Tailoring ZnO nanorods for efficient photocatalytic production of H2O2 from water without sacrificial agents: A study on length optimization

In this study, we investigated the optimal length of zinc oxide nanorods (ZnO NRs) for the production of photocatalytic hydrogen peroxide (H2O2) using a hydrothermal method at 150 °C with reaction times ranging from 2 to 12 h. The study found that the size of the crystals increased when the reaction duration was extended, resulting in an increase in the size from 26 to 48 nm. SEM measurements indicated that ZnO exhibited longitudinal growth along the c-axis, increasing the nanorod length from 1 μm to 3.5 μm. The bandgaps of the ZnO NRs were between 3.21 and 3.25 eV. The optimal conditions for H2O2 production were identified to be 10 min of sonication and 15 min of UV illumination. The generation of H2O2 increased with the dosage of ZnO, ranging from 0.01 to 0.3 g/20 ml. The highest H2O2 production was attained by employing ZnO NRs at 1.6 μm in length with 49 mgL−1 Under UV irradiation and 28 mgL−1 under sonication irradiation. This study offers new perspectives for the design and production of H2O2 using ZnO NRs of a certain length, which may be beneficial for environmental remediation and energy generation. [Display omitted] •The optimal length of ZnO NRs was examined for photocatalytic H2O2 production.•Photocatalytic activity of ZnO NRs was studied under sonication and UV irradiation.•ZnO crystals grew larger as the reaction time was increased, from 26 to 48 nm.•The optimal length of the ZnO NRs for H2O2 production from water was 1.6 μm.•ZnO NRs control H2O2 production for insight into other photocatalytic reactions.