Innovative catalysts: An expert review
With the help of innovative elctrocatalytic materials, water can be split up into oxygen and hydrogen. Hydrogen is a fuel storing chemical energy as long as needed. © Dr. Ziliang Chen
Highly efficient (electro-)catalysts are essential for the production of green hydrogen, the chemical industry, fertiliser production and other sectors of the economy. In addition to transition metals, a variety of other metallic or non-metallic elements have now moved into the focus of research. In a review article, experts from CatLab and Technische Universität Berlin present an overview on current knowledge and a perspective on future research questions.
Green hydrogen is an important component in a climate-neutral energy system. It is produced by electrolytically splitting water with wind or solar power and stores this energy in chemical form. But currently, the production of green hydrogen is not yet economical or efficient enough. The key to solving this problem is through the development of innovative electrocatalysts, which should not only work with high efficiencies but should also be available and inexpensive.
In addition to transition metals, which are already well studied for their catalytic properties, a wider choice of elements has now moved into the focus such as alkali metals, alkaline earth metals, rare earth metals, lean metals and metalloids. Some of these when combined with transition metal electrocatalysts can significantly improve performance and contribute to the development of next-generation high-performance electrocatalysts.
However, many of the processes that take place during electrocatalysis -when oxygen or hydrogen is formed - are still not understood in detail. In a review article, an international team of experts guides us through this exciting research field and draws a perspective, sketching the next steps catalyst research could take. “This contribution summarises the current state of knowledge on such unconventional s-, p-, and f-block metal-based materials and makes it comprehensible to a wider community of scientists”, Dr. Prashanth W. Menezes points out and adds: "Further, the essential role of such metals during water splitting electrocatalysis is described in great depth, as well as the modification strategy that should be considered when one wants to utilize them to mediate non-noble-based electrocatalysts. We hope to significantly accelerate research and development of novel, innovative catalyst materials with this review article."
Note: Dr. Prashanth W. Menezes is Head of Materials Chemistry for Thin-Film Catalysis Group in the CatLab-Project at HZB and Head of Inorganic Materials Group at TU Berlin.
His twitterhandle is @EnergycatLab
CatLab: Together with the Fritz Haber Institute of the Max Planck Society, HZB is setting up the Catalysis Laboratory CatLab, which is intended to accelerate research into innovative catalysts. CatLab is supported by the German Federal Ministry of Education and Research.
- Green hydrogen: How photoelectrochemical water splitting may become competitiveSunlight can be used to produce green hydrogen directly from water in photoelectrochemical (PEC) cells. So far, systems based on this "direct approach" have not been energetically competitive. However, the balance changes as soon as some of the hydrogen in such PEC cells is used in-situ for a catalytic hydrogenation reaction, resulting in the co-production of chemicals used in the chemical and pharmaceutical industries. The energy payback time of photoelectrochemical "green" hydrogen production can be reduced dramatically, the study shows.
- Perovskite solar cells from the slot die coater - a step towards industrial productionSolar cells made from metal halide perovskites achieve high efficiencies and their production from liquid inks requires only a small amount of energy. A team led by Prof. Dr. Eva Unger at Helmholtz-Zentrum Berlin is investigating the production process. At the X-ray source BESSY II, the group has analyzed the optimal composition of precursor inks for the production of high-quality FAPbI3 perovskite thin films by slot-die coating. The solar cells produced with these inks were tested under real life conditions in the field for a year and scaled up to mini-module size.
- Superstore MXene: New proton hydration structure determinedMXenes are able to store large amounts of electrical energy like batteries and to charge and discharge rather quickly like a supercapacitor. They combine both talents and thus are a very interesting class of materials for energy storage. The material is structured like a kind of puff pastry, with the MXene layers separated by thin water films. A team at HZB has now investigated how protons migrate in the water films confined between the layers of the material and enable charge transport. Their results have been published in the renowned journal Nature Communications and may accelerate the optimisation of these kinds of energy storage materials.