Morphology–photoactivity relationship: WO 3 nanostructured films for solar hydrogen production

Improving Photoelectrochemical Properties of Anodic WO3 Layers by Optimizing Electrosynthesis Conditions

“…On the other hand, Chin Wei Lai [10] studied the performance of WO 3 photoanodes electrochemically synthesized in electrolytes with various F − contents and confirmed an enhanced efficiency of well-developed nanotubular films under solar illumination compared to irregular nanoporous layers. Mohamed et al [27] compared photoelectrochemical performance of WO 3 nanoporous films with nanoflakes and found that the latter exhibit superior properties after annealing at 500 • C. Table 1 shows a comparison of photoelectrochemical properties (photocurrent densities) of anodic tungsten oxide obtained by anodization in various electrolytes. It is clearly seen that it is difficult to compare those values because different types and intensities of light sources, supporting electrolytes, and polarization of photoanodes were used.…”

“…On the other hand, Chin Wei Lai [ 10 ] studied the performance of WO 3 photoanodes electrochemically synthesized in electrolytes with various F − contents and confirmed an enhanced efficiency of well-developed nanotubular films under solar illumination compared to irregular nanoporous layers. Mohamed et al [ 27 ] compared photoelectrochemical performance of WO 3 nanoporous films with nanoflakes and found that the latter exhibit superior properties after annealing at 500 °C.…”

10-fold enhancement in light-driven water splitting using niobium oxynitride microcone array films

“…Owing to their exceptional stability, semiconducting properties, abundance and low cost, metal oxides have been extensively explored over the past few decades as photo electrodes for solardriven fuel production in photo electrochemical cells (PEC) [1][2][3][4][5][6]. However, the long-standing bottleneck is the fact that metal oxides are wide band gap materials, with limited absorption activity to the ultraviolet spectral region, which contains only 3-5% of the incident solar energy.…”

“…However, the structured metal oxide systems demonstrated to date are still circumscribed by the minimal visible light absorption, which can be expounded predictably based on the fact that the valence bands of oxide semiconductor materials are mainly formed by O 2p orbitals, which are fixed at an extremely positive level of around 3.0 V vs. the normal hydrogen electrode (NHE) [8]. Moreover, the oxides with narrow band gaps (o3.0 eV), for instance, Fe 2 O 3 and WO 3 , are either suffering from the stability issues or the improper alignment of band levels necessary for water splitting and, therefore, require large external bias [2].…”

The Use of Anodic Oxides in Practical and Sustainable Devices for Energy Conversion and Storage

“…Nanoporous WO 3 photoanodes were produced from anodization of high-purity W foils via potentiostatic [ 20 , 51 ] or pulsed methods [ 21 ]. The applied potential varied from 40 to 50 V, and the anodization time varied from 30 min to 20 h. Different electrolytes were employed: glycerol + NH 4 F aqueous solution [ 20 ]; (NH 4 ) 2 SO 4 + NH 4 F solution [ 21 ]; H 2 SO 4 + NaF solution [ 51 , 69 ]; K 2 HPO 4 /glycerin-based solutions [ 70 , 71 ]. Annealing for oxide crystallization was performed at 400–500 °C for 2–3 h [ 20 , 21 ].…”