Thermally Activated vs. Photochemical Hydrogen Evolution Reactions-A Tale of Three Metals
Document Type
Article
Publication Date
5-1-2023
Abstract
Molecular processes behind hydrogen evolution reactions can be quite complex. In macroscopic electrochemical cells, it is extremely difficult to elucidate and understand their mechanism. Gas phase models, consisting of a metal ion and a small number of water molecules, provide unique opportunities to understand the reaction pathways in great detail. Hydrogen evolution in clusters consisting of a singly charged metal ion and one to on the order of 50 water molecules has been studied extensively for magnesium, aluminum and vanadium. Such clusters with around 10-20 water molecules are known to eliminate atomic or molecular hydrogen upon mild activation by room temperature black-body radiation. Irradiation with ultraviolet light, by contrast, enables hydrogen evolution already with a single water molecule. Here, we analyze and compare the reaction mechanisms for hydrogen evolution on the ground state as well as excited state potential energy surfaces. Five distinct mechanisms for evolution of atomic or molecular hydrogen are identified and characterized.
Keywords
hydrated metal ions, hydrogen evolution, mass spectrometry, photochemistry, spectroscopy
Divisions
rms
Publication Title
Chemistry-A European Journal
Volume
29
Issue
26
Publisher
Wiley
Publisher Location
POSTFACH 101161, 69451 WEINHEIM, GERMANY