Colloid chemical properties of hydrated tungsten trioxide hydrosols

Investigation on the coloring and bleaching processes of WO3−x photochromic thin films

“…1a. The isoelectric point of our particles is at a very acidic pH of 1.5 as already listed in the literature 36,37 . Note that this can be interpreted as characteristic of a particle surface very rich in cations (W 6+ , W 5+ ), the surface therefore has a very clear tendency for hydroxylation at the expense of protonation.…”

The structure of particles of the dispersed phase in europium oxyhydroxide hydrosol

“…This is the simplest method for the determination of the density of the systems that can be diluted with retention of the composition of the dispersed phase. 8,10, 11 In this case the dependence of the sol density (ρ sol ) on the concentration с dph should be linear, while the density of particles ρ can be determined as the slope using formula (3):…”

Successive Strong Electrostatic Adsorptions of [RhCl6]3–on Tungstated-Ceria as an Original Approach to Preserve Rh Clusters From Sintering Under High-Temperature Reduction

“…The anionic and cationic adsorption capacities of the W­(W/nm 2 CeO 2 )/CeO 2 materials were probed by contacting 1 g of these solids with 100 mL of an aqueous solution of KCl (10 –2 mol/L) at a pH of 4 for 1 h. The suspensions were then centrifuged, and the solids were dried at 100 °C overnight before being analyzed by X-ray fluorescence. Even though Bertus and Carcel reported on a PZC of WO 3 close to 4, many studies agreed that the PZC of tungsten trioxide must be below 2. ,,− Apart from a few studies in which the PZC of CeO 2 has been reported to be as low as 3–4, the PZC of ceria is generally reported to be above 6. ,,− At a pH of 4, which appears to be intermediate between the PZC of WO 3 (<2) and that of CeO 2 (>6), , the tungstates must be negatively charged, whereas ceria must be positively charged (Figure a). The K + and Cl – ions should therefore interact preferentially with tungstates and ceria, respectively.…”

“…Despite Bertus and Carcel reported on a PZC of WO3 close to 4, 59 many studies agreed that the PZC of tungsten trioxide must be below 2. 26,27,[60][61][62] Apart from few studies in which the PZC of CeO2 has been reported to be as low as 3-4, 27 the PZC of ceria is generally reported to be above 6. 26,27,[63][64][65] At a pH of 4, which appears to be intermediate between the PZC of WO3 (< 2) and that of CeO2 (> 6), 26,27 the tungstates must be negatively-charged, whereas ceria must be positively-charged (Figure 1a).…”