基于CsPbBr3量子点的湿度传感器的制备及其在微裂纹检测中的应用

采用简单的溶液路线结合乙酰丙酮铁(AAI)改性技术，制备了分散性良好、尺寸均匀的钙钛矿型CsPbBr₃-Fe量子点(QDs)，通过X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)以及光致发光(PL)光谱对材料进行表征。并通过旋涂法构筑基于钙钛矿QDs的电阻式湿度传感器。湿敏特性测量结果表明：该湿度传感器在10%~100%的相对湿度(RH)的检测范围内具有良好的线性、快速响应特性；在70% RH时传感器的灵敏度为1.1，响应时间为33 s，恢复时间为38 s。此外，我们运用有限元方法模拟了管道微裂缝的泄漏行为，通过模拟不同流速、压力下的流速场和压力场分布，验证了利用湿度传感器检测泄漏点位置的可行性。     

pH值与湿度的光纤传感器研究

本文采用溶胶凝胶法和包埋法分别将对pH值和湿度敏感的指示剂修饰在光纤纤芯表面,制成了具有较宽检测范围的光纤pH传感器和光纤湿度传感器。通过X射线能谱仪(EDX)对所制备的pH和湿度敏感膜的表面成分进行了分析,并采用光功率计对敏感膜进行了光学检测。结果表明:当pH值在4.5~13的范围内变化时,光输出功率与pH值近似呈线性变化规律;当相对湿度(RH)在25%~80%的范围内变化时,光输出功率与RH值近似呈线性变化规律,并且二者在其检测范围内均具有良好的可逆性。     

石墨烯氧化物湿敏特性研究

在声表面波谐振器件上滴定石墨烯氧化物,制成了一种基于石墨烯氧化物薄膜的声表面波湿敏检测器件.此器件表现出优异的湿敏传感性能,在宽湿度范围内(10％ ～98％ RH),其灵敏度高达200 kHz/％RH以上;线性度超过0.9;温度系数小于0.5％ RH/℃;吸湿与脱湿响应速度均小于2s.结果表明:石墨烯氧化物具有优良的湿度敏感特性,有望应用于高性能湿度传感器的开发.     

石墨炔负载氧化锌量子点修饰电极用于多巴胺的电化学检测

在石墨炔(GDY)中引入氧化锌量子点(ZnO QDs)修饰玻碳电极(GCE)，作为电化学传感器用于多巴胺(DA)的检测。用X射线衍射仪(XRD)、高分辨率透射电子显微镜(HRTEM)、傅立叶红外光谱(FTIR)、X射线光电子能谱仪(XPS)表征了电极材料，用循环伏安法(CV)和差分脉冲伏安法(DPV)研究了ZnO/GDY传感器检测性能。结果表明，在0.05～100μmol/L线性范围内，ZnO QDs/GDY/GCE检测DA的检出限为13.4 nmol/L(S/N=3)，灵敏度为9.53μA/(μM·cm²)，最后，研究了人体血清样品中DA检测的加标实验，血清中的回收率在97.9%～99.5%之间，结果表明，该传感器具有较高的准确性，对于DA的检测，ZnO QDs/GDY建立一个新的传感平台，在实际应用中显示出巨大的潜力。     

基于L-半胱氨酸/CdTe量子点修饰电极的电化学传感器的制备及其对Pb~(2+)的检测

成功制备了由L-半胱氨酸和CdTe量子点作为修饰材料的电化学传感器并用于水体中Pb~(2+)的检测。巯基丙酸修饰的CdTe量子点通过水相合成,表面含有大量羧基,与L-半胱氨酸表面的氨基形成酰胺键,修饰于金电极表面。通过荧光分光光度计、透射电子显微镜、红外光谱、X射线衍射对L-Cys/CdTe QDs复合材料进行表征。采用循环伏安法(CV)研究了L-Cys/CdTe QDs修饰成分在金电极上的电化学性能及CdTe量子点的最佳自组装时间。采用差分脉冲溶出伏安法(DPSV)研究了铅离子在修饰电极上的电化学行为。在优化实验条件下,Pb~(2+)浓度在1.0×10~(-6)~1.0×10~(-2) mol/L范围内与其峰电流呈良好的线性关系,相关系数(r2)为0.993 8,检出限(3σ,n=5)为4.0×10~(-7) mol/L。该传感器具有良好的重现性和稳定性,有望用于实际水样中铅离子的检测。     

