Influence of Crystal Water on Crystal Structure, Electronic Structure, Band Structure, and Charge Separation of WO₃·2H₂O Nanosheets

Abstract

In this work, we mainly investigate the influence of structure water on crystal structure, electronic structure, band structure, and charge separation of WO3·2H2O. It is found, for the first time, that although water is a weak electron donor, a ligand-to-metal charge transfer (LMCT) from H2O to W occurs. The structure water contributes to the conduction band (CB) of WO3·2H2O, and the band gap of WO3·2H2O is obviously narrowed, thus increasing the light absorption obviously. Moreover, the results of EIS, photocurrent spectra, and PL show that structure water in WO3·2H2O also improves the charge separation and transfer efficiency of the catalyst. This is the first investigation on the LMCT transfer from structure water (a weak electron donor) to tungsten, which obviously improves light absorption and charge separation. Under visible light irradiation (λ ≥ 420 nm), WO3·2H2O nanosheets have a photocatalytic activity 2.3 times higher than that of WO3 for the degradation of methylene blue (MB). The kind number of photochemical materials can be increased greatly, because structure water-contained compounds widely exist in nature.

Highly efficient doping of titanium dioxide with sulfur using disulfide-linked macrocycles for hydrogen production under visible light

“…This value was about 0.60 eV smaller than the experimental result, which was due to the electron delocalization error in the generalized gradient approximation (GGA)-Perdew-Burke-Ernzerhof (PBE) method. 33,[52][53][54][55] Compared with native TiO 2 , the calculated conduction band and the valence band of S-TiO 2 had 0.19 eV and 0.70 eV upward shifts, respectively, which led to a significant reduction (0.51 eV) in the energy band gap of S-TiO 2 . These results were consistent with the upward shift of the valence band and the more negative conduction band potential of S-TiO 2 measured by the electrochemical experiments.…”

WO3 Inversce Opal Photonic Crystals: Unique Property, Synthetic Methods and Extensive Application

“…The crystalline structure of WO 3 is described as a 3D network of WO 6 octahedral with shared edges and corners interconnected by weak van der Waals force (shown in Figure 4). [ 23‐24 ] This unique structure provides open tunnels for photon and electron channels and the construction of monoclinic crystalline. Depending on the unit‐cell axis, the chevron patterns constructed by octahedral framework exhibit some octahedral site twists.…”

“…The crystal structures of WO 3 (Reproduced with permission from ref. [24]. Copyright 2016 The Royal Society of Chemistry.…”

Hydrated Orthorhombic/Hexagonal Mixed-Phase WO3 Core–Shell Nanoribbons for Hole-Mediated Photocatalysis

“…Liu et al reported the excellent photocatalytic activity of a mixed-phase o/m-WO 3 ·H 2 O compared to the pure m-WO 3 and o-WO 3 ·H 2 O phases . Shi et al studied the contribution of water content in the structure of o-WO 3 ·2H 2 O nanosheets in the degradation of MB …”

“…13 Liu et al reported the excellent photocatalytic activity of a mixedphase o/m-WO 3 •H 2 O compared to the pure m-WO 3 and o-WO 3 •H 2 O phases. 17 27 Recently, efforts have been devoted to synthesizing colored WO 3 with an extended absorption tail covering the visible and a near-infrared (NIR) window of the light spectrum. report by Bechinger et al shows an increase in WO 3 coloration efficiency by 40% as the oxygen content decreases from 50 to 5%.…”