Dependence of pyrolytic temperature on the growth of high quality MnO2 nanofibers

• First report on highly (1 0 1) oriented MnO2 nanofibers by novel spray deposition.
• Tunable band gap of MnO2 with suppressed defect emission, suitable for bio sensing.
• Homogeneously arranged nanofibers changed to nanoflakes at higher temperature.

Growth of highly (1 0 1) oriented MnO2 nanofibers were demonstrated by spray pyrolysis technique for different temperatures. The influence of deposition temperature on the orientation, microstructure, morphology and optical properties of MnO2 films were discussed. Based on X-ray diffraction results, the growth resulted in a well-defined crystal structure with preferred (1 0 1) orientation for MnO2 films prepared at 300 °C. The band gap decreased with increase in particle size, due to the effect of linear expansion with increase in temperature. The improved crystallinity of the MnO2 films revealed from increase in intensity of photoluminescence emission, with a substantially suppressed defect related emission band, established the development possibility of the nanofibers for biosensor devices. Scanning electron microscopy images show the uniform and well-aligned growth of MnO2 nanofibers at 300 °C, which provides higher capture efficiency favorable for bio sensing application.