Shuvo Shoumya Nandy, Ulloa Gomez Ana Maria, Mishra Avanish, Chen Winston Yenyu, Dongare Avinash M, Stanciu Lia A
Purdue University, West Lafayette, Indiana 47907, United States.
University of Connecticut, Storrs, Connecticut 06269, United States.
ACS Sens. 2020 Sep 25;5(9):2915-2924. doi: 10.1021/acssensors.0c01287. Epub 2020 Aug 25.
Two-dimensional titanium carbide MXenes, TiCT, possess high surface area coupled with metallic conductivity and potential for functionalization. These properties make them especially attractive for the highly sensitive room-temperature electrochemical detection of gas analytes. However, these extraordinary materials have not been thoroughly investigated for the detection of volatile organic compounds (VOCs), many of which hold high relevance for disease diagnostics and environmental protection. Furthermore, the insufficient interlayer spacing between MXene nanoflakes could limit their applicability and the use of heteroatoms as dopants could help overcome this challenge. Here, we report that S-doping of TiCT MXene leads to a greater gas-sensing performance to VOCs compared to their undoped counterparts, with unique selectivity to toluene. After S-doped and pristine materials were synthesized, characterized, and used as electrode materials, the as-fabricated sensors were subjected to room-temperature dynamic impedimetric testing in the presence of VOCs with different functional groups (ethanol, hexane, toluene, and hexyl-acetate). Unique selectivity to toluene was obtained by both undoped and doped TiCT MXenes, but an enhancement of response in the range of ∼214% at 1 ppm to ∼312% at 50 ppm (3-4 folds increase) was obtained for the sulfur-doped sensing material. A clear notable response to 500 ppb toluene was also obtained with sulfur-doped TiCT MXene sensors along with excellent long-term stability. Our experimental measurements and density functional theory analysis offer insight into the mechanisms through which S-doping influences VOC analyte sensing capabilities of TiCT MXenes, thus opening up future investigations on the development of high-performance room-temperature gas sensors.
二维碳化钛MXenes（TiCT）具有高表面积、金属导电性以及功能化潜力。这些特性使其在气体分析物的高灵敏度室温电化学检测方面极具吸引力。然而，对于挥发性有机化合物（VOCs）的检测，这些非凡的材料尚未得到充分研究，其中许多VOCs与疾病诊断和环境保护高度相关。此外，MXene纳米片之间的层间距不足可能会限制其适用性，而使用杂原子作为掺杂剂有助于克服这一挑战。在此，我们报告称，与未掺杂的TiCT MXene相比，S掺杂的TiCT MXene对VOCs具有更高的气敏性能，对甲苯具有独特的选择性。在合成、表征了S掺杂和原始材料并将其用作电极材料后，将制备好的传感器在存在不同官能团的VOCs（乙醇、己烷、甲苯和乙酸己酯）的情况下进行室温动态阻抗测试。未掺杂和掺杂的TiCT MXene均对甲苯具有独特的选择性，但硫掺杂传感材料的响应增强，在1 ppm时提高了约214%，在50 ppm时提高了约312%（增加了3 - 4倍）。硫掺杂的TiCT MXene传感器对500 ppb甲苯也有明显的显著响应，同时具有出色的长期稳定性。我们的实验测量和密度泛函理论分析深入了解了S掺杂影响TiCT MXenes对VOC分析物传感能力的机制，从而为高性能室温气体传感器的开发开辟了未来的研究方向。
