Exploring the potential of SrO-MgO nanocomposites: a sol–gel synthesis approach to gas sensing

Abstract In this study, SrO-MgO nanocomposites (NCs) were synthesized using the sol–gel method. SrO-MgO NCs with varying SrO concentrations (1, 3, 5, and 7 atomic weight %) were synthesized and systematically investigated for their structural, optical, and gas-sensing properties. Field Emission Scanning Electron Microscopy (FESEM) revealed a highly porous and agglomerated morphology. Energy Dispersive X-ray Spectroscopy (EDS) confirmed the elemental composition with Sr, Mg, and O, validating the successful incorporation of SrO into the MgO matrix. X-ray diffraction (XRD) confirmed the crystalline nature of the composites and the cubic phase of MgO with SrO incorporation, as evidenced by peak shifts and changes in crystallite size. Fourier Transform Infrared Spectroscopy (FTIR) reveals the broad absorption peaks observed in the 400–600 cm -1 region corresponding to the Mg–O and Sr–O stretching vibrations. The optical properties were analyzed using UV–VIS spectroscopy. The bandgap energies were determined using Tauc’s plot, showing an increase from 3.61 eV (1% SrO) to 3.76 eV (7% SrO) with increasing SrO content. This variation in bandgap suggests a variation in lattice structure due to SrO incorporation. The gas sensing characteristics were evaluated against H 2 S, NO 2 , CO 2 , NH 3 , CH 4 , and LPG over a 40–200 °C. The sensitivity studies revealed an optimum operating temperature of 120 °C, where the 7% SrO-MgO NCs exhibited the highest sensitivity (~ 83.11%), particularly toward H 2 S gas. The enhanced gas sensing performance was attributed to increased oxygen vacancies, improved charge carrier mobility, and modified surface states induced by SrO doping. The obtained results suggest that SrO-MgO NCs, particularly 7% doping concentration of SrO, have significant potential for applications in toxic gas detection due to their high sensitivity, selectivity, and quick response and recovery time. Graphical Abstract