Photocatalytically Activeγ-WO3 Films from Atmospheric Pressure CVD of WOCl4 with Ethyl Acetate or Ethanol

Synthesis of a highly reactive form of WO2Cl2, its conversion into nanocrystalline mono-hydrated WO3 and coordination compounds with tetramethylurea

A new form of WO₂Cl₂ was prepared from WCl₆. Conversion of WO₂Cl₂ into nanocrystalline WO₃·H₂O occurred upon air exposure at room temperature. The first coordination complexes of WO₂Cl₂ with an alkylurea are reported.

Towards highly efficient photoanodes: boosting sunlight-driven semiconductor nanomaterials for water oxidation

Harvesting energy directly from sunlight is a very attractive and desirable way to solve the rising energy demand. In the past few decades, considerable efforts have been focused on identifying appropriate materials and devices that can utilize solar energy to produce chemical fuels. Among these, one of the most promising options is the construction of a photoelectrochemical (PEC) cell that can produce hydrogen fuel or oxygen from water. Significant advancement in the understanding and construction of efficient photoanodes to improve performance has been accomplished within a short period of time owing to various newly developed ideas and approaches, including facilitating charge transportation in narrow band gap semiconductors or doping in wide band gap semiconductors for enhancing visible-light absorption; electrocatalysts for decreasing overpotentials; controlling the morphology of the materials for enhancing light absorption and shortening the transfer distance of minority carriers; and other methods such as using heterojunction structures for band-structure engineering, sensitization, and passivating layers. In this review, we focus on the recent developments of some promising visible-light active photoanode materials with high PEC performance, such as BiVO4, α-Fe2O3, WO3, TaON, and Ta3N5.

Partially fluorinated oxo-alkoxide tungsten(vi) complexes as precursors for deposition of WOx nanomaterials

Volatile partially fluorinated tungsten(vi) oxo-alkoxides yield tungsten oxide nanorods upon chemical vapour deposition.

Growth and characterization of stoichiometric tungsten oxide nanorods by thermal evaporation and subsequent annealing

Stoichiometric tungsten oxide (WO(3)) nanorods are synthesized on tungsten (W) substrates by a high-temperature, catalyst-free, physical deposition process and by subsequent annealing in oxygen atmosphere. Tungsten oxide nanorods are grown by thermal evaporation of WO(3) powder at elevated temperature in a tube furnace. XRD, TEM and XPS analysis shows that the as-grown nanorods are single crystalline and non-stoichiometric (WO(x)). Annealing of WO(x) nanorods at 700 °C under oxygen atmosphere has led to the formation of stoichiometric WO(3) as evidenced by XRD, XPS and Raman analysis.

WO3 thin films for photoelectrochemical purification of water

Tungsten trioxide thin films on transparent substrates (glass and F:SnO(2) or ITO-coated glass) were prepared by layer-by-layer brush painting and spin-coating using organic precursors. Well-crystallized WO(3) with monoclinic structure was formed on all substrates after annealing at 500 degrees C or above. The dense semiconducting films are specular and transparent outside the band-gap. Their photoactivity in junctions with aqueous electrolytes extends up to 470 nm, with incident photon to current conversion efficiencies around 0.9 at 313 nm and up to 0.1 at 436 nm. Films of 10 cm x 10 cm were used for the study of solute degradation reactions in a thin-film reactor under backside illumination. Dilute aqueous solutions of model substances for contaminants like oxalic acid were decomposed under continuous flow using broadband UVA illumination and electrical bias. Operation under solar illumination was also feasible. The advantage over operation without bias (conventional photocatalysis) prevailed for all decomposition reactions studied.