Sol-gel法制备ZnO-TiO_2厚膜及其气敏特性研究

以钛酸丁酯的水解反应制备了ZnO掺杂的纳米TiO2厚膜。通过XRD和SEM对不同退火温度下制备出的不同掺杂量的ZnO-TiO2粉体进行物相分析和表面形貌比较,并利用气敏测试系统检测其气敏特性。讨论了掺杂量和退火温度对ZnO-TiO2厚膜气敏特性的影响,同时分析了其气敏机理。结果表明:700℃退火,w(ZnO)=4%的ZnO-TiO2结晶尺寸达到26.8 nm,体现出对丙酮蒸气单一的选择性,灵敏度为8 913,响应和恢复时间均为2 s。     

ZnO/Ag 纳米线复合薄膜的光电导型紫外探测器

ZnO/Ag纳米线复合薄膜紫外探测器是利用水热法在旋涂制备的Ag纳米线薄膜上生长ZnO 纳米线阵列制备得到。此紫外探测器在4.9 mW cm_-2紫外光强和1V偏压下,其明暗电流比为3100,响应恢复时间分别为3.47s和3.28s,响应度为0.25A/W,探测度为6.9×10₁₂Jones。制备和工作参数被分析以优化紫外探测器结构和性能,如ZnO 纳米线的生长时间,Ag纳米线薄膜的旋涂转速和紫外探测器的工作温度。     

基于ZnO纳米片/纳米球复合结构光阳极的染料敏化太阳电池

将电沉积和溶剂热方法制备的ZnO纳米片阵列和ZnO纳米球组装成ZnO纳米片/纳米球复合结构光阳极,并应用 透射电镜(TEM)、扫描电镜(SEM)、X射线衍射仪(XRD)对合成产物的形貌和晶相进行表征.染料敏化太阳电池性能测试表 明,与单一光阳极结构的ZnO纳米片基电池相比,基于更大比表面积和更强光散射效应的ZnO纳米片...     

Self-assembly fabrication of ZnO hierarchical micro/nanospheres for enhanced photocatalytic degradation of endocrine-disrupting chemicals

ZnO hierarchical micro/nanospheres were successfully synthesized via a facile and surfactant-free chemical solution route. The field emission scanning electron microscopy and transmission electron microscopy observations showed that the ZnO micro/nanospheres were assembled by large amounts of interleaving nanosheets with the thickness of about 17 nm. The X-ray diffraction, energy dispersion X-ray and Raman results revealed that the as-synthesized products were well-crystalline and possessing wurtzite hexagonal phase pure ZnO. Under UV irradiation, the ZnO micro/nanospheres showed an enhanced photocatalytic performance compared with the ZnO nanorods and commercial TiO₂ in the degradation of phenol. The photocatalytic enhancement of ZnO micro/nanospheres was attributed to their unique hierarchical porous surface structure and large surface area which can enhance the electron–hole separation and increased the yield of hydroxyl radical quantities as evidenced by the photoluminescence spectra. By using a certain of radical scavengers, hydroxyl radical was determined to play a pivotal role for the phenol degradation. Moreover, the as-synthesized ZnO micro/nanospheres could be easily recycled without any significant loss of the photocatalytic activity. Other endocrine-disrupting chemicals such as resorcinol, bisphenol A and methylparaben were also successfully photodegraded under identical conditions. These characteristics showed the practical applications of the ZnO micro/nanospheres in environmental remediation.     

Photocatalytic degradation of methyl orange and gas-sensing performance of nanosized ZnO

ZnO nanoparticles were synthesized by calcining composites of zinc nitrate and poly(vinyl pyrrolidone) (PVP, molecular weight 30 000) at a mass ratio of 1:2 at 500 °C for 2 h. X-Ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques were used to characterize the as-synthesized ZnO nanoparticles. The particles ranged in size from 30 to 50 nm. Infrared spectra of PVP and the PVP+Zn(NO₃)₂·6H₂O composite revealed coordination between the carbonyl (C=O) of PVP and Zn²⁺ of zinc nitrate, which led to a uniform nanoparticle morphology. The gas-sensing properties and photocatalytic performance of the final product were systematically investigated. The results show that the ZnO nanoparticles exhibit both a high response for ethanol detection and excellent photocatalytic activity for degradation of methyl orange under UV irradiation for 30 min.     

