Nano-Plasmonic photo-catalysis – “Hot electrons” or just heating?

David Wang Auditorium, 3rd floor Dalia Maydan Bldg.
Prof. Yonatan Dubi

Prof. Yonatan Dubi

Department of Chemistry & Ilse Katz Center for
Nanoscale Science and Technology Ben-Gurion University

What happens to electrons in a metal when they are illuminated? This fundamental problem is a driving force in shaping modern physics since the discovery of the photo-electric effect. In recent years, this problem resurfaced from a new angle, owing to developments in the field of nano-plasmonics, where metallic nanostructures give rise to resonantly enhanced local electromagnetic fields (surface plasmons). Presumably, these plasmons can transfer their energy to the electrons in the metal very efficiently, creating “hot electrons”, i.e. energetic electrons out of equilibrium. Such energetic electrons have been demonstrated to be useful in a variety of ways, most recently in catalysis of chemical reactions. Or have they?

In this talk I will argue that what appears to be hot-electron-mediated photo-catalysis is really a simple heating effect. Gaining intuition from our recent theory of hot electrons (Nature LSA 2019), I will show how data from seminal experiments in the field claiming to show “hot electron photo-catalysis”, actually fits remarkably well a simple theory of heating. I will lead the listeners through the story of how such a surprising misunderstanding of experiments can take place and share some of my experience in swimming against the scientific stream.