Yichun Liu

Northeast Normal University, Hsin-ching, Jilin Sheng, China

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Publications (236)745.48 Total impact

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    ABSTRACT: We demonstrate a forming-free electrochemical metallization resistive memory device (Ag/TiOxNy/Pt) based on the nanoporous titanium oxynitride (TiOxNy) thin film. Due to the nanoporous structure of TiOxNy, Ag atoms can migrate into the film during the Ag electrode evaporation process, resulting in a pre-formed Ag conductive filament inside the switching layer. This is responsible for the forming-free resistive switching behavior. Subsequently, resistive switching with attractive performance is achieved after a reset process, including good endurance, low operation voltages, and fast switching speed. The forming-free and reliable switching characteristics suggest that nanoporous TiOxNy thin film is one of the promising material candidates for future nonvolatile memory applications.
    Journal of Alloys and Compounds 01/2016; 656:612-617. DOI:10.1016/j.jallcom.2015.10.020 · 3.00 Impact Factor
  • Lei Zhang · Haiyang Xu · Zhongqiang Wang · Hao Yu · Jiangang Ma · Yichun Liu ·

    Applied Surface Science 11/2015; DOI:10.1016/j.apsusc.2015.11.022 · 2.71 Impact Factor
  • Xiaoli Zhao · Yanhong Tong · Qingxin Tang · Yichun Liu ·

  • Journal of Energy Chemistry 10/2015; DOI:10.1016/j.jechem.2015.10.014 · 2.35 Impact Factor
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    ABSTRACT: Coexistence of nonvolatile and volatile resistive switching behaviors was demonstrated in Cu/amorphous carbon/Pt sandwich-structure memory devices by adjusting compliance currents (CCs) to control the size of Cu conductive filament (CF). It was observed that the retention time of the volatile switching strongly depends on the CF’s size, and can be tuned in a wide range from hundreds of milliseconds to tens of seconds. When the nanoscale CF contains only a small number of Cu atoms, the conductance quantization occurs in the relaxation process of resistance state. By quantitatively studying the dependence of relaxation time on CF’s size and temperature, the volatile behavior can be well understood within the framework of the Rayleigh instability, where the Cu-CF spontaneously dissolves to minimize the surface energy. The observed nonvolatile/volatile behaviors, as well as the spontaneous relaxation effect, bear many resemblances to the long-term/short-term plasticity of biological synapses, and thus can be fully utilized to develop artificial synaptic devices.
    Carbon 09/2015; 91. DOI:10.1016/j.carbon.2015.04.031 · 6.20 Impact Factor
  • Manshu Han · Jiangang Ma · Haiyang Xu · Yichun Liu ·
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    ABSTRACT: In this paper, single crystalline Bi2Se3 nanostructures including nanowires, nanoribbons, nanoplates and bridge-like nanostructures have been grown by physical vapor deposition. By investigating the morphological evolution of the Bi2Se3 nanostructures, we found that Bi2Se3 nanoribbons with the long axis along <112 @#x0305;0> could facilitate the formation of bridge-like nanostructures. Subsequently, a two-step growth process had been developed to increase both the size and the amount of the bridge-like Bi2Se3 nanostructures effectively, which shows great promise to realize the growth of large-size two dimensional materials for various optoelectronic and spintronic applications.
    CrystEngComm 09/2015; 17(44). DOI:10.1039/C5CE01329A · 4.03 Impact Factor
  • Weizhen Liu · Wei Wang · Haiyang Xu · Xinghua Li · Liu Yang · Jiangang Ma · Yichun Liu ·
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    ABSTRACT: A simple top electrode preparation process, employing continuous graphene oxide films as electrode supporting layers, was adopted to fabricate a ZnO nanorod array/p-GaN heterojunction LED. The achieved LED demonstrated different electroluminescence behaviors under forward and reverse biases: a yellow-red emission band was observed under forward bias, whereas a blue-UV emission peak was obtained under reverse bias. Electroluminescence spectra under different currents and temperatures, as well as heterojunction energy-band alignments, reveal that the yellowred emission under forward bias originates from recombinations related to heterointerface defects, whereas the blue-UV electroluminescence under reverse bias is ascribed to transitions from near-band-edge and Mg-acceptor levels in p-GaN.
    Applied Physics Express 09/2015; 8(9):095202. DOI:10.7567/APEX.8.095202 · 2.37 Impact Factor

