improving the performance of optoelectronic devices. However, extraction of the photoconductivi...An in-depth understanding of the photoconductivity and photocarrier density at the interface is of great significance for improving the performance of optoelectronic devices. However, extraction of the photoconductivity and photocarrier density at the heterojunction interface remains elusive. Herein, we have obtained the photoconductivity and photocarrier density of 173 nm Sb2Se3/Si(type-Ⅰ heterojunction) and 90 nm Sb2Se3/Si(type-Ⅱ heterojunction) utilizing terahertz(THz) time-domain spectroscopy(THz-TDS) and a theoretical Drude model. Since type-Ⅰ heterojunctions accelerate carrier recombination and type-Ⅱ heterojunctions accelerate carrier separation, the photoconductivity and photocarrier density of the type-Ⅱ heterojunction(21.8×10^(4)S·m^(-1),1.5 × 10^(15)cm^(-3)) are higher than those of the type-Ⅰ heterojunction(11.8×10^(4)S·m^(-1),0.8×10^(15)cm^(-3)). These results demonstrate that a type-Ⅱ heterojunction is superior to a type-Ⅰ heterojunction for THz wave modulation. This work highlights THz-TDS as an effective tool for studying photoconductivity and photocarrier density at the heterojunction interface. In turn, the intriguing interfacial photoconductivity effect provides a way to improve the THz wave modulation performance.展开更多
Background:Organic semiconductors have attracted much attention due to their excellent biocompatibility,tunable electronic structure,low cost,and antimicrobial phototherapy.However,owing to the high exciton binding en...Background:Organic semiconductors have attracted much attention due to their excellent biocompatibility,tunable electronic structure,low cost,and antimicrobial phototherapy.However,owing to the high exciton binding energies,organic semiconductor is constrained by their short exciton diffusion length,leading to inefficient transportation of photogenerated carriers and deficient antibacterial capability.Methods:To address this issue,a quad-channel synergistic antibacterial nano-platform of copper sulfide/organic semiconductor(CuS/IEICO-4F)heterojunctions with enhanced photocatalytic performance is designed and manufactured,which can produce localized heat and raise the levels of extracellular reactive oxygen species under near-infrared laser irradiation.Simultaneously,the released Cu2+can consume intrabacterial glutathione,destroying the defense system and ultimately leading to bacterial inactivation.Results:In vitro antibacterial experiments demonstrate that the organic-inorganic bio-heterojunctions possess the potent antibacterial capacity and effective bacterial eradication.Conclusion:This countermeasure shows great promise for application in infectious wound regeneration.展开更多
Beta gallium oxide(β-Ga_(2)O_(3)) has attracted significant attention for applications in power electronics due to its ultrawide bandgap of ~ 4.8 eV and the large critical electric field of 8 MV/cm. These properties ...Beta gallium oxide(β-Ga_(2)O_(3)) has attracted significant attention for applications in power electronics due to its ultrawide bandgap of ~ 4.8 eV and the large critical electric field of 8 MV/cm. These properties yield a high Baliga's figures of merit(BFOM) of more than 3000. Though β-Ga_(2)O_(3) possesses superior material properties, the lack of p-type doping is the main obstacle that hinders the development of β-Ga_(2)O_(3)-based power devices for commercial use. Constructing heterojunctions by employing other p-type materials has been proven to be a feasible solution to this issue. Nickel oxide(NiO) is the most promising candidate due to its wide band gap of 3.6–4.0 eV. So far, remarkable progress has been made in NiO/β-Ga_(2)O_(3) heterojunction power devices. This review aims to summarize recent advances in the construction, characterization, and device performance of the NiO/β-Ga_(2)O_(3) heterojunction power devices. The crystallinity, band structure, and carrier transport property of the sputtered NiO/β-Ga_(2)O_(3) heterojunctions are discussed. Various device architectures, including the NiO/β-Ga_(2)O_(3) heterojunction pn diodes(HJDs), junction barrier Schottky(JBS) diodes, and junction field effect transistors(JFET), as well as the edge terminations and super-junctions based on the NiO/β-Ga_(2)O_(3) heterojunction, are described.展开更多
The construction of heterojunctions in composite materials to optimize the electronic structures and active sites of energy materials is considered to be the promising strategy for the fabrication of high-performance ...The construction of heterojunctions in composite materials to optimize the electronic structures and active sites of energy materials is considered to be the promising strategy for the fabrication of high-performance electrochemical energy devices.In this paper,a one-step,easy processing and cost-effective technique for generating composite materials with heterojunctions was successfully developed.The composite containing Ni_(3)S_(4),NiS,and N-doped amorphous carbon(abbreviated as Ni_(3)S_(4)/NiS/NC)with multiple heterojunction nanosheets are synthesized via the space-confined effect of molten salt interface of recrystallized NaCl.Several lattice matching forms of Ni_(3)S_(4)with cubic structure and NiS with hexagonal structure are confirmed by the detailed characterization of heterogeneous interfaces.The C–S bonds are the key factor in realizing the chemical coupling between nickel sulfide and NC and constructing the stable heterojunction.Density functional theory calculations further revealed that the electronic interaction on the heterogeneous interface of Ni_(3)S_(4)/NiS can contribute to high electronic conductivity.The heterogeneous interfaces are identified to be the good electroactive region with excellent electrochemical performance.The synergistic effect of abundant active sites,the enhanced kinetic process and valid interface charge transfer channels of Ni_(3)S_(4)/NiS/NC multiple heterojunction can guarantee high reversible redox activity and high structural stability,resulting in both high specific capacitance and energy/power densities when it is used as the electrode for supercapacitors.This work offers a new avenue for the rational design of the heterojunction materials with improved electrochemical performance through space-confined effect of NaCl.展开更多
