Metal-Rich Chalcogenides as Sustainable Electrocatalysts for Oxygen Evolution and Reduction: State of the Art and Future Perspectives

The rational design of high-performance and cost-effective electrocatalysts is a key for the development of sustainable energy systems such as electrolyzers, fuel cells and metal-air batteries. Although water splitting and fuel cells are commercially mature technologies, they are still limited on large scale primarily due to the abundancy of the currently utilized expensive materials as well as the sluggish kinetics of the underlaying reactions, oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), and thus the required large observed overpotentials. Therefore, an efficient inexpensive catalyst is necessary. In the last decade, metal chalcogenides have been attractive materials in electrocatalysis of OER and ORR. Herein, we provide an overview on the recent advances on particularly metal-rich chalcogenides such as heazlewoodite- and pentlandite-types including their electrochemical activities and OER mechanisms. Likewise, examples of state-of-the-art metal chalcogenides revealing bifunctional activity for both OER and ORR are also presented. Diverse strategies to improve the catalytic performance are discussed and current challenges and future perspectives towards further development in this field are addressed.