Synthesis and investigation; influence of Mn doping on biological, optical, dielectric and electrochemical characteristics of Bi2O4 nanostructures

Abstract

In this research, bismuth oxide thin films were synthesized with the variation of Mn dopant (1-5 wt %) on a glass slide by sol-gel dip coating method. XRD corroborated the creation of a monoclinic phase for all the samples after annealing at 450 °C for 4 h. The non-uniform cuboid-like granular structures were observed by SEM with a significant number of grain boundaries. Different functional groups were examined by using FTIR spectroscopy. The optical band gap was reduced from 2.01 to 1.81eV by increasing the concentration of Mn dopant. The contribution of grain and grain boundaries to the material electrical response in various frequency ranges was distinguished by impedance analysis. The polaron mechanism was used to investigate conductivity with time variation. The efficiency of supercapacitors was significantly enhanced by using the monoclinic Bi2O4 phase of bismuth oxides, promoting the specific capacitance in the range of 2518.2–6890.2 Fg-1 with high energy and power density. That leads them to the fabrication of supercapacitors in advanced electronic devices. Magnetic analysis showed that saturation magnetization and remanent frequency decreased while coercivity of thin films increased with increasing Mn concentration which was successfully explained by the critical size effect and Néel's collinear two sub-lattice models, making them plausible candidates in spintronics. As from photocatalyst analysis, the number of reactive oxygen species ROS was increased by increasing Mn doping in the Bi2O4 crystal lattice. These species degraded the water pollutants under simple exposure to sunlight (i-e visible range). The production of ROS in the photocatalytic process was also correlated with antibacterial activity. Mn-doped Bi2O4 was found to be more effective towards K. pneumonia than other bacteria. The prepared Mn:Bi2O4 nanostructures with a higher percentage of manganese were effectively used for the treatment of bloodstream infections, meningitis, pneumonia, and urinary tract infections and stopped further bacterial growth.