Controllable synthesis of L-shaped V2O5 and the improved adsorption capacity by fluorine

In this work, V2O5 with an interesting L-shape is successfully prepared by a simple hydrothermal method without using any surfactant or template. The formation mechanism of L-shaped V2O5 has been proposed. We have also investigated the effect of fluoride on the morphology, crystal structure and adsorption ability of the samples. The samples are characterized by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) with select area electron diffraction (SAED), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, UV-vis diffuse reflectance spectroscopy (UV-DRS), photoluminescence (PL) spectroscopy and N-2 sorption isotherms. It is found that the addition of fluoride can restrain the formation of L-shaped V2O5, resulting in the high-energy {010} facets being exposed and an increased number of oxygen vacancies. Density functional theory (DFT) calculations and PL spectra further confirm the results above. As a result, F-doped V2O5 shows a significantly improved adsorption capacity for methylene blue (MB) compared to the undoped one. The adsorption kinetics follows well a pseudo-second-order model, with correlation coefficients (R) higher than 0.99.