Comparative study on photocatalytic degradation and sensor properties of Chonemorpha fragrans leaf extract assisted MgxZn1−xO (0 ≤ x ≤ 1) nanoparticles

Abstract

• Mg x Zn 1-x O (x = 0, 0.25, 0.5, 0.75 and 1) NPs were synthesized by Chonemorpha fragrans leaf extract assisted solution combustion method. • The photocatalytic degradation of Fast Blue (FB) and Malachite Green (MG) dyes were tested for all the samples. • MG dyes has higher (90%) degradation compared with FB (87% degradation) dye due to rise in the hydroxyl ions. • The low charge transfer resistance and high capacitance value of Mg x Zn 1-x O electrode were studied for all the samples. • The Nyquist plot is in the order MgO ˃ Zn 0.25 Mg 0.75 O ˃ Zn 0.50 Mg 0.50 O ˃ Zn 0.75 Mg 0.25 O ˃ ZnO. Chonemorpha fragrans leaf extract assisted solution combustion method was carried out for synthesizing Mg x Zn 1−x O (x = 0, 0.25, 0.5, 0.75 and 1) nanoparticles. The obtained samples were characterized using powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy, and diffuse reflection spectroscopy techniques. The powder X-ray diffraction patterns of Mg x Zn 1−x O (x = 0 and 1) show pure hexagonal and cubic phases respectively and x = 0.25, 0.5, and 0.75 shows mixed phases. The Rietveld refinement study was done to refine structural parameters of × = 0, 0.5, and 1. A scanning electron microscope shows the high agglomeration with increasing ‘x’ content. Based on the Williamson-Hall plot, the average size of crystallites was found to be between 25 and 40 nm. Transmission electron microscope results also revealed the formation of nanoparticles. The energy bandgap was calculated from diffuse reflectance spectra using the Kubelka Munk relation and found to vary from 3.2 to 5.28 eV. The photocatalytic degradation of Fast Blue and Malachite Green dyes for all the Mg x Zn 1−x O nanoparticles catalysts was tested under the irradiation of UV light. Mg x Zn 1−x O nanoparticles showed enhanced degradation with increasing ‘x’ contents for Fast Blue (87%) and Malachite Green (90%) dyes under UV light. This enhanced degradation is due to variation in the bandgap of Mg x Zn 1−x O. Mg x Zn 1−x O electrodes exhibit a reversible electrode reaction based on their low charge transfer resistance and high capacitance value. Based on our results, the synthesized nanoparticles are promising candidates for wastewater treatment and lead sensor applications.