Growth Time Dependence on Photoelectrochemical Property of Zinc Oxide Nanorods Prepared by Hydrothermal Synthesis

Abstract

Here, the dependence of growth time on the growth behavior, morphology and photoelectrochemical (PEC) properties of ZnOnanorods (ZnO-NRs) as a photoanode are demonstrated. Vertical-aligned ZnO-NRs with [Formula: see text]-axis perpendicular to substrate were accomplished via seed-assisted hydrothermal technique at the growth time varying between 0.5 and 24[Formula: see text]h. Growth behaviors of ZnO-NRs can be described into three regimes, which consist of the nucleation stage, ZnO-NRs growth and saturation growth, respectively. ZnO nanoparticles (NPs) corresponding to the nucleation site occur at the growth time below 1[Formula: see text]h. Afterward, the growth regime of ZnO-NRs, which originated from the competition between the vertical and the lateral growth, is clearly observed, and leads to increase in length and diameter. The whole growth of ZnO-NRs is terminated after 16[Formula: see text]h, attributed to low amount of Zn[Formula: see text] and OH− supplied from growth solution. PEC measurement reveals the fast solar response and high photostability of ZnO-NRs. Additionally, the photoconversion efficiency ([Formula: see text] improves with the growth time of 4[Formula: see text]h and degrades for longer time due to the change of total surface area. The maximum [Formula: see text] of 0.13% at 0.63[Formula: see text][Formula: see text] is obtained for the growth time of 4[Formula: see text]h. Our results highlight that the growth time plays a crucial role in controlling growth behavior and the total surface area directly related with the PEC properties of ZnO-NRs.

Some Distinct Attributes of ZnO Nanorods Arrays: Effects of Varying Hydrothermal Growth Time

“…Consequently, the photocurrent density was affected due to the decrease in the aspect ratio. These results were consistent with other findings [ 11 , 21 , 52 ]. The ZNRAs grown at 4, 6, 8, 10, and 12 h produced the J ph values of 0.32, 0.41, 0.63, 0.35, and 0.19 mA/cm 2 , respectively, indicating the strong dependence of photocurrent density on the hydrothermal growth durations of ZNRAs.…”

“…ZnO has many distinct traits: high breakdown voltage, broad range electric field conditions, good temperature stability, and lower electronic noise [ 10 ]. Compared to TiO 2 , ZnO has a 10- to 100-fold higher electron mobility, resulting in improved electron transmission efficiency [ 11 ]. Furthermore, ZnO has very high exciton binding energy (60 meV) at room temperature, indicating its prospect for numerous optoelectronic applications [ 12 , 13 ].…”

“…In this study, the hydrothermal approach was chosen to produce ZNRAs because it offers several advantages including low cost, minimal need for sophisticated instrumentation, and the flexibility to deposit a variety of materials on various substrates. These benefits are well-suited for large-scale deposition to vary thin-film characteristics by modifying and manipulating the experimental conditions of the deposition [ 11 ]. It can also produce high-quality semiconductor thin films due to the slow growth processes, which allow for better crystallite orientation with improved grain structure and configuration growth [ 22 ].…”