Synthesis of Nb2O5 Nanoplates and their Conversion into NbO2F Nanoparticles by Controlled Fluorination with Molecular Fluorine

Abstract

Following a synthesis protocol developed by us, nanoparticles of NbO2F were prepared for the very first time by the gas‐solid type fluorination of hexagonal‐shaped niobium pentoxide (Nb2O5) nanostructures with molecular fluorine (F2). The optimized fluorination parameters, like F2 pressure, gas‐solid reaction temperature, and duration, were very crucial for successful synthesis of the desired NbO2F nanomaterial. The hexagonal‐shaped Nb2O5 nanoplates were synthesized in a previous step by a hydrothermal method. The oxide to oxyfluoride transformation protocol is highly efficient, giving single‐phase NbO2F in the cubic crystal system, as confirmed by powder X‐ray diffraction (XRD) and energy dispersive X‐ray spectroscopy (EDX). The structures of Nb2O5 nanoplates and NbO2F nanoparticles were also characterized by vibrational spectroscopy (FTIR and Raman scattering). The morphologies of the materials were studied by transmission and scanning electron microscopy (T/SEM), which revealed that the hexagonal‐shaped plates of Nb2O5 disintegrated into nanoparticles with an approximate size of 27 nm upon fluorination to provide NbO2F. The lithiation and sodiation ability of nanostructured NbO2F is established with relevant electrochemical properties.