Abstract
Graphene has stimulated great enthusiasm in a variety of fields, while its chemically inert surface still remains challenging for functionalization towards various applications. Herein, we report an approach to fabricate non-covalently functionalized graphene by employing π–π stacking interactions, which has potentialities for enhanced ammonia detection. 5,5′-Di(4-biphenylyl)-2,2′-bithiophene (BP2T) molecules are used in our work for the non-covalent functionalization through strong π–π interactions of aromatic structures with graphene, and systematic investigations by employing various spectroscopic and microscopic characterization methods confirm the successful non-covalent attachment of the BP2T on the top of graphene. From our gas sensing experiments, the BP2T functionalized graphene is promising for ammonia sensing with a 3-fold higher sensitivity comparing to that of the pristine graphene, which is mainly attributed to the enhanced binding energy between the ammonia and BP2T molecules derived by employing the Langmuir isotherm model. This work provides essential evidence of the π–π stacking interactions between graphene and aromatic molecules, and the reported approach also has the potential to be widely employed in a variety of graphene functionalizations for chemical detection.
Highlights
Graphene with its single-atom-thick two-dimensional (2D) conjugated structure has been extensively explored as an ideal material for chemical detection owing to its exceptional properties, e.g. superior electrical properties, ultra-large speci c area, high mechanical sturdiness and good chemical stability.[1,2,3,4,5,6]
It can be seen that the starting pristine graphene shows a monolayer feature that is evidenced from the intensity ratio of 2D peak and G peak (I2D/IG) of more than 3, while the negligible D peak indicates the good quality of the graphene with a very low level of defects
BP2T molecules are employed for the non-covalent functionalization and the obtained graphene shows superior ammonia sensing capacities with the sensitivity 3 times higher comparing to that of the pristine graphene, and such gas sensing result corresponds well with our derived binding energies through Langmuir isotherm model
Summary
Graphene with its single-atom-thick two-dimensional (2D) conjugated structure has been extensively explored as an ideal material for chemical detection owing to its exceptional properties, e.g. superior electrical properties, ultra-large speci c area, high mechanical sturdiness and good chemical stability.[1,2,3,4,5,6] The high conductivity ensures graphene exhibits very little signal disturbance when working as a sensor, while the high chemical stability and strong mechanical performances ensure a long lifetime of such sensors.[7].
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