Continuous emission of carbon dioxide gas (CO₂) poses a significant effect on ambient environment, crop production, and human health, necessitating further improvement of CO₂ monitoring especially at low concentrations. To overcome the obstacles of elevated operation temperatures and faint response encountered by traditional CO₂-sensitive materials such as metal oxides and perovskites, a nitrogen-doped MXene Ti₃C₂T_x (N-MXene)/polyethyleneimine (PEI) composite film decorated with reduced graphene oxide (rGO) nanosheets was initiatively leveraged in this work to detect 8–3000 ppm CO₂ gas. Through subtle optimization in the aspects of componential constitutions, operation temperatures, PEI loading amounts, and relative humidity (RH), the ternary sensors with a PEI concentration of 0.01 mg/mL exhibited a reversible and superior performance over other counterparts under 62% RH at room temperature (20 °C). Apart from the inspiring detection limit of 8 ppm, favorable selectivity, repeatability, and long-term stability were demonstrated as well. During the humid CO₂ sensing of the composites, few rGO nanosheets acted as an excellent conduction platform to transfer and collect charge carriers. Layered N-MXene offered more active sites for coadsorption of both CO₂ and water, thereby facilitating the water-involving reactions. Rich amino groups of the PEI polymer were beneficial to bind CO₂ molecules and thus induce appreciable density variation of charge carriers via proton-conduction behavior. This work initiatively offers an alternative ion-conduction strategy to detect ppm-level CO₂ gas by harnessing rGO/N-MXene/PEI composites under a humid atmosphere at room temperature, simultaneously broadening the discrimination range of MXene-related gas sensing.

中文翻译：

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掺氮的Ti ₃ C ₂ T _x MXene /聚乙烯亚胺复合膜的减湿氧化离子导电痕量二氧化碳传感

持续排放二氧化碳气体（CO ₂）对周围环境，作物生产和人类健康具有重大影响，因此有必要进一步改善对CO _2的监测，尤其是在低浓度下。为了克服传统的对CO ₂敏感的材料（如金属氧化物和钙钛矿）遇到的工作温度升高和响应模糊的问题，装饰了氮掺杂的MXene Ti ₃ C ₂ T _x（N-MXene）/聚乙烯亚胺（PEI）复合膜在这项工作中，主动利用了氧化石墨烯（rGO）减少的纳米片来检测8–3000 ppm CO ₂加油站。通过在组成，操作温度，PEI加载量和相对湿度（RH）方面进行微妙的优化，PEI浓度为0.01 mg / mL的三元传感器在相对湿度为62％的条件下，表现出可逆的优越性能室温（20°C）。除了8 ppm的激发检测限外，还显示出良好的选择性，可重复性和长期稳定性。在复合材料的潮湿CO ₂感测期间，很少有rGO纳米片充当转移和收集电荷载流子的出色传导平台。层状N-MXene为CO _2的共吸附提供了更多的活性位和水，从而促进了涉及水的反应。PEI聚合物的丰富氨基有利于结合CO ₂分子，并因此通过质子传导行为引起电荷载流子的明显密度变化。这项工作通过在室温潮湿环境下利用rGO / N-MXene / PEI复合材料，主动提供了另一种离子传导策略来检测ppm级CO ₂气体，同时拓宽了与MXene相关的气体感应的判别范围。