C–Doping Induced Oxygen-Vacancy in WO₃ Nanosheets for CO₂ Activation and Photoreduction

Abstract

Sluggish charge kinetics and low CO 2 affinity seriously limit the photocatalytic CO 2 reduction reaction. Herein, the simultaneous promotion of charge transfer and CO 2 activation over two-dimensional (2D) WO 3 nanosheets is achieved by coupling surface C-doping and oxygen vacancy. The surface-doped C atoms reconstruct the atomic surface of WO 3 by extracting oxygen lattice to generate the intimate oxygen vacancy (C−OV coordination) as the active center, which facilitates the CO 2 adsorption/activation, thus inducing the formation *CO 2 species. As a charge delivery channel, an exclusive W−O−C covalent bond formed by C−OV coordination could enhance the electron transfer. As a result, the as-designed catalyst exhibits 85.8% selectivity for CO 2 photoreduction to CO under the gas−solid phase reaction, with a yield rate of 23.2 μmol g −1 h −1 and a stable long-term reactivity over 24 h. Moreover, the in situ DRIFTS and DFT results reveal that this specific C−OV coordination enables the spontaneous CO 2 activation and proton-coupled electron transfer to guarantee the sustained formation of *COOH and, thus, smooth the photocatalytic CO 2 reduction reaction. This work develops a feasible strategy for electronic structure modification of photocatalysts with doping-induced oxygen vacancy to boost CO 2 activation and photoreduction.

Oxygen vacancies assist a facet effect to modulate the microstructure of TiO2 for efficient photocatalytic O2 activation

“…Most scholars believe that vacancies contribute to the improvement of photogenerated electron-hole (e-h) separation efficiency, in which they could serve as capture centers for effectively limiting photoexcited electron transfer and hence prevent their recombination with photogenerated holes. [14][15][16] For instance, the Jiang group proved that S vacancies in CdS can efficiently confine electrons and improve the e-h separation efficiency, thereby refining its application performance in photocatalytic water splitting to produce H 2 . 17 However, some studies found that vacancies will become the recombination center of photogenerated charges, inhibiting the photocatalytic reaction.…”

Metal–Acid Interface Engineering in Pd–WOx Bifunctional Catalysts for the Hydroalkylation Tandem Reaction of Benzene

“…HR-TEM images (the inset in Figure 1d−f) display a lattice fringe of 0.224 nm for all of the three samples, corresponding to the Pd(111) plane. 37 It is worth noting that for the Pd−25WO x /MMT sample (Figure 1f), an additional lattice spacing assigned to the (200) plane of WO 3 (0.376 nm) is observed, 38 in consistent with the result of XRD.…”

Hydrogen Spillover-Accelerated Selective Hydrogenation on WO3 with ppm-Level Pd

“…However, the hexagonal phase (PDF #85-2459) was confirmed for the PdHD/WO 3 -350 and PdHD/WO 3 -450 catalysts (Figure c). Considering that the generation of oxygen vacancies on WO 3 would inevitably lead to the reduction of W 6+ to W 5+ ions, − the fraction of W 5+ was selected as the descriptor to display the amount of surface oxygen. For the as-synthesized WO 3 supports, the surface W 5+ fraction was only 2.1% from the X-ray photoelectron spectroscopy (XPS) analysis of the W 4f peak (Figures d and S3), revealing their low concentration of oxygen vacancies.…”