Wei Hsuan Hung1 Chien Jung Peng1 Kun Lin Yang1 Sz Nian Lai1 Chin Ru Yang1

1, Feng Chia University, Taichung, , Taiwan

In this study, a spontaneous charge spatial separation (SCSS) and simple hot press process (HPP) has been adopted to enhance the efficiency of photocatalytic water splitting. Originally, the photocatalytic activity of hematite is limited by its relatively poor absorptivity, very short excited-state lifetime, and a short hole diffusion length. To address these issues, pseudocubic polyhedral α-Fe2O3 phtoelectrode was fabricated and achieved the spontaneous charge spatial separation in water splitting process. The intrinsic charge spatial distribution has to be taken into account when selecting the facets, as it results in accumulation of photoexcited electrons and holes on certain semiconductor facets. Furthermore, we develop a new technology of using a simple hot press process to improve carrier transport, charge separation and longtime stability for photocatalytic water splitting. Without complicated nanostructure fabrication, this hot press process demonstrated a 2-fold enhanced photocurrent under A.M. 1.5 solar simulator irradiation. The enhancement is attributed to the improvement of carrier transport properties in TiO2-Fe2O3 matrix due to significant reduction of the film thickness after the hot press process. In addition, Tin (Sn) from the FTO substrate was diffused and doped into these polyhedral α-Fe2O3 and hot press TiO2-Fe2O3 during the sintering process to serves as an electron donor and increases the carrier density. In addition, plasmonic gold nanoparticles were incorporated into this two system, which would provide the strong field and hot electrons, resulting in the enhancement of visible light absorption efficiency and inhibit charge recombination, this leads the photocatalytic water splitting to achieve a further stage.