| dc.description.abstract | Photoelectrochemical (PEC) water splitting has recently gained particular attention as promising method to produce hydrogen through the conversion of solar light into chemical energy. A key challenge for this application is to reduce the high level of electron-hole recombination, which can significantly affect the efficiency of a PEC system. Ferroelectric polarization has emerged as new strategy to facilitate the separation of electron-hole pairs, driving them towards the opposite direction and consequently enhancing the water splitting performance. In this thesis, the influence of ferroelectric polarization on the photoelectrochemical properties of bare nanostructured BaTiO3 as well as nanostructured BaTiO3 combined with Fe2O3 photocatalyst is explored. Nanostructured BaTiO3 thin films are synthesized and employed as photoanodes for photocatalytic studies. Porous barium titanate (pBTO) thin films show a controllable porosity by tuning organic/inorganic ratios. Importantly, the switching of ferroelectric domains in pBTO thin films is still observed in the porous structures. The presence of porosity in pBTO thin films leads to a clear improvement of the PEC response. By electrochemical (EC) poling, the tuning of PEC performance of pBTO thin films via ferroelectric polarization is also demonstrated. In addition, the influence of oxygen vacancies on EC poling of pBTO thin films, prepared in different annealing conditions (O2, air, N2) is investigated, revealing that higher concentrations of oxygen vacancies limit the ability of these films to be controlled via poling. Lastly, Fe2O3/pBTO thin films are developed and studied. The composite film shows higher photocurrent density than pBTO and Fe2O3 and this is ascribed to the improved charge injection and separation in Fe2O3/pBTO. The possibility of achieving PEC performance enhancements in Fe2O3/pBTO by controlling ferroelectric polarisation is also demonstrated. This research reveals the role of ferroelectricity on the photocatalytic activity enhancements in nanostructured BaTiO3 and Fe2O3-BaTiO3 films, which could benefit future work on ferroelectric photocatalysts. | en_US |
