Optimization of TiO ₂ Nanotubes Anodization Assisted by Response Surface Methodology for Enhanced Photoelectrochemical Performance

Green hydrogen production plays a crucial role in the global transition toward sustainable energy sources. In this study, the Response Surface Methodology (RSM) technique was employed to optimize the photoelectrochemical performance of TiO 2 nanotube arrays (TNAs), aiming to maximize the photocurrent density ( J ) and minimize the interfacial electron transfer resistance ( R p ). For this purpose, the Central Composite Design (CCD) method was utilized to systematically evaluate three key parameters: ammonium fluoride concentration, anodization time, and applied potential, resulting in a total of 17 experimental runs. The optimized conditions resulted in longer (4.84 ± 0.10 µm) and well‐ordered TNAs with an aspect ratio of 33.79 ± 3.66. The experimentally obtained photoelectrochemical performance closely matched the predicted values from the experimental design, achieving a J equal to 0.285 ± 0.038 mA cm −2 and R p equal to 5.32 ± 0.32 kΩ. Moreover, the optimized TNAs exhibited superior hydrogen production efficiency, reaching a rate of 283.2 µL cm −2 h −1 , for the optimized condition, which is superior to the other conditions tested preliminarily in the work. The outcomes validate the effectiveness of employing CCD and RSM techniques for enhancing TiO 2 photoanodes, confirming this optimization strategy as a robust and promising approach for advancing clean energy technologies.