Presence Of WO3 Research Articles

Enhancing corrosion resistance and mechanical properties of laser-direct energy deposited 316 stainless steel via W addition

Additions of 1–5 wt% W element enhanced corrosion resistance and mechanical properties of LDED-316 SS. Microstructure characterized the grain refinement and precipitation of ferrite and W-Mo carbides. Mechanical tests showed enhanced tensile strength and hardness of 316–5 W by 37.4% and 30.8%, respectively. Electrochemical tests indicated an increasing pitting potential and polarization resistance of 316–3 W in 3.5 wt% NaCl solution by 0.535 VSCE and 1679 kΩ·cm2, respectively. Corrosion morphology showed the preferential dissolution of ferrite and W-Mo carbides rather than austenite cell. The change in corrosion processes and presence of WO3 in the passivation film significantly contributed corrosion resistance.

Nanofibers based on zein protein loaded with tungsten oxide for cancer therapy: fabrication, characterization and in vitro evaluation

Plant proteins have become attractive for biomedical applications such as wound dressing and drug delivery. In this research, nanofibers from pristine zein (plant protein) and zein loaded with tungsten oxide (WO3) were prepared (WO3@zein) using less toxic solvents (ethanol and acetic acid). Morphological and biological properties of the zein nanofiber were determined. Prepared nanofibers were defined by thermogravimetric analysis (TGA), X-ray diffraction (X-RD), Fourier-transform infrared spectroscopy (FT-IR), and scanning electron microscopy. The average fiber diameter was unchanged with an increase in WO3 concentration from 0.001 to 0.008%. FT-IR spectroscopy and X-RD indicated the presence of WO3 in WO3@zein nanofibers. In comparison to WO3-free, WO3@zein nanofibers showed higher safety and preserved the anticancer effect of WO3 against human melanoma cell line (A375) melanoma cells compared to WO3-free. Moreover, both WO3-free and WO3@zein caused a fourfold increase in the cellular proliferation of reactive oxygen species (ROS) in the treated A375 cells compared to untreated cells. ROS elevation led to apoptosis-dependent cell death of A375 cells as evidenced by up-regulating the expression of p53-downstream genes (p21 and Bax) (tumor-suppressor gene) while down-regulating the expression of key oncogenes (BCL2 and cyclin D). In conclusion, the prepared nanofiber represents a promising and safe candidate for anticancer applications.

Improved photocatalytic activity of zinc oxide through the formation of novel ternary tungsten trioxide/carbon nanotube/zinc oxide composite photocatalyst

This study aimed to resolve the inherent limitation of zinc oxide (ZnO) and produce a highly efficient photocatalyst through the formation of a novel ternary tungsten trioxide (WO3)/carbon nanotubes (CNT)/ZnO composite photocatalyst via sol-gel and deposition methods. The presence of WO3 and CNT enhances the photocatalytic activity of the ternary composite photocatalyst toward degradation of MB and BSA. The rate and efficiency of the photodegradation were elevated with increasing loading of WO3. This can be ascribed to the lower band gap energy, effective charge separation and charge transfer supplied CNT, and the Z-scheme heterojunction formed in the ternary composite photocatalyst. The highest photodegradation rate was attained by the 11 wt% WO3/CNT/ZnO composite photocatalyst in which a complete degradation of MB and BSA were achieved in 120 and 150 min, respectively. The ternary composite photocatalyst demonstrated a good stability by maintaining at least 95% of MB degradation after four consecutive cycles.

Tungsten(VI) oxide as a versatile support for Pd nanocatalysts for alkaline direct alcohol fuel cells