基于DNA电化学发光传感器研究金纳米颗粒对量子点的电化学发光影响

纳米金颗粒具有高的消光系数和良好的表面等离子体共振特性, 其等离子体共振特性受纳米金颗粒的尺寸和周围环境等因素的影响. 本文基于半导体纳米晶电化学发光信号对金纳米颗粒的距离依赖性制备了DNA电化学发光传感器. 首先利用循环伏安法(CV)在玻碳电极(GCE)表面原位沉积金纳米颗粒(AuNPs), 巯基丙酸包裹的CdS量子点(QDs)与氨基修饰的双链DNA (dsDNA)通过酰胺键缩合, 形成量子点修饰的双链DNA(QDs-dsDNA). 最后将QDs-dsDNA 通过dsDNA 另一端的巯基组装到纳米金表面, 得到CdS QDs-DNA/AuNPs/GCE电化学发光传感器. 在优化电极表面QDs-dsDNA密度、金纳米颗粒沉积方法等实验条件的基础上, 对不同传感器的表面性质进行了表征, 如形貌和电化学阻抗等. 进一步通过控制纳米金和CdS QDs之间的DNA研究了纳米金对CdS QDs发光信号的影响作用. 结果显示DNA链的长度和类型对发光信号有着重要的影响. 最后将此传感器用于环境污染物的DNA损伤检测, 显示出很好的灵敏响应.     

镉(Ⅱ)-半胱氨酸配合物对CdS量子点的荧光增强作用及其在离子检测中的应用

合成了弱配体柠檬酸三钠修饰的CdS量子点(Cit-CdS QDs), 透射电子显微镜表征结果表明, Cit-CdS QDs的粒径分布均匀(4~6 nm), 分散性好。 研究了金属离子(银(Ⅰ)离子、镉(Ⅱ)离子)、巯基化合物(巯基乙酸、半胱氨酸)以及金属离子(银(Ⅰ)离子、镉(Ⅱ)离子)与巯基化合物形成的配合物对Cit-CdS QDs荧光的影响。 发现金属离子(银离子、镉离子)与巯基化合物(巯基乙酸、半胱氨酸)形成的水溶性配合物可以显著增强Cit-CdS QDs的荧光, 配合物对Cit-CdS QDs的增强程度比单独的金属离子或巯基化合物均要高, 而且配合物修饰的CdS QDs对铜(Ⅱ)离子的响应要高于单独用金属离子或巯基化合物修饰的量子点。 建立了铜(Ⅱ)离子高灵敏度荧光检测方法, 该方法检测范围宽(1.0×10^-8~1.0×10^-6 mol/L), 检测限低(1.0×10^-9 mol/L)且具有很好的选择性, 拓展了配合物作为量子点修饰剂的应用。     

高灵敏赭曲霉毒素A电化学适配体传感器的构建

利用CdS QDs/SiO_2纳米粒子作为电子媒介体制备了一种高灵敏度的赭曲霉毒素A(OTA)电化学适配体传感器.实验过程中,首先合成了CdS QDs/SiO_2纳米粒子,之后采用透射电子显微镜、紫外吸收光谱方法等对制备的纳米材料进行了表征.该复合材料在保持了SiO_2纳米粒子良好的生物相容性和均一性的同时增加了CdS QDs的负载量,从而有利于传感器的信号放大.在组装过程中,先将捕获探针(cDNA)固定在金电极表面,适配体与捕获探针杂交形成双链,此时没有电化学信号;当OTA存在时,适配体会与OTA结合而从电极表面脱离,再将标记有CdS QDs/SiO_2纳米复合材料的信号探针(sDNA)与电极上自由的cDNA杂交,产生电化学信号.最优条件下,传感器电化学信号强度增加值与OTA浓度在0.5 pg/m L~10.0 ng/m L范围内呈现良好的线性关系,检测限低至0.091 pg/m L.     

