Excess charge driven dissociative hydrogen adsorption on Ti2O4

• Published in: Physical chemistry chemical physics : PCCP Vol. 19; no. 34; pp. 23154 - 23161
• Main Authors: Song, Xiaowei, Fagiani, Matias R, Debnath, Sreekanta, Gao, Min, Maeda, Satoshi, Taketsugu, Tetsuya, Gewinner, Sandy, Schöllkopf, Wieland, Asmis, Knut R, Lyalin, Andrey
• Format: Journal Article
• Language: English
• Published: 2017
• ISSN: 1463-9084
• DOI: 10.1039/c7cp03798h

The mechanism of dissociative D2 adsorption on Ti2O4-, which serves as a model for an oxygen vacancy on a titania surface, is studied using infrared photodissociation spectroscopy in combination with density functional theory calculations and a recently developed single-component artificial force induced reaction method. Ti2O4- readily reacts with D2 under multiple collision conditions in a gas-filled ion trap held at 16 K forming a global minimum-energy structure (DO-Ti-(O)2-Ti(D)-O)-. The highly exergonic reaction proceeds quasi barrier-free via several intermediate species, involving heterolytic D2-bond cleavage followed by D-atom migration. We show that, compared to neutral Ti2O4, the excess negative charge in Ti2O4- is responsible for the substantial lowering of the D2 dissociation barrier, but does not affect the molecular D2 adsorption energy in the initial physisorption step.