The instability of carbon support materials has motivated the development of metal oxides supports which are stable under the fuel cell environment. In this study, tungsten (VI) oxide (WO3) is utilized as a secondary support and cocatalyst for the electrooxidation of methanol and ethanol. Functionalized carbon nanodots employed as primary supports were blended with WO3 nanoparticles to form a composite support onto which Pd nanoparticles were deposited by a borohydride reduction method. The synthesized Pd/fCNDs-WO3 electrocatalysts were characterized by Transmission Electron microscopy (TEM), X-ray diffractometry (XRD) and X-ray photoelectron spectroscopy. XRD results proved that incorporating WO3 into Pd/fCNDs electrocatalyst shifts the Pd diffraction peaks to lower 2Ɵ value due to lattice relaxation. XPS results revealed that W exist in oxidised form and confirmed the strong interaction between the support material and the catalyst. The Pd/fCNDs-WO3 electrocatalysts exhibited a remarkable catalytic activity towards methanol and ethanol oxidation. High current densities of 87.24 mA cm−2 and 44.23 mA cm−2 were obtained for ethanol and methanol oxidation, respectively, using a catalyst with 2.5% Pd loading. EIS, CA and stability tests revealed that the presence of WO3 in Pd/fCNDs electrocatalyst improves the kinetics, tolerance to poisoning and long-term durability in alkaline conditions. This superior performance is attributed to the electronic coupling between Pd and WO3 nanoparticles.

Catalytic and time stability effects of photocatalysts on ozone production of a surface dielectric barrier discharge in air

We investigated the effect of various photocatalysts - titanium, zinc, barium, and tungsten oxides on ozone generation of the surface dielectric barrier discharge in air. The layers of these catalysts were deposited on the side of the glass plate opposite the active electrode so that the emission from the discharge irradiated them. We found that TiO2, ZnO, and BaTiO3 catalysts increase the concentration of ozone generated by the discharge. On the other hand, the presence of WO3 in the discharge does not affect the ozone concentration. All these catalysts show no substantial effect on the electrical parameters of the discharge.

Fabrication of Cu2MoS4 decorated WO3 nano heterojunction embedded on chitosan: Robust photocatalytic efficiency, antibacterial performance, and bacteria detection by peroxidase activity.

In this study, the Cu2MoS4/WO3 supported on chitosan was prepared by precipitation method, and applied to photocatalyst, antibacterial agent and biosensor. The presence of WO3 and Cu2MoS4 crystals were confirmed by XRD analysis. The elemental information was investigated by EDS. FTIR spectra shows the presence of chitosan in nanocomposites. The as-synthesized Cu2MoS4/WO3/Chitosan nanocomposites has a bandgap of 2.18eV and it is effective for visible light condition. The average particle size of the Cu2MoS4/WO3/Chitosan is 71nm. The photocatalysis activity Cu2MoS4/WO3/Chitosan was higher than Cu2MoS4 or WO3.The Cu2MoS4/WO3/Chitosan nanocomposites shows the highest efficiency (100%) in photocatalysis degradation of dye under visible light irradiation in 80min. The •O2- plays a main role in degradation process. The as-synthesized Cu2MoS4/WO3/Chitosan nanocomposites depicted the antibacterial activity toward G+/- bacteria. Determination of enterococcus faecalis is important for human health. The DNA template was used to the Cu2MoS4/WO3/Chitosan nanocomposites and applied in detection of enterococcus faecalis by H2O2 and 3,3',5,5' -tetramethylbenzidine in peroxidase like activity. The detection limit of enterococcus faecalis by DNA-Cu2MoS4/WO3/Chitosan in peroxidase-like catalysis was about 55CFU/mL. Therefore, the Cu2MoS4/WO3/Chitosan can be applied in the photocatalysis, bactericidal and peroxidase process.

Facile Hydrothermal Synthesis of Tungsten Tri-oxide/Titanium Di-oxide Nanohybrid Structures as Photocatalyst for Wastewater Treatment Application

