Tuning the Electrocatalytic Properties of Trimetallic Pentlandites: Stability and Catalytic Activity as a Function of Material Form and Selenium Concentration

Pentlandites are one possible cost-effective alternative to platinum group metals for green hydrogen production. This study delves into the catalytic performance of trimetallic pentlandite systems, exploring the influence of selenium concentration and material form on their efficiency by combining the investigation of materials in various forms (powder catalysts, ingots, and highly densified pellets) with a computational investigation. The experimentally observed solubility limit of selenium was clarified based on the formation energies approach. The best and most stable defect combination, namely, Se:S substitution and S vacancy, was identified and correlated with improved catalytic properties of the systems with small Se addition. Further findings highlight the evolving importance of intrinsic material properties, such as bond properties, intermetallic interactions, or electronic structure, over surface effects, including the activation process, as the material density increases. The research contributes valuable insight into the intricate mechanisms governing pentlandite catalysis. Understanding these dynamics allows for intentional modifications, advancing the application of pentlandites in hydrogen production

Trimetallic Pentlandites (Fe,Co,Ni)₉S₈ for the Electrocatalytical HER in Acidic Media

Recently, pentlandite materials have been shown to exhibit promising properties with respect to the hydrogen evolution reaction (HER). A whole series of trimetallic FeCoNi-pentlandite materials and composites have been synthesized from the elements using high-temperature synthesis and categorized in terms of purity. Furthermore, the electrocatalytic properties regarding the HER were determined and correlated to hydrogen adsorption energies, which were determined by means of density functional theory (DFT) calculations. The relationships between activity and its origin generated in this way help to better understand the pentlandite system and provide meaningful approaches for catalyst synthesis

Die lokale Oberflächenstruktur und ‐zusammensetzung bestimmt die Wasserstoffentwicklung an Eisen‐Nickelsulfiden

AbstractUm leistungsfähigere Elektrokatalysatoren zu entwickeln, ist es notwendig, den Einfluss der Oberflächenstruktur und ‐zusammensetzung von Materialien mit hoher lokaler Auflösung besser zu verstehen. Dies trifft insbesondere auf die Entwicklung geeigneter Alternativen für Platin bei der elektrokatalytischen Wasserstofferzeugung zu. Elektrochemische Rasterzellmikroskopie (scanning electrochemical cell microscopy, SECCM) wurde benutzt, um die lokale elektrochemische Aktivität der Wasserstoffbildung an einkristallinen (111)‐Oberflächen von Fe4.5Ni4.5S8, einem hochaktiven Elektrokatalysator für die Wasserstofferzeugung, zu untersuchen. In Kombination mit strukturaufklärenden Methoden zeigen wir, dass kleinste Veränderungen der chemischen Zusammensetzung die Aktivität signifikant verändern können. Somit stellen die auf der Nanoskala durchgeführten elektrochemischen Messungen, ergänzt mit lokalen strukturellen Messungen sowie Kenntnis der lokalen Zusammensetzung ein wichtiges Hilfsmittel für das rationale Design neuer Katalysatoren dar