Sustainable Energy Generation and Storage

The University of Twente stands at the forefront of innovative advancements crucial for driving the transition towards renewable energy. This presentation offers a comprehensive overview of the pioneering research at the University, encompassing significant developments in renewable energy generation technologies, such as wind and solar energy, organized in the Solar Center Twente. Recognizing the inherent challenges of intermittency in wind and solar energy generation, the University is actively exploring energy storage solutions through the Battery Center Twente. Moreover, the University is developing hydrogen technologies, another promising avenue for addressing energy storage challenges. In summary, the University of Twente's pivotal role in innovative research, its focus on renewable energy generation technologies, and its dedication to tackling energy storage challenges make it a driving force in advancing sustainable and renewable energy solutions.

The free-space luminescent solar concentrator (FSLSC) is a photonic device able to concentrate and collimate diffuse light using the concepts of luminescent down-shifting, photon recycling and spectro-angular emission control enabled by a notch filter. Current research efforts are aimed at synthesising and characterizing state-of-the-art inorganic luminophores, namely lead halide perovskites, to increase the concentration efficiency of the FSLSC. We have successfully synthesised UV-absorbing, near infrared-emitting Yb:CsPbCl₃ nanocrystals (NCs) with the hot-injection method and have thoroughly investigated their structural and optical properties. This investigation indicated that effectively controlling the doping reaction with the hot-injection method presents itself as a challenge, due to the presence of unwanted by-products and low optical performance. Future research involves the use of a more controllable method, namely mechanochemical synthesis. This is a solvent-free and up-scalable synthetic method for producing lead halide perovskite powders which will enable a more accurate investigation of Yb-incorporation in the perovskite lattice.

To reach a long term viable green hydrogen economy, rational design of active oxygen evolution reaction (OER) catalysts is critical. An important hurdle in this reaction stems from the fact that both hydrogen and water are singlet molecules, while the oxygen molecule has a triplet ground state with parallel spin alignment, implying that magnetic order in the catalyst is essential.

Following this idea, multiple experimentalists reported a positive effect of external magnetic fields on OER activity of ferromagnetic catalysts. However, it remains a challenge to investigate the influence of the intrinsic magnetic order on catalytic activity and a wide variety of possible origins for the effects exists. In this talk, I will discuss the OER enhancement due to intrinsic magnetic order in, and external magnetic fields on,  the catalytic activity of epitaxial La0.67Sr0.33MnO3 thin film model catalysts. By combining the effects shown using this model system with existing literature I propose a unifying picture for spin polarized OER.

The energy grid of the future will require substantial energy storage capacity to deal with intermittend solar and wind supply. An ideal candidate for large-scale, long-duration storage is the hydrogen-bromine flow battery, due to its high efficiency and low cost of active materials. The hydrogen reactions are catalyzed by electrocatalysts in the form of expensive carbon-supported platinum nanoparticles (similar to PEM fuel cells or electrolyzers). This catalyst is highly active, but unfortunately can be degraded by the harsh environment. In this presentation I will explain how we improved the catalyst design by protecting the surface with hydrogen-permeable nano-membranes and by tuning the nano-particle shape and composition, thereby managing to extend the lifespan by up to 30 times without loss of performance.