3D Vanadium Oxide Inverse Opal Growth by Electrodeposition

Abstract

Three-dimensional vanadium pentoxide (V 2 O 5 ) material architectures in the form of inverse opals (IOs) were fabricated using a simple electrodeposition process into artificial opal templates on stainless steel foil using an aqueous solution of VOSO 4 .χH 2 O with added ethanol. The direct deposition of V 2 O 5 IOs was compared with V 2 O 5 planar electrodeposition and confirms a similar progressive nucleation and growth mechanism. An in-depth examination of the chemical and morphological nature of the IO material was performed using X-ray crystallography, X-ray photoelectron spectroscopy, Raman scattering and scanning/transmission electron microscopy. Electrodeposition is demonstrated to be a function of the interstitial void fraction of the artificial opal and ionic diffusivity that leads to high quality, phase pure V 2 O 5 inverse opals is not adversely affected by diffusion pathway tortuosity. Methods to alleviate electrodeposited overlayer formation on the artificial opal templates for the fabrication of the porous 3D structures are also demonstrated. Such a 3D material is ideally suited as a cathode for lithium ion batteries, electrochromic devices, sensors and for applications requiring high surface area electrochemically active metal oxides. The growth in portable electronics and the need for cleaner energy solutions has led to the rising interest in materials research and energy storage material architectures that may help drive advancement in energy storage technologies to mitigate current issues in some energy storage materials and batteries such as capacity fading and lower life times, for example. [1][2][3][4] In recent years, three-dimensional (3D) material architectures 5 have become a particularly attractive approach to achieving significant improvements in charge rate performance, maintenance of specific capacity and opportunities for higher power density supercapacitors. [6][7][8][9] For this reason, the development of synthesis routes for the fabrication of three-dimensional nanostructured active materials onto metallic current collector substrates is important. [10][11][12][13] Electrodeposition is a particularly facile route for the formation of metal and metal oxide films on a variety of conductive substrates and has recently gained a lot of attention for synthesising three-dimensional materials when combined with templates and sacrificial architecture-directing structures. [14][15][16][17] Vanadium pentoxide is a particularly attractive replacement cathode material with its mixed valence, V 4+ and V 5+ , making it an ideal candidate for a large number of redox-dependent applications. 23-26 While the lattice structure is theoretically maintained upon mild intercalation, phase changes are known to occur and the interlayer van der Waals spacing characteristic of its layered orthorhombic crystal structure can become deformed at lower voltages (higher Li mole fraction). 27,28 Large particle sizes can also limit the solid state diffusional rate of cation insertion. The growth of a porous, thre...

The Influence of Colloidal Opal Template and Substrate Type on 3D Macroporous Single and Binary Vanadium Oxide Inverse Opal Electrodeposition

“…7,25,32,42 The IO materials were electrodeposited into PS sphere templates on stainless-steel (SS) foil substrates and also on fluorine-doped tin oxide (FTO) coated glass under potentiostatic conditions at a range of voltages, and the respective chronoamperograms are shown in Fig. 1a.…”

“…The slightly reduced charge passed on FTO corresponds to a lower overall current during the diffusion-limited growth phase. The theoretical electrodeposited mass was also calculated by integration of the total charge passed assuming an n = 1 reaction 25 are also plotted in Fig. 3.…”

“…25,36 To date, a wide range of nanostructured V 2 O 5 mate- * Electrochemical Society Member. z E-mail: c.odwyer@ucc.ie rials (including nanowires, nanorods, etc.…”

“…25,61 The tortuosity in opals was previously examined experimentally and also from computational analysis and shown to be nearly negligible in thick inverse opals already soaked in electrolyte, formed using 350 nm spheres onto a heated-SS substrate. Figure 7a shows the D fcc values determined in the framework of the Cottrell relation under potentiostatic conditions, where the current indicates the resulting reduction and V 2 O 5 growth rate.…”

2D and 3D photonic crystal materials for photocatalysis and electrochemical energy storage and conversion

“…To overcome this, the use of 3D structured current collectors was posited to keep ion and electron diffusion distances as small as possible; an influence that can be rationally tuned and tested with this design. [110,111]…”