Improved intrinsic emission efficiency and photocatalysis of Nb2WO8 by Li+-doping

Transition metal oxide semiconductors have been reported to be potential for light-energy conversion and storage-related applications because of the unique structures and properties. This work reports a transition metal oxide Nb2WO8 synthesized by the sol-gel synthesis. The crystal structure, optical band nature, intrinsic luminescence, and photocatalytic properties were investigated. Nb2WO8 is a typical indirect allowed semiconductor and the band transition energy is 3.58 eV. The top of the valence band (EVB) and the minimum of the conduction band (ECB) are +2.88 eV and & minus;0.7 eV, respectively. Nb2WO8 presents an intrinsic emission at 300 K with the maximum wavelength at 510 nm and the lifetime was 1.96 mu s. The introduction of the impurity ions Li+ into the lattices of Nb2WO8 resulted in the improved luminescence efficiency. Meanwhile, compared with the undoped sample, the luminescence thermal stability of Nb2WO8:Li was also enhanced. The decay lifetime of Nb2WO8:Li was prolonged to 2.41 mu s. The slow decay time could delay the recombination of the photo-produced holes and electrons after light excitation. This improves photocatalytic performances by delaying the charge-separation. Therefore, the photodegradation of RhB by Nb2WO8:Li is much more efficient than that by the reference sample of Nb2WO8 under visible light irradiation. Li+ doping is an effective way to modify the optical properties of Nb2WO8 semiconductor. (c) 2021 Elsevier B.V. All rights reserved.

Automated summary

The transition metal oxide semiconductor Nb2WO8 synthesized by sol-gel method exhibits good optical properties and photocatalytic performance, especially showing higher efficiency and stability after Li+ doping.