[01] G. R. Ahmed Jamal, Department of Electrical and Electronic Engineering, University of Asia Pacific, Dhaka, Bangladesh. [02] Mokter M. Chowdhury, Department of Electrical and Electronic Engineering, Bangaldesh University of Engineering and Technology, Dhaka, Bangladesh. [03] Fahrin Rahman, Department of Electrical and Electronic Engineering, University of Asia Pacific, Dhaka, Bangladesh. [04] M. Aminur Rahman, Department of Electrical and Electronic Engineering, University of Asia Pacific, Dhaka, Bangladesh. [05] Sharika Shabnaz, Department of Electrical and Electronic Engineering, University of Asia Pacific, Dhaka, Bangladesh. [06] Umma Habiba, Department of Electrical and Electronic Engineering, University of Asia Pacific, Dhaka, Bangladesh.

Potential of Graphene nanoribbon (GNR) as a gas sensor is investigated in this work through a simulation based on semi empirical computations. The interactions between GNR (both pristine and defective) and three gas molecules (Ammonia, Mithane and Water) are deeply studied. A summary of some recent studies is presented so as to show that all GNRs, especially all sub-10 nm GNRs, exhibit semiconducting behavior with finite bandgap which is good to be used as a sensor. A sub-10 nm armchair-edged GNR is selected here to be used as sensing element for these three gases. All three gas molecules showed much stronger adsorption on the defective GNR than that on the pristine GNR. The change in density of state DOS diagram of pristine GNR before and after contacting gas molecules was found to be almost negligible near Fermi level. Change in GNR band feature due to donor type gas molecules was observed to be completely opposite of that for acceptor type gas molecules. The simulation result was compared with previous theoretical and experimental works so as to confirm that the observations from this work are consistent with relevant earlier works. Effect of distance and number of interacting gas molecules on Density of states of GNR was also shown. This work reveals that GNR can be a better sensor than graphene and the sensitivity of GNR-based chemical gas sensors could be drastically improved by introducing the appropriate defect.

