Investigating Water Sensing Capabilities of Ca‐ and Sr‐Containing (BaTiO3)3 Clusters: A Computational Study of Electronic Properties and Chemical Effects in Surface‐Enhanced Raman Spectroscopy

ABSTRACT Nanomaterials capable of detecting water or water vapor have significant industrial and environmental applications. Barium titanate (BaTiO ) exhibits spontaneous electric polarization, making it suitable for water vapor sensing. By adjusting the polarization of small BaTiO clusters, researchers can develop new nanostructures with enhanced sensing capabilities. The present computational study investigates the water‐sensing ability of the (BaTiO ) cluster and its strontium (Sr)‐ and calcium (Ca)‐containing counterparts, focusing on their electronic characteristics and the chemical effects observed in surface‐enhanced Raman scattering (SERS) spectra. The geometries of the (BaTiO ) clusters, along with their Sr and Ca doped configurations and water adsorbed states, are optimized using the M06/6‐31G(d,p) level of theory (with LANL2DZ for Ca, Sr, and Ba). The findings indicate a notable increase in binding energy per atom of the clusters with Sr and Ca at interstitial sites. The adsorption of water molecule on Sr(BTO) and Ca(BTO) clusters significantly alters the electronic polarizability and enhances Raman activity for vibrational modes of water. The observed trends are supported by vibrational energy‐dependent electronic polarizability values. Additionally, calculations of excitation wavelength‐dependent electronic polarizability and electron transfer from the cluster to the water molecule further demonstrate that the (BaTiO ) cluster, with Sr or Ca at the interstitial site, are promising candidates for the development of SERS‐based substrates for sensing the water molecules.