A colloidal approach to prepare binder and crack-free TiO2 multilayer coatings from particulate suspensions: application in DSSCs

Well-compacted and crack-free TiO⁠2 multilayer coatings have been manufactured from a colloidal approach based on the preparation of particulate suspensions for DSSC. The study of the suspension parameters to optimize dispersion and stabilization of the TiO⁠2 nanoparticle in the liquid media as well as a thermal stabilization step between the layers have been defined as two key points in the processing method to obtain interconnected microstructures, free of defects and heterogeneities, that prevent the application of an additional scattering layer or any kind of specific or clean conditions during deposition. The sintering process at low temperature, 450⁰C, has allowed obtaining open microarchitectures avoiding the complete densification and favoring the dye adsorption. A thickness of 12.8 μm resulted in a successful dye loading of 4.52×10⁠−10 mol·mm⁠−2 and a photoefficiency of 5.7%, both in the range of the others particulate systems. EIS measurements were also made to study the transfer charge phenomena

Heteroacoagulation of lignocellulose fibers-based biotemplates and functionalized TiO2 nanoparticles to tailor film microstructures

The heterocoagulation of lignocellulose nanofibers (LCNFs) with functionalized TiO2 nanoparticles (NPs) is presented as an innovative revalorization strategy for the exploitation of lignocellulose pastes. Their use as bio-templates could be considered a promising alternative in a current biorefinery scheme, since the massive production of porous materials in numerous nanotechnological applications, could offer new alternatives of exploitation. The surface modification of TiO2 NPs by adsorption of polyetilenimine (PEI) favors its anchorage with LCNFs through a peptide bond during heterocoagulation in aqueous suspension. The functionalization of LCNFs with TiO2 NPs results in organic–inorganic core–shell nanostructures, used to shape coatings by dipping, and sinter them at low temperature (450 C). In this process, the LCNFs were used as endotemplates for shaping stable porous coatings, when they burn during the consolidation of the inorganic structure. In this work, the successful inclusion and homogeneous distribution of biomaterials (LCNF templates) in the semiconductor inorganic microstructure is discussed in terms of dye loading (by UV–Visible Spectroscopy), photovoltaic efficiency and charge transfer (by Electrochemical Impedance Spectroscopy, EIS) in a Dye Sensitized Solar Cell (DSSC). Results confirm that the TiO2/template network yielded better photoefficiency and electron transport properties than mesoporous films assembled only from TiO2 NPs. The preparation of TiO2-based photoanodes with enhanced performance (with an efficiency value around 6%, for a thickness of 8.7 lm) allows validating the successful colloidal procedure herein employed

Proteomic Study of Response to Copper, Cadmium, and Chrome Ion Stress in <i>Yarrowia lipolytica</i> Strains Isolated from Andean Mine Tailings in Peru

Mine tailings are produced by mining activities and contain diverse heavy metal ions, which cause environmental problems and have negative impacts on ecosystems. Different microorganisms, including yeasts, play important roles in the absorption and/or adsorption of these heavy metal ions. This work aimed to analyze proteins synthesized by the yeast Yarrowia lipolytica AMJ6 (Yl-AMJ6), isolated from Andean mine tailings in Peru and subjected to stress conditions with common heavy metal ions. Yeast strains were isolated from high Andean water samples impacted by mine tailings from Yanamate (Pasco, Peru). Among all the isolated yeasts, the Yl-AMJ6 strain presented LC50 values of 1.06 mM, 1.42 mM, and 0.49 mM for the Cr+6, Cu+2, and Cd+2 ions, respectively. Proteomic analysis of theYl-AMJ6 strain under heavy metal stress showed that several proteins were up- or downregulated. Biological and functional analysis of these proteins showed that they were involved in the metabolism of proteins, nucleic acids, and carbohydrates; response to oxidative stress and protein folding; ATP synthesis and ion transport; membrane and cell wall; and cell division. The most prominent proteins that presented the greatest changes were related to the oxidative stress response and carbohydrate metabolism, suggesting the existence of a defense mechanism in these yeasts to resist the impact of environmental contamination by heavy metal ions