The European Green Deal should ensure that Europe becomes the first climate neutral continent by 2050. This will mean a cleaner environment, more affordable energy, smarter transport, new jobs and overall a better quality of life. Ensuring the quality of water is an important part of this ambitious target. Conventional water- and wastewater-treatment plants (WWTPs) were originally designed for the removal of suspended solids and biodegradable organic matter. As such they exhibit widely varying efficiencies (from 0 to 100%) for the removal of “new pollutants” like pharmaceuticals, pesticides and hormones. Several new technologies have been investigated to reduce the potential risks associated with these pollutants and their impact on the environment and human health, including photocatalysis. There is an urgent need for an effective, safe, low-cost, high-technology-readiness-level (TRL) strategy for removing emerging pollutants from water and wastewater.
In addition, ensuring the production of green hydrogen is also an important part of the European Green Deal, since after its use in fuel cells only water vapour is produced. The green hydrogen is generated when the process of obtaining hydrogen fuel involves the use of renewable energy sources like solar, wind, or hydroelectric power. Breaking the water molecule to generate H2 and O2, i.e. the water splitting process, is a good strategy to generate green hydrogen. However, the current state-of-the-art catalysts for water splitting (Pt, RuO2, IrO2, NiO) are critical raw materials and/or doesn’t present long-term stability. As a consequence, the search for highly efficient and high-performance catalyst for the water splitting process is essential to address the sustainable energy production challenge.
High-entropy oxides (HEOs) are a new category of materials constituted of five or more elements that are randomly distributed in a single phase. Such materials can have better properties than conventional oxides, related to the lattice distortion and synergistic effects of the components. Due to this lattice distortion and the uneven electron-cloud distribution between the metals and the oxygen, HEOs can impact different catalytic reactions, such as CO2 reduction, H2S removal and the degradation of pollutants. It is well known that doping or co-doping of conventional catalysts can promote changes in the crystalline structure and improve the photocatalytic activity. Thus, the use of new, multi-element materials such as HEOs appears to be an excellent, innovative alternative to overcome these drawbacks. HEOs can be synthesised by the anodic oxidation of high-entropy alloys (HEAs), creating strongly attached nanostructures with enhanced photo(electro)catalysts properties. Using this strategy, our ambition is to develop a new and highly efficient (photo)(electro)catalyst to be applied in the water splitting process and/or pollutants degradation, which will contribute to a major step forward in catalysis.
