Bismuth atom tailoring of indium oxide surface frustrated Lewis pairs boosts heterogeneous CO2 photocatalytic hydrogenation

The surface frustrated Lewis pairs (SFLPs) on defect-laden metal oxides provide catalytic sites to activate H₂ and CO₂ molecules and enable efficient gas-phase CO₂ photocatalysis. Lattice engineering of metal oxides provides a useful strategy to tailor the reactivity of SFLPs. Herein, a one-step solvothermal synthesis is developed that enables isomorphic replacement of Lewis acidic site In³⁺ ions in In₂O₃ by single-site Bi³⁺ ions, thereby enhancing the propensity to activate CO₂ molecules. The so-formed Bi_xIn_2-xO₃ materials prove to be three orders of magnitude more photoactive for the reverse water gas shift reaction than In₂O₃ itself, while also exhibiting notable photoactivity towards methanol production. The increased solar absorption efficiency and efficient charge-separation and transfer of Bi_xIn_2-xO₃ also contribute to the improved photocatalytic performance. These traits exemplify the opportunities that exist for atom-scale engineering in heterogeneous CO₂ photocatalysis, another step towards the vision of the solar CO₂ refinery.

Surface frustrated Lewis pairs (SFLPs) provide a unique class of active sites that enable efficient gas-phase CO₂ photocatalysis. How to tailor the reactivity of the SFLPs represents a major challenge, which the authors address here by single-site Bi³⁺ ion substitution of the SFLPs.

Effect of TiO2 on the photocatalytic properties of bismuth oxide

Bi2-xTixO3+x/2 (x = 0.05, 0.10 and 0.15) photocatalysts are prepared by solid-state technique. The band gap of the prepared sample was estimated from the onset of UV-Vis absorption spectra. The photocatalytic activities of as prepared samples are investigated under UV light irradiation for the decomposition of methyl orange (MO). It has been observed that the rate of decomposition of MO increased with increasing Ti4+ content in the present samples. Moreover, it shows better photocatalytic activity than undoped Bi2O3 and TiO2. The lowest band gap is observed for x = 0.15 sample, i.e. 2.55 eV, which also showed the highest photocatalytic activity in the present sample.

The visible light-driven photocatalytic degradation of Alizarin red S using Bi-doped TiO2 nanoparticles

Ultrasonic assisted sol–gel synthesized Bi-doped TiO₂ mesoporous nanoparticles with a good crystallinity and high surface area were prepared. The 1% Bi-doped TiO₂ catalyst showed the highest photocatalytic activity under visible light.

Electrospun nanofibers of Bi-doped TiO2 with high photocatalytic activity under visible light irradiation

Bi-doped TiO(2) nanofibers with different Bi content were firstly prepared by an electrospinning method. The as-prepared nanofibers were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), photoluminescence spectra (PL), and UV-vis diffuse reflectance spectroscopy (DRS). The results indicated that Bi(3+) ions were successfully incorporated into TiO(2) and extended the absorption of TiO(2) into visible light region. The photocatalytic experiments showed that Bi-doped TiO(2) nanofibers exhibited higher activities than sole TiO(2) in the degradation of rhodamine B (RhB) and phenol under visible light irradiation (λ>420 nm), and 3% Bi:TiO(2) samples showed the highest photocatalytic activities.