Nickel-doped zinc tartrate (Ni@ZnT) nanocrystals: Synthesis, optical properties, and antimicrobial activity

This work used the sol-gel method to synthesize nickel-doped zinc tartrate nanocrystals (Ni@ZnT NCs) to study their optical properties and antimicrobial activities. Using the Scanning electron microscopy study, these NCs show irregular-shaped morphology. Their crystalline nature and average crystalline size of 45 ​nm were studied by X-ray diffraction. Using an Energy-Dispersive X-ray confirmed the presence of zinc (Zn), nickel (Ni), carbon (C), hydrogen (H), and oxygen (O) elements. FTIR analysis was used to identify several functional groups like O–H stretching (3461.6 ​cm⁻¹), CO stretching mode (2367.55 ​cm⁻¹), and stretching vibrations of Ni–Zn–O (below 800 ​cm⁻¹). The thermal stability was confirmed by thermogravimetric analysis. UV–Vis spectroscopy studied the optical properties; an absorption peak represents the Zn–Ni transition at about 336 ​nm and a band gap of 3.86 ​eV and was also used to calculate the refractive index and extinction coefficient at 280 ​nm. For ZnT and Ni@ZnT NCs, the maximum absorption λ was found to be 295 ​nm and 278 ​nm. The antibacterial activity of ZnT and Ni@ZnT NCs was evaluated against Bacillus subtilis and Escherichia coli; for these strains, the NCs (15.3 ​mm and 15.6 ​mm) showed a somewhat larger zone of inhibition than ZnT (13.6 ​mm and 12.3 ​mm). The study also evaluated the antifungal activity of these materials against some fungal strains, such as Penicillium chrysogenum, Aspergillus niger, Candida albicans, and Fusarium spp, the zone of inhibition varied from 12 to 13.6 ​mm, and there was a significant difference between the two materials. Therefore, this work successfully synthesized Ni@ZnT NCs and studied their optical properties and antimicrobial activity.