新型室温硫化氢纳米传感器的制备及性能

采用溶胶-凝胶法在叉指金电极表面制备纳米二氧化钛(TiO₂)多孔薄膜, 并用浓度为2.5×10⁴ mol/L的花青素对其进行敏化, 制备了一种能在室温条件下检测硫化氢(H₂S)的高灵敏度传感器. 从材料的光谱特性、 微观结构和传感器的灵敏度等方面对该传感器的性能进行了评价, 并讨论了传感器的响应机理以及温度和湿度对灵敏度的影响. 结果表明, 材料表面的可见吸收光谱比花青素红移了约50 nm, 吸收能力有所提高; 纳米TiO₂颗粒呈层状堆积排列, 颗粒之间具有较多缝隙, 比表面积大. 在室温下, 该气体传感器对浓度为5~50 mL/m³的H₂S具有良好的敏感特性, 传感器灵敏度与H₂S浓度呈线性相关, 相关系数为0.939, 响应时间为50~70 s, 恢复时间为160~180 s. 计算和测试结果表明, 环境湿度约为50%时传感器的灵敏度最佳; 在10~50 ℃范围内, 温度与传感器的灵敏度存在负相关性. 该方法为简单、 经济制备室温条件下工作的气体传感器提供了新思路和新方法.

Fabrication and Characteristics Investigation of a Novel Nanosensor for Sulfuretted Hydrogen Operating at Room Temperature†

A sulfuretted hydrogen sensor operating at room temperature based on pigment-sensitized TiO₂ films was fabricated. TiO₂ was prepared by sol-gel method and deposited on glass slides containing gold electrodes. The film was then immersed in a 2.5×10^-4 mol/L ethanol solution of cyanidin to absorb the pigment. For characterization of texture, UV-Vis diffuse reflectance spectra, field emission scanning electron microscopy, sulfuretted hydrogen adsorption-desorption measurements and temperature, humidity measurements were adop-ted. The results demonstrate that the sol-gel layers show a high porosity, a slightly more compact material close to the substrate. The cyanidin-sensitized TiO₂ nanosheets exhibit a clear red shift(50 nm) compared with cyanidin. The hybrid organic-inorganic formed film can detect sulfuretted hydrogen reversibly at room temperature. The sensitivity of the films increased almost linearly with increasing the concentrations of sulfuretted hydrogen(R²=0.939). The response time to increasing concentrations of the sulfuretted hydrogen is about 50~70 s, and the corresponding values for decreasing concentrations 160~180 s. At low humidity, sulfuretted hydrogen could be ionized by the cyanidin on the TiO₂ film and thereby decrease in the proton concentration at the surface. The resistance response to sulfuretted hydrogen of the sensors was nearly independent on temperature from 10 ℃ to 50 ℃. This preliminary work proposes simpler and cheaper processes to fabricate gas sensor for room temperature applications.