陶瓷片表面处理对p-PAn/n-BaTiO_3复合材料性能的影响

用电化学方法在 ｎ型 ＢａＴｉＯ３陶瓷表面进行苯胺的聚合，制备了具有 ｐ－ｎ异质结的 ｐ－ＰＡｎ／ｎ－ＢａＴｉＯ３复合材料测定了电流－电压特性曲线和压敏非线性系数α值，发现此材料具有良好的整流特性用电子扫描显微镜观察分析了聚苯胺的表面形态和异质结的界面形态讨论了陶瓷片表面的处理对异质结性能的影响．

Fabrication and photocatalytic properties of Cu_2S/T-ZnO_w heterostructures via simple polyol process

The Cu2S/tetrapod-like ZnO whisker（T-ZnOw） heterostructures were successfully synthesized via a simple polyol process employing the poly（vinyl pyrrolidone）（PVP） as a surfactant.The as-prepared heterostructures were characterized by X-ray diffraction（XRD）,field emission scanning electron microscopy（FESEM）,X-ray photoelectron spectroscopy（XPS） and Fourier transform infrared（FTIR）.The photocatalytic properties of Cu2S/T-ZnOw nanocomposites synthesized with different PVP concentrations were evaluated by photodegradation of methyl orange（MO） under UV irradiation.The results show that the Cu2S/T-ZnOw nanocomposites exhibit remarkable improved photocatalytic property compared with the pure T-ZnOw.The sample prepared with 3.0 g/L PVP shows an excellent photocatalytic property and the highest photodegradation rate of MO is 97% after UV irradiation for 120 min.Besides,the photocatalytic activity of the photocatalyst has no evident decrease even after four cycles,which demonstrates that the Cu2S/T-ZnOw photocatalyst exhibits an excellent photostability.Moreover,the photocatalytic mechanism of the Cu2S/T-ZnOw nanocomposites was also discussed.

Preparation of high-mechanical-property medium-entropy CrCoNi alloy by asymmetric cryorolling

In order to obtain good strength−plasticity synergy for a medium entropy alloy(MEA)CrCoNi,cold rolling,asymmetric rolling,cryorolling and asymmetric-cryorolling with subsequent annealing at different temperatures were conducted.The results showed that the asymmetric-cryorolled alloy achieved a high strength of over 1.6 GPa.After annealing at 1073 K,it retained a high strength of~1 GPa while the elongation reached nearly 60%.After annealing,the heterogeneous characteristics were formed in asymmetric-cryorolled samples,which were found to be more distinct than those of the samples subjected to asymmetric rolling.This resulted in the generation of high strength and ductility.

Effects of extrusion temperature on microstructure evolution and mechanical properties of heterogeneous Mg−Gd alloy laminates via accumulated extrusion bonding

The influence of extrusion temperature on microstructure and mechanical properties of heterogeneous Mg−1Gd/Mg−13Gd laminate prepared by accumulated extrusion bonding was investigated.The results reveal that the Mg−1Gd/Mg−13Gd laminate forms a significant difference in grain size between the successive layers when extruded at 330℃,and this difference gradually disappears as the extrusion temperature increases from 380 to 430℃.Besides,the growth rate of recrystallized grains in fine-grained layers is faster than that in coarse-grained layers.Moreover,the diffusion ability of Gd element increases with elevating extrusion temperatures,promoting the increase and coarsening of precipitates in fine-grained layers.Tensile tests indicate that the sample extruded at 380℃ has a superior combination of strength and ductility.This is mainly attributed to the synergy of the heterogeneous texture between coarse and fine-grained layers,hetero-deformation induced strengthening and hardening.The fine-grained layers facilitate the activation of prismaticáañslips,while coarse-grained layers make it easier to active basaláañand pyramidalác+añslips,especially for the sample extruded at 380℃.The activation of pyramidalác+añslips contributes to coordinating further plastic deformation.

Influences of Low Energy Ion Implantation onProperties of Polyaniline/Si Heterojunction Solar Cells

Ion implantation may favorably modify the properties of polyaniline/Si heterojunction solar cells fabricated by the electrochemical method. Influences of the implantation on the absorption spectrum and the thermal stability were discussed and output properties were measured. The results show that the absorption spectrum of the polyaniline films modified by ion implantation is much wider; its pyrolytic temperature increases by 40℃, and the polyaniline/Si cell efficiency increases 18 and 3 times under the illumination of （10.92） and 37.2W/m2, respectively.

