Enhanced No₂ Gas Sensing Using Surface Plasmon Resonance Sensor Based on MXene and Black Phosphorus

Abstract

For sensitivity improvement, a Kretschmann-configured SPR gas sensor with a monolayer of MXene (Ti <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> ), a bimetal layer of silver (Ag)–gold (Au), and 40 layers of black phosphorous (BP) is proposed. A sodium fluoride (NaF) glass prism is used here as a coupling substrate. The performance of the sensor is examined using the angular interrogation technique. BP surface is used for the attachment of gas molecules due to its unique binding properties for gas molecules. It is observed that the proposed gas sensor shows the maximum sensitivity of 248°/refractive index unit (RIU) at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$R_{\mathrm {min}}$ </tex-math></inline-formula> value of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$6.5\times 10^{-4}$ </tex-math></inline-formula> (a.u.) and a remarkable figure of merit. Numerical results show that the use of multilayer BP improves the sensor performance over a conventional gas sensor. In addition, the capability of the proposed gas sensor to detect gases ranging from helium to carbon dioxide has been demonstrated.