Free chlorine is widely used in industry as a bleaching and oxidizing agent. Its concentration is tightly monitored to avoid environmental contamination and deleterious human health effects. Here, we demonstrate a solid state chemiresistive sensor using graphene like carbon (GLC) to detect free chlorine in water. A 15–20 nm thick GLC layer on a PET substrate was modified with a redox-active aniline oligomer (phenyl-capped aniline tetramer, PCAT) to increase sensitivity, improve selectivity, and impart fouling resistance. Both the bare GLC sensor and the PCAT-modified GLC sensor can detect free chlorine continuously and, unlike previous chemiresistive sensors, do not require a reset. The PCAT-modified sensor showed a linear response with a slope of 13.89 (mg/L)⁻¹ to free chlorine concentrations between 0.2 and 0.8 mg/L which is relevant for free chlorine monitoring for drinking water and wastewater applications. The PCAT-modified GLC sensors were found to be selective and showed less than 0.5% change in current in response to species such as nitrates, phosphates and sulfates in water. They also were resistant to fouling from organic material and showed only a 2% loss in signal. Tap water samples from residential area were tested using this sensor which showed good agreement with standard colorimetric measurement methods. The GLC and PCAT-GLC sensors show high sensitivity and excellent selectivity to free chlorine and can be used for continuous automated monitoring of free chlorine.

中文翻译：

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耐用的化学阻性传感器，可利用类石墨烯碳连续监测游离氯

游离氯在工业上被广泛用作漂白剂和氧化剂。对其浓度进行严格监控，以避免环境污染和对人体健康的有害影响。在这里，我们演示了一种固态化学电阻传感器，该传感器使用像碳这样的石墨烯（GLC）来检测水中的游离氯。用氧化还原活性苯胺低聚物（苯基封端的苯胺四聚体，PCAT）对PET基材上的15-20 nm厚的GLC层进行了改性，以提高灵敏度，改善选择性并赋予耐污性。裸露的GLC传感器和经过PCAT修改的GLC传感器都可以连续检测游离氯，并且与以前的化学电阻式传感器不同，不需要重置。经PCAT修改的传感器显示线性响应，斜率为13.89（mg / L）^-1游离氯浓度在0.2至0.8 mg / L之间，这与饮用水和废水应用中的游离氯监测有关。发现PCAT修饰的GLC传感器具有选择性，并且对水中的硝酸盐，磷酸盐和硫酸盐等物质显示出小于0.5％的电流变化。它们还可以抵抗有机材料的污染，并且信号损失仅为2％。使用该传感器测试了居民区的自来水样品，该传感器与标准比色测量方法显示出良好的一致性。GLC和PCAT-GLC传感器显示出对游离氯的高灵敏度和出色的选择性，可用于连续自动监测游离氯。