Dye-sensitized solar cells (DSSCs) that utilize natural dyes have garnered interest due to their low cost, eco-friendly manufacturing process, and competitive photovoltaic performance. However, their ...efficiency and stability issues have hindered their widespread implementation. To enhance their performance, this paper proposes a novel approach of modifying the photoanode with carbon dots (CDs) to align the band gap for easier carrier collection. The material properties were thoroughly characterized by examining their structural, morphological, optical, and electrical properties. In this study, titanium dioxide (TiO2) was synthesized using the microwave-assisted solvothermal method, while nitrogen-doped CDs derived from Citrus medica fruit juice were prepared using a simple hydrothermal treatment. Three sets of Natural Dye Sensitized Solar Cells (NDSSC) devices were created using co-activated photoanode (CD/TiO2) and unmodified photoanode (TiO2) with Platisol T/sp coated ITO serving as the counter electrode. Hibiscus (Hibiscus rosa-sinensis) and Onion (Allium cepa) peel extracts were utilized as sensitizers and Iodolyte HI-30 as the electrolyte. The most efficient device attained an efficiency of 3.5 % with Voc = 0.81 V and Jsc = 6.57 mA/cm2. This marks the highest efficiency reported using Hibiscus as a sensitizer with the current configuration, accompanied by prolonged device stability. This study showcases the potential of Citrus medica-derived nitrogen-doped CDs in achieving durable device stability.
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•Synthesis of TiO2 using a microwave-assisted solvothermal method for DSSC photoanode application.•Modification of the photoanode with carbon dots derived from biomass.•Enhancement of photovoltaic parameters through a co-activation strategy.•Utilization of natural sensitizers for cost-effective and environmentally friendly DSSC fabrication.•Improved device stability through the use of carbon dot-modified photoanodes.
Recently, there has been an increasing interest towards the fabrication/finishing of bioactive materials using natural plant extracts, which can achieve a wide range of functional properties and ...environmental benefits. This study presents an environmentally benign bioactive finishing of wool fabric via the use of unexplored tannin-rich waste/fallen leaves extract of Chinese tallow/Sapium sebiferum L. through simple adsorption technique. Simple aqueous extraction followed by the evaluations of build-up properties on wool fabric using Chinese Tallow (CT) leaves extract were studied in due course of this study. Optimization of extraction and dyeing variables/conditions such as pH, temperature, CT concentration, and time were conducted using UV–Visible and reflectance spectral method. The nature of functional groups of the extracted dye were investigated through FT-IR spectral analysis with further in depth thermal analyses using TG and DSC measurements. Additionally, the extracted dye was subjected to quantitative analytical tests to check the relative amounts of total phenolics and flavonoid with respect to gallic acid and catechin equivalents, respectively. Build-up properties and fastness characteristics were studied in the presence and absence of mordants (two metal and one biomordant) under corresponding ISO standards. Results showed that wool fabric treated with CT leaves extract exhibit excellent antioxidant activity, good UV protection and high antibacterial activities against E. coli and S. aureus. The use of biomordant to alter the functional properties provide an eco-friendly method for wool finishing. In general, the treated wool fabric in this work has shown a promising future for the preparation of health and hygiene-related textile materials.
•An environmentally friendly benign cleaner production procedure has been presented.•Waste/fallen leaves of Sapium sebiferum L. were used for natural dye production.•Extracted dye was characterized by UV–visible and FT-IR analysis.•Potential antibacterial and antioxidant wool fabrics were produced.•Finished wool fabric possesses excellent UV protective properties.
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•The co-sensitization approach employed to achieve panchromatic light-harvesting.•The treated cocktail with multi-anchor groups increased electron transfer channels.•Homogeneous ...dispersion of the pigment molecules improved dye adsorption efficiency.•The acidified cocktail enhanced the DSSC short current and efficiency.•Significant improvement in NDSSC stability was achieved using co-sensitization.
