WO3 is one of the most interesting materials for photocatalysis due to its optical absorption in UV-vis, good charge carrier transport, and stability against photocorrosion. A detailed knowledge of the hydration state of WO3 is indispensable to gain more precise mechanistic insights into its photocatalytic activity. To the best of our knowledge, the hydration process of WO3 has been scarcely studied so far and only from a theoretical point of view, mostly by means of static density functional theory calculations. Here, we use manometric gas sorption experiments combined with extensive ab initio molecular dynamics simulations to investigate the hydration mechanisms of WO3 at room temperature. We demonstrate that water adsorbs molecularly in a two-step mechanism: the first water sublayer interacts with the under-coordinated surface tungsten atoms through electrostatic interactions, and, in a second step, a full layer is formed through hydrogen bonds established with the pre-adsorbed water molecules and with the under-coordinated surface oxygen atoms. The computed value of -90 kJ center dot mol-1 for the isosteric enthalpy of adsorption of the first water molecules is in excellent agreement with the experimental value estimated using the Clausius-Clapeyron approach from the experimental adsorption isotherms. The isosteric enthalpy of adsorption steadily decreases in absolute value when the surface coverage is increased to tend toward the enthalpy of condensation of water after three adsorption layers.

Hydration Mechanisms of Tungsten Trioxide Revealed by Water Adsorption Isotherms and First-Principles Molecular Dynamics Simulations

Caramori Stefano;Pastore Mariachiara
Ultimo
2023

Abstract

WO3 is one of the most interesting materials for photocatalysis due to its optical absorption in UV-vis, good charge carrier transport, and stability against photocorrosion. A detailed knowledge of the hydration state of WO3 is indispensable to gain more precise mechanistic insights into its photocatalytic activity. To the best of our knowledge, the hydration process of WO3 has been scarcely studied so far and only from a theoretical point of view, mostly by means of static density functional theory calculations. Here, we use manometric gas sorption experiments combined with extensive ab initio molecular dynamics simulations to investigate the hydration mechanisms of WO3 at room temperature. We demonstrate that water adsorbs molecularly in a two-step mechanism: the first water sublayer interacts with the under-coordinated surface tungsten atoms through electrostatic interactions, and, in a second step, a full layer is formed through hydrogen bonds established with the pre-adsorbed water molecules and with the under-coordinated surface oxygen atoms. The computed value of -90 kJ center dot mol-1 for the isosteric enthalpy of adsorption of the first water molecules is in excellent agreement with the experimental value estimated using the Clausius-Clapeyron approach from the experimental adsorption isotherms. The isosteric enthalpy of adsorption steadily decreases in absolute value when the surface coverage is increased to tend toward the enthalpy of condensation of water after three adsorption layers.
2023
Foucaud, Yann; Ben Jannet, Azza; Caramori, Stefano; Canevesi, Rafael; Said, Moncef; Celzard, Alain; Fierro, Vanessa; Badawi, Michael; Pastore, Mariach...espandi
File in questo prodotto:
File Dimensione Formato  
foucaud-et-al-2023-hydration-mechanisms-of-tungsten-trioxide-revealed-by-water-adsorption-isotherms-and-first.pdf

solo gestori archivio

Descrizione: versione editoriale
Tipologia: Full text (versione editoriale)
Licenza: Copyright dell'editore
Dimensione 7.85 MB
Formato Adobe PDF
7.85 MB Adobe PDF   Visualizza/Apri   Richiedi una copia

I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11392/2538911
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 1
  • ???jsp.display-item.citation.isi??? 1
social impact