Green synthesis and characterizations of bi-functional Mo-doped ZnO nanostructures for antimicrobial and photocatalytic applications

Abstract

The preparation of effective and excellent antimicrobial agent is becoming a severe issue from last few decades against human tested bacteria. Also, the polluted wastewater from industries severely required a sophisticated photocatalyst. Beside of all other semiconductor oxides, ZnO gained the great attention because of its unique and versatile antimicrobial and photocatalytic properties. In this work, its antimicrobial and photocatalytic nature is improved by preparing using green synthesis approach i.e extract of moringa oleifera seeds as these are naturally anti-oxidizing and antimicrobial agents. The XRD spectroscopic tool was used to reveal the structural properties of as prepared samples. SEM and HRTEM techniques were employed for in depth morphological study. EDX analysis tool was employed to check the purity and for compositional analysis of samples. For further structural study, SAED technique was also employed. UV–vis and PL tools were used to investigate the optical properties and recombination rates of charge carriers. The as developed nanostructures possessing much reduced grain sizes have significantly improved the antibacterial and photocatalytic performance of ZnO based samples by offering much enhanced active surface area and active sites for their working. The charge carriers’ dynamics was evaluated by studying EIS and photocurrent intensity response by as prepared samples. The green synthesized Mo doped ZnO has exhibited a reduced band gap i.e 3.11 eV than 3.25 eV offered by pure ZnO. The antimicrobial activity against B. subtilis and E. coli bacteria explored that the as green synthesized Mo doped ZnO nanomaterial was very competent for the inhibition of bacterial growth. Moreover, this green Mo-doped ZnO sample has also exhibited its excellent photocatalytic nature against a well-known rhodamine-B water pollutant by degrading its 89.6% just after 180 min. Also, this sample has shown good catalytic stability i.e 81 %. The reproducibility of the samples was made sure by preparing batches of three samples and taking the best out of them showing very small performance error. These superior antimicrobial and photocatalytic properties shown by green synthesized Mo-doped ZnO have opened new platform for bacteria inhibition and water purification applications.