  • Applied Surface Science 09/2015; DOI:10.1016/j.apsusc.2015.09.182 · 2.71 Impact Factor
  • Source
    Mingyi Zhang · Changlu Shao · Xin Zhang · Yichun Liu ·
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    ABSTRACT: In this paper, a two-step synthesis route combining an electrospinning technique and solvothermal method has been accepted as a straightforward protocol for the exploitation of BiOCl-carbon nanofibers (CNFs) hierarchical heterostructures. Photocatalytic tests showed that the BiOCl-CNFs heterostructures possess a much higher degradation rate of 4-nitrophenol (4-NP) than pure BiOCl. The enhanced photocatalytic activity could be attributed to the effective separation of photogenerated carriers driven by the photoinduced potential difference generated at the BiOCl-CNFs heterojunction interface. The ·OH radicals played a critical role in the photocatalytic degradation of 4-NP over the BiOCl–CNFs heterostructures. Moreover, the heterostructures could be reclaimed easily by sedimentation without a decrease of the photocatalytic activity.
    CrystEngComm 08/2015; 17(38). DOI:10.1039/C5CE01012H · 4.03 Impact Factor
  • Guorui Wang · Qingxin Tang · Yanhong Tong · Wenping Hu · Yichun Liu ·
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    ABSTRACT: The conductive, transparent, and flexible SnO2:Sb single-crystal nanowires are shown as electrodes for F16CuPc single-crystal nanowire devices on the flexible plastic which includes anisotropic-transport OFETs, electrode-movable OFETs, and p-n junction photovoltaic devices. The SnO2:Sb nanowires provide the good energy level match and the excellent soft contact with F16CuPc nanowire, leading to the multifacet applications of the SnO2:Sb nanowire in nanowire electronics and optoelectronics, and the high device performance. Combined with their good size compatibility these results shows that the conductive SnO2:Sb single-crystal nanowire opens a window into the fundamental understanding of the intrinsic properties of highly ordered organic semiconductors, optimization and miniaturization of the organic nanocircuits, and development of new-generation flexible organic nanodevice.
    08/2015; 3(37). DOI:10.1039/C5TC01920F
  • Changhua Wang · Xintong Zhang · Yichun Liu ·

