Effect of deoxycholic acid on the performance of liquid electrolyte dye-sensitized solar cells using a perylene monoimide derivative

The effect of coadsorption with deoxycholic acid (DCA) on the performance of dye-sensitized solar cell based on perylene monoimide derivative (PCA) as sensitizer and liquid electrolyte had been investigated. The current-voltage characteristics under illumination and incident photon to current efficiency (IPCE) spectra of the DSSCs showed that the coadsorption of DCA with the PCA dye results in a significant improvement in short circuit photocurrent and slight increase in the open circuit photovoltage, which lead to an overall power conversion efficiency. The enhancement of short circuit current was attributed to the increased electron injection efficiency from the excited state of PCA into the conduction band of TiO2 and charge collection efficiency. The current-voltage characteristics in dark indicates a positive shift in the conduction which also supports the enhancement in the photocurrent. The coadsorption with DCA suppressed charge recombination as indicated from the electrochemical impedance spectra and thus improved the open circuit photovoltage

Efficiency enhancement in dye sensitized solar cells through step wise cosensitization of TiO2 electrode with N719 and metal free dye

656-664We have used a step-wise cosensitization process to improve the power conversion efficiency (PCE) of dye sensitized solar cells employing N719 and metal free dye TA-St-CA. The DSSC sensitized with N719/TA-St-CA shows a PCE of 8.27% which is higher than for the DSSCs sensitized with either N719 (5.78 %) or TA-St-CA (4.45%). The improved PCE is attributed to the enhanced overall dye loading as well the reduced dye aggregation that has resulted from the usage of dyes with different anchoring units. The enhancement in the PCE has also been attributed to increase in both short circuit photocurrent and open circuit voltage. This was due to the reduced dark current and suppression of back recombination of injected electrons in the conduction band of TiO2 photoanode with the Iions in the electrolyte

Diagnosis of carbonation induced corrosion initiation and progression in reinforced concrete structures using piezo-impedance transducers

In addition to chloride induced corrosion, the other commonly occurring type of rebar corrosion in reinforced concrete structures is that induced by the ingress of atmospheric carbon dioxide into concrete, commonly referred to as ‘carbonation induced corrosion’. This paper presents a new approach for detecting the onset and quantifying the level of carbonation induced rebar corrosion. The approach is based on the changes in the mechanical impedance parameters acquired using the electro-mechanical coupling of a piezoelectric lead zirconate titanate (PZT) ceramic patch bonded to the surface of the rebar. The approach is non-destructive and is demonstrated though accelerated tests on reinforced concrete specimens subjected to controlled carbon dioxide exposure for a period spanning over 230 days. The equivalent stiffness parameter, extracted from the frequency response of the admittance signatures of the PZT patch, is found to increase with penetration of carbon dioxide inside the surface and the consequent carbonation, an observation that is correlated with phenolphthalein staining. After the onset of rebar corrosion, the equivalent stiffness parameter exhibited a reduction in magnitude over time, providing a clear indication of the occurrence of corrosion and the results are correlated with scanning electron microscope images and Raman spectroscopy measurements. The average rate of corrosion is determined using the equivalent mass parameter. The use of PZT ceramic transducers, therefore, provides an alternate and effective technique for diagnosis of carbonation induced rebar corrosion initiation and progression in reinforced concrete structures non-destructively

Monitoring hydration in lime - metakaolin composites

This paper describes a study of the micro-macro property relationships relating to hydraulic setting reactions in air lime - metakaolin mixtures

Photocatalytic Lime Render for Indoor and Outdoor Air Quality Improvement

This article reports a novel photocatalytic lime render for indoor and outdoor air quality improvement that is composed of a lime binder and doped TiO2 (KRONOClean 7000®) nanoparticles. These nanoparticles were distributed throughout the bulk of the finishing render, instead of as a thin coating, thus ensuring the durability of the photocatalytic properties upon superficial damage. The physical properties of these renders were not affected by the addition of nanoparticles except in the case of surface area, which increased significantly. In terms of their photocatalytic activity, these novel lime renders were shown to degrade up to 12% NOx under UV light and up to 11% formaldehyde under visible light.This research was funded by the European Union’s Seventh Framework Programme for research, technological development, and demonstration under the Grant Agreement No. 609234 related to the ECO-SEE project: “Eco-innovative, Safe and Energy Efficient wall panels and materials for a healthier indoor environment” This work was partly developed within the scope of the project CICECO–Aveiro Institute of Materials, UIDB/50011/2020 & UIDP/50011/2020, financed by national funds through the FCT/MEC and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement. David Maria Tobaldi is overly grateful to Portuguese national funds (OE), through FCT, I.P., in the scope of the framework contract foreseen in the numbers 4, 5 and 6 of the article 23, of the Decree-Law 57/2016, of 29 August, changed by Law 57/2017, of 19 July

Impedance analysis and dielectric properties of Ce modified bismuth titanate lead free ceramics synthesized using solution combustion route

Cerium modified bismuth titanate ceramics were studied as potential lead-free ferroelectric materials over a broad temperature range. Polycrystalline samples of Bi4-xCexTi3O12 (x = 0.2, 0.4, 0.6, 0.8) (BCeT) were prepared using the solution combustion technique. The effect of Ce doping on their crystalline structure, ferroelectric properties and electrical conduction characteristics were explored. An increase in the dielectric constant and decrease in loss tangent is observed due to addition of Ce in bismuth titanate lattice up to a certain threshold doping concentration. The presence of pyrochlore phase decreases the density of ceramics with composition x = 0.8 which may be due to grain inhibitor property of Ce. The value of remnant polarization increases with increasing doping content up to x = 0.6 due to decrease in defect sites in the samples, further increase in cerium content induces leakage current which makes the sample lossy. The real-imaginary impedance plots are interpreted using RC model, this explains the contribution of the grain-bulk and the grain boundary resistivities to the total resistivity of the materials. Activation energy increases with increasing Ce concentration indicating a decrease in defect sites due to which the conductivity of the doped ceramics reduces