In this study, tungsten trioxide/titanium dioxide (WO3–TiO2) nanohybrid structures were prepared using a facile hydrothermal method. The nanosheets-like morphology was achieved for the prepared WO3–TiO2 nanohybrid that were confirmed by scanning electron microscopy. Provided X-ray photoelectron spectroscopy results also confirm the element existence and surface composition of the nanohybrid structure. The optical properties of the WO3–TiO2 nanohybrid were verified using UV–Visible diffuse reflectance spectroscopy (UV–Vis DRS) and photoluminescence spectroscopy. The UV–Vis DRS results indicated that the absorption edge for the WO3–TiO2 nanohybrid found a red shift towards the visible region due to the reduced bandgap (2.83 eV). The photocatalytic activity of the as-prepared WO3–TiO2 nanohybrid was evaluated by the photocatalytic degradation of Orange G dye in wastewaters under visible light. 94% Orange G dye was degraded in 210 min at neutral pH in the presence of WO3–TiO2 nanohybrid, which indicates the enhanced photocatalytic activity. The photo-luminescence technique has also confirmed the formation of –OH radicals during photodegradation by utilizing terephthalic acid as a probe molecule. These results indicate that the prepared nanohybrid material is a simple, low-cost, and efficient photocatalyst for the degradation of pollutants in wastewater treatment applications.

Plasma-catalytic Efficiency on the Discolouration of Sunset Yellow FCF in a Glidarc Plasma Reactor in Presence of WO₃ Used as Catalyst

In this work, we highlight the plasma-catalytic effect of gliding arc discharge on the bleaching of azo dye sunset yellow FCF in aqueous solution. The effect has been studied in the presence of tungsten oxide as a catalyst in the glidarc reactor. The catalyst has been synthesized via acid precipitation process. The product obtained was characterized by X-ray powder diffraction (XRD), Fourier Transform Infrared (FTIR) and Nitrogen Physisorption. The results showed firstly monoclinic structure of WO3 catalyst. The maximum bleaching rates obtained are 17% and 52.5% after 30 min for initial dye concentration of 25 mg.L-1 for plasma alone and plasma-catalyst, respectively. These results have clearly shown that gliding arc discharge has a double effect, in on hand as a source of hydroxyl radical and on other hands as a source of radiation able to excite the catalyst. The effects of initial pH and photocatalyst loading have been studied.

The influence of the addition of tungsten trioxide nanoparticle size on structure, thermal, and electroactivity properties of hybrid material–reinforced PANI

Nanomaterials are synthetized by aniline with different contents of WO3 nanoparticles using a chemical oxidative polymerization method. FTIR, ultraviolet–visible, XPS, SEM, and XRD confirmed the successful synthesis of the three PANI@WO3 samples. Thermogravimetric analysis shows an improved thermal stability by the presence of WO3 in nanocomposites compared with PANI. Interestingly, the analysis of the band gap shows lowest value of optical band gap of 1.88 eV for PANI@WO3 (0.5) compared with PANI@WO3 (1.0) and PANI@WO3 (1.5) with 1.91 eV and 1.98 eV, respectively. In addition, the electroactivity properties were investigated by cyclic voltammetry to explore the benefits of these types of hybrid materials in electrochemical applications.

Investigation of the applicability of TiO2, BiVO4, and WO3 nanomaterials for advanced photocatalytic membranes used for oil‐in‐water emulsion separation

AbstractIn the present study, a commercial TiO2, several BiVO4 photocatalysts, a WO3 nanomaterial, and their composites were used to prepare photocatalytic polyvinylidene fluoride (PVDF) ultrafilter membranes. Their photocatalytic activities and the effects of coatings on the filtration of oil‐in‐water emulsion (crude oil; coil = 100 mg L−1) were investigated. Fluxes, filtration resistances, purification efficiencies, and fouling resistance abilities—like flux decay ratios (FDRs) and flux recovery ratios (FRRs)—were compared. The solar light‐induced photocatalytic decomposition of the foulants was also investigated. WO3 was used as a composite component to suppress the electron–hole recombination with the goal of achieving higher photocatalytic activity, but the presence of WO3 was not beneficial concerning the filtration properties. However, the application of TiO2, one of the investigated BiVO4 photocatalysts, and their composites was also beneficial. In the case of the neat membrane, only 87 L m−2 h−1 flux was measured, whereas with the most beneficial BiVO4 coating, 464 L m−2 h−1 flux was achieved. Pure BiVO4 coating was more beneficial in terms of filtration properties, whereas pure TiO2 coating proved to be more beneficial concerning the photocatalytic regeneration of the membrane. The TiO2(80%)/BiVO4(20%) composite was estimated to be the most beneficial combination taking into account both the aspects of photocatalytic activity and filtration properties.

