Gas sensors are crucial in various applications such as environmental monitoring, industrial safety, and air quality control. However, many of these sensors still encounter significant challenges, including complex fabrication processes, low sensitivity, and poor stability. This study presents the development of a novel photochromic sensor using spiropyran (SP), waterborne polyurethane (WPU), and cellulose nanofiber (CNF) aerogel, aiming to overcome these challenges and provide highly sensitive detection of acidic gases. Under ultraviolet (UV) irradiation, the SP component in the aerogel isomerizes to its open-ring merocyanine (MC) form, which is further protonated to protonated merocyanine (MCH) in the presence of acid vapors. Systematic testing reveals that the SP/WPU/CNF aerogel sensor exhibits a rapid response time of 20 s under UV light irradiation and retains 75 % of its photoresponsivity after 20 cycles, demonstrating excellent durability. Additionally, the sensor exhibits a response time of 20 s to acidic gases, with a color change from purple to yellow when exposed to HCl gas at concentrations as low as 1 ppm. After undergoing five protonation and recovery cycles, the sensor maintains a certain level of acid responsiveness. These exceptional properties highlight the potential of the SP/WPU/CNF aerogel-based sensor to be a highly sensitive, efficient, and stable solution for acidic gas detection.

中文翻译：

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基于 SP/WPU/CNF 复合材料的酸性气体检测用高灵敏度光致变色气凝胶传感器


气体传感器在环境监测、工业安全和空气质量控制等各种应用中都至关重要。然而，其中许多传感器仍然面临重大挑战，包括复杂的制造工艺、低灵敏度和较差的稳定性。本研究介绍了使用螺吡喃 （SP）、水性聚氨酯 （WPU） 和纤维素纳米纤维 （CNF） 气凝胶开发的新型光致变色传感器，旨在克服这些挑战并提供高灵敏度的酸性气体检测。在紫外线 （UV） 照射下，气凝胶中的 SP 组分异构化为开环美菁 （MC） 形式，在酸蒸气存在下进一步质子化为质子化美菁 （MCH）。系统测试表明，SP/WPU/CNF 气凝胶传感器在紫外光照射下表现出 20 秒的快速响应时间，并在 20 次循环后保持 75% 的光响应率，表现出优异的耐用性。此外，该传感器对酸性气体的响应时间为 20 秒，当暴露于浓度低至 1 ppm 的 HCl 气体时，颜色会从紫色变为黄色。在经历 5 次质子化和恢复循环后，传感器保持一定程度的酸响应性。这些卓越的特性凸显了基于 SP/WPU/CNF 气凝胶的传感器成为高灵敏度、高效和稳定的酸性气体检测解决方案的潜力。