Photocatalysis has received much attention owing to current energy and environmental crises. The use of an appropriate photocatalyst is important to a photocatalytic process. The development of photocatalysts that abs...Photocatalysis has received much attention owing to current energy and environmental crises. The use of an appropriate photocatalyst is important to a photocatalytic process. The development of photocatalysts that absorb light over a wide range of wavelengths and efficiently separate charge carriers remains a challenge and hot research topic. With strong visible-light-absorption ability, bismuth-containing photocatalysts are of great interest to scientists. However, measures have to be taken to enhance the light absorption efficiency and to lessen the problem of the recombination of charge carriers. Known approaches are the formation of heterojunctions through（1） loading of a noble metal,（2） semiconductor combination,（3） metal and nonmetal doping,（4） carbon-based material modification, and（5） Bi metal loading. The present review summarizes recent advances in this respect. Finally, the future development and potential applications of bismuth-containing photocatalysts with heterojunctions are briefly discussed.展开更多
Novel Bi2WO6-BiPO4 photocatalysts with heterojunction structure were fabricated through a facile hydrothermal route. The photocatalytic properties of Bi2WO6-BiPO4 composites were evaluated by photocatalytic degradatio...Novel Bi2WO6-BiPO4 photocatalysts with heterojunction structure were fabricated through a facile hydrothermal route. The photocatalytic properties of Bi2WO6-BiPO4 composites were evaluated by photocatalytic degradation of rhodamine B （Rh B） under simulated sunlight irradiation. The results showed that Bi2WO6-BiPO4 photocatalysts displayed much higher photocatalytic performances for Rh B degradation than the single BiPO4 and Bi2WO6. The best photocatalytic activity of Bi2WO6-BiPO4 with nearly 100% Rh B degradation located at molar ratio of 1：1 after 20 min irradiation. The enhanced photo-catalytic performance could be mainly ascribed to the formation of heterojunction interface in Bi2WO6-BiPO4 which facilitated the transfer and separation of photogenerated electron-hole pairs, as well as the strong visible light absorption originating from the sensitization role of Bi2WO6 to BiPO4. It was also found that the photodegradation of Rh B molecules was mainly attributed to the oxidation action of the generated O2^· - radicals and partly to the action of hvb^＋ via direct hole oxidation process.展开更多
Utilizing first-principles band structure method, we studied the trends of electronic structures and band offsets of the common-anion heterojunctions GaX/ZnGeX_2(X = N, P, As, Sb). Here, ZnGeX_2 can be derived by atom...Utilizing first-principles band structure method, we studied the trends of electronic structures and band offsets of the common-anion heterojunctions GaX/ZnGeX_2(X = N, P, As, Sb). Here, ZnGeX_2 can be derived by atomic transmutation of two Ga atoms in GaX into one Zn atom and one Ge atom. The calculated results show that the valence band maximums(VBMs) of GaX are always lower in energy than that of ZnGeX_2, and the band offset decreases when the anion atomic number increases. The conduction band minimums(CBMs) of ZnGeX_2 are lower than that of GaX for X = P, As, and Sb, as expected. However, surprisingly, for ZnGeN2, its CBM is higher than GaN. We found that the coupling between anion p and cation d states plays a decisive role in determining the position of the valence band maximum, and the increased electronegativity of Ge relative to Ga explains the lower CBMs of ZnGeX_2 for X = P, As, and Sb. Meanwhile, due to the high ionicity, the strong coulomb interaction is the origin of the anomalous behavior for nitrides.展开更多
Persulfate decontamination technologies utilizing radical‐driven processes are powerful tools for the treatment of a broad range of impurities.However,the design of high‐performance catalytic activators with multi‐...Persulfate decontamination technologies utilizing radical‐driven processes are powerful tools for the treatment of a broad range of impurities.However,the design of high‐performance catalytic activators with multi‐functionality remains a great challenge.Therefore,in this study,three‐dimensional multifunctional FexOy/N‐GN/CNTs(N‐GN:nitrogen‐doped graphene,CNTs:carbon nanotubes)heterojunctions,which can be employed as microwave absorbers and catalysts,were synthesized via a solvothermal method and applied to activate peroxymonosulfate for the degradation of methylene blue(MB).X‐ray diffraction(XRD),Fourier transform infrared spectrometer(FTIR),scanning electron microscope(SEM),and X‐ray photoelectron microscopy(XPS)analyses revealed that the FexOy were anchored in‐situ onto the N‐GN network.Using MB as the model organic dye,various factors,such as degradation systems,PMS loading,initial organic pollutant concentration,and catalyst dosage were optimized.The results revealed that the remarkable efficiency was attributable to the synergistic effects of carbon,nitrogen,and iron‐based species.The oxidation system corresponded to the pseudo‐first‐order kinetic with a k value of^0.33 min^-1.It was demonstrated that both SO4^-and OH^-were the predominant reactive species through quenching experiments.Because these heterojunctions were employed as microwave absorbers and have a semiconductor‐like texture,the Fe/N co‐rich hierarchical porous carbon skeleton favored electron transport and storage.These heterojunctions increase the options for transitional metal catalysts and highlights the importance of designing other heterojunctions for specific applications,such as supercapacitors,energy storage,CO2 capture,and oxygen reduction electrocatalysts.展开更多
