Oxygen Vacancy Structure Associated Photocatalytic Water Oxidation of BiOCl

Abstract

A central issue in understanding photocatalytic water splitting on a stoichiometric or defective nanostructured oxide surface is its adsorption mode and related reactivity. More than just improving the adsorption of water on oxide surfaces, we demonstrate in this work that surface oxygen vacancies (OVs) also offer a possibility of activating water toward thermodynamically enhanced photocatalytic water oxidation, while the water activation state, as reflected by its capability to trap holes, strongly depends on the structures of OVs. Utilizing well-ordered BiOCl single-crystalline surfaces, we reveal that dissociatively adsorbed water on the OV of the (010) surface exhibits higher tendency to be oxidized than the molecularly adsorbed water on the OV of the (001) surface. Analysis of the geometric atom arrangement shows that the OV of the BiOCl (010) surface can facilitate barrierless O–H bond breaking in the first proton removal reaction, which is sterically hindered on the OV of the BiOCl (001) surface, and also allow more localized electrons transfer from the OV to the dissociatively adsorbed water, leading to its higher water activation level for hole trapping. These findings highlight the indispensable role of crystalline surface structure on water oxidation and may open up avenues for the rational design of highly efficient photocatalysts via surface engineering.

Unprecedented Eighteen‐Faceted BiOCl with a Ternary Facet Junction Boosting Cascade Charge Flow and Photo‐redox

“…As shown by the Fourier transform (FT) of k2c(k)f unctions (Figure 1k), BiOCl-10 and BiOCl-100 show little difference in the Bi L-edge extended XAFS k2c(k) oscillation curves with the almost same distance of BiÀOb ond (1.82 )a nd BiÀCl bond (2.81 ). [21] While the amplitude of BiOCl-10 is lower than that of BiOCl-100, which may be attributed to the better crystallinity of BiOCl-100 than BiOCl-10. All BiOCl samples show similar Raman spectra, which consist of two remarkable bands at approximately 144 and 200 cm À1 .T he two bands located at 144 cm À1 and 200 cm À1 are assigned to the A 1g internal Bi-Cl stretching mode and E g internal Bi-Cl stretching mode,r espectively.T he gradually increased intensity of Raman peaks also confirms the high crystallinity of the BiOCl samples with longer reaction time ( Figure S8).…”

Recent Advances in Bismuth‐Based Nanomaterials for Photoelectrochemical Water Splitting

“…[59] Notably,a fter the introduction of oxygen vacancies in the (0 01)a nd (0 10)p lanes of BiOCl, this material exhibits different relaxation behavior.A s projected in Figure 3b,c for the (0 01)s urface of BiOCl, the Bi-Cl bond length relaxes parallel to (0 01), whereas the BiÀCl bond lengths hortens by undergoing out-of-plane relaxation. [59] Notably,a fter the introduction of oxygen vacancies in the (0 01)a nd (0 10)p lanes of BiOCl, this material exhibits different relaxation behavior.A s projected in Figure 3b,c for the (0 01)s urface of BiOCl, the Bi-Cl bond length relaxes parallel to (0 01), whereas the BiÀCl bond lengths hortens by undergoing out-of-plane relaxation.…”

“…BiOI possesses as uitable band gap, that is, 1.8 to 1.9 eV,a nd it can thus utilize the entire solar spectrum. a) Crystal structureo fB iOCl depicting the layered structure, b) in-plane [59] and c) out-plane relaxation [59] over the atoms around the oxygen vacancy on the BiOCl (0 01)a nd (0 10 )surfaces, respectively.Reproduced from Ref. [66] In the BiOI system,t he BiÀId istance is greater than the BiÀBr distance, which can induce as trong electric field between the Bi atom and the Io rOa tom.…”

“…[65] Unlike the valence band BiOCl, that of BiOX consists of Bi 6s, Bi 6p, O2p, and I5p orbitals, and the conduction band minimum mainly comprises Bi 6p with ac ontribution from the I5po rbital, as depicted in Figure 4a. [59] with permissionfrom the AmericanC hemical Society. It is believed that the strong built-in electric field facilitates charges eparation for PEC performance (Figure 4b).…”

Synthesis, Characterization and Excellent Photocatalytic Performance of Iron-Carbon-Codoped Mesoporous Titania Nanocrystallines

“…Moreover, the carbonaceous species as photosensitizer might result in the extended band tailing. It has been accepted that metal doping can introduce a new dopant energy level into the band gap of TiO 2 , close to and above the valence band [26,27]. Therefore, the red shift of the absorption edge for the Fe-C-TiO 2 samples can be ascribed to electronic transitions from the dopant level to the conduction band of TiO 2 partly.…”