Effect of Ideal Thickness on Boosting Efficiency of Photoelectrochemical Cell Photoanode via Maximal Absorption

Abstract

A key role of the thin film is to absorb as much incident light as possible to generate electron-hole pairs for the photoelectrochemical reaction. In this study, we utilize the ability of ideal thickness to optimize the efficiency of PEC cell by designing three photoanodes for an efficient water splitting process. These photoanodes cover the UV, visible, and NIR regions with maximum absorption in a regulated manner. The carefully selected materials that were drop-casted onto the FTO substrate comprised of CeO₂ nanoparticles, copper nanoparticles, and the exclusive material (Epolight™ 1178) as a dye sensitizer. Comprehensive characterization of the photoanode was performed using analytical techniques. Cross-sectional images of the three fabricated photoanodes have been acquired to prove the successful achievement of the ideal thickness requirement which ranged between 8-12 µm. The optical properties were characterized and they prove that for the first photoanode, the maximum absorption peak was at 296 nm, the second absorbs at 294 nm 446, 646, and 709. The third photoanode peaks at 357, 473, 634, and 857 nm covering the three regions. Linear sweep voltammograms were collected in dark and under the illumination of LED source with AM 1.5 G condition at 100 mW/cm². The photoanodes exhibited a significant photocurrent response, indicating efficient photoactivity with the current densities of 14.3, 23.0, and 34.2 mA.cm^-2 at 0.99 V vs. Ag/AgCl for the three photoanodes respectively. A significant enhancement in the efficiency of PEC cell was recorded as it increased from 3.4% to 8.2%.