n-VO2/p-GaN based oxide-nitride heterojunctions were realized by growing high quality VO2 films with precisely controlled thickness on p-GaN/sapphire substrates by oxide molecular beam epitaxy(O-MBE).The high crystall...n-VO2/p-GaN based oxide-nitride heterojunctions were realized by growing high quality VO2 films with precisely controlled thickness on p-GaN/sapphire substrates by oxide molecular beam epitaxy(O-MBE).The high crystalline quality of the n-VO2/p-GaN heterojunctions were confirmed by X-ray diffraction(XRD)and scanning electron microscope(SEM)analysis.The phase transition characteristics of the as-grown n-VO2/p-GaN heterojunctions were systematically investigated by temperature-dependent resistivity and infrared transmittance measurements.The results indicated that an excellent reversible metal-to-insulator(MIT)transition is observed with an abrupt change in both resistivity and infrared transmittance(IR)at 330 K,which was lower than the 341 K for bulk single crystal VO2.Remarkably,the resistivity-temperature curve was well consistent with that obtained from the temperature dependent IR transmittance.Meanwhile,the current-voltage characteristics originated from the n-VO2/p-GaN interface were demonstrated both before and after MIT of VO2 overlayer,which were attributed to the p-n junction behavior and Schottky contact character,respectively.The design and modulation of the n-VO2/p-GaN based heterostructure devices will benefit significantly from these achievements.展开更多
Fabrication of large-area atomically thin transition metal dichalcogenides is of critical importance for the preparation of new heterojunction-based devices.In this paper, we report the fabrication and optical investi...Fabrication of large-area atomically thin transition metal dichalcogenides is of critical importance for the preparation of new heterojunction-based devices.In this paper, we report the fabrication and optical investigation of large-scale chemical vapor deposition(CVD)-grown monolayer MoS2 and exfoliated few-layer GaS heterojunctions.As revealed by photoluminescence(PL) characterization, the as-fabricated heterojunctions demonstrated edge interaction between the two layers.The heterojunction was sensitive to annealing and showed increased interaction upon annealing at 300℃ under vacuum conditions, which led to changes in both the emission peak position and intensity resulting from the strong coupling interaction between the two layers.Low-temperature PL measurements further confirmed the strong coupling interaction.In addition, defect-related GaS luminescence was observed in our few-layer GaS, and the PL mapping provided evidence of edge interaction coupling between the two layers.These findings are interesting and provide the basis for creating new material systems with rich functionalities and novel physical effects.展开更多
A novel photodetector based on double-walled carbon nanotube （DWCNT） film/TiO2 nanotube array （TNA） heterojunctions was fabricated, which exhibited high photoresponse in a broad spectral range. The photoresponse o...A novel photodetector based on double-walled carbon nanotube （DWCNT） film/TiO2 nanotube array （TNA） heterojunctions was fabricated, which exhibited high photoresponse in a broad spectral range. The photoresponse of the detector was dramatically dependent on the length of the TNAs. High photocurrent-to-dark current ratio with a value of 3360 was observed in the visible range by optimizing the lengths of the TNAs. The photosensitive regions could be extended into the near-infrared range. These results reveal that DWCNT film/TNA heterojunctions show potential applications for broad band photodetectors.展开更多
n-InAs/p-InAsSb heterojunctions with a cutoff wavelength of 4.8 μm were successfully grown by one-step liquid phase epitaxy （LPE） tech-nology. Scanning electron microscopy （SEM） images and X-ray diffraction （XRD...n-InAs/p-InAsSb heterojunctions with a cutoff wavelength of 4.8 μm were successfully grown by one-step liquid phase epitaxy （LPE） tech-nology. Scanning electron microscopy （SEM） images and X-ray diffraction （XRD） patterns showed the mirror smooth surface, flat interface, and good crystalline quality of the heterojunctions. Fourier transform infrared （FTIR） transmittance spectra exhibited that the cutoff wave-lengths of InAsSb epilayers reach 4.8 μm. The standard current-voltage （I-V） characteristics with a high differential-resistance-area-product at zero bias （R0A） of 1.02×10-1 Ωcm2 at room temperature indicate that the fine p-n junctions have been obtained.展开更多
Shortening the distance between the depletion region and the electrodes to reduce the trapped probability of carriers is a useful approach for improving the performance of heterojunction.The CdS/Si nanofilm heterojunc...Shortening the distance between the depletion region and the electrodes to reduce the trapped probability of carriers is a useful approach for improving the performance of heterojunction.The CdS/Si nanofilm heterojunctions are fabricated by using the radio frequency magnetron sputtering method to deposit the amorphous silicon nanofilms and Cd S nanofilms on the ITO glass in turn.The relation of current density to applied voltage(I-V)shows the obvious rectification effect.From the analysis of the double logarithm I-V curve it follows that below~2.73 V the electron behaviors obey the Ohmic mechanism and above~2.73 V the electron behaviors conform to the space charge limited current(SCLC)mechanism.In the SCLC region part of the traps between the Fermi level and conduction band are occupied,and with the increase of voltage most of the traps are occupied.It is believed that Cd S/Si nanofilm heterojunction is a potential candidate in the field of nano electronic and optoelectronic devices by optimizing its fabricating procedure.展开更多
The interface formations of the heterojunctions concerning Ⅳ and Ⅱ Ⅵ semiconductors were studied via synchrotron radiation photoemission spectroscopy. Experimental results show that the overlayer growths of Si...The interface formations of the heterojunctions concerning Ⅳ and Ⅱ Ⅵ semiconductors were studied via synchrotron radiation photoemission spectroscopy. Experimental results show that the overlayer growths of Si or Ge on Ge, ZnSe and ZnS substrates are in compliance with an ideal two dimensional (2D) growth mode. However, deviations from 2D mode were also observed during the interfaces formation of Ge/CdTe and Si/CdTe, and are ascribed to large lattice mismatching and interfacial reaction.展开更多