Al掺杂ZnO厚膜的sol-gel法制备及其气敏性能研究

以硝酸锌、硝酸铝和氢氧化钠为原料,采用sol-gel法制备铝掺杂的纳米氧化锌厚膜(样品),并利用XRD和SEM对其微观结构进行了表征。研究了铝掺杂量和退火温度对ZnO厚膜的气敏性能的影响。结果表明:700℃退火、掺w(Al)为2.9%的样品对体积分数为4.0×10–1的丙酮有很好的选择性,最大灵敏度达到7 779左右,最佳工作温度约为162℃,响应、恢复时间均为1 s,最后讨论了铝掺杂纳米氧化锌的气敏机理。     

紫外光照下金属氧化物薄膜气敏特性研究进展

介绍了近期文献中对紫外光照下半导体金属氧化物薄膜气敏特性的研究结果:紫外光照引起SnO2,In2O3,ZnO薄膜电导显著增大;提高室温下薄膜对CO,NO2气体检测的灵敏度,减少响应和恢复时间;介绍了一种对紫外光增强气敏机制的物理模型分析方法。最后讨论了当前存在的难点问题(室温下气体检测的灵敏度不高及使用紫外光源不便)及未来研究方向(借改变薄膜的制备方法、工艺条件、优化金属氧化物薄膜的结构;通过掺杂复合改变薄膜的成分以及寻找禁带宽度窄的半导体材料等)。     

ZnO Hemisphere Pits Nanowire/CdS Photoelectrode for High-Efficiency Photoelectrochemical Water Splitting

In this paper, a ZnO hemisphere pits nanowire (HPW) photoelectrode is fabricated by using polystyrene (PS) nanospheres as templates, and CdS is deposited on ZnO nanowires to improve further its photoelectrochemical performance. Firstly, PS nanospheres are deposited on ZnO seed layers by air–liquid interface self-assembling method. Subsequently, ZnO HPWs are grown which effected by PS nanospheres. Finally, CdS nanoparticles were deposited on the ZnO HPWs to construct ZnO/CdS heterojunction photoanodes by successive ionic layer adsorption and reaction method. This hemisphere pits nanowires composite structure demonstrated a highly efficient photoelectrocatalytic performance with a remarkable photocurrent density of 2.27 mA cm^?2 determined at 0.8 V versus Ag/AgCl. The enhanced performance of ZnO hemisphere pits nanowires/CdS nanoparticles (ZnO/CdS) composite photoanodes originated from the enhanced light absorption in the visible region and reduced photogenerated charges recombination rate. Furthermore, compared with ordinary nanowire arrays, hemisphere pits nanowire structure can reflect light more times to facilitate light harvesting. This work exhibits the important significance in constructing photoelectrodes for photoelectrochemical water splitting and other photoelectric devices.     

多孔ZnO纳米花电子传输层对有机太阳能电池性能的优化

通过水热法制备了多孔、单晶结构的三维ZnO纳米花材料。研究了不同生长时间下(6h、9h和12h)的ZnO材料的形貌及光电性能。结果表明,反应9h的多孔ZnO纳米花材料具有较高透光率、低缺陷密度以及高载流子迁移率等优点,是较为理想的电子传输层材料。将这些材料应用于有机太阳能电池的制备,性能测试结果表明,以生长时间为9h的多孔ZnO纳米花材料作为电子传输层的器件性能最佳,与无ZnO修饰层的参比器件相比,其短路电流密度Jsc和光电转化效率(PCE)明显提高,分别达到了5.68mA/cm2和1.24%。     

Enhanced formaldehyde-sensing properties of mixed Fe2O3–In2O3 nanotubes

Pure In₂O₃ and mixed Fe₂O₃–In₂O₃ nanotubes were prepared by simple electrospinning and subsequent calcination. The as-prepared nanotubes were characterized by scanning electron microscopy, powder X-ray diffraction, and energy-dispersive X-ray spectrometry. Gas sensors were fabricated to investigate the gas-sensing properties of In₂O₃ and Fe₂O₃–In₂O₃ nanotubes. Compared to pure In₂O₃, Fe₂O₃–In₂O₃ nanotubes exhibited better gas-sensing properties for formaldehyde at 250 °C. The response of the Fe₂O₃–In₂O₃ nanotube gas sensor to 100 ppm formaldehyde was approximately 33, which is approximately double the response of the pure In₂O₃ nanotube gas sensor. In both cases the response time was ~5 s and the recovery time was ~25 s.     

