Composites Based on Electrodeposited WO[sub.3] and TiO[sub.2] Nanoparticles for Photoelectrochemical Water Splitting
Photoelectrochemically active WO[sub.3] films were fabricated by electrodeposition from an acidic (pH 2), hydrogen-peroxide-containing electrolyte at −0.5 V vs. SCE. WO[sub.3]-TiO[sub.2] composites were then synthesized under the same conditions, but with 0.2 g/L of anatase TiO[sub.2] nanoparticles...
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Veröffentlicht in: | Materials 2024-10, Vol.17 (19) |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | Photoelectrochemically active WO[sub.3] films were fabricated by electrodeposition from an acidic (pH 2), hydrogen-peroxide-containing electrolyte at −0.5 V vs. SCE. WO[sub.3]-TiO[sub.2] composites were then synthesized under the same conditions, but with 0.2 g/L of anatase TiO[sub.2] nanoparticles (⌀ 36 nm), mechanically suspended in the solution by stirring. After synthesis, the films were annealed at 400 °C. Structural characterization by XRD showed that the WO[sub.3] films exhibit the crystalline structure of a non-stoichiometric hydrate, whereas, in WO[sub.3]-TiO[sub.2], the WO[sub.3] phase was monoclinic. The oxidation of tungsten, as revealed by XPS, was W[sup.6+] for both materials. Ti was found to exist mainly as Ti[sup.4+] in the composite, with a weak Ti[sup.3+] signal. The efficiency of the WO[sub.3] films and composites as an oxygen evolution reaction (OER) photo-electrocatalyst was examined. The composite would generate approximately three times larger steady-state photocurrents at 1.2 V vs. SCE in a neutral 0.5 M Na[sub.2]SO[sub.4] electrolyte compared to WO[sub.3] alone. The surface recombination of photogenerated electron–hole pairs was characterized by intensity-modulated photocurrent spectroscopy (IMPS). Photogenerated charge transfer efficiencies were calculated from the spectra, and at 1.2 V vs. SCE, were 86.6% for WO[sub.3] and 62% for WO[sub.3]-TiO[sub.2]. Therefore, the composite films suffered from relatively more surface recombination but generated larger photocurrents, which resulted in overall improved photoactivity. |
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ISSN: | 1996-1944 1996-1944 |
DOI: | 10.3390/ma17194914 |