Le Pr. Gunther ANDERSSON, Professeur à Flinders University, en Australie, donnera un séminaire le jeudi 1 juin 2023 à 15h00 à l’Auditorium intitulé :
Surfaces for Phot- and Electrocatalysis for Hydrogen Production
Abstract :
There are several pathways for generating hydrogen from renewable energy. The most established technology is electrocatalysis which requires efficient and cost-effective electrodes. One of the challenges of this technology is developing electrodes for catalytic water splitting which use the least possible amount of precious metals. Photocatalysis is a further method and is using sunlight to split directly water for producing hydrogen. The challenge of this method is developing photocatalysts which use efficiently light in the visible part of the solar spectrum and to use the least amount of precious metal possible. In this presentation examples for developing catalytic active surfaces for both methods will be presented.
Single atom catalysts of precious metals in a graphitic framework can be used for electrodes in electrocatalysis. Developing such catalysts requires demonstrating that the precious metal is embedded into the graphitic framework indeed as single atoms and comparing the activity of such electrodes with those of established reference electrodes.
Metal clusters with a size of less than 100 atoms are suitable for modifying the electronic properties of semiconductor surfaces to develop photocatalysts. [1, 2] Metal clusters have been shown to be promising candidates as co-catalysts for photocatalytic water splitting.[3] However, using such clusters as co-catalysts requires implementing processes which suppress their agglomeration on catalyst surfaces. In order to avoid agglomeration of the metal clusters and in order to retain their specific electronic structures, the coverage of the surface with metal clusters has to be kept below 10%. The main challenges in this field are a) to maintain the size and thus the properties of the metal clusters and b) to determine the electronic structure of the clusters.
[1] D. P. Anderson, J. F. Alvino, A. Gentleman, H.Al Qahtani, L. Thomsen, G. F. Metha, V. B. Golovko, and G. G. Andersson, PCCP 15, 3917 (2013).
[2] G. Krishnan, H. S. Al Qahtani, J. Li, Y. Yin, N. Eom, V. B. Golovko, G. F. Metha, G. G. Andersson, J. Phys. Chem. C, 121, 28007 (2017).
[3] W. Kurashige, R. Kumazawa, D. Ishii, R. Hayashi, Y. Niihori, S. Hossain, L. V. Nair, T. Takayama, A. Iwase, S. Yamazoe, T. Tsukuda, A. Kudo, Y. Negishi, J. Phys. Chem. C, 122, 13669 (2018).