Oxygen vacancy defects-boosted deep oxidation of NO by β-Bi2O3/CeO2-δ p-n heterojunction photocatalyst in situ synthesized from Bi/Ce(CO3)(OH) precursor
Flower-like n -type CeO 2-δ is hybridized with p -type β-Bi 2 O 3 nanoparticles to design a novel β-Bi 2 O 3 /CeO 2-δ p - n heterojunction photocatalyst via a thermal treatment process of Bi/Ce(CO 3 )(OH) precursor. The synthesized β-Bi 2 O 3 /CeO 2-δ exhibits a remarkable enhancement in NO removal and significant suppression of toxic intermediates nitrogen dioxide (NO 2 ) under visible light irradiation. The superior photocatalytic activity of β-Bi 2 O 3 /CeO 2-δ for NO removal is mainly derived from the synergistic effects of the oxygen vacancies (OVs) and p-n heterojunction. The OVs not only enhance the visible light utilization and boost the separation of electron-hole pairs but also improve the adsorption and activation of NO and O 2 . Particularly, the p-n heterojunction is beneficial for the interfacial migration of photogenerated charge carriers. Electron spin resonance (ESR) and trapping experiment reveal that the synergistic effects of OVs and p-n heterojunction can induce the generation of more active species. The electrochemical measurements and density-functional theory (DFT) calculations in-depth confirm that both p-n heterojunction and OVs can accelerate the interfacial charge transfer, resulting in the deep oxidation of reactants. Therefore, the flower-like β-Bi 2 O 3 /CeO 2-δ p-n heterojunction photocatalyst exhibits an advanced photocatalytic activity for deep NO removal and a suppressed NO 2 generation. In addition, monitoring the reaction products by in situ Fourier transform infrared spectrum (FTIR) further validates that the main products of nitrates are formed during the photocatalytic process. This work demonstrates a straightforward approach for construction of p-n heterojunction photocatalysts, which can enhance the effective photocatalytic activity and stability for NO removal.
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