The CuO-doped ZnO thick films were prepared by the screen printing technique. The CuO doped ZnO composite materials were obtained by mixing AR grade （99.9% pure） Zinc Oxide powder mechanochemically in acetone medium...The CuO-doped ZnO thick films were prepared by the screen printing technique. The CuO doped ZnO composite materials were obtained by mixing AR grade （99.9% pure） Zinc Oxide powder mechanochemically in acetone medium with various weight percentages of Copper Chloride （CulCI2.2H20） powder （1, 3, 5, 7 and 9wt.%）. The prepared materials were sintered at 1,000 ℃ for 12 h in air ambience and ball milled to ensure sufficiently fine particle size. The films were characterized by different techniques with respect to their surface morphology and compositional property by means of SEM （scanning electron microscope） and EDXA （energy dispersive x-ray analysis）. The surface morphology of the films was studied by SEM and it shows the films are porous in nature and petal-shaped grains of sizes varies from 220 nm to 250 nm were observed. The final composition of each film was determined by the EDXA analysis. The gas response of undoped ZnO and CuO doped ZnO films was studied for different gases such as CO, C12, NH3, Ethanol, H2S and LPG at operating temperature ranging from 50 ℃ to 400 ℃. The 7wt.% CuO-doped ZnO film shows good response to H2S gas （100 ppm） at 250 ℃.展开更多
The fabrication of multicomponent heterojunctions is an effective strategy to improve the performance of TiO2 based photocatalysts. We provide a new strategy for improving the charge separation and photocatalytic perf...The fabrication of multicomponent heterojunctions is an effective strategy to improve the performance of TiO2 based photocatalysts. We provide a new strategy for improving the charge separation and photocatalytic performance of ZnO /TiO2 composites by the formation of multichannel charge separated heterojunctions. ZnO /P25 composites were prepared by an incipient wetness impregnation method, and applied for the photocatalytic destruction of gaseous toluene. The ZnO /P25 composites consist of anatase TiO2（ATiO2）, rutile TiO2（RTiO2） and hexagonal zincite structures. The parasitic phase of ZnO in P25 leads to the formation of ZnO（002）/ATiO2（101）/RTiO2（110） heterojunctions that exhibit enhanced light absorption and improved multichannel electron/hole separation. ZnO /P25 heterojunctions can completely oxidize toluene into CO2 and H2O under ultraviolet light irradiation at room temperature, and show enhanced photocatalytic activity in comparison with P25 owing to the efficient electron-hole separation. Such a multichannel charge separated design strategy may provide new insight into the design of highly effective photocatalysts and their potential technological applications.展开更多
To increase the number of active sites and defects in TiO2 and promote rapid and efficient transfer of photogenerated charges, a g-C3N4@C-TiO2 composite photocatalyst was prepared via in situ deposition of g-C3N4 on a...To increase the number of active sites and defects in TiO2 and promote rapid and efficient transfer of photogenerated charges, a g-C3N4@C-TiO2 composite photocatalyst was prepared via in situ deposition of g-C3N4 on a carbon-doped anatase TiO2 surface. The effects of carbon doping state and surface modification of g-C3N4 on the performance of g-C3N4@C-TiO2 composite photocatalysts were studied by X-ray diffraction, X-ray photoelectron spectroscopy, UV-visible diffuse-reflectance spectroscopy, transmission electron microscopy, electrochemical impedance spectroscopy, photoluminescence, and electron paramagnetic resonance. With increasing carbon doping content, the carbon doping state in TiO2 gradually changed from gap to substitution doping. Although the number of oxygen vacancies gradually increased, the degradation efficiency of g-C3N4@C-TiO2 for RhB (phenol) initially increased and subsequently decreased with increasing carbon content. The g-C3N4@10C-TiO2 sample exhibited the highest apparent reaction rate constant of 0.036 min儃1 (0.039 min儃1) for RhB (phenol) degradation, which was 150 (139), 6.4 (6.8), 2.3 (3), and 1.7 (2.1) times higher than that of pure TiO2, 10C-TiO2, g-C3N4, and g-C3N4@TiO2, respectively. g-C3N4 was grown in situ on the surface of C-TiO2 by surface carbon hybridization and bonding. The resultant novel g-C3N4@C-TiO2 photocatalyst exhibited direct Z-scheme heterojunctions with non-local impurity levels. The high photocatalytic activity can be attributed to the synergistic effects of the improved visible light response ability, higher photogenerated electron transfer efficiency, and redox ability arising from Z-type heterojunctions.展开更多
基金supported by National Natural Science Foundation of China(No.51902250).
文摘The crossmodal interaction of different senses,which is an important basis for learning and memory in the human brain,is highly desired to be mimicked at the device level for developing neuromorphic crossmodal perception,but related researches are scarce.Here,we demonstrate an optoelectronic synapse for vision-olfactory crossmodal perception based on MXene/violet phosphorus(VP)van der Waals heterojunctions.Benefiting from the efficient separation and transport of photogenerated carriers facilitated by conductive MXene,the photoelectric responsivity of VP is dramatically enhanced by 7 orders of magnitude,reaching up to 7.7 A W^(−1).Excited by ultraviolet light,multiple synaptic functions,including excitatory postsynaptic currents,pairedpulse facilitation,short/long-term plasticity and“learning-experience”behavior,were demonstrated with a low power consumption.Furthermore,the proposed optoelectronic synapse exhibits distinct synaptic behaviors in different gas environments,enabling it to simulate the interaction of visual and olfactory information for crossmodal perception.This work demonstrates the great potential of VP in optoelectronics and provides a promising platform for applications such as virtual reality and neurorobotics.
基金supported by the National Natural Science Foundation of China(grant nos.21975026 and 22005033)the National Postdoctoral Program of China(no.BX20180037)+1 种基金China Postdoctoral Science Foundation(no.2018M640077)the Beijing Institute of Technology Research Fund Program for Young Scholars(no.XSQD-202108005).