纳米晶LaCoxFe1-xO3的合成、表征及湿敏特性

采用PEG溶胶-凝胶法合成了纳米晶LaCoxFe1-xO3, 并用DTA-TGA、XRD以及SEM对样品进行表征. 结果表明, 所有样品的原粉在600 ℃焙烧下都形成了稳定的钙钛矿纳米晶, Co含量对形成纳米晶的固相反应和纳米晶的平均粒子尺寸都有明显的影响. 此外, 还研究了纳米晶LaCoxFe1-xO3的湿敏特性, 发现在所有的样品中, LaCo0.3Fe0.7O3表现出比其它样品好的湿敏特性, 但是此材料只在相对湿度(RH)大于54%时对湿度的变化有较高的灵敏度, 掺杂适量的Na2CO3可以改善此材料的湿敏特性, 使它在全程湿度范围(RH 11%-95%)内对湿度变化都有很好的响应.     

不同形貌Bi4Ti3O12粒子的可控合成及光催化性能

研究了用一步水热法制备的不同形貌的钛酸铋(Bi₄Ti₃O₁₂, BIT)粒子的光学和可见光催化性能, 并对其晶体结构和微观结构用X射线衍射(XRD)、场发射扫描电子显微镜(FESEM)、透射电子显微镜(TEM)和高分辨透射电子显微镜(HRTEM)等手段进行了表征. XRD结果表明, 所制备的BIT 样品为层状钙钛矿结构. FESEM结果表明, 通过控制水热过程的反应参数可以得到不同形貌的纳米粒子. 紫外-可见漫反射光谱(UV-Vis DRS)表明BIT 样品的带隙能约为2.88-2.93 eV. 利用可见光(λ>420 nm)照射下的甲基橙(MO)降解实验评价了BIT 样品的光催化性能. 结果表明, BIT 的光催化活性比掺氮TiO₂ (N-TiO₂)高得多. 研究了形貌对BIT 光催化性能的影响. 所制备的BIT纳米带光催化效率最高, 经可见光照射360 min, 甲基橙溶液的降解率可达到95.0%.     

Ultra-thin CoAl layered double hydroxide nanosheets for the construction of highly sensitive and selective QCM humidity sensor

To achieve real-time monitoring of humidity in various applications, we prepared facile and ultra-thin CoAl layered double hydroxide (CoAl LDH) nanosheets to engineer quartz crystal microbalances (QCM). The characteristics of CoAl LDH were investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectric spectroscopy (XPS), Brunauer–Emmett–Telle (BET), atomic force microscopy (AFM) and zeta potential. Due to their large specific surface area and abundant hydroxyl groups, CoAl LDH nanosheets exhibit good humidity sensing performance. In a range of 11.3% and 97.6% relative humidity (RH), the sensor behaved an ultrahigh sensitivity (127.8 Hz/%RH), fast response (9.1 s) and recovery time (3.1 s), low hysteresis (3.1%RH), good linearity (R² = 0.9993), stability and selectivity. Besides, the sensor can recover the initial response frequency after being wetted by deionized water, revealing superior self-recovery ability under high humidity. Based on in-situ Fourier transform infrared spectroscopy (FT-IR), the adsorption mechanism of CoAl LDH toward water molecules was explored. The QCM sensor can distinguish different respiratory states of people and wetting degree of fingers, as well as monitor the humidity in vegetable packaging, suggesting excellent properties and a promising application in humidity sensing.     

