Engineering of Electrodes for Renewable Energy Storage and Hydrogen Production: Improvement of Materials and Scale-Up

Renewable energy is considered a key element in achieving a sustainable energy transition and a reliable alternative to achieve zero emissions. Among the different renewable sources, solar and wind energy have shown the most significant growth, supported by technological advances in photovoltaic, eolic, and wave energy conversion systems, which make them ready to use. However, these sources are inherently intermittent, as their output strongly depends on weather conditions and time of day, leading to fluctuations in power generation. To ensure a stable and reliable energy supply, the development of efficient energy storage systems is of paramount importance. This can be achieved through different electrochemical technologies depending on the required storage time. Short and medium-term storage can be provided by batteries and supercapacitors, while long-term storage is more efficiently realized using redox flow batteries or through the conversion of electricity into chemical fuels such as hydrogen. Among the various energy storage strategies, the use of hydrogen as an energy vector represents a promising and flexible solution. Hydrogen can be produced by water electrolysis using renewable electricity, stored, transported, and later reconverted into energy without generating carbon emissions. In this way, hydrogen offers a pathway to couple renewable power generation with industrial and transportation sectors, supporting the development of a carbon-neutral energy system. Producing green hydrogen through water electrolysis is one of the most promising approaches to implement in a large-scale renewable energy plant. Accordingly, the anion exchange membrane water electrolyzer (AEMWE) represents a desirable approach, combining the efficiency of proton exchange membrane water electrolyzers (PEMWE) with the use of non-precious materials in a mid-alkaline environment. However, as a technology still under development, further research is required to design new electrodes and electrocatalysts that can not only enhance performance and efficiency but also provide long-term durability, especially at an industrial scale. This thesis focuses mainly on the development of spinel nanostructured electrocatalysts and electrodes, synthesized and optimized to achieve high activity, stability, and scalability for practical AEMWE and with the aim to be operated not only at the lab scale but also at higher current loads for longer duration at the industrial scale.