High-Throughput Preparation of Metal Oxide Nanocrystals by Cathodic Corrosion and Their Use as Active Photocatalysts

Abstract

Nanoparticle metal oxide photocatalysts are attractive because of their increased reactivity and ease of processing into versatile electrode formats; however, their preparation is cumbersome. We report on the rapid bulk synthesis of photocatalytic nanoparticles with homogeneous shape and size via the cathodic corrosion method, a simple electrochemical approach applied for the first time to the versatile preparation of complex metal oxides. Nanoparticles consisting of tungsten oxide (HWO) nanoplates, titanium oxide (TiO) nanowires, and symmetric star-shaped bismuth vanadate (BiVO) were prepared conveniently using tungsten, titanium, and vanadium wires as a starting material. Each of the particles were extremely rapid to produce, taking only 2-3 min to etch 2.5 mm of metal wire into a colloidal dispersion of photoactive materials. All crystalline HWO and BiVO particles and amorphous TiO were photoelectrochemically active toward the water oxidation reaction. Additionally, the BiVO particles showed enhanced photocurrent in the visible region toward the oxidation of a sacrificial sulfite reagent. This synthetic method provides an inexpensive alternative to conventional fabrication techniques and is potentially applicable to a wide variety of metal oxides, making the rapid fabrication of active photocatalysts with controlled crystallinity more efficient.

Anomalous Phase Transition of Layered Lepidocrocite Titania Nanosheets to Anatase and Rutile

“…[1][2][3][4][5][6][7] To meet the ever-increasing energy demand, intensive efforts have been devoted to develop the titanium oxides with tunable compositions, morphologies and structures. [8][9][10][11] Understanding the properties of the materials as a function of the crystallographic structure and the phase transition amongst these polymorphs, e.g. the transformation of lepidocrocite-type TiO2 nanosheets into rutile or anatase is essential to establish protocols of synthesis of these materials and their subsequent applications.…”

Electrochemical Synthesis of Nanostructured Metal-Doped Titanates and Investigation of Their Activity as Oxygen Evolution Photoanodes

“…In contrast, electrochemical routes have been shown to greatly reduce the time taken to produce nanostructured titanate catalysts. [41][42] Electrodeposition is a one-pot technique that enables: (i) control over deposition thicknesses, (ii) direct deposition of the catalyst onto the conductive substrate, maximizing the electrical connection, (iii) ease of access to multicomponent, mixed metal oxide materials. [42][43][44] Unfortunately, control over the uniform morphology of the electrodeposits is lacking.…”

Controllable synthesis of nanostructured metal oxide and oxyhydroxide materials via electrochemical methods

“…Such differences on size and shape are highly relevant on the photoelectrochemical activity of the oxides towards water splitting. [26] Similar pulse potential methods for the electrochemical synthesis of metal oxide NPs have been reported. Such methods compromise the reduction of the electrodes and oxidation of the electro-generated species by use of identical-sized working and counter electrodes.…”

“…Electrochemical routes have been shown to be powerful methods for synthesis of metal oxides and oxyhydroxides nanostructures and more recent improvements in the methodologies have demonstrated the potential to control the composition and/or morphological features in the absence of adsorbing capping agents. [23][24][25][26] The purpose of this short review is to highlight some of new electrochemical methods of synthesis of metal oxides and oxyhydroxide nanomaterials. It does not aim to cover all the methods of synthesis but to provide a personal view of notable methods that, given their advantages, could potentially be commercialized.…”