    Applied Surface Science 08/2015; DOI:10.1016/j.apsusc.2015.08.055 · 2.71 Impact Factor
  • Guiru Xue · Qingxin Tang · Yanhong Tong · Yichun Liu ·
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    ABSTRACT: Conventional graphene nanoribbon (GNR) field-effect transistor (FET) fabrication involved the wet process with the separated nanoribbon formation and device fabrication. Here, we demonstrate one simple and novel non-solution method to integrate the GNR formation and the FET fabrication, where a gold film is used as mask for electrode deposition, following by using a SnO2 nanoribbon as mask for the formation of GNR. The channel length and width can be controlled by the widths of the gold film and the SnO2 nanoribbon, respectively. It is found that the GNR with the width up to 330 nm presents the promising ambipolar field-effect properties in air ambient, the hole and electron mobilities are respectively as high as 904 and 703 cm2 V−1 s−1, which benefits from the all dry process for both GNR fabrication and device fabrication.
    Synthetic Metals 07/2015; 205. DOI:10.1016/j.synthmet.2015.03.024 · 2.25 Impact Factor
  • Lina Kong · Changhua Wang · Han Zheng · Xintong Zhang · Yichun Liu ·
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    ABSTRACT: Doping TiO2 photocatalysts with foreign ions has been deemed an effective method to enhance visible light absorption and thus increase their photocatalytic performance. Herein, we report that Nb-doped TiO2 porous microspheres prepared by ultrasonic spray pyrolysis of peroxide precursor solution are yellow, and the yellow coloration becomes increasingly conspicuous with increasing Nb dopant concentration. Comprehensive spectral analyses show that both surface peroxo species and bulk Ti3+ are introduced into TiO2 microsphere samples together by charge compensation with Nb5+ dopant and are responsible for the coloration of TiO2. The Nb-doped microspheres show higher photocatalytic rates than undoped TiO2 for the degradation of gaseous acetaldehyde under visible irradiation but slower rates under ultraviolet light. Moreover, the photocatalytic mineralization rates of acetaldehyde to CO2 are lowered with Nb doping under both visible and UV irradiation. Correlation between the results of surface photovoltage spectroscopic (SPS) characterizations and photocatalytic tests suggests that surface peroxo states are relevant to the visible-light-stimulated charge separation and photocatalytic reactions, albeit holes trapped in these states have lower reactivity than in valence band. On the other hand, the enhanced photoluminescence in the near-infrared region, reduced SPS response in the UV region, and photochromic phenomena during photocatalytic process indicated that Ti3+ defects serve as charge carrier recombination centers and display adverse effect to photocatalytic activity of Nb-doped TiO2, especially under UV irradiation.
    The Journal of Physical Chemistry C 07/2015; 119(29):16623-16632. DOI:10.1021/acs.jpcc.5b03448 · 4.77 Impact Factor
  • Fujun Miao · Changlu Shao · Xinghua Li · Na Lu · Kexin Wang · Xin Zhang · Yichun Liu ·
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    ABSTRACT: Abstract Three-dimensional porous polyacrylonitrile/polyaniline core-shell (PAN@PANI) nanofibers are fabricated by electrospinning technique combining in situ chemical polymerization of aniline monomers. The obtained PAN@PANI nanofibers possess unique continuous and homogeneous core-shell nanostructures and high mass loading of PANI (∼60 wt%) as active materials, which have greatly improved the electrochemical performance with a specific capacitance up to 577 F/g at a scan rate of 5 mV/s. Moreover, the porous networks of randomly arrayed PAN@PANI nanofibers provide binder-free and freestanding electrodes for flexible solid-state supercapacitors. The obtained devices based on PAN@PANI networks present excellent electrochemical properties with an energy density of 12.6 Wh/kg at a power density of 2.3 kW/kg and good cycling stability with retaining more than 98% of the initial capacitance after 1000 charge/discharge cycles, showing the possibility for practical applications in flexible electronics.
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    ABSTRACT: Ag/TiO2 nanocomposite films present a stable optical memory based on localized surface plasmon resonance but still suffer from the problem of the low efficiency of holographic storage. Here, we report that the response time and diffraction efficiency of the high-density holographic storage of Ag/TiO2 nanocomposite films at 403.4 nm can be improved significantly and further modulated by introducing the auxiliary 532 nm irradiation with s or p linear polarization state. Absorbance at ∼600 nm, contrast of holographic fringes, and brightness of reconstruction image were all enhanced under the bicolor excitation. The observations were explained by Ag+ ions migration, Ag nanoparticle dissolution, and their redeposition, with the help of concentration and electronic-field gradient forces. Taking these factors in account, a phenomenological model describing the growth of two competitive-phase gratings is proposed. The localized surface plasmon resonance with the composite wave provides new possibilities for Ag/TiO2 nanocomposite films in application of long-life and high-density optical memory.
    The Journal of Physical Chemistry C 07/2015; 119(32):150717223820001. DOI:10.1021/acs.jpcc.5b04409 · 4.77 Impact Factor
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    ABSTRACT: Despite the excellent photo-generated charge separation and transport properties of 1D rutile TiO2 nanowire (NW) array, insufficient light harvesting due to low surface area is a key factor that limiting the photovoltaic performance of TiO2 NW-based solar cells. Herein, we apply semiconductor Sb2S3 as light absorber and sprayed p-CuI as hole conductor for TiO2 NW solar cells. The Sb2S3-sensitized device displays significantly improved light absorption than its corresponding dye-sensitized device, with a peak incident-photon-to-current conversion efficiency (IPCE) of 64%. Moreover, CuI film deposited by spray technique enables improved pore filling and better electrical contact between Sb2S3 absorber and CuI, as well as CuI crystals themselves, and facilitates hole transfer from Sb2S3 to CuI crystals and hole transportation in CuI layer. As a result, the TiO2 NW/Sb2S3/CuI-spray/Au device exhibits an overall power conversion efficiency of 1.18% under AM 1.5G simulated solar irradiation, which is about 2.88 times and 2.11 times higher than TiO2 NW/N719/CuI-spray/Au and TiO2 NW/Sb2S3/CuI-drop coating/Au devices, respectively. This study thus demonstrates the superiority of Sb2S3 sensitizer for TiO2 NW solar cells and spray technique for preparation of p-CuI hole conductor.
