| Title |
Improved photocatalytic water splitting activity of highly porous WO3 photoanodes by electrochemical H+ intercalation / |
| Authors |
Levinas, Ramūnas ; Tintaru, Natalia ; Murauskas, Tomas ; Cesiulis, Henrikas |
| DOI |
10.3389/fceng.2021.760700 |
| Full Text |
|
| Is Part of |
Frontiers in chemical engineering.. Lausanne : Frontiers Media SA. 2021, vol. 3, art. no. 760700, p. [1-17].. eISSN 2673-2718 |
| Keywords [eng] |
water splitting ; WO3 films ; photocatalyst ; photoelectrochemical reaction |
| Abstract [eng] |
In this study, WO3 films of up to 3.9 μm thickness were obtained by galvanostatic anodization of tungsten foil in a neutral-pH Na2SO4 and NaF electrolyte, also containing a NaH2PO2 additive (to suppress O2 accumulation on the pore walls). Additionally, the WO3 photoanodes were modified by applying a cathodic reduction (H+ intercalation) and anodic activation treatment in-situ. XPS spectra revealed that intercalation modifies WO3 films; the amount of W5+-O and O-vacancy bonds was increased. Furthermore, subsequent activation leads to a decrease of the W5+ signal, but the amount of O-vacancy bonds remains elevated. The as-prepared and reduced (intercalated & activated) films were tested as OER photoanodes in acidic 0.1 M Na2SO4 media, under illumination with a 365 nm wavelength LED. It was observed that thinner films generated larger photocurrents. The peculiarities detected by XPS for reduced films correlate well with their improved photocatalytic activity. Photo-electrochemical impedance and intensity modulated photocurrent spectroscopies were combined with steady-state measurements in order to elucidate the effects of H+ intercalation on photoelectrochemical performance. The reduction results in films with enhanced photoexcited charge carrier generation/separation, improved conductivity, and possibly even suppressed bulk recombination. Thus, the intercalation & activation adopted in this study can be reliably used to improve the overall activity of as-synthesized WO3 photoanodes, and particularly of those that are initially poorly photoactive. |
| Published |
Lausanne : Frontiers Media SA |
| Type |
Journal article |
| Language |
English |
| Publication date |
2021 |
| CC license |
|
