Designing Polychromatic Er3+/Yb3+-Codoped Bi2WO6 Upconverting Nanoparticles with Enhanced Visible-Light-Triggered Photocatalytic Properties toward Tetracycline Degradation

To address the unsatisfactory photodegradation capacities of photocatalysts, Er 3+ /Yb 3+ -codoped Bi 2 WO 6 (Bi 2 WO 6:Er 3+ / x Yb 3+ ) nanoparticles (NPs) with polychromatic upconversion (UC) emission and boosted visible-light-triggered photocatalytic abilities were designed. First-principles density functional theory was employed to study the impact of Er 3+ and Yb 3+ codoping on the electronic structure of Bi 2 WO 6 . Upon 980 nm excitation, the resultant NPs emitted polychromatic UC emissions caused by energy back transfer from Er 3+ to Yb 3+ . Moreover, the involved UC emission mechanism was clarified through examining the pump power related to UC emission spectra. By investigating the visible-light-induced tetracycline (TC) decomposition, the photocatalytic activities of developed NPs were explored, where Bi 2 WO 6:Er 3+ /0.07Yb 3+ NP can degrade 81.76% of TC within 30 min, with a k value of 0.0552 min –1 . Both the theoretical calculation and trapping results reveal that the • O 2 –, h +, and • OH were formed during the pollutant removal process. Additionally, the toxic TC can be photodegraded to nontoxic products via the synthesized photocatalysts, leading to wastewater purification. These achievements manifest that Bi 2 WO 6:Er 3+ / x Yb 3+ NPs are promising visible-light-triggered photocatalysts to degrade pollutants, and our findings also propose a facile approach to regulate the photocatalytic activities of photocatalysts via utilizing doping and UC emission strategies.