MIL-125(Ti)及其氨基功能化材料修饰石英晶体微天平的湿敏性能

采用简单的溶剂热法制备金属有机框架化合物MIL-125(Ti)和NH_2-MIL-125(Ti)材料,并通过X射线衍射仪、扫描电子显微镜、傅氏转换红外线光谱分析仪和比表面积测试仪对所得样品进行表征。将2种材料修饰构建为石英晶体微天平传感器,测试其在11%～97%RH相对湿度范围内的湿度感测性能。实验结果表明,基于MIL-125(Ti)和NH_2-MIL-125(Ti)构建的传感器对湿度具有灵敏度高、重复性好、响应/恢复快等特点。相对于没有氨基修饰的MIL-125(Ti),NH_2-MIL-125(Ti)材料修饰的传感器对湿度表现出更高的响应性能。在环境湿度约52%时,NH_2-MIL-125(Ti)传感器对11%RH湿度响应值比MIL-125(Ti)湿度传感器的大57 Hz,说明氨基功能化对MIL-125(Ti)的湿敏性能有显著的增强作用。此外,通过Materials Studio模拟计算获得了水分子与MIL-125(Ti)及NH_2-MIL-125(Ti)作用的吸附焓,也证明氨基功能化对MIL-125(Ti)的湿度敏感性能具有增强作用。     

Highly Luminescent and Ultrastable CsPbBr3 Perovskite Quantum Dots Incorporated into a Silica/Alumina Monolith

We successfully prepared QDs incorporated into a silica/alumina monolith (QDs‐SAM) by a simple sol–gel reaction of an Al–Si single precursor with CsPbBr₃ QDs blended in toluene solution, without adding water and catalyst. The resultant transparent monolith exhibits high photoluminescence quantum yields (PLQY) up to 90 %, and good photostability under strong illumination of blue light for 300 h. We show that the preliminary ligand exchange of didodecyl dimethyl ammonium bromide (DDAB) was very important to protect CsPbBr₃ QDs from surface damages during the sol–gel reaction, which not only allowed us to maintain the original optical properties of CsPbBr₃ QDs but also prevented the aggregation of QDs and made the monolith transparent. The CsPbBr₃ QDs‐SAM in powder form was easily mixed into the resins and applied as color‐converting layer with curing on blue light‐emitting diodes (LED). The material showed a high luminous efficacy of 80 lm W⁻¹ and a narrow emission with a full width at half maximum (FWHM) of 25 nm.     

Amino‐Assisted Anchoring of CsPbBr3 Perovskite Quantum Dots on Porous g‐C3N4 for Enhanced Photocatalytic CO2 Reduction

Halide perovskite quantum dots (QDs) have great potential in photocatalytic applications if their low charge transportation efficiency and chemical instability can be overcome. To circumvent these obstacles, we anchored CsPbBr₃ QDs (CPB) on NH_x‐rich porous g‐C₃N₄ nanosheets (PCN) to construct the composite photocatalysts via N?Br chemical bonding. The 20 CPB‐PCN (20 wt % of QDs) photocatalyst exhibits good stability and an outstanding yield of 149 μmol h^?1 g^?1 in acetonitrile/water for photocatalytic reduction of CO₂ to CO under visible light irradiation, which is around 15 times higher than that of CsPbBr₃ QDs. This study opens up new possibilities of using halide perovskite QDs for photocatalytic application.     

Evaluation of co-polyaniline nanocomposite thin films as humidity sensor

Spin coated films of Co-Polyaniline nanocomposite are evaluated for their transmission properties using He-Ne laser for humidity sensing. The thickness (17-29 microm) of the films is varied by multiple deposition of Co-Polyaniline nanocomposite on a glass substrate. The samples exhibit typically two to three regions in their sensitivity curve when tested in the relative humidity (RH) range of 20-95%. The sensitivity ranges from 0.1 mV/%RH to 12.26 mV/%RH for lower to higher thickness. The sensors show quick response of 8s (20-95%RH), and a recovery time of 1 min (95-20%RH) with good repeatability, reproducibility and low hysteresis effect. The sensitivity of the sensor increases with humidity and thickness. Material characterization is done by X-ray diffraction (XRD), scanning electron micrograph (SEM) and Fourier transform infra-red spectroscopy (FTIR).     

