The effect of surface hydroxyl groups on the adsorption properties of nanocrystalline TiO

Nanocrystalline TiO2/Brij and TiO2/Pluronic films were prepared with a view to their application in electrochromic and Grätzel cells and examination of their photocatalytic effect. The films were prepared from titanium (IV) isopropoxide with the addition of Brij 56 or Pluronic F127. Films were deposited by dip-coating, thermally treated at 500 ∘C and analysed by XRD, TEM and IR analysis. XRD and TEM analyses revealed the presence of anatase nanoparticles embedded in the amorphous phase. The presence of the latter was also confirmed by a broad high-frequency shoulder of the Ti-O stretching mode at 436 cm−1 that was found for films prepared with both kinds of surfactants. Addition of surfactants decreased the size of the particles and increased the surface roughness, and consequently in IR spectra the surface hydroxyl Ti-OH modes appear between 3800 and 3600 cm−1. IR measurements also revealed that TiO2 films with surfactants have a higher photocatalytic effect which was tested for stearic acid by following the integral intensity of C-H and C=O IR bands

Nature and Lability of Northern Adriatic Macroaggregates

The key organic constituents of marine macroaggregates (macrogels) of prevalently phytoplankton origin, periodically occurring in the northern Adriatic Sea, are proteins, lipids and especially polysaccharides. In this article, the reactivity of various macroaggregate fractions in relation to their composition in order to decode the potentially »bioavailable« fractions is summarized and discussed. The enzymatic hydrolysis of the macroaggregate matrix, using α-amylase, β-glucosidase, protease, proteinase and lipase, revealed the simultaneous degradation of polysaccharides and proteins, while lipids seem largely preserved. In the fresh surface macroaggregate samples, a pronounced degradation of the α-glycosidic bond compared to β-linkages. Degradation of the colloidal fraction proceeded faster in the higher molecular weight (MW) fractions. N-containing polysaccharides can be important constituents of the higher MW fraction while the lower MW constituents can mostly be composed of poly- and oligosaccharides. Since the polysaccharide component in the higher MW fraction is more degradable compared to N-containing polysaccharides, the higher MW fraction represents a possible path of organic nitrogen preservation. Enzymatic hydrolysis, using α-amylase and β-glucosidase, revealed the presence of α- and β-glycosidic linkages in all fractions with similar decomposition kinetics. Our results indicate that different fractions of macroaggregates are subjected to compositional selective reactivity with important implications for macroaggregate persistence in the seawater column and deposition

Comparison of electrochromic properties of Ni1−xO in lithium and lithium-free aprotic electrolytes: From Ni1−xO pigment coatings to flexible electrochromic devices

Electrochromic nickel oxide (Ni1−xO) pigment powder which was made from nickel acetate reacting with H2O2/urea solution followed by heat treatment of xerogels at 400 °C (24 h) was milled with zirconia beads in pure water or water with added nickel oxyhydroxy precipitate acting simultaneously as the dispersant and the coating binder. The corresponding pigment particle suspensions were spin coated on FTO glass and flexible ITO-PET foils, respectively, and cured at 150 °C. The optical properties of the deposited pigment coatings on FTO glass substrates were determined with an UV VIS spectrometer, providing total direct transmittance (TT), total diffuse transmittance (DT) and haze (in %). Haze increased with the coating thickness but did not exceed 4%. SEM micrographs of the deposited pigment coatings revealed that they consisted of agglomerated Ni1−xO pigment with voids. Potential cycling of Ni1−xO pigment coatings and Ni1−xO thin films was performed in 1 M LiClO4/PC and 0.1 M TBA+ triflate/PC electrolytes, revealing that the pigment coatings exhibited electrochemical and electrochromic activity also in lithium free (aprotic) electrolyte, while variations of the oxidation and reduction reaction peaks at various scan rates confirmed the presence of surface electrochemical reactions. The near-grazing incidence angle reflection-absorption spectroscopic technique (IR RA) was employed for identifying surface and inner-grain Ni-O stretching modes, the former being responsible for observed electrochemical properties, which was also demonstrated from the ex situ IR RA measurements performed for coatings charged/discharged in 1 M LiClO4/PC and 0.1 M TBA+ triflate/PC electrolytes. The results disclosed in this study suggest that the electrochromic effect was not in direct correlation with the de-insertion/insertion of small ions into the NiO (bunsenite) grains but rather the pigment coatings behave similarly to nickel oxide electrochemical capacitors. The electrochromic response of a flexible EC devices made either of PEDOT (self-standing foil) or WO3 and Ni1−xO pigment coatings glued with PMMA based electrolytes without and with lithium salt were recorded for the demonstration of the possible practical application of wet deposited Ni1−xO pigment coatings made as "electrochromic" paints