Oxygen Vacancies Engineering–Mediated BiOBr Atomic Layers for Boosting Visible Light‐Driven Photocatalytic CO₂ Reduction

Abstract

CO2 photoreduction into valuable chemicals is a sustainable and prospective technology to alleviate greenhouse effects and the energy crisis. However, the photocatalytic efficiency is impeded by undesirable recombination of photogenerated carriers and poor CO2 activation performance. Herein, oxygen vacancies (OVs) are introduced into BiOBr atomic layers by ultraviolet light assisting to increase the efficiency of carrier separation and CO2 adsorption–activation performance, enhancing the CO2 reduction activity. The introduction of OVs can effectively enhance the visible light absorption, boost the photogenerated carrier separation migration, and tune the adsorption/desorption process for CO2 and products on the surface of photocatalysts. The optimized OVs engineering–mediated photocatalyst achieves a high CO generation rate of 10.15 μmol g−1 under visible light irradiation for 5 h in pure water, which is 1.99 times compared with that of pristine BiOBr atomic layers. The possible photocatalytic mechanism is investigated by in situ Fourier transform infrared spectroscopy (in situ FT‐IR) spectrometry. Also, an opportunity to design OVs‐rich ultrathin semiconductors for high‐performance CO2 reduction is offered.

Construction of Few-Layer Ti3C2 MXene and Boron-Doped g-C3N4 for Enhanced Photocatalytic CO2 Reduction

“…As shown in Figure b, water (H 2 O; 1650 cm –1 ), monodentate carbonate (m-CO 3 2– ; 1362, 1515, and 1541 cm –1 ), bidentate carbonate (b-CO 3 2– ; 1620 and 1703 cm –1 ), bicarbonate (HCO 3 – ; 1306, 1457, and 1600 cm –1 ), and formaldehyde (−CHO; 1679 cm –1 ) appeared. ,,, Most intensities of the above-mentioned peaks became stronger under illumination. To be noted, new absorptions of formate (−HCOO – ; 1416 cm –1 ) and COO – species (1558 cm –1 ) appeared when the light was switched on. , Several studies have found that COOH* is an important intermediate, and its formation is a rate-limiting step during the photoreduction of CO 2 to CO. , …”

Vacancy Engineering of Ultrathin 2D Materials for Photocatalytic CO2Reduction

“…Different from above‐mentioned methods requiring the implantation of high temperature or pressure, ultraviolet irradiation is a relatively green and safe means to create vacancy in ultrathin 2D materials [33] . In recent work, Li et al [47] . utilized ultraviolet irradiation to introduce oxygen vacancy into BiOBr atomic layers.…”

Bandgap Engineering and Oxygen Vacancies of NixV2O5+x (x = 1, 2, 3) for Efficient Visible Light‐Driven CO2 to CO with Nearly 100% Selectivity

“…It is primarily because their valence band (VB) edges are mainly derived from the O 2 p orbitals located at much higher potential than the H 2 O/O 2 potential of 0.82 V versus NHE (pH = 7). In this regard, mixed‐anion compounds such as oxynitrides, [ 15 ] oxysulfides, [ 16 ] and oxyhalides [ 17 ] are promising candidates because the lower electronegativity of the nonoxide anion pushes the valence band maximum (VBM) a higher energy relative to O 2 p orbitals, thereby expanding the available bandwidth of the solar spectrum. However, most of these mixed‐anion semiconductors are subject to deactivation through the self‐oxidation of the nonoxide anions by the photogenerated holes.…”