文摘Developing effective strategies to improve the initial Coulombic efficiency(ICE)and cycling stability of hard carbon(HC)anodes for sodium-ion batteries is the key to promoting the commercial application of HC.In this paper,homotype heterojunctions are designed on HC to induce the generation of stable solid electrolyte interfaces,which can effectively increase the ICE of HC from 64.7%to 81.1%.The results show that using a simple surface engineering strategy to construct a homotypic amorphous Al_(2)O_(3) layer on the HC could shield the active sites,and further inhibit electrolyte decomposition and side effects occurrence.Particularly,due to the suppression of continuous decomposition of NaPF 6 in ester-based electrolytes,the accumulation of NaF could be reduced,leading to the formation of thinner and denser solid electrolyte interface films and a decrease in the interface resistance.The HC anode can not only improve the ICE but elevate its sodium storage performance based on this homotype heterojunction composed of HC and Al_(2)O_(3).The optimized HC anode exhibits an outstanding reversible capacity of 321.5mAhg^(−1) at 50mAg^(−1).The cycling stability is also improved effectively,and the capacity retention rate is 86.9%after 2000 cycles at 1Ag^(−1) while that of the untreated HC is only 52.6%.More importantly,the improved sodium storage behaviors are explained by electrochemical kinetic analysis.
基金Hunan Provincial Innovation Foundation for Postgraduate,Grant/Award Number:CX20200454National Natural Science Foundation of China,Grant/Award Number:51972178。
文摘We report the scalable fabrication of CdS/ZnS 1D/2D heterojunctions under ambient air conditions(i.e.,room temperature and atmospheric pressure)in which ZnS nanoparticles are anchored on the surface of CdS nanosheets.The as-formed heterojunctions exhibit a significantly enhanced photocatalytic H_(2) evolution rate of 14.02 mmol h^(-1) g^(-1) when irradiated with visible light,which is~10 and 85 times higher than those of pristine CdS nanosheets and CdS nanoparticles,respectively,and superior to most of the CdS-based photocatalysts reported to date.Furthermore,they provide robust photocatalytic performance with demonstratable stability over 58 h,indicating their potential for practical applications.The formation of 1D/2D heterojunctions not only provides improved exposed active sites that respond to illumination but also provides a rapid pathway to generate photogenerated carriers for efficient separation and transfer through the matrix of single-crystalline CdS nanosheets.In addition,first-principles simulations demonstrate that the existence of rich Zn vacancies increases the energy level of the ZnS valence band maximum to construct type-II and Z-scheme mixed heterojunctions,which plays a critical role in suppressing the recombination of carriers with limited photocorrosion of CdS to enhance photocatalytic behavior.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 12261141662, 12074311, and 12004310)。
文摘An in-depth understanding of the photoconductivity and photocarrier density at the interface is of great significance for improving the performance of optoelectronic devices. However, extraction of the photoconductivity and photocarrier density at the heterojunction interface remains elusive. Herein, we have obtained the photoconductivity and photocarrier density of 173 nm Sb2Se3/Si(type-Ⅰ heterojunction) and 90 nm Sb2Se3/Si(type-Ⅱ heterojunction) utilizing terahertz(THz) time-domain spectroscopy(THz-TDS) and a theoretical Drude model. Since type-Ⅰ heterojunctions accelerate carrier recombination and type-Ⅱ heterojunctions accelerate carrier separation, the photoconductivity and photocarrier density of the type-Ⅱ heterojunction(21.8×10^(4)S·m^(-1),1.5 × 10^(15)cm^(-3)) are higher than those of the type-Ⅰ heterojunction(11.8×10^(4)S·m^(-1),0.8×10^(15)cm^(-3)). These results demonstrate that a type-Ⅱ heterojunction is superior to a type-Ⅰ heterojunction for THz wave modulation. This work highlights THz-TDS as an effective tool for studying photoconductivity and photocarrier density at the heterojunction interface. In turn, the intriguing interfacial photoconductivity effect provides a way to improve the THz wave modulation performance.
基金jointly funded by the National Natural Science Foundation of China(32271392,52302351)China Postdoctoral Science Foundation(2023M732477)+1 种基金Sichuan University Postdoctoral Interdisciplinary Innovation Fund(JCXK2205)Sichuan University Post-Doctor Research Project(2023SCU12116).
文摘Background:Organic semiconductors have attracted much attention due to their excellent biocompatibility,tunable electronic structure,low cost,and antimicrobial phototherapy.However,owing to the high exciton binding energies,organic semiconductor is constrained by their short exciton diffusion length,leading to inefficient transportation of photogenerated carriers and deficient antibacterial capability.Methods:To address this issue,a quad-channel synergistic antibacterial nano-platform of copper sulfide/organic semiconductor(CuS/IEICO-4F)heterojunctions with enhanced photocatalytic performance is designed and manufactured,which can produce localized heat and raise the levels of extracellular reactive oxygen species under near-infrared laser irradiation.Simultaneously,the released Cu2+can consume intrabacterial glutathione,destroying the defense system and ultimately leading to bacterial inactivation.Results:In vitro antibacterial experiments demonstrate that the organic-inorganic bio-heterojunctions possess the potent antibacterial capacity and effective bacterial eradication.Conclusion:This countermeasure shows great promise for application in infectious wound regeneration.
基金supported by the Guangdong Basic and Applied Basic Research Foundation under Grant No. 2022A1515012163。
文摘Beta gallium oxide(β-Ga_(2)O_(3)) has attracted significant attention for applications in power electronics due to its ultrawide bandgap of ~ 4.8 eV and the large critical electric field of 8 MV/cm. These properties yield a high Baliga's figures of merit(BFOM) of more than 3000. Though β-Ga_(2)O_(3) possesses superior material properties, the lack of p-type doping is the main obstacle that hinders the development of β-Ga_(2)O_(3)-based power devices for commercial use. Constructing heterojunctions by employing other p-type materials has been proven to be a feasible solution to this issue. Nickel oxide(NiO) is the most promising candidate due to its wide band gap of 3.6–4.0 eV. So far, remarkable progress has been made in NiO/β-Ga_(2)O_(3) heterojunction power devices. This review aims to summarize recent advances in the construction, characterization, and device performance of the NiO/β-Ga_(2)O_(3) heterojunction power devices. The crystallinity, band structure, and carrier transport property of the sputtered NiO/β-Ga_(2)O_(3) heterojunctions are discussed. Various device architectures, including the NiO/β-Ga_(2)O_(3) heterojunction pn diodes(HJDs), junction barrier Schottky(JBS) diodes, and junction field effect transistors(JFET), as well as the edge terminations and super-junctions based on the NiO/β-Ga_(2)O_(3) heterojunction, are described.
