Journal of Physical Chemistry C;
MAY 13 2021.
Web of Science Citations:
The comprehension of the solid-liquid interface associated with the poor charge carrier dynamic of hematite has prevented its commercial application as a photoanode in a photoelectrochemical cell. The development of a low-cost and scalable strategy to overcome such drawbacks is still being pursued by the scientific community. Here, a simple surface modification of hematite photoanode designed with different thicknesses was carried out by employing an ultrasonic treatment (UST) process. UST creates an inhomogeneous defect distribution based on the solid-liquid energetics. The thicker photoanodes (H-4h) showed that the mechanical process can contribute to removing unstable layers, creating favorable sites for oxygen evolution without compromise the solid-solid interface. The UST approach for H-2h has promoted surface states pinning and possibly increased the stress between hematite and FTO. The effects on thinner photoanodes (H-2h) can drastically create polarized states that enhance surface trapping states, reducing the photogenerated charge lifetime. The outcome findings reveal that the surface hydroxylation might be extremely dependent on the electrode thickness. This study indicates that the UST approach is an efficient tool to boost the performance of thicker photoanodes, as desired for practical applications. Thus, for thinner layers, the stress induced at the hematite-FTO interface can be aggravated by mechanical treatment overcoming the beneficial effects at the solid-liquid interface. In fact, hydroxylation conducted via the sonication process is highly recommended for designing thicker films. (AU)