Unveiling the Synthesis, Hirshfeld Surface Insights, and Interesting Photocatalytic Ability of [C7H8N3]6(BiBr6)2·3H2O

This research centers on the synthesis of a unique organic-inorganic hybrid material, [C7H8N3]6(BiBr6)2.3H2O, achieved through slow evaporation at room temperature. Single crystal X-ray diffraction revealed a centrosymmetric P1¯ space group within the triclinic system, featuring two [BiBr6]3− octahedral anions, six [C7H8N3]+ monoprotonated cations and three water molecules. A three-dimensional network is created by N-H...Br and N-H...O hydrogen bonds, as well as π-π interactions. Hirshfeld surface analysis, supported by 2D fingerprint plots, quantitatively visualized crucial intermolecular interactions. Verification of functional groups was carried out using Fourier transform infrared and Fourier transform Raman spectroscopies. Thermal stability and transformation were explored using thermogravimetric analysis (TGA-DSC), aligning with Nuclear Magnetic Resonance (NMR) spectra. Optical absorption measurements identified absorption bands at 332 and 376 nm, corresponding to energy levels of 3.74 and 3.3 eV. Utilizing this structure, a Bi-TiO2 photocatalyst was obtained through the sol-gel method, characterized by X-ray diffraction (XRD), infrared (IR) absorption spectroscopy, and UV-visible diffuse reflectance spectroscopy (DRS). Results demonstrated successful integration of Bi3+ ions into TiO2, extending absorption into the visible light range. Photocatalytic tests revealed superior activity of Bi-doped TiO2 over pristine TiO2 in methylene blue (MB) degradation under UV light irradiation.