基金supported by the National Natural Science Foundation of China(Grant Nos.U1804126,U21A2077 and U1804129)the Support Program of Science and Technology Innovation Leading Talent of Zhongyuan(Grant 204200510014)PhD program of Shanghai University and Program for Interdisciplinary Direction Team in Zhongyuan University of Technology.
文摘The construction of heterojunctions in composite materials to optimize the electronic structures and active sites of energy materials is considered to be the promising strategy for the fabrication of high-performance electrochemical energy devices.In this paper,a one-step,easy processing and cost-effective technique for generating composite materials with heterojunctions was successfully developed.The composite containing Ni_(3)S_(4),NiS,and N-doped amorphous carbon(abbreviated as Ni_(3)S_(4)/NiS/NC)with multiple heterojunction nanosheets are synthesized via the space-confined effect of molten salt interface of recrystallized NaCl.Several lattice matching forms of Ni_(3)S_(4)with cubic structure and NiS with hexagonal structure are confirmed by the detailed characterization of heterogeneous interfaces.The C–S bonds are the key factor in realizing the chemical coupling between nickel sulfide and NC and constructing the stable heterojunction.Density functional theory calculations further revealed that the electronic interaction on the heterogeneous interface of Ni_(3)S_(4)/NiS can contribute to high electronic conductivity.The heterogeneous interfaces are identified to be the good electroactive region with excellent electrochemical performance.The synergistic effect of abundant active sites,the enhanced kinetic process and valid interface charge transfer channels of Ni_(3)S_(4)/NiS/NC multiple heterojunction can guarantee high reversible redox activity and high structural stability,resulting in both high specific capacitance and energy/power densities when it is used as the electrode for supercapacitors.This work offers a new avenue for the rational design of the heterojunction materials with improved electrochemical performance through space-confined effect of NaCl.
基金supported by the National Natural Science Foundation of China(2140105421476065)+1 种基金the China Postdoctoral Science Foundation(2014M562098)the Fundamental Research Funds for the Central Universities~~
文摘Photocatalysis has received much attention owing to current energy and environmental crises. The use of an appropriate photocatalyst is important to a photocatalytic process. The development of photocatalysts that absorb light over a wide range of wavelengths and efficiently separate charge carriers remains a challenge and hot research topic. With strong visible-light-absorption ability, bismuth-containing photocatalysts are of great interest to scientists. However, measures have to be taken to enhance the light absorption efficiency and to lessen the problem of the recombination of charge carriers. Known approaches are the formation of heterojunctions through（1） loading of a noble metal,（2） semiconductor combination,（3） metal and nonmetal doping,（4） carbon-based material modification, and（5） Bi metal loading. The present review summarizes recent advances in this respect. Finally, the future development and potential applications of bismuth-containing photocatalysts with heterojunctions are briefly discussed.
基金This work was supported by the National Natural Science Foundation of China （No.21407059） and the Science Development Project of Jilin Province （No.20130522071JH and No.20140101160JC）.
文摘Novel Bi2WO6-BiPO4 photocatalysts with heterojunction structure were fabricated through a facile hydrothermal route. The photocatalytic properties of Bi2WO6-BiPO4 composites were evaluated by photocatalytic degradation of rhodamine B （Rh B） under simulated sunlight irradiation. The results showed that Bi2WO6-BiPO4 photocatalysts displayed much higher photocatalytic performances for Rh B degradation than the single BiPO4 and Bi2WO6. The best photocatalytic activity of Bi2WO6-BiPO4 with nearly 100% Rh B degradation located at molar ratio of 1：1 after 20 min irradiation. The enhanced photo-catalytic performance could be mainly ascribed to the formation of heterojunction interface in Bi2WO6-BiPO4 which facilitated the transfer and separation of photogenerated electron-hole pairs, as well as the strong visible light absorption originating from the sensitization role of Bi2WO6 to BiPO4. It was also found that the photodegradation of Rh B molecules was mainly attributed to the oxidation action of the generated O2^· - radicals and partly to the action of hvb^＋ via direct hole oxidation process.
基金financially supported by the Major State Basic Research Development Program of China under Grant No2016YFB0700700the National Natural Science Foundation of China(NSFC)under Grants Nos.11634003,11474273,61121491 and U153040+2 种基金the Science Challenge Project,under Grant No.TZ20160003supported by the National Young 1000 Talents Plansupported by the Youth Innovation Promotion Association of CAS(No.2017154)
文摘Utilizing first-principles band structure method, we studied the trends of electronic structures and band offsets of the common-anion heterojunctions GaX/ZnGeX_2(X = N, P, As, Sb). Here, ZnGeX_2 can be derived by atomic transmutation of two Ga atoms in GaX into one Zn atom and one Ge atom. The calculated results show that the valence band maximums(VBMs) of GaX are always lower in energy than that of ZnGeX_2, and the band offset decreases when the anion atomic number increases. The conduction band minimums(CBMs) of ZnGeX_2 are lower than that of GaX for X = P, As, and Sb, as expected. However, surprisingly, for ZnGeN2, its CBM is higher than GaN. We found that the coupling between anion p and cation d states plays a decisive role in determining the position of the valence band maximum, and the increased electronegativity of Ge relative to Ga explains the lower CBMs of ZnGeX_2 for X = P, As, and Sb. Meanwhile, due to the high ionicity, the strong coulomb interaction is the origin of the anomalous behavior for nitrides.
