Improved electrochemical and photocatalytic activity of datura leaf extract mediate ZnO nanoparticles for the degradation of synthetic organic dyes.

Abstract

In photocatalytic and electrochemical applications, it is highly desirable to develop environmentally friendly and scalable methods for synthesizing semiconductor nanoparticles. In this study, ZnO nanoparticles were synthesized via a green, datura leaf extract by using hydrothermal method. A series of samples were prepared via using varying extract volumes of 2 mL (sample 1), 4 mL (sample 2), 6 mL (sample 3), and 8 mL (sample 4) of datura leaf extract. Structural characterization using SEM, PXRD, FTIR, and EDS confirmed the formation of uniform ZnO nanoparticles with a hexagonal wurtzite phase and dominant Zn-O bonding, with Zn and O as the principal elements. UV-visible spectroscopy revealed a progressive decrease in the optical band gap with increasing datura extract concentration, indicating improved visible-light absorption. Photocatalytic performance was evaluated for the degradation of malachite green (MG) and (MB) under natural sunlight. The sample 4 of ZnO nanoparticles exhibited superior activity, achieving 99.8% degradation of 3.8 × 10^-5 M MG at pH 12 after using 15 mg catalyst. While the 98.3% degradation of MB in 2.81 × 10^-5 M was observed for the sample 4. Systematic investigation of operational parameters, including catalyst dosage, dye concentration, and solution pH, confirmed their significant influence on degradation efficiency. Reactive species trapping experiments indicated that e^-, h⁺, and ˙OH radicals play dominant roles in the photocatalytic process. Furthermore, sample 4 of ZnO demonstrated excellent reusability, maintaining high degradation efficiency over multiple cycles, highlighting its stability and practical applicability for wastewater treatment. The sample 4 of ZnO was seen highly active for the electrochemical detection of MB in 0.1 M NaOH and observed performance was witnessed through the detection range of 0.005 mM to 4 mM and a low limit of detection (LOD) was found to be about 0.0005 mM. The enhanced photocatalytic and electrochemical performance were attributed to the surface modification, band gap tuning, and improved charge carrier dynamics of ZnO. This study establishes a cost-effective and sustainable platform for designing high-performance ZnO-based photocatalysts for environmental remediation applications.