electrocatalysts – Lightsources.org

New Oxygen-Reduction Electrocatalysts for Alkaline Fuel Cells

2024/08/122024/08/19

Hydrogen fuel cells are among the most promising next-generation power sources for future automotive transportation. Developing efficient, durable, and low-cost electrocatalysts to accelerate the sluggish oxygen reduction reaction (ORR) is urgently needed to advance fuel cell technologies.Now, in a new paper appearing in the Journal of the American Chemical Society, a team of researchers from Cornell and the University of Wisconsin report new catalysts which exhibit superior ORR activity and robust stability. The team has characterized metal–organic framework-derived nonprecious dual metal single-atom catalysts (SACs), consisting of Co–N₄ and Zn–N₄ local structures. Their remarkable performance was validated under realistic fuel cell working conditions, achieving a record-high peak power density of ∼1 W cm^–2 among the reported SACs for alkaline fuel cells. Operando X-ray absorption spectroscopy studies at the PIPOXS beamline at CHEXS revealed that the Co atom in the Co–N₄ structure is the main catalytically active center. This work provides a comprehensive mechanistic understanding of the active sites in the Zn/Co–N–C catalysts and will pave the way for the future design and advancement of high-performance single-site electrocatalysts for fuel cells and other energy applications.

Read more on CHESS website

Image: Isolated Zinc and Cobalt atoms on a metal-organic-framework scaffold occupy local environments which are coordinated by 4 Nitrogen atoms. Using x-ray spectroscopy inside operating hydrogen fuel cells, the Cornell/Wisconsin team (with then-PhD-student Weixuan Xu as first author) were able to directly observe that specifically the Co-N₄ sites were responsible for highly efficient catalysis of the oxygen reduction reaction. As oxygen bonds to a Co-N₄ site, the Co XANES edge shifts to higher energy, providing a clear fingerprint for the reaction mechanism.

Electrocatalysis – Iron and Cobalt Oxyhydroxides examined

2023/02/162023/02/23

A team led by Dr. Prashanth W. Menezes (HZB/TU-Berlin) has now gained insights into the chemistry of one of the most active anode catalysts for green hydrogen production. They examined a series of Cobalt-Iron Oxyhydroxides at BESSY II and were able to determine the oxidation states of the active elements in different configurations as well as to unveil the geometrical structure of the active sites. Their results might contribute to the knowledge based design of new highly efficient and low cost catalytical active materials.

Very soon, we need to become fossil free, not only in the energy sector, but as well in industry. Hydrocarbons or other raw chemicals can be produced in principle using renewable energy and abundant molecules such as water and carbon dioxide with the help of electrocatalytically active materials. But at the moment, those catalyst materials either consist of expensive and rare materials or lack efficiency.

Key reaction in water splitting

A team led by Dr. Prashanth W. Menezes (HZB/TU-Berlin) has now gained insights into the chemistry of one of the most active catalysts for the anodic oxygen evolution reaction (OER), which is a key reaction to supply electrons for the hydrogen evolution reaction (HER) in water splitting. The hydrogen can then be processed into further chemical compounds, e.g., hydrocarbons. Additionally, in the direct electrocatalytic carbon dioxide reduction to alcohols or hydrocarbons, the OER also plays a central role.

Read more on the HZB website

Image: LiFe_x-1Co_x Borophosphates have been used as inexpensive anodes for the production of green hydrogen. Their dynamic restructuring during OER as well as their catalytically active structure, have been elucidated via X-ray absorption spectroscopy.

A scientist’s life: At the edge of what is known

2021/12/022021/12/02

Quinn Carvalho is a PhD student at Oregon State University and a user at the Advanced Light Source (ALS) at Lawrence Berkeley National Lab in California. Quinn and his colleagues are using spectroscopic techniques to develop design strategies for electrocatalysts that will provide the resources we need for a carbon-free world. In his #LightSourceSelfie, Quinn shares what excites him about his research and his experiences on the support provided by beamline staff at the ALS. Reflecting on what drives him as a research scientist, Quinn explains, “That moment when you realise that you’re the first person to observe, measure and describe a physical phenomenon is one of the greatest sensations I’ve experienced as a professional and something that motivates me still to this day.”