    New Journal of Chemistry 07/2015; 39(9). DOI:10.1039/C5NJ00299K · 3.09 Impact Factor
  • Kexin Wang · Changlu Shao · Xinghua Li · Xin Zhang · Na Lu · Fujun Miao · Yichun Liu ·
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    ABSTRACT: Hierarchical heterostructures of p-type BiOCl nanosheets/n-type TiO2 nanofibers (p-BiOCl/n-TiO2 HHs) were prepared by combining the electrospinning technique and solvothermal method. BiOCl nanosheets with exposed {001} facets were densely and uniformly grown on the electrospun TiO2 nanofibers. The obtained p-BiOCl/n-TiO2 HHs exhibited enhanced UV-light photocatalytic activity due to the effects of p-n heterojunctions and high surface areas. Experiments proved that the generation rate of hydroxyl radicals for p-BiOCl/n-TiO2 HHs was much larger than that of TiO2 nanofibers. Moreover, the p-BiOCl/n-TiO2 HHs could be recycled easily by sedimentation because of their nanofibrous nonwoven web structure.
    Catalysis Communications 07/2015; 67. DOI:10.1016/j.catcom.2015.03.037 · 3.70 Impact Factor
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    ABSTRACT: Clarification of the energy-transfer (ET) mechanism is of vital importance for constructing efficient upconversion nanoplatforms for biological/biomedical applications. Yet, most strategies of optimizing these nanoplatforms were casually based on a dynamic ET assumption. In this work, we have modeled quantitatively the shell-thickness-dependent interplay between dynamic and static ET in nanosystems and validated the model in a typical biofunctional upconversion nanoplatform composed of NaYF4:Er, Yb/NaYF4 upconversion nanoparticles (UCNPs), and energy-acceptor photosensitizing molecule Rose Bengal (RB). It was determined that with a proper thickness shell, the energy transferred via dynamic ET as well as static ET in this case could be significantly improved by ∼4 and ∼9 fold, respectively, compared with the total energy transferred from bare core UCNPs. Our results shall form the bedrock in designing highly efficient ET-based biofunctional nanoplatforms.Keywords: NaYF4:Yb3+; Er3+/NaYF4; Förster resonant energy transfer; reabsorption; inner filter effect; quantitative analysis; optimal shell thickness; upconversion
    Journal of Physical Chemistry Letters 07/2015; 6(13):2518-2523. DOI:10.1021/acs.jpclett.5b00999 · 7.46 Impact Factor
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    ABSTRACT: In this study, investigation of the unipolar resistive switching (RS) of InGaZnO film indicates that the reset voltage polarity can strongly affect the RS region. The dependence of the RS characteristics on the top electrode (Pt, Al, or Cu) was investigated. Asymmetrical electrodes (Cu/InGaZnO/Al) were chosen and the dependence of the RS parameters (e.g., high and low resistance states, set and reset voltages) on these two diverse electrodes can provide two indicators to trace the location of the RS region. The RS region is usually located near the anode when the applied set and reset voltages have the same polarity. In comparison, when the reset voltage has the opposite polarity to the set voltage, the RS region prefers to be located near the anode of the reset process rather than the cathode (which is used as the anode in the set process), indicating the movement of the RS region during the reset process. With the aid of joule heating, oxygen ions can overcome the energy barrier during the reset process under small voltage, resulting in the CFs restructuring and having the inverse shape, which is responsible for the drift mechanism of the RS region.
    Physica Status Solidi (A) Applications and Materials 07/2015; 212(10). DOI:10.1002/pssa.201532235 · 1.62 Impact Factor
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    ABSTRACT: It has long been known that efficient interfacial charge transfer between different phases of TiO2 is beneficial for enhanced photocatalysis. However, there has been considerable debate over the direction of charge transfer across the interface of different TiO2 phases. In this work, we study a case of TiO2 with novel anatase/TiO2(B) heterojunction (ABHJ), wherein charge carrier transfer across the heterojunction interface is intensively investigated. The ABHJ is prepared by a two-step alkaline hydrothermal route and features nanotubes with large surface area. Comprehensive analysis including UV-Vis-DR, XPS, Mott-Schottky measurement, EPR and transient photovoltage techniques provide evidence for a type II band alignment in ABHJ and migration of photogenerated electrons from anatase to TiO2(B), by which could effectively inhibit the recombination rate of photo-induced electrons-holes. Photocatalytic tests demonstrate that as-obtained ABHJ shows higher activity than both single phase and P25 for not only hydrogen production but also photodegradation of gaseous acetaldehyde, which is due to the synergistic effect between efficient charge separation at the interface and high surface area.
    Dalton Transactions 06/2015; 44(29). DOI:10.1039/C5DT01860A · 4.20 Impact Factor

Publication Stats

5k Citations
745.48 Total Impact Points


  • 2000-2015
    • Northeast Normal University
      • • Center for Advanced Optoelectronic Functional Materials Research
      • • Department of Chemistry
      Hsin-ching, Jilin Sheng, China
  • 2002-2006
    • Changchun Institute of Optics, Fine Mechanics and Physics
      Hsin-ching, Jilin Sheng, China
  • 2003
    • National Space Science
      Peping, Beijing, China
  • 2000-2003
    • Chinese Academy of Sciences
      • Graduate School
      Peping, Beijing, China