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

Abstract

Well-compacted and crack-free TiO 2 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 TiO 2 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 4.52x10-10 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 Keywords TiO 2 coatings; particulate suspensions, colloidal processing; crack-free; DSSCs *Manuscript Click here to view linked References

3D Printing of Photocatalytic Filters Using a Biopolymer to Immobilize TiO2Nanoparticles

“…Consequently after PEI addition, the PEI-TiO 2 suspension (at pH 8) exhibits a zeta potential of +66 mV, due to the adsorbed protonated PEI, and a shear-thinning behavior with a manageable viscosity of 70 mPas (at shear rate of 100 s −1 ). 27 Moreover, the DLS measurements were also performed to determine the particle size after the surface modification. Figure 1b shows the particle size distribution of the PEI-TiO 2 NPs where one narrow peak, centred on 120 nm (D V50 ) was observed as additionally confirmed by the cumulative volume % curve.…”

“…The procedure used for the particles dispersion and the adsorption of PEI onto the NPs surfaces has been described previously elsewhere. 27 However, to improve the centrifugation of well dispersed NPs, the conditions for the suspension coagulation were stabilised. In this sense, the modification of the zeta potential for TiO 2 NPs induced by the absorption of PEI was determined in a wider pH range (2-12) using the laser Doppler velocimetry technique in a ZetasizerNano ZS (Malvern, UK), and then compared to zeta potential determination in a similar pH range for the bare nanopowder.…”

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

“…The withdrawal rate of the dip coating process was optimized in previous work (Gonzalez et al 2019) to avoid these microstructural defects. All samples were made at withdrawal rate 2.5 mm/s.…”

“…Therefore, the pH 8 was selected in order to have more protonated amine groups favoring the adsorption (with a train configuration) and the later interaction with the surface of nanofibers. More data about the specific procedure has been previously described elsewhere (Gonzalez et al 2019). The suspension was ball milled during 90 min using Al 2 O 3 balls.…”

Controlled SrR Delivery by the Incorporation of Mg Particles on Biodegradable PLA-Based Composites

“…The colloidal approach is based on the control of the interparticle forces in the liquid media, which implies significant advantages in terms of correct phase distribution and final homogeneity of a composite. The manipulation of the colloidal chemistry in the suspensions of inorganic particles in polymers solutions is the keystone to break down weak agglomerates, stabilize, and facilitate particle mixing, removing defects that degrades the relevant properties of the biomaterials [ 29 ]. Moreover, the use of processing additives helps to tailor other important parameters, such as the viscosity, flow, surface tension, wettability, etc., adapting the flux of the suspension to the manufacturing technique while controlling the arrangement of the particles in a polymeric matrix.…”