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SO <sub/>2</sub> -sensing properties of NiO nanowalls synthesized by the reaction of Ni foil in NH <sub/>4</sub> OH solution
摘要： Nickel oxide (NiO) is a p-type metal-oxide semiconductor with wide-ranging applications. Recent studies have focused on the gas-sensing properties of this semiconductor. This study introduces an easy process for growing NiO nanowalls on a glass substrate using Ni foil and aqueous NH4OH. The morphology and structure of the NiO nanowalls are investigated and confirmed by field-emission scanning electron microscopy and x-ray diffraction (XRD) analyses. The gas-sensing properties of the prepared nanowalls are tested using a dynamic gas-testing system wherein the target gases are H2S, NO2, NH3 and SO2. Gas-sensing data show that the synthesized NiO nanowalls are highly responsive toward SO2. Additionally, a sensing device prepared based on the NiO nanowalls is found to be stable during measurements, exhibiting a linear variation with changes in SO2 concentration.
关键词： gas sensors,surface reactions,nanowalls,NiO
更新于2025-09-23 15:23:52
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Graphene-Nanowalls/Silicon Hybrid Heterojunction Photodetectors
摘要： We study and fabricate graphene nanowalls /silicon hybrid heterojunction photoconductive detector to provide process technology of the device and theoretical foundation for the purpose of preparation of high-performance photodetectors. The graphene nanowalls (GNWs) film is patterned by double-layered photoresist-based photolithography and reactive ion etching (RIE) process to achieve high quality GNWs channel and fabricate three different GNWs/Si heterojunction photoconductive detectors with n-doped, intrinsic and p-doped silicon substrates (n-Si, i-Si, p-Si), respectively. The GNWs film not only acts as a photoconductive channel for carrier transport, but also constructs a Schottky heterojunction with the silicon to participate in the separation and transport of photogenerated carriers. Since the injection of holes needs to pass through the Schottky junction region, the height of the Schottky barrier determines the injection ability of photogenerated carriers, which directly affects the photoconductive gain of the GNWs and silicon. In addition, under low bias VDS, the GNWs/n-Si photoresponse current is maximum and the GNWs/p-Si photoresponse current is minimum. The photoresponse is attributed to the barrier heights of the GNWs/n-Si, GNWs/i-Si, and GNWs/p-Si with values of 0.73 eV, 0.69 eV, and 0.63 eV, respectively. The higher the barrier, the more the number of photogenerated carriers injected into the GNWs will be, and the photoresponse current is large as well.
关键词： photoresponse,Schottky barrier,photoconductive,graphene nanowalls
更新于2025-09-23 15:19:57
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CVD preparation of vertical graphene nanowalls/VO2 (B) composite films with superior thermal sensitivity in uncooled infrared detector
摘要： Vanadium dioxide with superior thermal sensitivity is one of the most preferred materials used in microbolometer, and the B phase of VO2 is particularly prominent. However, conventional VO2 (B) undergoes low temperature-coefficient of resistance (TCR) values and large resistances. In this paper, simple controllable composite films of vertical graphene nanowalls/VO2 (B) (i.e., VGNWs/VO2 (B)) with a suitable square resistance (12.98 k?) and a better temperature-coefficient of resistance (TCR) (-3.2 %/K) were prepared via low pressure chemical vapor deposition. The VGNWs can provide a fast channel for electron transport and enhance the conductivity of VO2 (B). This preparation method can provide a low cost, facile and simple pathway for the design and fabrication of high performance VO2 (B) thin films with superior electrical properties for its application in uncooled infrared detectors.
关键词： Chemical vapor deposition,VO2 (B) films,Vertical graphene nanowalls,Uncooled infrared detectors
更新于2025-09-23 15:19:57
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Resistive-type UVa??visible photodetector based on CdS NWs /ZnO nanowalls heterostructure fabricated using in-situ synthesis method
摘要： Here, the resistivity-type UV-visible photodetectors are designed and fabricated by implementation of direct integration between CdS nanowires(NWs) and vertical standing ZnO nanowalls with a facile in-situ synthesis method, in which ZnO nanowalls are employed as good support for anchoring well-dispersed CdS NWs to overcome its random distribution. The photodetectors based on CdS/ZnO heterojunctions demonstrate higher photo response activity than the prinstine CdS NWs and pure ZnO nanowalls photodetectors . The high performance could be attributed to the charge carrier separation efficiency and fast charge transportation facilitated by effective and close contact between CdS NWs and ZnO nanowalls. The results indicate that the ZnO/CdS heterojunctions fabricated by in-situ synthesis method provide a facile approach for nanoscale optoelectronic device.
关键词： photodetector,in-situ synthesis,CdS NWs,ZnO nanowalls
更新于2025-09-23 15:19:57
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Ag nanorods assembled with ZnO nanowalls for near-linear high-response UV photodetectors
摘要： We developed a simple method of sonication combined with annealing treatment method to construct ZnO/Ag heterostructures from Ag nanorods assembled in-situ with ZnO nanowalls, which were then characterized by FESEM, EDS, XRD, XPS, PL, UV-vis spectra. A perfect heterojunction was formed by Ag nanorods inserted into the holes of 3D ZnO nanowalls. Compared with pure ZnO nanowalls, the ZnO/Ag heterostuctures have more vacancy defects and a red shift in absorption. The effects of the working temperature on sensors fabricated with ZnO/Ag heterojunction were investigated. The photodetector demonstrated higher photo response activity as well as a faster response speed and excellent environmental stability compared to pristine ZnO nanowalls, and the photoresponse exhibited a better linear relationship at 10 oC ~70 oC. The mechanism of UV photo sensing for the ZnO/Ag heterojunction was discussed. The results indicated that ZnO/Ag heterojunction could act as an interesting material for UV photodetectors with near-linear responses in outdoor temperatures.
关键词： ZnO/Ag heterostucture,near-liner,Ag nanorods,UV photodetectors,ZnO nanowalls
更新于2025-09-19 17:13:59
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Synthesis of vertical graphene nanowalls by cracking n-dodecane using RF inductively coupled plasma enhanced chemical vapor deposition
摘要： A facile and controllable one-step method to treat liquid hydrocarbons and synthesize vertical graphene nanowalls (VGs) has been developed by using the technique of inductively coupled plasma enhanced chemical vapor deposition (ICP-ECVD) for plasma cracking of n-dodecane. Herein, the morphology and microstructure of solid carbon material and graphene nanowalls are characterized in terms of different operating conditions, i.e., input power, H2/Ar ratio, injection rate, and reaction temperature. The results revel that the optimal operating conditions were 500 W, 5:10, 30 μL/min and 800 oC for the input power, H2/Ar ratio, injection rate and reaction temperature, respectively. In addition, the degree of graphitization and the gaseous product are analyzed by Raman spectroscopy and gas chromatography (GC) detection. It can be calculated from the Raman spectrum that the relative intensity of ID/IG is approximately 1.55, and I2D /IG is approximately 0.48, indicating that the graphene prepared from n-dodecane has a rich defect structure and a high degree of graphitization. By calculating the mass loading and detecting the outlet gas, we find that the cracking rate of n-dodecane is only 6%-7% and that the gaseous products below C2 mainly include CH4, C2H2, C2H4, C2H6 and H2. Among them, the proportion of hydrogen in the outlet gas of n-dodecane cracking ranges from 1.3% to 15.1% under different hydrogen flows. Based on our research, we propose a brand new perspective for both liquid hydrocarbon treatment and other value-added product syntheses.
关键词： n-dodecane cracking,ICPECVD,vertical graphene nanowalls
更新于2025-09-11 14:15:04