High-performance planar heterojunction perovskite solar cells： Preserving long charge carrier diffusion lengths and interracial engineering

We demonstrate that charge carrier diffusion lengths of two classes of perovskites, CH3NH3PbI3-xClx and CH3NH3PbI3, are both highly sensitive to film processing conditions and optimal processing procedures are critical to preserving the long carrier diffusion lengths of the perovskite films. This understanding, together with the improved cathode interface using bilayer-structured electron transporting interlayers of [6,6]-phenyl-C61-butyric acid methyl ester （PCBM）/ZnO, leads to the successful fabrication of highly efficient, stable and reproducible planar heterojunction CH3NH3PbI3-xCl2 solar cells with impressive power-conversion efficiencies （PCEs） up to 15.9%. A 1-square-centimeter device yielding a PCE of 12.3% has been realized, demonstrating that this simple planar structure is promising for large-area devices.

Achieving highly stable Sn-based anode by a stiff encapsulation heterostructure

Rationally designed heterostructures provide attractive prospects for energy storage electrodes by combining different active materials with distinct electrochemical properties.Herein,through a phase separation strategy,a heterostructure of SnO_(2) encapsulated by amorphous Nb_(2)O_(5) is spontaneously synthesized.Insertion-type anode Nb_(2)O_(5) outer shell,playing as reaction containers and fast ionic pathways,physically inhibits the Sn atoms’migration and enhances the reaction kinetics.Moreover,strong chemical interactions are found at the SnO_(2)/Nb_(2)O_(5) interfaces,which ensure the solid encapsulation of the SnO_(2) cores even after 500 cycles.When used for lithium-ion batteries,this heterostructured anode exhibits high cycling stability with a capacity of 626 mAhg^(-1) after 1000 cycles at 2Ag^(-1)(85% capacity retention)and good rate performance with the capacity of 340 mAhg^(-1) at 8Ag^(-1).

Surface plasmonic effect and scattering effect of Au nanorods on the performance of polymer bulk heterojunction solar cells

The surface plasmonic effect and scattering effect of gold nanorods(AuNRs) on the performance of bulk heterojunction photovoltaic devices based on the blend of polythiophene and fullerene are investigated.AuNRs enhance the excitation since the plasmonic effect increases the electric field,mainly in the area near the interface between the active layer and AuNRs.The results show that the incident photo-to-electron conversion efficiency(IPCE) obviously increases for the device with a layer of gold nanorods,resulting from the plasmonic effect of AuNRs in the range of 500-670 nm and the scattering effect in the range of 370-410 nm.The power conversion efficiency(PCE) is increased by 7.6% due to the near field effect of the localized surface plasmons(LSP) of AuNRs and the scattering effect.The short circuit current density is also increased by 9.1% owing to the introduction of AuNRs.However,AuNRs can cause a little deterioration in open circuit voltage.

Novel Cu_3P/g-C_3N_4 p-n heterojunction photocatalysts for solar hydrogen generation

Developing efficient heterostructured photocatalysts to accelerate charge separation and transfer is crucial to improving photocatalytic hydrogen generation using solar energy. Herein, we report for the first time that p-type copper phosphide（Cu3P） coupled with n-type graphitic carbon nitride（g-C3N4） forms a p-n junction to accelerate charge separation and transfer for enhanced photocatalytic activity.The optimized Cu3P/g-C3N4 p-n heterojunction photocatalyst exhibits 95 times higher activity than bare g-C3N4, with an apparent quantum efficiency of 2.6% at 420 nm. A detail analysis of the reaction mechanism by photoluminescence,surface photovoltaics and electrochemical measurements revealed that the improved photocatalytic activity can be ascribed to efficient separation of photo-induced charge carriers. This work demonstrates that p-n junction structure is a useful strategy for developing efficient heterostructured photocatalysts.

Fabrication and properties of well-ordered arrays of single-crystalline NiSi2 nanowires and epitaxial NiSi2/Si heterostructures

In this study, we reported the design, fabrication, and characterization of well- ordered arrays of vertically-aligned, epitaxial NiSi2/Si heterostructures and single- crystalline NiSi2 nanowires on （001）Si substrates. The epitaxial NiSi2 with {111} facets was found to be the first and the only silicide phase formed inside the Si nanowires after annealing at a temperature as low as 300℃. Upon annealing at 500 ℃ for 4 h, the residual parts of Si nanowires were completely consumed and the NiSi2/Si heterostructured nanowires were transformed to fully silicided NiSi2 nanowires. XRD, TEM and SAED analyses indicated that all the NiSi2 nanowires were single crystalline and their axial orientations were parallel to the [001] direction. The obtained vertically-aligned NiSi2 nanowires, owing to their well-ordered arrangement, single-crystalline structure, and low effective work function, exhibit excellent field-emission properties with a very low turn-on field of 1.1 V/m. The surface wettability of the nanowires was found to switch from hydrophobic to hydrophilic after the formation of NiSi2 phase and the measured water contact angle decreased with increasing extent of Ni silicidation. The increased hydrophilicity can be explained by the Wenzel model. The obtained results present the exciting prospect that the new approach proposed here will provide the capability to fabricate other highly-ordered, vertically-aligned fully silicided nanowire arrays and may offer potential applications in constructing vertical silicide-based nanodevices.

