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Ultra-sensitive gas phase detection of 2,4,6-trinitrotoluene by non-covalently functionalized graphene field effect transistors.
Analyst ( IF 3.6 ) Pub Date : 2020-02-03 , DOI: 10.1039/c9an01962f Ashwini S Gajarushi 1 , Sandeep G Surya , Mrinalini G Walawalkar , M Ravikanth , V Ramgopal Rao , Chandramouli Subramaniam
Analyst ( IF 3.6 ) Pub Date : 2020-02-03 , DOI: 10.1039/c9an01962f Ashwini S Gajarushi 1 , Sandeep G Surya , Mrinalini G Walawalkar , M Ravikanth , V Ramgopal Rao , Chandramouli Subramaniam
Affiliation
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The high energy density (4.2 MJ kg-1) and low vapour pressure (7.2 × 10-9 atm) of chemical explosives such as TNT (2,4,6-trinitrotoluene) pose a grave security risk demanding immediate attention. Detection of such hazardous and highly challenging chemicals demands specific, ultra-sensitive and rapid detection platforms that can concomitantly transduce the signal as an electrical readout. Although chemo-sensitive strategies have been investigated, the majority of them are restricted to detecting TNT from solutions and are therefore not implementable in real-time, on-field situations. Addressing this demand, we report an ultra-sensitive (parts-per-billion) and rapid (∼40 s) detection platform for TNT based on non-covalently functionalized graphene field effect transistors (GFETs). This multi-parametric GFET detector exhibits a reliable and specific modulation in its Dirac point upon exposure to TNT in the vapour phase. The chemical specificity provided by 5-(4-hydroxyphenyl)-10,15,20-tri(p-tolyl) zinc porphyrin (ZnTTPOH) is synergistically combined with the high surface sensitivity of graphene through a non-covalent functionalization approach to realise p-doped GFETs (Zn-GFETs). Such a FET platform exhibits extremely sensitive shifts in Dirac point (ΔDP) that correlate with the number of nitro groups present in the analyte. Analytes with mono-, di-, and tri-nitro substituted aromatic molecules exhibit distinctly different ΔDP, leading to unprecedented specificity towards TNT. Additionally, the Dirac point of Zn-GFETs is invariant for common and potential interferons such as acetone and 2-propanol (perfume emulsifiers) thereby validating their practical applicability. Furthermore, the ΔDP is also manifested as changes in the contact potential of GFETs, indicating that sub-monolayer coverage of ZnTTPOH is sufficient to modulate the transfer characteristics of GFETs over an area 1000 times larger than the dopant dimensions. Specifically, ZnTTPOH-functionalized GFETs exhibit p-doped behaviour with positive ΔDP with respect to pristine GFETs. Such p-doped Zn-GFETs undergo selective charge-transfer mediated interactions with TNT resulting in enhanced electron withdrawal from Zn-GFETs. Thus the ΔDP shifts to a higher positive gate voltage leading to the dichotomous combination of the highest signal generation (1.2 × 1012 V mol-1) with ppb level molecular sensitivity. Significantly, the signal generated due to TNT is 105 times higher in magnitude compared to other potential interferons. The signal reliability is established in cross-sensitivity measurements carried out with a TNT-mDNB (1 : 10 molar ratio) mixture pointing to high specificity for immediate applications under atmospherically relevant conditions pertaining to homeland security and global safety.
