Investigation on the structural, optical, and biofunctional properties of MgO-NiO nanocomposites under influence of calcined temperature

The MgO-NiO nanocomposites was prepared using the co-precipitation method, followed by calcination at 450 and 550 °C to investigate the influence of calcination temperature on their physicochemical, optical, and biological properties. The face-centered cubic (FCC)-structured NiO with overlapped MgO was confirmed from the XRD study. The interactions between the Ni[sbnd]O and Mg[sbnd]O bonds have been identified using FT-IR and Raman spectroscopy analysis. The SEM photographs of MgO-NiO reveal that the nanoflake shape and size dimensions increased with an increasing calcination temperature from 450 to 550 °C. EDX indicated a reduction in Ni content from 29.38 % to 8.01 % and an increase in Mg content from 16.24 % to 34.19 % as the calcination temperature was raised. EDX mapping of both calcined MgO-NiO composites also traced Mg, Ni, and O elements. The chemical oxidation states and their corresponding binding energy values of Mg, Ni, and O were traced using recorded XPS spectra of both calcined MgO-NiO composites. The BET measurements were taken for both calcined MgO-NiO and its results exhibit that the mean pore diameter, total pore volume and surface area values were significantly decreased with an increasing calcined temperature of MgO-NiO. The bandgap was reduced from 2.52 eV to 2.26 eV. Increased PL intensity with a slight shift in CIE colour coordinates was observed in the MgO-NiO calcined at 550 °C when compared to the calcined sample at 450 °C. Antimicrobial evaluations revealed significant inhibition of E. coli and S. aureus, exhibiting enhanced efficacy of the MgO-NiO composite calcined at 450 °C compared to the composite calcined at 550 °C. The hemolysis rate of calcined MgO-NiO composites was under 2 %, suggesting good hemocompatibility. DPPH assays indicated improved antioxidant performance at 450 °C compared to the composite calcined at 550 °C, attributed to increased surface defects and oxygen vacancies. These results underscore the tuning of calcined temperature on the structural, optical, and biofunctional behavior of MgO-NiO nanocomposites, indicating their potential for biomedical applications.