Highly sensitive optical humidity probe

A highly sensitive optical humidity probe based on reflectance measurements has been developed using Nafion^®-crystal violet (CV) films. This sensor can be used to calibrate relative humidity (RH) in the range 0-0.25% with a detection limit (blank signal + 3σ_b, where σ_b = the standard deviation (S.D.) of the blank signal) of 0.018% RH (∼4.37 ppm) and exhibited low hysteresis. The sensor films were fully reversible in dry nitrogen and reversal times were shown to be dependent on exposure time and % RH. The response to 1% RH was highly reproducible (S.D. = 1.67%, number of samples (n) = 5). Hydrogen chloride gas did not interfere with the response of the sensor to RH but did reduce sensor reversal times. This sensor displayed sufficient sensitivity that it could be used to detect ppm levels of moisture in process gases such as nitrogen and HCl.     

High‐Purity Inorganic Perovskite Films for Solar Cells with 9.72 % Efficiency

All‐inorganic perovskite solar cells with high efficiency and improved stability are promising for commercialization. A multistep solution‐processing method was developed to fabricate high‐purity inorganic CsPbBr₃ perovskite films for use in efficient solar cells. By tuning the number of deposition cycles (n) of a CsBr solution, the phase conversion from CsPb₂Br₅ (n ≤3), to CsPbBr₃ (n=4), and Cs₄PbBr₆ (n≥5) was optimized to achieve vertical‐ and monolayer‐aligned grains. Upon interfacial modification with graphene quantum dots, the all‐inorganic perovskite solar cell (without a hole‐transporting layer) achieved a power conversion efficiency (PCE) as high as 9.72 % under standard solar illumination conditions. Under challenging conditions, such as 90 % relative humidity (RH) at 25 °C or 80 °C at zero humidity, the optimized device retained 87 % PCE over 130 days or 95 % over 40 days, compared to the initial efficiency.     

Highly sensitive and ultrafast response surface acoustic wave humidity sensor based on electrospun polyaniline/poly(vinyl butyral) nanofibers

Polyaniline (PANi) composite nanofibers were deposited on surface acoustic wave (SAW) resonator with a central frequency of 433 MHz to construct humidity sensors. Electrospun nanofibers of poly(methyl methacrylate), poly(vinyl pyrrolidone), poly(ethylene oxide), poly(vinylidene fluoride), poly(vinyl butyral) (PVB) were characterized by scanning electron microscopy, and humidity response of corresponding SAW humidity sensors were investigated. The results indicated that PVB was suitable as a matrix to form nanofibers with PANi by electrospinning (ES). Electrospun PANi/PVB nanofibers exhibited a core–sheath structure as revealed by transmittance electron microscopy. Effects of ES collection time on humidity response of SAW sensor based on PANi/PVB nanofibers were examined at room temperature. The composite nanofiber sensor exhibited very high sensitivity of ∼75 kHz/%RH from 20 to 90%RH, ultrafast response (1 s and 2 s for humidification and desiccation, respectively) and good sensing linearity. Furthermore, the sensor could detect humidity as low as 0.5%RH, suggesting its potentials for low humidity detection. Attempts were done to explain the attractive humidity sensing performance of the sensor by considering conductivity, hydrophilicity, viscoelasticity and morphology of the polymer composite nanofibers.     

Humidity Sensing Properties of the Sensor Based on V‐doped Nanoporous Ti0.9Sn0.1O2 Thin Film

Vanadium doped nanoporous Ti_0.9Sn_0.1O₂ thin film has been prepared on an alumina substrate by sol‐gel method with Pluronic P123 as the organic template, and humidity sensing properties of it has been investigated. It is found that V‐doped nanoporous Ti_0.9Sn_0.1O₂ thin film shows good humidity sensing properties, and impendence of it decreases more than four orders of magnitude in the relative humidity (RH) range of 11%–95% at 25°C. The response and recovery time of this sensor are about 13 and 17 s, respectively. High sensitivity, narrow hysteresis loop, rapid response and recovery, prominent stability and good repeatability are obtained. A possible mechanism is suggested to explain the humidity sensitive properties.