Porosity-Controlled Conductivity in Nanosheet Networks Facilitates Chemiresistive Sensing

Transition metal dichalcogenides such as molybdenum disulfide (MoS₂) are layered materials of great interest due to their unique thickness-dependent properties and potential for a range of printed electronic devices. Networks of MoS₂ nanosheets are exfoliated in a surfactant-assisted liquid phase; often water-based systems are ideal for cost effective production of inks on the larger scale. The non-covalent relationship between surfactant and nanosheet allows for the effective isolation of polydisperse nanomaterials [1]. This work looks at the subsequent size selection and deposition of MoS₂ sheets used to assemble chemiresistive devices capable of sensing ammonia (NH₃) and nitrogen dioxide (NO₂) down to levels of 10 ppb and 50 ppb. An enhancement of the nanosheet network conductivity by two orders of magnitude from 10^-5 S m^-1 to 10^-3 S m^-1 can be interpreted in terms of the nanosheet size and network distribution [2,3]. The optimisation of the porosity and nanosheet size comprising these networks results in the sensitive response to chemical analytes. The built devices show to be sensitive to 10 ppb NH₃ and exhibit a current response over multiple cycles highlighting the potential for MoS₂ devices for chemical sensing.<br/><br/><b>References</b><br/><br/>1. S.P. Ogilvie, M.J. Large, M.A. O’Mara, P.J. Lynch, C.L. Lee, A.A.K. King, C. Backes and A.B. Dalton, <i>2D Materials </i><b>6 </b>(3), 031002 (2019). 10.1088/2053-1583/ab0dc3<br/>2. S. Barwich, J. Medeiros de Araújo, A. Raffert, C. Gomes da Rocha, M.S. Ferreira, J.N. Coleman, <i>Carbon </i><b>171</b>, 306-319 (2021). 10.1016/j.carbon.2020.09.015<br/>3. A.G. Kelly, D. O’Suilleabhain, C. Gabbett and J.N. Coleman, <i>Nature Reviews Materials </i><b>7</b>, 217–234 (2022). 10.1038/s41578-021-00386-w