Metal oxide photocatalysts: the role of surface and nanostructure

Human activities are causing severe environmental impacts, above all global warming and water insecurity. The widespread presence of contaminants of emerging concerns (CECs) in water effluents is causing deleterious effects on living beings. Photo-driven advanced oxidation processes (AOPs), including heterogeneous photocatalysis, have been demonstrated to be highly efficient for wastewater treatment. Additionally, addressing energy demand and its sustainable production is urgently needed to mitigate the deleterious effects of global warming. In this frame, hydrogen (H2) has been considered one of the most promising renewable energy carriers, thus extensive efforts have been made to achieve low-emission H2 production and develop new technologies for large-scale production. Specifically, scientific interest has been focused on finding new photocatalysts for both CECs photodegradation and H2 production driven by solar light irradiation. In line with Goals 6 and 7 of the 17 Sustainable Development Goals (SDGs) Agenda 2030, the present doctoral thesis explores the design and development of novel metal oxide-based nanostructured materials as efficient photocatalysts for dyes and drugs photodegradation and H2 production through photoelectrochemical water splitting (PEC WS) and photoreforming. In detail, focusing on titanium dioxide (TiO2), considered the benchmark photocatalyst, several strategies have been investigated to tailor and improve its optical and electronic properties, using smart and cost-effective synthetic routes to boost both the overall photoresponse and catalytic activity. A direct correlation among morphological, structural, optical, and electronic properties and the photoactivity of the synthesized nanomaterials has been established by critically discussing the experimental results obtained by using advanced experimental techniques. Overall, the research findings provided by the nanostructured systems designed and investigated in this thesis aim to significantly contribute to the development of new and sustainable solar-driven technologies for future large-scale applications in the field of heterogeneous photocatalysis.