2D hetero-structures based on transition metal dichalcogenides:fabrication,properties and applications

Recently,two dimensional transition metal dichalcogenides MX_2(M = Mo,W,etc; X = S,Se,Te) have ignited immense interests because of their unique structural and physical properties for the potential applications in the nano-optoelectronics,valley-spintronics etc. In terms of the structural compatibility and van der Waals interaction,two dimensional(2D) MX_2 layers can be fabricated into various lateral and vertical hetero-structures. The atomically-thin hetero-structures comprising different layered MX_2 provide a new platform for exploring fundamental physics and device technologies with unprecedented phenomenon and extraordinary functionalities. In this review,we report the recent progress about the fabrication,properties and applications of 2D hetero-structures based on transition metal dichalcogenides.

High-performance flexible and broadband photodetectors based on PbS quantum dots/ZnO nanoparticles heterostructure

Flexible and broadband photodetectors have drawn extensive attention due to their potential application in foldable displays, optical communications, environmental monitoring, etc. In this work, a flexible photodetector based on the crystalline PbS quantum dots(QDs)/ZnO nanoparticles(NPs) heterostructure was proposed. The photodetector exhibits a broadband response from ultraviolet-visible(UV-Vis)to near infrared detector(NIR) range with a remarkable current on/off ratio of 7.08×10^3under 375 nm light illumination.Compared with pure ZnO NPs, the heterostructure photodetector shows the three orders of magnitude higher responsivity in Vis and NIR range, and maintains its performance in the UV range simultaneously. The photodetector demonstrates a high responsivity and detectivity of4.54 A W-1and 3.98×10^12Jones. In addition, the flexible photodetectors exhibit excellent durability and stability even after hundreds of times bending. This work paves a promising way for constructing next-generation high-performance flexible and broadband optoelectronic devices.

Performance improvement of organic bulk heterojunction solar cells by using dihydroxybenzene as additive

We report the enhanced performance of organic solar cells(OSCs) based on regioregular poly(3-hexylthiophene)(P3HT) and methanofullerene [6,6]-phenyl C61-butyric acid methyl ester(PCBM) blend by using dihydroxybenzene as additive in the active layer.The effect of the content of the additives on electrical characteristics of the device is studied.The device with 0.2 wt% dihydroxybenzene additive achieves the best power conversion efficiency(PCE) of 4.58% with Jsc of 12.5 mA/cm2,Voc of 0.65 V,and FF of 66.6% under simulated solar illumination of AM 1.5G(100 mW/cm2),compared with the control device with PCE of 3.39%(35% improvement compared with the control device).The XRD measurement reveals that the addition of additives induces the crystallization of P3HT and establishes good inter-network to increase the contact area of donor and acceptor,and then helps charge to be effectively transferred to the electrode to reduce the chance of recombination.All evidences indicate that the dihydroxybenzene is likely to be a promising new type additive that can enhance the performance of organic bulk heterojunction solar cells.

Flexible fabric gas sensors based on PANI/WO3 p−n heterojunction for high performance NH3 detection at room temperature

A PANI/WO3@cotton thread-based flexible sensor that is capable of detecting NH3 at room temperature is developed here.A layer of WO3 with PANI nanoparticles can be deposited by in-situ polymerization.The morphology and structure of the specimens were investigated by utilizing TEM,SEM,XRD and FTIR.The sensing performance of the PANI/WO3@cotton sensors with different WO3 molar ratios to NH3 at room temperature was examined.The results show that the optimal sensor(10 mol%WO3)has a response of 6.0 to 100 ppm NH3,which is significantly higher than that of the sensors based on pristine PANI and other composites.The PANI/WO3@cotton sensor also displays excellent selectivity,gas response,and flexibility even at room temperature.The unique fiber structure,p-n heterojunction,and the increased protonation of PANI in the composites contribute to the enhanced sensing property.