Photoresponse of composites of zinc oxide and poly(3-hexythiophene) under selective UV and white-light illumination

We investigate charge transport in UV sensing devices based on organic-inorganic semiconductor composites with the metal-semiconductor-metal (MSM) structure. Composite materials of zinc oxide (ZnO) nanoparticles and poly(3-hexylthiophene) (P3HT) were prepared by drop-casting their colloidal mixture in chloroform onto low-cost interdigitated copper electrodes. The current-voltage characteristics of the devices were investigated under both dark and illuminated conditions in the UV–visible range. The highest photoresponse was observed for an optimal P3HT:ZnO ratio of 1:8 w/w in the wavelength range between 310 and 380 nm. The dynamic response was investigated by pulsing a 365 nm UV light with a long period to reveal the response time of 4 s and the recovery time of less than 1 s. The photoresponse of the materials was also investigated for a shorter period of UV pulsing, using a rotating chopper. The response time and recovery time for the short UV pulse were found to be approximately 20 m and 25 m, respectively. The dual response times should stem from the presence of two types of semiconductor materials, namely ZnO with a high electron mobility and P3HT with a moderate hole mobility. To probe the charge generation and transport mechanisms, we further investigate the photoresponse using UV pulsing under background white light of different intensities, and vice versa. The background white light was found to deteriorate the UV photoresponse of the materials. On the other hand, the background UV illumination produced an anomalous photoresponse pattern with the white light pulsing. Understanding the charge transport mechanisms for composite materials is highly important for future applications in low-cost UV sensors and tunable optoelectronic devices.     

Formaldehyde OTFT Sensors Based on Airbrushed Different Ratios of P3HT/ZnO Films

The formaldehyde (HCHO) detecting at room temperature is of great significance. Different ratios of P3HT/ZnO composite films (3:1, 1:1, and 1:3) were deposited on the organic thin film transistor (OTFT) by spray-deposition technology, and the electrical properties and HCHO-sensing properties of all the prepared OTFT devices were measured by Keithley 4200-SCS source measurement unit. The results show that the OTFT sensor based on the P3HT/ZnO films with the ratio of 1:1 exhibited the best output and transfer curves. Different changing tendency were observed with the increase of ZnO proportion when exposed to HCHO at room temperature, and the device with the ratio of 1:1 behaved a good response and recovery characteristics.     

Hydrothermal synthesis of SnO2 nanocorals,nanofragments and nanograss and their formaldehyde gas-sensing properties

Morphology plays an important role in the properties of nanomaterials. We successfully synthesized three new SnO₂ morphologies, nanocorals, nanofragments and nanograss, via a simple hydrothermal method with surfactant additives. The final products were characterized by field-emission scanning electron microscopy and X-ray diffraction. We found that the surfactants played a critical role in the synthesis of different SnO₂ nanostructures. In particular, when poly(ethylene glycol) was added as a surfactant, a unique grass-like structure was obtained. The mechanism of formation for this novel structure is discussed. The gas-sensing performance of all the products was investigated. The results show that the nanograss morphology had a superior gas response to formaldehyde than the other morphologies.     

核-壳结构ZnO@CuO光阳极的制备及其光电性能研究

ZnO是钙钛矿太阳电池(PSCs)电子传输层(ETL)的优良材料,但ZnO与钙钛矿吸收层界面有很大的热不稳定性,从而导致该界面严重的电荷复合。文章采用水热法在FTO导电玻璃上制备出具有良好取向性的ZnO纳米棒阵列(NAs)。通过调控电化学沉积时间,在ZnO NAs上沉积一层CuO纳米颗粒,获得ZnO@CuO纳米复合材料薄膜。利用场发射扫描电镜(FESEM)、X射线衍射(XRD)对复合薄膜的形貌和物相进行了观察和分析。通过紫外-可见光漫反射(UV-Vis DRS)和瞬态荧光光谱(PL)对其光学性能进行了测定。结果表明,制备的ZnO NAs阵列均匀且垂直度较好,直径约为120 nm;通过电化学沉积CuO纳米颗粒(尺寸为34～44 nm)后,复合薄膜的可见光吸收能力增强,载流子分离效率提高;在电化学沉积时间为40 s时,所得到的ZnO@CuO NAs的光电流密度最高,约为ZnO NAs的3.37倍,表现出良好的光电转换性能。     

