Fabrication of (Calcein–ZnS)n Ordered Ultrathin Films on the Basis of Layered Double Hydroxide and Its Ethanol Sensing Behavior

Abstract

(Calcein–ZnS)n ultrathin films (UTFs) were fabricated through a two-step procedure including the layer-by-layer (LBL) assembly of calcein and exfoliated Zn2Al layered double hydroxide (LDH) nanosheets, followed by an in situ gas/solid reaction with H2S. The assembly process of calcein and exfoliated LDH was monitored by UV–vis absorption measurements to get a stepwise and regular growth of the (calcein–LDH)n UTFs upon increasing the deposited cycles. By an in situ gas–solid reaction with H2S, the resulting sulfurization derivatives denoted as (calcein–ZnS)n UTFs were obtained. The resulting (calcein–ZnS)30 UTF possesses high ethanol sensing performance (response value is 8.9–100 ppm ethanol) at relatively low working temperature (90 °C). The LBL assembly process and chemical conversion technique based on Zn2Al–LDH combine the functional organic molecules and inorganic semiconductor, which enables us to develop innovative composite materials with adjustable compositions for a broad range of applications.