Two-dimensional SnO_2/graphene heterostructures for highly reversible electrochemical lithium storage

The ever-growing market demands for lithium ion batteries have stimulated numerous research efforts aiming at the exploration of novel electrode materials with higher capacity and long-term cycling stability.Two-dimensional (2D)nanomaterials and their heterostructures are an intense area of study and promise great potential in electrochemical lithium storage owing to their unique properties that result from structural planar confinement.Here we report a microwave chemistry strategy to integrate ultrathin SnO2 nanosheets into graphene layer to construct surface-to-surface 2D heterostructured architectures,which can provide unique structural planar confinement for highly reversible electrochemical lithium storage.The as-synthesized 2D SnO2/graphene heterostructures can exhibit high reversible capacity of 688.5mAh g^-1 over 500cycles with excellent long-term cycling stability and good rate capability when used as anode materials for lithium ion batteries.The present work definitely reveals the advantages of 2D heterostructures featured with a surface-to-surface stack between two different nanosheets in energy storage and conversion devices.

Dielectric and insulating properties of SrTiO_3/Si heterostructure controlled by cation concentration

SrTiO3 films with different cation concentration were deposited on Si（001） substrates by oxide molecular beam epitaxy. An amorphous layer was observed at the interface whose thickness depends on the oxygen pressure and the substrate temperature during growth. Although lowering the oxygen vacancy concentration in SrTiO3 led to better insulating performance as indi- cated by the lowered leakage current density of the heterostructure, the dielectric performance was deteriorated because of the thickened interracial layer that dominated the capacitance of SrTiO3/Si heterostructure. Instead of adjusting the oxygen vacan- cy concentration, we propose that controlling the film cation concentration is an effective way to tune the dielectric and insu- lating properties of SrTiO3/Si at the same time.

The improved performance in the ternary bulk heterojunction solar cells

The ternary blend films have been fabricated via adding 4,4'-N,N'-dicarbazole-biphenyl(CBP,a hole transport material widely used in organic light emitting diodes) into the poly(3-hexylthiophene):[6,6]-phenyl C 61-butyric acid methyl ester(P3HT:PCBM).Despite the wide bandgap(3.1 eV) of the CBP,the solar cell utilizing the optimized P3HT:PCBM:CBP blend film showed an increase of 16% in power conversion efficiency and 25% in short-circuit current than the compared standard P3HT:PCBM blend film.This is attributed to the fact that the addition of the CBP could enhance the aggregation of the P3HT chains and thereby reduce the hole-electron recombination at the interface of P3HT and PCBM.We provide a simple,effective way to improve the performance of P3HT based bulk heterojunction solar cells.

Bimetallic phthalocyanine heterostructure used for highly selective electrocatalytic CO_(2) reduction

Heterogeneous molecular catalysts,such as metal phthalocyanines,are efficient electrocatalysts for CO_(2) reduction reaction(CO_(2)RR).However,the rational design and synthesis of a molecular catalyst-based heterostructure for CO_(2)RR remains challenging.Herein,we developed a crystalline bimetallic phthalocyanine heterostructure electrocatalyst(CoPc/FePc HS),which achieved an excellent CO_(2)-to-CO conversion efficiency(99%)and outstanding long-term stability after 10 h of electrocatalysis.Density functional theory calculations revealed that the enhancement of CO_(2)RR performance could be attributed to the distinct electron transfer pattern between FePc and CoPc.The heterostructural engineering in molecular catalysts would inspire a unique approach for improving CO_(2)RR performance.

Enhanced visible-light photocatalytic activity of a g-C_3N_4/m-LaVO_4 heterojunction: band offset determination

Band offset is a dominant factor affecting the photocatalytic performance of heterostructure photocatalysts. Therefore, controlling the band gap structure of semiconductors is a key challenge in the development of efficient photocatalysts. We used a typical in situ-method to prepare diverse graphite-phase carbon nitride(g-C_3N_4)samples from melamine, thiourea, and a mixture thereof,and found that they exhibited band gaps between2.3–2.8 e V. From UV–Vis spectra and X-ray photoelectron spectroscopy measurements, we determined that the g-C_3N_4 samples exhibited different band gap values and valence band positions. On this basis, we constructed g-C_3N_4/m-La VO_4 heterojunctions with different band offsets. UV–Vis spectra and X-ray photoelectron spectroscopy measurements revealed that the valence band offsets(VBOs) of the different heterojunctions were similar, but their conduction band offsets(CBOs) were significantly different. Photocatalytic experiments revealed that the reaction rate was enhanced with an increase in the CBO value. Furthermore, the three-phase g-C_3N_4/g-C_3N_4/mLa VO_4 heterojunction composed of m-La VO_4 and mixed g-C_3N_4 showed the highest photocatalytic activity, which was mainly due to the construction of a multilevel structure. This work investigates the influence of the band offset on heterojunction photoelectrochemical properties and provides a new strategy to improve the photocatalytic activity by constructing multilevel structures.