Graphene, GNR, Armchair, Adsorption, Gas Molecule, Density of States

[01] Novoselov K S, Geim A K, Morozov S V, et al., “Electric field effect in atomically thin carbon films”, Science, 306:666, 2004. [02] A. K. Geim and K. S. Novoselov, “The Rise of Graphene”, Nat. Mater., 6, pp.183–9, 2007. [03] Brey, L.; et al. Edge states and the quantized Hall effect in graphene. Phys. Rev. B, 73, 195408, 2006. [04] Brey, L.; et al. Electronic states of graphene nanoribbons studied with the Dirac equation. Phys. Rev. B, 73, 235411, 2006. [05] V. Barone, O. Hod, and G. E. Scuseria, “Electronic Structure and Stability of Semiconducting Graphene Nanoribbons”, Nano Lett. 6, pp.2748-2754, 2006. [06] K. Nakada, M. Fujita, G. Dresselhaus, M. S. Dresselhaus, Phys. Rev. B 54, 17954, 1996. [07] Son, Y. W., Cohen, M. L. & Louie, S. G., “Energy gaps in graphene nanoribbons”, Phys. Rev. Lett. 97, 216803, 2006. [08] Nakada, K., Fujita, M., Dresselhaus, G. & Dresselhaus, M. S. Edge state in graphene ribbons: nanometer size effect and edge shape dependence. Phys. Rev. B 54, pp. 17954–17961, 1996. [09] Barone, V., Hod, O. & Scuseria, G. E., “Electronic structure and stability of semiconducting graphene nanoribbons”, Nano Lett. 6, 2748–2754, 2006. [10] Yang, L. et al., “Quasiparticle energies and band gaps in graphene nanoribbons”, Phys. Rev. Lett. 99, 186801, 2007. [11] Li, X. L. et al. Chemically derived, ultrasmooth graphene nanoribbon semiconductors. Science 319, 1229–1232, 2008. [12] Wang, X. R. et al., “Room-temperature all-semiconducting sub-10-nm graphene nanoribbon field-effect transistors”, Phys. Rev. Lett. 100, 206803, 2008. [13] Chen, Z. H., Lin, Y. M., Rooks, M. J. & Avouris, P., “Graphene nano-ribbon electronics”, Physica E (Amsterdam) 40, 228–232, 2007. [14] Han, M. Y., Ozyilmaz, B., Zhang, Y. B. & Kim, P., “Energy band-gap engineering of graphene nanoribbons”, Phys. Rev. Lett. 98, 206805, 2007. [15] Y. C. Chen et al., “Tuning the Band Gap of Graphene Nanoribbons Synthesized from Molecular Precursors”, ACS Nano, Vol. 7 ’ No. 7, pp.6123–6128, 2013. [16] Kong J, Franklin NR, Zhou C, Chapline MG, Peng S, Cho K, Dai H., “Nanotube molecular wires as chemical sensors”, Science, 287(5453), pp.622-5. 2000. [17] Collins PG, Bradley K, Ishigami M, Zettl A., “Extreme oxygen sensitivity of electronic properties of carbon nanotubes”, Science, 287(5459), pp.1801-4, 2000. [18] Lu, Y.; Li, J.; Han, J.; Ng, H T.; Binder, C.; Partridge, C.; Meyyappan, M. “Room temperature methane detection using palladium loaded single-walled carbon nanotube sensors. Chem. Phys. Lett. 2004, 391, 344–348. [19] J Liu and G Li, “A Remote Sensor for Detecting Methane Based on Palladium-Decorated Single wall carbon nanotube”, Sensors, 13, pp.8814-8826, 2013. [20] J G Aguilar, I M García, A B Murcia, D C Amoros, “Single wall carbon nanotubes loaded with Pd and NiPd nanoparticles for H2 sensing at room temperature”, Carbon, Volume 66, pp.599–611, 2014. [21] F. Schedin, A. K. Geim, S. V. Morozov, E. W. Hill, P. Blake, M. I. Katsnelson & K. S. Novoselov, “Detection of individual gas molecules adsorbed on graphene”, Nature Materials 6, pp. 652 – 655, 2007. [22] Y. Zhang, Y. Chen, K. Zhou, C. Liu, J. Zeng, H. Zhang and Y. Peng, “Improving gas sensing properties of graphene by introducing dopants and defects: a first principles study”, Nanotechnology 20, 185504, 2009. [23] K. R. Amin, A. Bid, “Graphene as a sensor”, Current Science, vol. 107, no. 430 3, August 2014. [24] A Hasan, “Ab Initio Simulations of Graphene-based Nanosensor for Detecting NO2 and Li”, M. Sc thesis, Department of Mechanical and Material Engineering, Ohio State University, 2009. [25] H J Yoon, D H Jun, J H Yang, Z Zhou, S S Yang, M M Cheng, “Carbon dioxide gas sensor using a graphene sheet”, Sensors and Actuators B 157, pp. 310– 313, 2011. [26] R. Pearce, T. Iakimov, M. Andersson, L. Hultman, A. L. Spetz and R. Yakimova, “Epitaxially grown graphene based gas sensors for ultra sensitive NO2 detection”, Sensors and actuators. B, Chemical, (155), 2, pp.451-455, 2011. [27] E. W. Hill, A. Vijayaragahvan, and K. Novoselov, “Graphene Sensors”, IEEE Sensors Journal, Vol. 11, No. 12, 2011. [28] M. Law, H. Kind, B. Messer, F. Kim, and P. Yang, “Photochemical Sensing of NO2 with SnO2 Nanoribbon Nanosensors at Room Temperature”, Angew. Chem. Int. Ed., 41, No. 13, 2002. [29] Capone, S., et al. “Solid state gas sensors: state of the art and future activities”, J. Optoelect. Adv. Mater. 5, 1335-1348, 2003. [30] H. S. Philip Wong, Deji Akiwande, Carbon Nanotube and Graphene Device Physics, Published by: Cambridge University Press, 2011, page 69. [31] Atomistix ToolKit version 13.8, Quantum Wise A/S (www.quantumwise.com) [32] M. Brandbyge, J.-L. Mozos, P. Ordejón, J. Taylor, and K. Stokbro, Phys. Rev. B 65, 165401, 2002. [33] J. M. Soler, E. Artacho, J. D. Gale, A. García, J. Junquera, P. Ordejón, and D. Sánchez-Portal, J. Phys. Condens. Matter 14, 2745, 2002. [34] K. Stokbro, D. E. Petersen, S. Smidstrup, A. Blom, M. Ipsen and K. Kaasbjerg, Phys. Rev. B 82, 075420, 2010.