A review on the optical characterization of V2O5 micro-nanostructures

Bulk V2O5 is a diamagnetic semiconductor with a band gap (Eg) of about 2.3 eV, which is based on the ionic configuration with filled O2p and unoccupied V3d orbitals. However, the band edge absorption and photoluminescence (PL) peak positions of low-dimensional V2O5 materials do not coincide and are distributed over wide ranges of 0.75–3.49 eV and 0.73–3.3 eV, respectively. This review summarizes the fabrication processes, structure, and optical characterization of V2O5 micro-nanostructures, including 0D, 1D, 2D, and 3D morphologies. The wide ranges of band edge absorption and broad PL of V2O5 micro-nanostructures are clarified in terms of factors such as the morphology, synthesis method, growth conditions, crystal size, micro-nano size, phase transition, and measurement conditions. The relations among the separation, diffusion, recombination, and degradation of the electron-hole pairs in V2O5 micro-nanostructures are also discussed. Fundamental understanding of the optical characteristics plays a key role in V2O5 micro-nano device applications. The review also demonstrates the role of V2O5 micro-nanostructures and other materials (MOs) in V2O5/OMs heterostructures for slowing down recombination, prolonging lifetime, improving electron-hole separation, and increasing photocurrent to enhance the photocatalytic activity.