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This method allows for the reproducible deposition of smooth and homogeneous films as shown by SEM measurements Fig. By comparison, spray cast of MoS3 suspensions in acetone yields rough and non-homogeneous films in our conditions Fig. The thicknesses of spray-cast films are therefore given with large error bars and it was not possible to get films with thickness under 15 nm. The catalytic activity of the electrode towards HER was studied by cyclic voltammetry at 50 mV.
The catalytic layer showed high activity for HER at pH 0 0. We note that the catalytic current is proportional to the proton concentration Fig. Production of hydrogen was confirmed by gas chromatography measurements. The particles synthesized at different pH displayed similar catalytic current and onset potential Fig. It is worth to note that no catalytic activity was observed on bare ITO electrodes under the same conditions.
Film thickness: 15nm purple , 40nm red , 90nm blue , nm green. Electrode surface area: 0. The influence of the thickness of the MoS3 films on the catalytic activity was then investigated Fig. We first describe the results obtained on spin-coated samples for which reproducible and homogeneous thicknesses are obtained. The decrease of MoS3 performances due to catalyst release for very thin films can be visually assessed by the reduced color intensity of the film.
The same behavior is observed for spray-cast films Fig. Sprayed MoS3 films show the same electrocatalytic properties as spin coated films, though the current densities are lower, e. Figure 4 compares the electrocatalytic performances of three sprayed films with distinct thicknesses. High thickness results in increased onset overpotentials and lower current densities. Again, optimal catalytic performances are obtained for films with thickness between 40 and nm. RHE close to the onset potential in 0.
The XPS survey spectra Fig. S9 shows peaks due to molybdenum and sulfur, as well as some impurities such as sodium and oxygen present in the precursors used for the synthesis , and carbon atmospheric contamination. Mo3d spectra before after CV Fig. Analysis of the S2p region before after CV Fig. S11 reveals two types of sulfur atoms: peaks at Quantification based on S2p and Mo3d areas using Wagner coefficients shows an initial S:Mo ratio of 2. The MoS3 structure has been widely discussed since the first studies by Ratnasamy and coll.
After CV, the area of MoIV and MoVI signals both decreased, indicating that Mo is released in aqueous media which may be the reason for the observed decrease in activity. However, due to the high resistivity of MoS3, a low catalytic HER activity is obtained for thick films.
In addition, the coating of the OPV layer favors recombination inside the light-harvesting material. In bulk-heterojunction polymer solar cells, densely packed n-type oxide TiO2 is often placed between the light-harvesting active layer and the charge-collecting electrode. The long-term stability is also enhanced since TiO2 prevents direct contact between oxygen and water and the active layer. We thus decided to mix our MoS3 material with commercially available TiO2 particles. Cyclic voltammograms were measured at 50 mV.
The overpotential for hydrogen evolution is similar to MoS3 alone. Impedance measurements Fig. Therefore, it seems that TiO2, besides acting as a good electron contact for electrons generated by the OPV layer, also improves the charge transfer from ITO to MoS3 thanks to its good electron photoconductivity.
Our primary goal was to deposit each layer by spin-coating. We therefore turn to spray-casting on the heated substrate to coat the active layer with the catalyst. It is worth to note that each layer was deposited from solutions by processes that can be easily scaled up to industrial processes such as roll-to-roll printing and spray-coating. Same conditions time and concentrations as previously developed were however used.
Two distinct photocathodes were prepared: one containing a catalytic layer based on MoS3 and a second one with a thicker mixed TiO2:MoS3 catalytic layer. In order to discriminate between the effects of MoS3 and TiO2 on the performances, we also prepared two reference photoelectrodes, one without catalytic layer and another one only with a TiO2 layer. We then investigated the photoelectrocatalytic performances of the two photocathodes containing either MoS3 or mixed TiO2:MoS3 as catalytic layer.
The photocathodes were interfaced with a 0. Electrode area: 0. Linear sweep voltammetry measurements were carried out at 5 mV. Two groups were followed: patients admitted to the ICU during the remifentanil shortage July 1, to September 30, and a control group one year after the remifentanil shortage July 1, to September 30, Included patients were adults, received mechanical ventilation for at least 6 h, were admitted less than 90 days in the respective ICU, and survived their admission.
Results: For comparison, Poisson count regression models and logistic regression models were computed. To compensate for multiple testing, the significance level was split 0. Patients in the remifentanil shortage group received significantly longer mechanical ventilation risk ratio 2.
Conclusions: The remifentanil shortage caused a significant impairment of essential outcome parameters in the ICU.
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