中文翻译：
非共价官能化石墨烯场效应晶体管对2,4,6-三硝基甲苯的超灵敏气相检测。
TNT（2,4,6-三硝基甲苯）等化学炸药的高能量密度（4.2 MJ kg-1）和低蒸气压（7.2×10-9 atm）构成严重的安全风险，需要立即引起注意。对此类危险和极具挑战性的化学物质的检测需要特定的，超灵敏和快速的检测平台，这些平台可以同时将信号转换为电读数。尽管已经研究了对化学敏感的策略，但大多数策略仅限于从解决方案中检测TNT，因此无法在实时，现场的情况下实施。为了满足这一需求，我们报告了一种基于非共价功能化石墨烯场效应晶体管（GFET）的TNT超灵敏（十亿分之一）和快速（〜40 s）检测平台。该多参数GFET检测器在气相中暴露于TNT时，其狄拉克点表现出可靠且特定的调制。5-（4-羟苯基）-10,15,20-三（对甲苯基）卟啉锌（ZnTTPOH）提供的化学特异性通过非共价官能化方法与石墨烯的高表面敏感性协同作用实现掺杂的GFET（Zn-GFET）。这样的FET平台在狄拉克点（ΔDP）中表现出极为灵敏的位移，该位移与分析物中存在的硝基数量相关。具有单，二和三硝基取代的芳族分子的分析物表现出明显不同的ΔDP，从而导致对TNT的空前特异性。此外，Zn-GFET的Dirac点对于常见和潜在的干扰素（例如丙酮和2-丙醇（香水乳化剂））是不变的，从而验证了它们的实际适用性。此外，ΔDP还表现为GFET接触电势的变化，表明ZnTTPOH的亚单层覆盖足以在大于掺杂剂尺寸1000倍的区域上调制GFET的传输特性。具体而言，相对于原始GFET，ZnTTPOH-官能化的GFET表现出p掺杂行为，其ΔDP为正值。此类p型掺杂Zn-GFET与TNT进行选择性电荷转移介导的相互作用，从而增强了从Zn-GFET撤出的电子。因此，ΔDP移到较高的正栅极电压，导致产生最高信号的二分法组合（1。2×1012 V mol-1），具有ppb级分子灵敏度。值得注意的是，与其他潜在干扰素相比，TNT产生的信号强度高105倍。信号可靠性是通过使用TNT-mDNB（1:10摩尔比）混合物进行的交叉敏感性测量确定的，该混合物具有很高的特异性，可以在与国土安全和全球安全有关的与大气有关的条件下立即应用。
更新日期：2020-02-13
中文翻译：
非共价官能化石墨烯场效应晶体管对2,4,6-三硝基甲苯的超灵敏气相检测。
TNT（2,4,6-三硝基甲苯）等化学炸药的高能量密度（4.2 MJ kg-1）和低蒸气压（7.2×10-9 atm）构成严重的安全风险，需要立即引起注意。对此类危险和极具挑战性的化学物质的检测需要特定的，超灵敏和快速的检测平台，这些平台可以同时将信号转换为电读数。尽管已经研究了对化学敏感的策略，但大多数策略仅限于从解决方案中检测TNT，因此无法在实时，现场的情况下实施。为了满足这一需求，我们报告了一种基于非共价功能化石墨烯场效应晶体管（GFET）的TNT超灵敏（十亿分之一）和快速（〜40 s）检测平台。该多参数GFET检测器在气相中暴露于TNT时，其狄拉克点表现出可靠且特定的调制。5-（4-羟苯基）-10,15,20-三（对甲苯基）卟啉锌（ZnTTPOH）提供的化学特异性通过非共价官能化方法与石墨烯的高表面敏感性协同作用实现掺杂的GFET（Zn-GFET）。这样的FET平台在狄拉克点（ΔDP）中表现出极为灵敏的位移，该位移与分析物中存在的硝基数量相关。具有单，二和三硝基取代的芳族分子的分析物表现出明显不同的ΔDP，从而导致对TNT的空前特异性。此外，Zn-GFET的Dirac点对于常见和潜在的干扰素（例如丙酮和2-丙醇（香水乳化剂））是不变的，从而验证了它们的实际适用性。此外，ΔDP还表现为GFET接触电势的变化，表明ZnTTPOH的亚单层覆盖足以在大于掺杂剂尺寸1000倍的区域上调制GFET的传输特性。具体而言，相对于原始GFET，ZnTTPOH-官能化的GFET表现出p掺杂行为，其ΔDP为正值。此类p型掺杂Zn-GFET与TNT进行选择性电荷转移介导的相互作用，从而增强了从Zn-GFET撤出的电子。因此，ΔDP移到较高的正栅极电压，导致产生最高信号的二分法组合（1。2×1012 V mol-1），具有ppb级分子灵敏度。值得注意的是，与其他潜在干扰素相比，TNT产生的信号强度高105倍。信号可靠性是通过使用TNT-mDNB（1:10摩尔比）混合物进行的交叉敏感性测量确定的，该混合物具有很高的特异性，可以在与国土安全和全球安全有关的与大气有关的条件下立即应用。
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