Enhanced Photocatalytic Water Splitting on Very Thin WO₃ Films Activated by High-Temperature Annealing

Abstract

Further advancement in sunlight-driven splitting of water as a means of producing hydrogen and oxygen is mainly hampered by the availability of easy-to-prepare, inexpensive n-type semiconductor materials able to operate as stable and efficient photoanodes in a water photoelectrolysis cell. Here, we demonstrate that photocatalytic water oxidation currents on thin-layer semitransparent WO 3 electrodes, deposited by using a one-step sol−gel method on conductive oxide F-SnO 2 substrates, are dramatically improved following additional highertemperature (ca. 700 °C) annealing. Largely reduced recombination of charge carriers photogenerated in activated WO 3 associated with enhanced light absorption yields at 1.23 V vs RHE, under simulated solar AM 1.5G irradiation (100 mW cm −2 ), water photo-oxidation currents close to 4.2 mA cm −2 on a 1.2-μmthick photoanodeapproximately 2 times larger than on the electrodes of the same thickness only annealed at 550 °C. The relative enhancement of the photocurrent induced by the further annealing at 700 °C scaled up with decreasing the film thickness with a 3-fold increase observed for the thinnest tested, 0.25-μm-thick WO 3 electrode that reaches 2.75 mA cm −2 . We obtained such high photocatalytic water splitting performance without depositing any additional water oxidation catalyst.

On‐Site Detection for Hazardous Materials in Chemical Accidents

“…In the past decade, tungsten oxides (WO 3 ) have been extensively studied as one of the research hotspots in nanoanalytical technology due to their physicochemical properties leading to numerous gas‐sensing applications 103 . There are reports on the synthesis of WO 3 with different physicochemical properties—ultrathin WO 3 nanodisks utilizing long‐chain poly(ethylene glycol), 104 different crystallographic and morphologic structures of WO 3 by hydrothermal synthesis at 180 °C, 105 and WO 3 films on F‐SnO 2 substrates, 106 another author reported the preparation of nanocomposites as WO 3 :polyaniline with different weight ratios 107 . Specially, the WO 3 nanorods coated on the surface of tapered fiber led to a microfiber interferometer NH 3 gas sensor 25 .…”

Insights into the Nature of the Active Sites of Pt-WOx/Al2O3 Catalysts for Glycerol Hydrogenolysis into 1,3-Propanediol

“…These results, together with the study of in situ titrants, i.e., 2,6-di-tert-butylpyridine or pyridine, were used to gain insights into the nature of the bifunctional active sites leading to the selective hydrogenolysis of glycerol into 1,3-PDO. The stability study of Pt nanoparticles and polytungstates in the aqueous-phase reaction environment [21,22] was beyond the scope of this article.…”

Self‐Assembled Urchin‐Like CuWO4/WO3 Heterojunction Nanoarrays as Photoanodes for Photoelectrochemical Water Splitting

“…[4,5] Hence, exploring efficient photoanode materials toward oxygen evolution reaction (OER) are essential to for PEC water splitting. The single metal oxides, such as ZnO, [6] TiO 2, [7,8] α-Fe 2 O 3 [9,10] and WO 3, [11,12] have been extensively investigated as photoanodes. However, their measured performance towards PEC water oxidation is still far from satisfaction as a result of the inherent defects.…”