Microwave-assisted synthesis of SnO2:ZnO nanocomposites for photocatalytic, antimicrobial and electrochemical urea detection applications

Abstract

In this work, we have synthesized SnO2:ZnO nanocomposites (0.25, 0.5, 0.75, and 1 M ZnO) by employing an efficient microwave-assisted synthesis method. The synthesized nanocomposite's structural, morphological, and optical characteristics are examined using different physicochemical techniques. The X-ray diffraction patterns revealed that the SnO2 and ZnO nanoparticles crystallize in tetragonal and hexagonal crystal systems, respectively. This observation is further substantiated by the results obtained in the Raman analysis. The Field Emission Scanning Electron Microscope study of SnO2:ZnO nanocomposites (NCs) reveals a few rod-shaped nanoparticles as well as big, irregularly shaped particles of reduced size. Additionally, the absorption edge of diffuse reflectance UV–visible spectra exhibits a red shift, and the band gap value of SnO2:ZnO NCs at equal proportion is determined to be 3.3 eV. In the presence of hydrogen peroxide (H2O2), the photocatalytic degradation efficiency of the synthesized nanocomposites is investigated for different dyes. With a degradation efficiency of 98 %, the nanocomposites tend to be more reactive towards crystal violet dye (20 ppm) than the other dyes while adding 20 mg of synthesized SnO2:ZnO NCs in equal proportions. The impact of pH and reactive oxygen species involved in the degradation process is also tested. SnO2:ZnO material showed nearly similar degradation efficiency even after six recycles. The study of electrochemical detection of urea employing SnO2:ZnO NCs showed a two-fold increase in peak current value with a detection limit between 0.05 and 4 mM urea. In addition, Escherichia coli and Bacillus subtilis strains were used to test the nanocomposite's antibacterial capabilities, which showed promise as potential antimicrobial agents.