Fabrication of WO3–reduced graphene oxide (WO3–G) nanocomposite for enhanced optical and electrical properties

We report an easy and efficient route for the preparation of WO3–G nanocomposites via a one-pot microwave-assisted method. The changes induced by the addition of graphene oxide (GO) on surface morphology, microstructure, thermal, optical, and electrical properties of the composite were investigated. The crystallographic structure and phase composition were confirmed by X-ray diffraction analysis. Fourier transform-infrared spectroscopy results indicate the presence of WO3 and reduced graphene oxide (rGO) in composites and field emission scanning electron microscopy results confirm the growth of WO3 nanoparticles on reduced graphene oxide sheets. Raman measurements show a decrease of carbon–oxygen functional groups and an increase in graphitic carbon content leading to the reduction of graphene oxide in the composites. UV–Vis diffuse reflectance spectroscopy and Photoluminescence spectroscopy were used to study the optical properties. Thermogravimetric analysis results revealed the higher thermal stability of WO3–G nanocomposites. The frequency-dependent dielectric properties of WO3 nanoparticles and WO3–G nanocomposites at various temperatures were investigated and compared. WO3–G nanocomposites exhibited high dielectric constant and low dielectric loss with a decrease in frequency and an increase in the temperature. The Cole–Cole analysis confirmed that WO3–G nanocomposites have better conductivity and show non-Debye-type relaxation in the applied frequency range. The results showed that WO3–G nanocomposites possess improved optical and electrical properties, which would be promising for practical applications in future nanotechnology.

Tungsten oxide modified AlTUD-1 mesoporous acid catalyst for synthesis of thiazole aryl imines and phenylhydrazones

A non-surfactant route synthesized mesoporous AlTUD-1 (Si/Al = 25) with interconnected porous networks effectively utilized as a support for 10 wt% tungsten oxide (WO3) dispersions. The synthesized WO3/AlTUD-1 catalyst was characterized by different techniques. N2 sorption and XRD studies were confirmed its amorphous mesoporous nature, which measured a pore diameter of 6.4 nm and a surface area of 510 m2 g−1. Presence of WO3 on the pores and silica TUD-1 wormhole structure were evaluated by techniques including DRUV Visible and FT-Raman. The catalyst possessed both Lewis (L) and Bronsted (B) acidity, as measured by pyridine adsorbed FT-IR, which is responsible for the catalyst activity. WO3/AlTUD-1 acid catalyst showed an excellent catalytic performance yield of about 80% at 80 °C in reflux condition, for different 1-substituted benzylidene 4-methylbenzo[d]thizole-2-amines (thiazole based aryl imines) and substituted phenylhydrazone compounds.

Insights on the photocatalytic degradation processes supported by TiO2/WO3 systems. The case of ethanol and tetracycline

TiO2/WO3 composites are widely in the literature as engineered systems for photocatalytic and (photo)electrochemical applications, since the presence of WO3 can promote both visible light absorption and electron transfer phenomena of TiO2. The preparation of these system, depending on the preparation method, can also affect the surface feature with respect to TiO2, modifying adsorption and performance, as well as the reaction mechanisms. Here, TiO2/WO3 composites were prepared by precipitation of WO3 onto the TiO2 surface and characterized in terms of their structural, morphological, optical and surface properties. Raman and IR spectroscopy as well as a marked shift in the isoelectric point support the preferential surface location of WO3. Samples were photocatalytically tested towards the degradation of ethanol and of tetracycline and the adsorption and degradation behaviour were studied, suggesting, in both cases, significant variations of the reaction paths by the addition of WO3.

