Fluorographene based Ultrasensitive Ammonia Sensor

Abstract

Single molecule detection using graphene can be brought by tuning the interactions via specific dopants. Electrostatic interaction between the most electronegative element fluorine (F) and hydrogen (H) is one of the strong interactions in hydrogen bonding, and here we report the selective binding of ammonia/ammonium with F in fluorographene (FG) resulting to a change in the impedance of the system. Very low limit of detection value of ~0.44 pM with linearity over wide range of concentrations (1 pM–0.1 μM) is achieved using the FG based impedance sensor, andthisscreen printed FG sensor works in both ionized (ammonium) and un-ionized ammonia sensing platforms. The interaction energies of FG and NH3/NH4+ are evaluated using density functional theory calculations and the interactions are mapped. Here FGs with two different amounts of fluorinecontents −~5 atomic% (C39H16F2) and ~24 atomic% (C39H16F12) - are theoretically and experimentally studied for selective, high sensitive and ultra-low level detection of ammonia. Fast responding, high sensitive, large area patternable FG based sensor platform demonstrated here can open new avenues for the development of point-of-care devices and clinical sensors.

Sensing at the Surface of Graphene Field‐Effect Transistors

“…[112] Moreover, the reduced carrier mobility of highly hydrogenated graphene is still sufficient for sensor applications. [113] Fluorographene, on the other hand, was applied for the detection of ammonia, [114] ascorbic acid, and uric acid. [115] The fluorine-enriched material could also be further functionalized with thiol groups for genosensing.…”

Fluorographene: Synthesis and sensing applications

“…7,42 The main advantage of FG for sensing is its high electrocatalytic activity and hence augmented electron transfer, and its specificity toward certain analyte due to the presence of C-F bonds. It is also reported that the highly electronegative fluorine bound to the graphene scaffold would affect the surface properties and sensing performance for various analytes and biomarkers.…”

“…24 Ammonia is another analyte studied for FG based sensing. 7 Various sensing methods are existing for ammonia due to its importance in diverse industrial and biological processes, and also due to its natural and industrial origin. Low dosages of ammonia can cause problems to human respiratory, skin, eyes etc., and its prolonged exposure can lead to pulmonary oedema, a situation of fluid accumulation in the tissues and air spaces of the lungs.…”

“…Hence graphene based platforms were searched for ammonia sensing. 7 DFT calculations were conducted to study the interactions between GO and ammonia. 16 It is found that adsorption of ammonia on GO is stronger than that in graphene due to the presence of oxygen containing functional groups such as hydroxyl and epoxy-where formation hydrogen bonding with ammonia will lead to a charge transfer process.…”

“…It is also found to be unselective with weak adsorption of molecules, while it is found that introducing defects or active adsorption sites in graphene can improve its selectivity and sensitivity in the detection of molecules. 1,7 Functional derivatives of graphene-graphene honeycomb lattice containing induced defects such as heteroatoms or adatoms, attached functional groups or adsorbed groups, size or shape engineered graphene structures inducing the dimensions dependent band gap variations and adsorption centers, and van der Waals stacked solids containing graphene are coined here as functional derivatives, are known to the research community for the long time and they are receiving tremendous scientific attention since after ground breaking research of graphene. [8][9][10][11][12] It is found that these functional derivatives can abruptly change the electronic properties and low temperature fluctuations in graphene depending upon the nature of the chemical modifications, and hence this can bring exotic properties such as localized magnetic moments, high electric polarization, low surface energy along with specificity in adsorption of molecules by tuning the interactions.…”