Abstract
Confined nanosized spaces at the interface between a metal and a seemingly inert material, such as a silicate, have recently been shown to influence the chemistry at the metal surface. In prior work, we observed that a bilayer (BL) silica on Ru(0001) can change the reaction pathway of the water formation reaction (WFR) near room temperature when compared to the bare metal. In this work, we looked at the effect of doping the silicate with Al, resulting in a stoichiometry of Al0.25Si0.75O2. We investigated the kinetics of WFR at elevated H2 pressures and various temperatures under interfacial confinement using ambient pressure X-ray photoelectron spectroscopy. The apparent activation energy was lower than that on bare Ru(0001) but higher than that on the BL-silica/Ru(0001). The apparent reaction order with respect to H2 was also determined. The increased residence time of water at the surface, resulting from the presence of the BL-aluminosilicate (and its subsequent electrostatic stabilization), favors the so-called disproportionation reaction pathway (*H2O + *O ↔ 2 *OH), but with a higher energy barrier than for pure BL-silica.
Highlights
The effects of nanoscale confinement are common in nature, and their importance is becoming increasingly recognized in different chemical research areas [1,2]
density functional theory (DFT) calculations were performed using the projector augmented wave method implemented in the Vienna Ab initio simulation package (VASP) [55,56]
The initial coverage was obtained by annealing the sample in an oxygen atmosphere (3 × 10−6 Torr) at 823 K for 30 min
Summary
The effects of nanoscale confinement are common in nature, and their importance is becoming increasingly recognized in different chemical research areas [1,2]. Zeolitic materials have been applied in a wide variety of industrial processes (Fischer–Tropsch, partial oxidation of aromatic molecules, C–C coupling, etc.) because of their structural versatility and outstanding thermal and chemical stabilities [11] Another type of architecture that attracted growing attention in past decades is the confined space that appears in weakly bound composites formed by a metal substrate and a thin film or layered 2D structure. Some of the aforementio fore, significant efforts have been made to understand the fundamentals of this process, in steps occurnew in hydrogen or that oxygen evolution reactions The surface was exposed to 3 × 10−6 Torr
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