Design and characterization of functional nanomaterials on surfaces

Resumo

The urgent need for developing new strategies to afford the increasing energy demand remains a challenge for many research fields, such as material science or energy engineering. In this respect, the field of nanoscience has emerged as a powerful field towards the design of functional nanomaterials, synthesized from both organic and inorganic materials. This new scientific discipline has led to the design of novel materials and opened up new avenues for traditional compounds. For instance, transition metal oxides have been proposed as promising catalysts in the oxygen evolution reaction for water splitting, of crucial relevance in clean energy. Additionally, the development of organic electronics, focused on the study of the electronic properties of carbon-based materials, plays an important role in the synthesis and transformation of traditional electronics by designing low-cost, flexible and sustainable electronic devices. In this thesis, we have grown and studied different nanomaterials on metallic surfaces related to energy efficiency, targeting to achieve global sustainability. First, we have studied the catalytic activity of CoO at the atomic scale towards the water splitting reaction. We have grown single bilayer CoO nanoislands, where the co-existence of two distinct phases has been observed. Such polymorphism has been rationalized due to the distinct lattice parameter and the registry with the substrate which induces the modification of its electronic properties, reactivity and, hence, of its catalytic activity. In addition, we have shown the capability to tune the phase by an electric field. Second, we have described the on-surface synthesis of new π-conjugated polymers with important applications in organic electronics. An innovative strategy towards the synthesis of low band gap π-conjugated polymers formed by acene or periacene units has been developed, which allows the control of their electronic structure, resonance form and topological quantum class by tuning the repeating unit size. Our results shed light into the atomistic adsorption and dissociation of water on a CoO model catalyst. Furthermore, we introduced pathways for controlling the electronic properties and quantum topological class of one dimensional polymers on metallic surfaces