Microwave and combustion methods: a comparative study of synthesis, characterization, and applications of NiO nanoparticles

Synthesis of NiO NPs was achieved using microwave (MW) and solution combustion (SC) method, with the help of tender jackfruit extract as a green fuel. The efficiency of the two methods was compared by focusing on some of the important parameters like particle size, structure, optical property, photodegradation, supercapacitor, and sensing activity. Treatment of Nickel(II) nitrate hexahydrate solution with jackfruit extract, stable NiO NPs were obtained. Further, the characterization part involves PXRD, FTIR, UV, SEM, EDS analysis. PXRD patterns illustrate the FCC structure for NiO NPs for both methods and the crystallite size was obtained to be 3.9 nm and 3.8 nm. The FTIR spectra indicate the Ni-O stretching vibrations of synthesized NiO NPs. UV-Vis spectra shows the absorbance at 324 nm and 271 nm by SC and MW method, respectively. The bandgap energy of the MW method (2.3 eV) was more as compared to the combustion method (2.55 eV). Results of photodegradation experiments showed that MW synthesized NiO NPs were more effective as compared to SC synthesized NiO NPs against Rhodamine-B dye. Finally, impedance plots exhibit the supercapacitor activity and also NiO NPs showed excellent sensing activities.