Novel tree-like WO 3 nanoplatelets with very high surface area synthesized by anodization under controlled hydrodynamic conditions

Abstract

In the present work, a new WO 3 nanostructure has been obtained by anodization in a H 2 SO 4 /NaF electrolyte under controlled hydrodynamic conditions using a Rotating Disc Electrode (RDE) configuration. Anodized samples were analyzed by means of Field Emission Scanning Electronic Microscopy (FE-SEM), Confocal Raman Microscopy and photoelectrochemical measurements. The new nanostructure, which consists of nanoplatelets clusters growing in a tree-like manner, presents a very high surface area exposed to the electrolyte, leading to an outstanding enhancement of its photoelectrochemical activity. Obtained results show that the size of nanostructures and the percentage of electrode surface covered by these nanostructures depend strongly on the rotation velocity and the electrolyte composition.

Fabrication of Ordered and High-Performance Nanostructured Photoelectrocatalysts by Electrochemical Anodization: Influence of Hydrodynamic Conditions

“…For example, tree-like globular clusters of WO 3 nanoplatelets were obtained in a 1.5 M H 2 SO 4 + 0.1 M NaF electrolyte and at different rotation velocities of the RDE. Figure 9 shows the FE-SEM images of the samples anodized in that electrolyte at different rotation velocities (0 and 375 rpm) [23,58]. It can be observed that in both cases, the nanostructures formed on the tungsten surface presented nanoplatelet morphology, as other authors reported when anodizing in similar acid electrolytes [53-55, 57, 58].…”

“…This decrease has been associated with the formation of a compact WO 3 layer on the electrode surface[19,23,58,60]. Subsequently, current density started increasing, indicating the dissolution of the WO 3 layer due to the effect of H + and F −[23,58,61]. This dissolution process resulted in the release of soluble cationic species, such as WO2 2+ (or [W(OH) 4 (H 2 O) 4 ] 2+ in its hydrated form) or [WF n ]…”

Highly Crystalline WO3 Nanoparticles Are Nontoxic to Stem Cells and Cancer Cells

“…In this way, 0D (dots), 1D (rods, whiskers, and fibres), 2D (plates, films), or 3D (large particles, blocks) WO 3 materials can be synthesized. Various types of nanostructured tungsten oxide have been reported, from simple, spherical nanoparticles [34] to WO 3 -based aerogel networks [35], quantum dots [36][37][38][39], nanostructured films [40] (including nanoplate films [41], nanorod films [42], honeycomb-structured films [43], and mesoporous films [44]), nanobelts [45], nanofibres [46], nanowires [30,46,47], bundle-like nanowires [30,48], nanonetworks [49], hollow spheres [50], macroporous spheres [51], wedge-like architectures [52], nanorods [53,54], nanocuboids [34], square nanoplates [55], nanosheets [56], nanoleaves [57], and urchin-like [30,58], flower-like [59][60][61], and tree-like nanostructures [62,63], etc.…”

A simple method to fabricate high-performance nanostructured WO3 photocatalysts with adjusted morphology in the presence of complexing agents

“…Besides, WO3 can also absorb a part of the visible rays of the solar spectrum (its band-gap is Eg ≈ 2.6 eV, which corresponds approximately to a wavelength of ∼480 nm) [1][2][3][4]. Tungsten trioxide has been employed in technologically advanced fields, such as photoelectrochemistry and photodegradation of organic pollutants [4][5][6][7][8][9][10][11][12][13][14], dye-sensitized solar cells [15], gas sensors [16] or electrochromic devices [17][18][19].…”