The water electrolysis is an electrochemical way for production of hydrogen, which is considered as one of the future energy carrier molecules. Therefore, looking at numerous advantages of proton exchange membrane electrolysis compared to the classical alkaline variant, it’s efficiency and applicability on the large scale is of huge importance nowadays. However, the slow kinetics of the anode oxygen evolution reaction (OER) limits the overall electrolysis process and requires an active and stable electrocatalyst. Such need inspired the scientists of Chemical Metal Science and Physics of Correlated Matter departments at MPI CPfS together with the Fritz-Haber-Institut in Berlin to employ their longstanding expertise in chemistry of intermetallic compounds, electronic features of solid matter and electrocatalysis to make a step forward in this challenging direction. As a result of fruitful teamwork, the concept of cooperative phases with different stabilities under OER conditions was successfully demonstrated with the intermetallic compound Hf2B2Ir5 as a self-optimizing electrocatalyst for OER.
Based on chemical bonding analysis, the intermetallic compound Hf2B2Ir5 has a cage-like type of the crystal structure: the two-dimensional layers of B2Ir8 units are interconnected by two- and three-center Ir-Ir interactions to polyanionic framework and hafnium atoms are guesting in such anionic cages. The atomic interactions features are reflected in the electronic structure of Hf2B2Ir5 and its chemical behaviour under OER conditions. The initial electrochemical OER activity of Hf2B2Ir5 sustains during the continuous operation at elaborated current densities of 100 mA cm-2 for at least 240 h (Figure 1) and positions this material among Ir-based state-of-the-art electrocatalysts. The harsh oxidative conditions of OER activate the surface-limited changes of the pristine material and as a result the electrochemical performance is related to the cooperative work of Ir-terminated surface of the ternary compound itself and agglomerates of IrOx(OH)y(SO4)z particles (inset of Figure 1). The latter are formed mainly due to the oxidation of HfB4Ir3 secondary phase and near-surface oxidation of the investigated compound. The presence of at least two OER-active states of Ir, originated from the Hf2B2Ir5 under OER conditions, was confirmed by the XPS analysis (Figure 2). The experimental data (electrochemical results, material characterization using bulk-and surface-sensitive methods, elemental analysis of the used electrolyte) are consistent with the chemical bonding analysis. The illustrated concept of cooperative phases with different chemical stabilities under OER conditions can be explored to other systems and offers a perspective knowledge-based way for discovery of new effective OER-electrocatalysts.
Iryna Antonyshyn/IA
Figure 1. OER performance of Hf2B2Ir5 anode material, represented by linear sweep voltammograms measured during the long-term chronopotentiometry experiment (0.1 M H2SO4, j = 100 mA cm-2, t = 0 ... 240 h). Inset: morphology of Hf2B2Ir5 material afterwards.
Figure 1. OER performance of Hf2B2Ir5 anode material, represented by linear sweep voltammograms measured during the long-term chronopotentiometry experiment (0.1 M H2SO4, j = 100 mA cm-2, t = 0 ... 240 h). Inset: morphology of Hf2B2Ir5 material afterwards.
Figure 2. Ir 4f core levels in Hf2B2Ir5 material: pristine state (black) and after 240 h of chronopotentiometry at 100 mA cm-2 current density (pink). The reference lines are drawn for Ir 4f in intermetallic Hf2B2Ir5 (black dashed), elemental Ir (grey dashed) and rutile IrO2 (red dashed).
Figure 2. Ir 4f core levels in Hf2B2Ir5 material: pristine state (black) and after 240 h of chronopotentiometry at 100 mA cm-2 current density (pink). The reference lines are drawn for Ir 4f in intermetallic Hf2B2Ir5 (black dashed), elemental Ir (grey dashed) and rutile IrO2 (red dashed).
With great enthusiasm, we had the opportunity to present our research work to schoolchildren as part of the Schüler Campus 2023 and to interested citizens as part of the Science Café.
Claire Donnelly has been awarded a Starting Grant from the European Research Council (ERC). She is the Lise Meitner Group Leader of Spin3D at the MPI CPfS and will use the grant to explore the effects of three dimensionality on quantum nanomaterials.
On September 4, 2023, Saxony's Minister-President Michael Kretschmer and Max Planck President Patrick Cramer will be hosting a ceremonial event at the Kulturpalast in Dresden to mark the 30-year success story of the Max Planck Society in Leipzig and Dresden.
The Boehringer Ingelheim Foundation awards funding through the Plus 3 Perspectives program to Dr. Eteri Svanidze, group leader of the REALM group at MPI CPfS. Through this highly coveted program, she will receive independent funding, which is aimed at supporting outstanding junior group leaders during their first appointment.
The Condensed Matter Division of the European Physical Society awards its 2023 EPS Europhysics Prize to Claudia Felser, director at the Max Planck Institute for Chemical Physics of Solids in Dresden and B. Andrei Bernevig, professor of physics at Princeton University “for seminal contributions to the classification, prediction, and discovery of…
Dr. Yu Pan won the International Thermoelectric Society (ITS) Postdoctoral Scholar in Thermoelectrics Award at the 39th International Conference on Thermoelectrics in Seattle (June 21-25, 2023).
Dr. Qun Yang belong to the Topological Quantum Chemistry department has been awarded both the precious Otto-Hahn-Medal and the Otto Hahn Award as one of the leading young researchers at Max Planck Society.
An impressive picture of the 30th Dragon Boat Festival on the banks of the Elbe in Loschwitz and the competitions on the water was presented to the spectators, who strolled across the "Blue Wonder" and in some cases stopped to watch the 62 teams racing. One of them was Team “Planckton”, which consisted of 19 members of the different working groups…