Microplasma-assisted electrochemical synthesis of ZnO nanostructures for photocatalytic and antibacterial applications

Zinc oxide nanostructures (ZnO NSs) have been extensively studied because of their many applications in different fields. In this study, an attempt has effectively been made for the synthesis of ZnO nanostructures by using fast and environment-friendly microplasma electrochemical technique. The prepared nanostructures were examined in terms of their morphological, optical, structural, electrical, and compositional properties by using different characterization techniques. Results demonstrated that the highly crystalline ZnO nanostructures were produced with a single hexagonal (wurtzite structure) phase. Results also indicated the crystallite size increases with increasing precursor concentration. The optical band gap of ZnO is found to decrease (from 3.48eV to 3.40 eV) with increasing crystallite size. I-V characteristics of ZnO are measured by two probe technique which shows semiconducting behavior of prepared ZnO. The antibacterial and photocatalytic properties of the synthesized nanostructures were also investigated. It was observed that the degradation efficiency of zinc oxide photocatalyst increases with the irradiation time. About 85% of Rhd B dye was degraded by ZnO after 120 min at a rate of 0.01339 min−1 under direct sunlight irradiation. The antibacterial activity of ZnO was carried out against different gram-positive and gram-negative bacterial strains, by using the diffusion well method. Higher antibacterial activities were observed against gram-negative bacteria as well as for a higher concentration of ZnO. This study will be helpful to synthesize low-cost and effective materials to remove microorganisms and toxic industrial organic dyes which is a serious threat to terrestrial and aquatic life.