Preparation of Niobium Pentoxide Nanotube Powders By a Facile Electrochemical Anodization

Abstract

Niobium pentoxide (Nb2O5) nanostructures are promising candidate for various applications including solar cells, sensors, supercapacitors, photocatalysis, and electrochromic coatings, etc. And the morphologies, crystal structures, and surface areas of Nb2O5 nanostructures greatly affect their devices performances. The electrochemical anodization is a versatile and facile method to fabricate various metal oxide nanostructures, for example, TiO2, Al2O3, WO3, Nb2O5, and Ta2O5. The usual form of obtained anodic metal oxides is thin oxide film attached on metal substrates with nanotube, nanopore or nanochannel structures. Here we report on the fabrication of Nb2O5 nanotube powders by a direct electrochemical anodization method. By simply adjusting the anodization conditions, such as applied voltage, electrolyte composition, and bath temperature, the anodically formed Nb2O5 nanostructures can be spontaneously and continuously released into the anodization electrolyte during the reaction process. After washing and centrifugation, porous powders can be obtained. Under the optimized conditions, the highly porous Nb2O5 powder with nanotube morphology can be obtained, which can provide a very high specific surface area and can be used for various applications. By coating the Nb2O5 nanotube powders onto transparent conducting glasses, the oxide films can be used as the photoanodes for dye-sensitized solar cells with the front-side illumination configuration, leading to a high light harvesting efficiency. The nanotube powders can also be used as an efficient photocatalyst to decompose organic contaminant, with a high decomposition efficiency. The rapid and continuous electrochemical anodization to the formation of Nb2O5 nanotube powders is a promising method for mass production of functional Nb2O5 nanostructures for various applications.