Synthesis and characterization of two-dimensional (2D) Aminoethyl Methacrylate Perovskite with improved stability for Ammonia gas detection

Lead-based perovskite materials have captured enormous attention due to their remarkable properties for gas detection. However, stability has become a limitation to the extent that it leads to severe material degradation. Therefore, this study was conducted to synthesise and investigate the effects of changes in physical properties on the stability of materials that affect the performance of two-dimensional (2D) perovskites. New materials based on different lead-based materials to form the final perovskites of I-AMP and N-AMP were prepared and stored under different storage conditions. The physical properties of (H2C=C(CH3)CO2CH2CH2NH3)2PbCl2X2 perovskites, where X is an anion (I- or NO3-) of iodide-based (I-AMP) and nitrate-based (N-AMP) materials changed over time. Each of I-AMP and N-AMP exhibited distinct characteristics, in which I-AMP showed incomplete coverage on the surface that was visible under room temperature conditions, while N-AMP material showed almost full coverage under all conditions. XRD perovskite peaks could be observed approximately at 25.35° (I-AMP) and 23.1° (N-AMP). However, a major shift was observed in the perovskite peaks of I-AMP over a period of time, which caused drastic changes in the full width at half maximum (FWHM), crystallite size, and crystallinity percentage, highlighting the instability of the iodide-based material. In contrast, N-AMP showed superior stability, with the highest crystallinity percentage of 96.76% even on day 20 under silica storage condition. When both materials were exposed to ammonia gas, a new XRD peak was identified as ammonium lead iodide (NH4PbI3), with a red-shifted perovskite peak (101) being observed for the case of I-AMP. Based on the FWHM, crystallite size, crystallinity, and lattice strain analysis, it can be concluded that N-AMP’s stability was maintained even after the exposure to ammonia gas. XPS analysis of both samples showed the changes that occurred in the composition of atoms after gas exposure. Based on the electrical measurements for both AMPs, the sensitivity values were found to decrease after long exposure as the surface of perovskite became saturated with ammonia gas molecules. The findings also highlighted the better sensitivity of N-AMP (0.976) compared to I-AMP (0.855), emphasising that N-AMP exhibits a faster response to ammonia gas. In conclusion, these novel 2D perovskite materials show great potential for the detection of ammonia gas with their enhanced stability.