MIL-53 (Fe)-based photo-sensitive composite for degradation of organochlorinated herbicide and enhanced reduction of Cr(VI)

Abstract Highly robust composite photocatalyst (WO3/MIL-53(Fe)) was synthesized and characterised. WO3/MIL-53(Fe) exhibits remarkable photocatalytic efficiency for reduction of Cr(VI) and oxidation of 2,4-dichlorophenoxyacetic acid (2,4-D) organochlorinated herbicide. After 240 min sunlight irradiation, only ∼30% reduction ratio of Cr(VI) was recorded in the presence of WO3. However, about 70% and 94% Cr(VI) reduction were achieved in the presence of MIL-53(Fe) and WO3/MIL-53(Fe), respectively. The removal efficiency proceeds more rapidly in the binary mixture of 2,4-D and Cr(VI) than in the single component system, indicating synergetic effect between the photooxidation and reduction reactions. O2 − played a key role in the reduction of Cr (VI) and h+ is confirmed to be the dominant active species in the degradation of 2,4-D.

Activation of Reduced-Graphene-Oxide Supported Pt Nanoparticles by Aligning with WO3-Nanowires toward Oxygen Reduction in Acid Medium: Diagnosis with Rotating-Ring-Disk Voltammetry and Double-Potential-Step Chronocoulometry

The chemically-reduced graphene-oxide has been used as support to anchor catalytic Pt nanoparticles and, while subsequently modified with tungsten oxide nanowires, has produced a hybrid electrocatalytic system for electroreduction of oxygen in acid medium. Such characteristics of reduced graphene oxide as defective surface and low degree of organization of graphitic structures facilitate dispersion of platinum nanocenters. Further combination with WO3 nanonowires is expected to increase the system's interfacial hydrophilicity and porosity. Most likely WO3 nanostructures are attached mainly to the edges of graphene thus preventing its stacking and creating space for the flux of oxygen and the reaction products. The results of electrochemical diagnostic experiments are consistent with the view that the electrocatalytic activity of the system utilizing tungsten oxide nanowires toward the reduction of oxygen in acid medium has been enhanced even at the Pt loading as low as 30 μg cm−2. Furthermore, the rotating ring-disk electrode voltammetry data is consistent with decreased formation of the undesirable hydrogen peroxide intermediate in the presence of WO3. The conclusions are supported with mechanistic and kinetic studies performed with use of double-potential-step chronocoulometry as an alternative diagnostic tool to rotating ring-disk voltammetry.

WxC-β-SiC Nanocomposite Catalysts Used in Aqueous Phase Hydrogenation of Furfural.

This study investigates the effects of the addition of tungsten on the structure, phase composition, textural properties and activities of β-SiC-based catalysts in the aqueous phase hydrogenation of furfural. Carbothermal reduction of SiO2 in the presence of WO3 at 1550 °C in argon resulted in the formation of WxC-β-SiC nanocomposite powders with significant variations in particle morphology and content of WxC-tipped β-SiC nano-whiskers, as revealed by TEM and SEM-EDS. The specific surface area (SSA) of the nanocomposite strongly depended on the amount of tungsten and had a notable impact on its catalytic properties for the production of furfuryl alcohol (FA) and tetrahydrofurfuryl alcohol (THFA). Nanocomposite WxC-β-SiC catalysts with 10 wt % W in the starting mixture had the highest SSA and the smallest WxC crystallites. Some 10 wt % W nanocomposite catalysts demonstrated up to 90% yield of THFA, in particular in the reduction of furfural derived from biomass, although the reproducible performance of such catalysts has yet to be achieved.

Photo-electrochemical and interfacial-process analysis of WO3 nanostructures supported on TiO2: An approach to BPA oxidation

The photo-electrooxidation of bisphenol A (BPA) at the interface of nanostructured materials of TiO2 and WO3-TiO2 was studied under neutral conditions. The tested materials were synthesized via the sol-gel method, and characterized by X-ray diffraction (XRD), UV–Vis diffuse reflectance spectroscopy (DRS), high-resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscopy (XPS); as well as electrochemical techniques. X-ray diffraction indicated the formation of pure anatase phase and the presence of monoclinic WO3. XRD-HRTEM revealed WO3 nanoparticles of ca. 5nm in diameter and anatase nanoparticles of 14.8–24nm. The XPS analysis confirmed the predominance of WO3 (W6+) and TiO2 (Ti4+) as an heterostructured couple. The semiconductor properties of the synthesized composites were evaluated in 0.1M KCl using cyclic voltammetry, linear sweep voltammetry, chronoamperometry and electrochemical impedance spectroscopy (EIS). The electrochemical analysis confirmed the formation of the tungsten-oxide bronze sites, and it is proposed that WO3–(OH)ads species are responsible of BPA oxidation. The assays using frequency variation demonstrated that both the flat-band potential and the electrical resistance decrease in the presence of WO3. The evaluation from linear voltammetry during illumination in visible-light region confirmed that the better performance for BPA oxidation was with nanostructured WO3-TiO2 obtaining a faster rate of interfacial electron transfer.