SnO_2厚膜NO_2新型气敏元件的研制

根据霍耳效应,用真空镀膜法制备之SnO2厚膜,制备了NO2新型气敏元件,并对其气敏性能进行了测试。结果表明:在一定的温度和湿度下,即使没有加热,元件对体积分数为20×10–6的NO2气体的灵敏度可达5.94,响应时间为36 s,恢复时间为22 s。因此,利用霍耳效应来制作气敏元件是一条可行的新思路。     

Magnetic properties of different temperature treated Co- and Ni-doped ZnO hollow nanospheres

The effect of different annealing temperatures on magnetic properties of Co- and Ni-doped ZnO hollow nanospheres was investigated. It was found that the hollow structures and room-temperature ferromagnetism were kept when the Co- and Ni-doped ZnO samples were annealed at low temperature of 550 °C. When the temperature was elevated to 700 °C, the hollow structures partially collapsed and the samples still exhibited ferromagnetic behavior. The hollow structures were completely broken with annealing temperature above 1200 °C. The ferromagnetic behavior of Co-doped ZnO disappeared, while the Ni-doped ZnO still exhibited reduced ferromagnetism. However, the ferromagnetism in high-temperature annealed Ni-doped ZnO nanospheres was extrinsic and probably originated from secondary phases.     

气敏元件室温光激发气敏性能研究

研究了WO3掺杂的ZnO基气敏元件在紫外(UV)光激发下,对乙醇气体的室温气敏性能。结果表明:在UV光照射下,各元件在室温下对体积分数为100×10–6的乙醇气体显示了很好的光敏、气敏性能,响应、恢复时间均在8s以内,其中以掺杂X(WO3)为1%的元件W(1)为最佳,从而实现了室温下的气敏测试。     

ZnO薄膜紫外探测器的光电性质

采用直流反应磁控溅射的方法制备ZnO薄膜, 用X射线衍射仪(XRD)、扫描电镜(SEM)和紫外-可见光谱仪(UV-Vis)分别表征ZnO薄膜的晶体结构和表面形貌等特征。并用此材料制备Au/ZnO/Au金属-半导体-金属(MSM)结构光电导型ZnO薄膜紫外光探测器。实验结果表明, ZnO探测器在360 nm出现明显光响应,其光电流为2.5 mA, 在5 V偏置电压下暗电流为250 μA; ZnO紫外探测器在250～380 nm的紫外波段, 探测器有很明显的光响应, 且光电流响应比较平坦; 在380～430 nm区域, 光响应明显下降; 其光响应的上升与下降弛豫时间分别为20 s与80 s。从光谱响应图中可以看出紫外(360 nm)比可见区(450 nm)的光响应高出3个数量级, 薄膜表面存在的缺陷(如氧空位)在ZnO紫外探测器的光电效应中有重要作用。     

纳米金刚石和氧化锌纳米线的协同效应提高紫外光电响应

氧化锌基紫外光电探测器较小的开关比和长的响应时间,制约其在紫外检测中的实际应用。一种简易制备纳米金刚石修饰氧化锌纳米线紫外光电探测器的方法,纳米金刚石和氧化锌纳米线混合物光电探测器的光电性能比氧化锌光电探测器有明显的提升:快的响应时间和好的开关比;优异的光电性能得益于纳米金刚石和纳米线之间的协同效应。这种策略为设计和制备新型光电系统提供了一种可能。     

Study on TiO2-doped ZnO thick film gas sensors enhanced by UV light at room temperature

The gas-sensing properties of titanium oxide (TiO₂)-doped zinc oxide (ZnO) thick film sensor specimens to typical ethanol vapor under UV light activation at room temperature have been investigated. Zinc nanoparticles were mixed with commercial TiO₂ in various weight percentage (0%, 1%, 5%, and 10%) and sintered at 650 °C for 2 h to prepare the thick film sensors. The sensors exhibit better photosensitivity and gas sensitivity to ethanol analyte. The response and recovery times are within 8 s. TiO₂ doping can improve the sensors stability and reproducibility. X-ray diffraction (XRD) and scanning electron microscopy (SEM) characterization of the film materials revealed that Zn₂TiO₄ and TiO₂ phases hindered the rod- or needle-like structure growth and subsequently affected the gas sensitivity. UV absorption spectra of the sensing film material completely dispersed in ethanol solution exhibited that the red shifts were caused with the doping of a small amount of TiO₂ into ZnO then blue shift was caused with higher TiO₂ level. The results of the UV spectra are well consistent with the photosensitive performance. The maximum sensitivity can be achieved by doping the amount of TiO₂ (5 wt%).