基金supported by the National Natural Science Foundation of China(21676039)Innovative talents in Liaoning universities and colleges(LR2017045)the Opening Foundation of State Key Laboratory of Inorganic Synthesis and Preparative Chemistry of Jilin University(2016–04)~~
文摘Persulfate decontamination technologies utilizing radical‐driven processes are powerful tools for the treatment of a broad range of impurities.However,the design of high‐performance catalytic activators with multi‐functionality remains a great challenge.Therefore,in this study,three‐dimensional multifunctional FexOy/N‐GN/CNTs(N‐GN:nitrogen‐doped graphene,CNTs:carbon nanotubes)heterojunctions,which can be employed as microwave absorbers and catalysts,were synthesized via a solvothermal method and applied to activate peroxymonosulfate for the degradation of methylene blue(MB).X‐ray diffraction(XRD),Fourier transform infrared spectrometer(FTIR),scanning electron microscope(SEM),and X‐ray photoelectron microscopy(XPS)analyses revealed that the FexOy were anchored in‐situ onto the N‐GN network.Using MB as the model organic dye,various factors,such as degradation systems,PMS loading,initial organic pollutant concentration,and catalyst dosage were optimized.The results revealed that the remarkable efficiency was attributable to the synergistic effects of carbon,nitrogen,and iron‐based species.The oxidation system corresponded to the pseudo‐first‐order kinetic with a k value of^0.33 min^-1.It was demonstrated that both SO4^-and OH^-were the predominant reactive species through quenching experiments.Because these heterojunctions were employed as microwave absorbers and have a semiconductor‐like texture,the Fe/N co‐rich hierarchical porous carbon skeleton favored electron transport and storage.These heterojunctions increase the options for transitional metal catalysts and highlights the importance of designing other heterojunctions for specific applications,such as supercapacitors,energy storage,CO2 capture,and oxygen reduction electrocatalysts.
基金the National Natural Science Foundation of China(No.51872036)the Dalian Science and Technology innovation fund(No.2018J12GX033)the Fundamental Research Funds for the Central Universities(No.DUT19LAB07)。
文摘n-VO2/p-GaN based oxide-nitride heterojunctions were realized by growing high quality VO2 films with precisely controlled thickness on p-GaN/sapphire substrates by oxide molecular beam epitaxy(O-MBE).The high crystalline quality of the n-VO2/p-GaN heterojunctions were confirmed by X-ray diffraction(XRD)and scanning electron microscope(SEM)analysis.The phase transition characteristics of the as-grown n-VO2/p-GaN heterojunctions were systematically investigated by temperature-dependent resistivity and infrared transmittance measurements.The results indicated that an excellent reversible metal-to-insulator(MIT)transition is observed with an abrupt change in both resistivity and infrared transmittance(IR)at 330 K,which was lower than the 341 K for bulk single crystal VO2.Remarkably,the resistivity-temperature curve was well consistent with that obtained from the temperature dependent IR transmittance.Meanwhile,the current-voltage characteristics originated from the n-VO2/p-GaN interface were demonstrated both before and after MIT of VO2 overlayer,which were attributed to the p-n junction behavior and Schottky contact character,respectively.The design and modulation of the n-VO2/p-GaN based heterostructure devices will benefit significantly from these achievements.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11104250,61274099,and 11774313)the Science Technology Department of Zhejiang Province,China(Grant No.2012C21007)+1 种基金Zhejiang Province Innovation Team,China(Grant No.2011R50012)Zhejiang Provincial Natural Science Foundation,China(Grant No.LY17A040003)
文摘Fabrication of large-area atomically thin transition metal dichalcogenides is of critical importance for the preparation of new heterojunction-based devices.In this paper, we report the fabrication and optical investigation of large-scale chemical vapor deposition(CVD)-grown monolayer MoS2 and exfoliated few-layer GaS heterojunctions.As revealed by photoluminescence(PL) characterization, the as-fabricated heterojunctions demonstrated edge interaction between the two layers.The heterojunction was sensitive to annealing and showed increased interaction upon annealing at 300℃ under vacuum conditions, which led to changes in both the emission peak position and intensity resulting from the strong coupling interaction between the two layers.Low-temperature PL measurements further confirmed the strong coupling interaction.In addition, defect-related GaS luminescence was observed in our few-layer GaS, and the PL mapping provided evidence of edge interaction coupling between the two layers.These findings are interesting and provide the basis for creating new material systems with rich functionalities and novel physical effects.
基金financially supported by the National Natural Science Foundation of China (Nos. 10974108 and 11174172)
文摘A novel photodetector based on double-walled carbon nanotube （DWCNT） film/TiO2 nanotube array （TNA） heterojunctions was fabricated, which exhibited high photoresponse in a broad spectral range. The photoresponse of the detector was dramatically dependent on the length of the TNAs. High photocurrent-to-dark current ratio with a value of 3360 was observed in the visible range by optimizing the lengths of the TNAs. The photosensitive regions could be extended into the near-infrared range. These results reveal that DWCNT film/TNA heterojunctions show potential applications for broad band photodetectors.
基金the National Natural Science Foundation of China(No.60777022)
文摘n-InAs/p-InAsSb heterojunctions with a cutoff wavelength of 4.8 μm were successfully grown by one-step liquid phase epitaxy （LPE） tech-nology. Scanning electron microscopy （SEM） images and X-ray diffraction （XRD） patterns showed the mirror smooth surface, flat interface, and good crystalline quality of the heterojunctions. Fourier transform infrared （FTIR） transmittance spectra exhibited that the cutoff wave-lengths of InAsSb epilayers reach 4.8 μm. The standard current-voltage （I-V） characteristics with a high differential-resistance-area-product at zero bias （R0A） of 1.02×10-1 Ωcm2 at room temperature indicate that the fine p-n junctions have been obtained.