Oxidation mechanism of W substituted Mo-Si-B alloys

The oxidation mechanism of a Mo55W15Si15B15 alloy was established, and the effects of W content, oxidation temperature and microstructural length scale were determined. In addition to influencing the oxidation mechanism, the addition of W also destabilized the A15 phase which is consistent with our previous experiments in ternary Mo-W-Si alloys [1]. Microstructural investigation of the oxidized alloy revealed entrapped tungsten oxides at temperatures below 1300 °C, which volatilize above 1400–1500 °C. The presence of WO3 in the oxide scale interrupts the surface coverage by the glassy borosilicate, thereby adversely affecting the oxidation behavior. In order to determine the effects of length scale, the microstructural evolution during the transient oxidation of cast and sintered alloys, with different microstructural length scales, was studied at 1100 and 1400 °C. Finer microstructure promoted faster borosilicate surface coverage at 1400 °C.

Enhanced Low-Temperature Response of PPy-WO3 Hybrid Nanocomposite Based Gas Sensor Deposited by Electrospinning Method For Selective and Sensitive Acetone Detection

In this paper, PPy-WO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> hybrid nanocomposites with different weight percentages of WO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> nanoparticles (5-40%wt) dispersed in polypyrrole (PPy) matrix were prepared and utilized as a new sensing material for acetone detection. PPy-WO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> hybrid nanocomposite were deposited on interdigitated electrode by the electrospinning technique. WO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> nanoparticles and PPy-WO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> nanocomposites sensor were characterized by X-ray diffraction and field emission scanning electron microscopy, respectively. The presence of WO3 in PPy matrix was confirmed by EDAX. The resistance changes of different nanocomposites in exposure to acetone and methanol in three temperature (70 °C, 90 °C, and 110 °C) was tested and the results were compared with polypyrrole-based sensor. It was found that enhanced acetone sensing properties of PPy-WO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> nanocomposite films strongly influenced by the WO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> weight percentage and temperature. Comparing with PPy-based sensor, prepared PPy-WO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> hybrid nanocomposite films exhibit excellent acetone vapor sensing properties at low temperature. The detection limit of PPy-WO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> (20%) hybrid nanocomposite sensor is about 16 times better than PPy sensor and it shows fast response (<; 5 s) toward acetone vapor at operating temperature of 90 °C. As a result, PPy-WO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> hybrid nanocomposite sensor can be a good candidate for high performance acetone detection.

Printable WO3 electron transporting layer for perovskite solar cells: Influence on device performance and stability

In this work the differences between two electron transporting materials used as n-type selective contacts for perovskite solar cells cells based on CH3NH3PbI3-xClx are evaluated: the classical titanium dioxide (TiO2) and tungsten oxide (WO3) as a potential alternative. WO3 presents the advantage of being printable and does not require high annealing temperature: allowing cheap, expendable and efficient solar cells. Although few reports have demonstrated the strong potentialities of WO3 as efficient electron transporting layer for perovskite solar cells, we specifically focus our analysis on its influence on device stability. In this context, while solar cell performance under ambient conditions and continuous standard illumination is rapidly decreasing in the presence of WO3, we observe a drastic improvement of device stability in the dark under ambient conditions of WO3-based devices compared to TiO2. Exploiting Kelvin probe force microscopy (KPFM) the lower open-circuit voltage is explained, through transient photoluminescence measurements the crucial role played by oxygen vacancies and moisture is pointed out to rationalize this behavior. Finally, demonstrations of perovskite solar cells containing spincoated or printed WO3 processed under ambient condition and presenting power conversion efficiency close to 10% are provided.