Improving Photoelectrochemical Properties of Anodic WO3 Layers by Optimizing Electrosynthesis Conditions

Abstract

Although anodic tungsten oxide has attracted increasing attention in recent years, there is still a lack of detailed studies on the photoelectrochemical (PEC) properties of such kind of materials grown in different electrolytes under various sets of conditions. In addition, the morphology of photoanode is not a single factor responsible for its PEC performance. Therefore, the attempt was to correlate different anodizing conditions (especially electrolyte composition) with the surface morphology, oxide thickness, semiconducting, and photoelectrochemical properties of anodized oxide layers. As expected, the surface morphology of WO3 depends strongly on anodizing conditions. Annealing of as-synthesized tungsten oxide layers at 500 °C for 2 h leads to obtaining a monoclinic WO3 phase in all cases. From the Mott-Schottky analysis, it has been confirmed that all as prepared anodic oxide samples are n-type semiconductors. Band gap energy values estimated from incident photon−to−current efficiency (IPCE) measurements neither differ significantly for as−synthesized WO3 layers nor depend on anodizing conditions such as electrolyte composition, time and applied potential. Although the estimated band gaps are similar, photoelectrochemical properties are different because of many different reasons, including the layer morphology (homogeneity, porosity, pore size, active surface area), oxide layer thickness, and semiconducting properties of the material, which depend on the electrolyte composition used for anodization.

Ultrafast Microwave Synthesis of WO3 Nanostructured Films for Solar Photocatalysis

“…[ 88 ] In fact, it has been reported that WO 3 materials exhibit donor densities in the range of 10 19 –10 22 cm −3 , in accordance with the results obtained. [ 88 ] When comparing both materials, the N D values are in the same range with a slight difference between both conditions, which can be related to the similar photocatalytic behavior observed.…”

Improved Photocatalytic Water Splitting Activity of Highly Porous WO3 Photoanodes by Electrochemical H+ Intercalation

“…Moreover, the morphological, structural, and even photocatalytic properties of WO 3 films can be improved with the use of certain additives/complexing agents during anodization (Fernández-Domene et al, 2017). Fluoride is widely used, and it is known to increase the rate of dissolution of the W 2 O 5 intermediate and WO 3 , which typically has an effect on the morphology of the pores (Karastoyanov and Bojinov, 2008;Zych et al, 2020).…”

Improving the photoelectrochemical performance of porous anodic SnO x films by adjusting electrosynthesis conditions

“…1 Moreover, the field of nanomaterials synthesized via the electrochemical processes is still continuously growing both in terms of the development of electrosynthesis methods as well as applications of electrochemically generated nanostructures. 1 Up to now, many different metals have been successfully anodized to obtain nanostructured oxides including aluminum, 2-4 titanium, 5,6 tungsten, 7,8 copper, 9 zinc, 10,11 iron, 12,13 tin, [14][15][16] and many others. 17 Among many different applications of anodic metal oxides, particular attention is put on semiconducting nanostructures that can be used in modern energy conversion systems, like photovoltaic (PV), 18,19 photocatalytic (PC), and photoelectrochemical (PEC) devices.…”

“…Moreover, the field of nanomaterials synthesized via the electrochemical processes is still continuously growing both in terms of the development of electrosynthesis methods as well as applications of electrochemically generated nanostructures 1 . Up to now, many different metals have been successfully anodized to obtain nanostructured oxides including aluminum, 2‐4 titanium, 5,6 tungsten, 7,8 copper, 9 zinc, 10,11 iron, 12,13 tin, 14‐16 and many others 17 …”