基金Project supported by the Natural Science Foundation of Henan Province,China(Grant No.202300410304)the Key Research Project for Science and Technology of the Education Department of Henan Province,China(Grant No.21A140021)。
文摘Shortening the distance between the depletion region and the electrodes to reduce the trapped probability of carriers is a useful approach for improving the performance of heterojunction.The CdS/Si nanofilm heterojunctions are fabricated by using the radio frequency magnetron sputtering method to deposit the amorphous silicon nanofilms and Cd S nanofilms on the ITO glass in turn.The relation of current density to applied voltage(I-V)shows the obvious rectification effect.From the analysis of the double logarithm I-V curve it follows that below~2.73 V the electron behaviors obey the Ohmic mechanism and above~2.73 V the electron behaviors conform to the space charge limited current(SCLC)mechanism.In the SCLC region part of the traps between the Fermi level and conduction band are occupied,and with the increase of voltage most of the traps are occupied.It is believed that Cd S/Si nanofilm heterojunction is a potential candidate in the field of nano electronic and optoelectronic devices by optimizing its fabricating procedure.
文摘The interface formations of the heterojunctions concerning Ⅳ and Ⅱ Ⅵ semiconductors were studied via synchrotron radiation photoemission spectroscopy. Experimental results show that the overlayer growths of Si or Ge on Ge, ZnSe and ZnS substrates are in compliance with an ideal two dimensional (2D) growth mode. However, deviations from 2D mode were also observed during the interfaces formation of Ge/CdTe and Si/CdTe, and are ascribed to large lattice mismatching and interfacial reaction.
文摘The CuO-doped ZnO thick films were prepared by the screen printing technique. The CuO doped ZnO composite materials were obtained by mixing AR grade （99.9% pure） Zinc Oxide powder mechanochemically in acetone medium with various weight percentages of Copper Chloride （CulCI2.2H20） powder （1, 3, 5, 7 and 9wt.%）. The prepared materials were sintered at 1,000 ℃ for 12 h in air ambience and ball milled to ensure sufficiently fine particle size. The films were characterized by different techniques with respect to their surface morphology and compositional property by means of SEM （scanning electron microscope） and EDXA （energy dispersive x-ray analysis）. The surface morphology of the films was studied by SEM and it shows the films are porous in nature and petal-shaped grains of sizes varies from 220 nm to 250 nm were observed. The final composition of each film was determined by the EDXA analysis. The gas response of undoped ZnO and CuO doped ZnO films was studied for different gases such as CO, C12, NH3, Ethanol, H2S and LPG at operating temperature ranging from 50 ℃ to 400 ℃. The 7wt.% CuO-doped ZnO film shows good response to H2S gas （100 ppm） at 250 ℃.
基金supported by the National Natural Science Foundation of China(21576298,21425627)the Science and Technology Plan Project of Guangdong Province(2013B090500029)+1 种基金Natural Science Foundation of Guangdong Province(2014A030313135,2014A030308012)the State Key Laboratory of Chemical Resource Engineering(CRE-2015-C-301),China~~
文摘The fabrication of multicomponent heterojunctions is an effective strategy to improve the performance of TiO2 based photocatalysts. We provide a new strategy for improving the charge separation and photocatalytic performance of ZnO /TiO2 composites by the formation of multichannel charge separated heterojunctions. ZnO /P25 composites were prepared by an incipient wetness impregnation method, and applied for the photocatalytic destruction of gaseous toluene. The ZnO /P25 composites consist of anatase TiO2（ATiO2）, rutile TiO2（RTiO2） and hexagonal zincite structures. The parasitic phase of ZnO in P25 leads to the formation of ZnO（002）/ATiO2（101）/RTiO2（110） heterojunctions that exhibit enhanced light absorption and improved multichannel electron/hole separation. ZnO /P25 heterojunctions can completely oxidize toluene into CO2 and H2O under ultraviolet light irradiation at room temperature, and show enhanced photocatalytic activity in comparison with P25 owing to the efficient electron-hole separation. Such a multichannel charge separated design strategy may provide new insight into the design of highly effective photocatalysts and their potential technological applications.
基金supported by the National Natural Science Foundation of China(51772140)the Natural Science Foundation of Jiangxi Province,China(20161BAB206111,20171ACB21033)the Scientific Research Foundation of Jiangxi Provincial Education Department,China(GJJ170578)~~
文摘To increase the number of active sites and defects in TiO2 and promote rapid and efficient transfer of photogenerated charges, a g-C3N4@C-TiO2 composite photocatalyst was prepared via in situ deposition of g-C3N4 on a carbon-doped anatase TiO2 surface. The effects of carbon doping state and surface modification of g-C3N4 on the performance of g-C3N4@C-TiO2 composite photocatalysts were studied by X-ray diffraction, X-ray photoelectron spectroscopy, UV-visible diffuse-reflectance spectroscopy, transmission electron microscopy, electrochemical impedance spectroscopy, photoluminescence, and electron paramagnetic resonance. With increasing carbon doping content, the carbon doping state in TiO2 gradually changed from gap to substitution doping. Although the number of oxygen vacancies gradually increased, the degradation efficiency of g-C3N4@C-TiO2 for RhB (phenol) initially increased and subsequently decreased with increasing carbon content. The g-C3N4@10C-TiO2 sample exhibited the highest apparent reaction rate constant of 0.036 min儃1 (0.039 min儃1) for RhB (phenol) degradation, which was 150 (139), 6.4 (6.8), 2.3 (3), and 1.7 (2.1) times higher than that of pure TiO2, 10C-TiO2, g-C3N4, and g-C3N4@TiO2, respectively. g-C3N4 was grown in situ on the surface of C-TiO2 by surface carbon hybridization and bonding. The resultant novel g-C3N4@C-TiO2 photocatalyst exhibited direct Z-scheme heterojunctions with non-local impurity levels. The high photocatalytic activity can be attributed to the synergistic effects of the improved visible light response ability, higher photogenerated electron transfer efficiency, and redox ability arising from Z-type heterojunctions.
