Nanostructured CuS Thin Film via a Spatial Successive Ionic Layer Adsorption and Reaction Process Showing Significant Surface-Enhanced Infrared Absorption of CO2
Infrared (IR) imaging gas sensing technique is excellent for CO2 gas detection systems that require high accuracy and safety standards; however, there is a significant barrier in application due to its high cost and difficulty in miniaturization. CO2 sensors that are functional within near- or short-wavelength IR have the potential to reduce this barrier. In this work, a highly sensitive plasmonic material based on nanostructured covellite copper sulfide (CuS), which exhibits desired localized surface plasmon resonance for surface-enhanced IR absorption (SEIRA) throughout near- and mid-IR ranges, was investigated. We prepared CuS thin films facilely in an additive manner based on a spatial successive ionic layer adsorption and reaction, Spatial SILAR, process. The Spatial SILAR can be implemented in a direct-write, demonstrating also in this study, to fabricate patterned films. The resulting CuS thin film possesses a porous microstructure consisting of hexagonal nanoflakes and demonstrates significant SEIRA for 100-ppm CO2 with an enhancement factor of 10^4.