Energy-Transfer Processes at Interfaces: Theoretical studies on the interfaces of metal oxides with water, electric-field phenomena, and advances in machine-learning force-fields

In order to enhance and bridge the lacuna of knowledge relating to the fundamental approaches and techniques that contribute industrially towards physico-chemical of photoelectrochemical (PEC) water splitting processes, in this thesis, various molecular-dynamics (MD) simulation techniques and machine-learning force-fields have been applied at liquid-solid interfacial systems and for water exposed to external electric fields. The current state-of-the-art of molecular simulations and techniques implemented in the study of the behaviour of bulk or interfacial water in contact with titanium dioxide (TiO2) and hematite (α-Fe2O3) serve primarily to improve our understanding of materials required for the development of photo-energy conversion devices. Photoelectrochemical water splitting has been proven to be a great potential for low-cost, environmentally-friendly solar-hydrogen production required to support the future Hydrogen Economy; therefore, properties studied such as; behavioural pattern, dielectric response, emergence of vibrational modes, translational-librational motion, hydrogen bond kinetics, H-bonds lifetime, atomistic surface contours of semiconductor surface, structural, and dynamical properties. Indeed, both water-induced externally-applied electric fields either in bulk environment or interfacial phase play extensive roles in the improvement of photo-energy conversion devices, and, in particular, towards expanding the “boundaries of knowledge” that would indelibly contribute towards addressing the development of new functions required in ‘interfacial engineering’ of the local morphology of the semiconductor layer. In particular, the greater understanding gleaned from elucidating mechanisms of energy transfer at interfaces serves to improve the industrial processing of semiconductors materials or multifunctional optoelectronic devices.