Co-sensitization is an effective strategy to achieve panchromatic light-harvesting and to enhance dye-sensitized solar cell performance. In this work, the potential of the extracted natural dyes from Malva verticillata and Syzygium cumini was evaluated as mono and co-sensitizers in DSSCs. The UV–vis absorption spectra revealed that the combination of studied dyes had a high molar extinction coefficient and cumulative absorption properties in a way that its absorption spectra overlapped the spectral domain where the original sensitizers lacked light-harvesting. Moreover, all investigated dyes were characterized using circular dichroism, dynamic light scattering, zeta potential, cyclic voltammetry, and Fourier-transform infrared spectroscopy. The results of zeta potential analysis showed that the pigment aggregation and their colloidal stability, which has implications for the pigment adsorption process on TiO2 nanoparticles, were effectively controlled by varying the pH of the dye extract. Based on the CV results, the studied dyes indicated excellent redox stability and sufficient thermodynamic driving force for efficient electron injection. Based on the photovoltaic results, the acidified cocktail-DSSC had the highest Isc and η of 3.15 mA and 1.84 %, respectively. This superiority could be ascribed to the panchromatic light-harvesting, the excellent optical activity, and the appropriate energy levels of the acidified cocktail. Moreover, the loading of acidified cocktail dyes on the TiO2 surface was enhanced due to their homogeneous dispersion, less steric hindrances, and multi-anchor groups attached to the semiconductor surface. Based on the stability results, the treated cocktail-DSSC retained about 52.51 % of its as-fabricated efficiency after seven days while NDSSCs sensitized with acidified Syzygium cumini, Malva verticillata, Syzygium cumini, and cocktail retained about 26.24 %, 14.80 %, 16.35 %, and 15.25 %, respectively.
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•A novel pH indicator based on bacterial nanocellulose was fabricated.•Black carrot anthocyanins was used as a pH indicator.•A significant correspondence of fish freshness and ...indicator was found.•Consumers recognized the freshness/spoilage of fish by the naked eye.
A novel intelligent pH-sensing indicator based on bacterial nanocellulose (BC) and black carrot anthocyanins (CA) was developed and characterized to monitor the freshness/spoilage of rainbow trout and common carp fillet during the storage at 4 °C. The indicator displayed wide color differences from red to gray over the 2–11 pH range, which was clearly discerned by the naked eye. The fabricated pH-sensing indicator showed distinguishable color changes during fresh (deep carmine color), best to eat (charm pink color), and spoiled (jelly bean blue and khaki colors) stages of both fish fillets. Moreover, a strong and positive correlation was obtained between the total color differences values of the indicator and bacterial count (R = 0.952 and 0.991) and total volatile basic nitrogen (R = 0.815 and 0.92) in rainbow trout and common carp samples. The results of this work demonstrated a significant correspondence of fish shelf life and color changes of a nanocellulose-based pH-sensing indicator.
Energy crisis is the world major concern due to the rapid depletion of fossil fuel sources and its contribution to climate change. Among the solution in the clean and renewable energy sector is by ...employing one of the third-generation solar cell technologies known as a dye-sensitized solar cell (DSSC). The advantages of it include low cost, simple fabrication works, good performance at low illumination level and provide multi-color options of dyes either synthetic or natural dyes. Although the efficiency of DSSCs still low compared to the silicon or thin film-based solar cells, the performance of DSSCs can be improved by enhancing the dye part. The dye is one of the main components that influence the cell’s performance whereby the implementation of the natural dyes is a promising way since natural sources are abundant, easy extraction processes and involve environmentally friendly energy concepts. However, the detailed mechanism of the charge transfer processes occurring inside the DSSC based natural dyes is still limited. Electrochemical impedance spectroscopy (EIS) analysis gave an enormous benefit in analyzing these mechanisms. It has been widely employed in the DSSC work to describe the relationship between the cell’s performance, architectures and novel materials being used. This review aims to explore the electron transport properties that used the EIS concept and application. A brief introduction of EIS will be given, followed by a review of its application in the TiO2-DSSCs based natural dyes. Finally, a brief discussion of future research directions and recommendations on this topic will be presented.
•Sustainable green sources for solar energy harvesting.•Capsicum annuum and Tamarindus indica as natural dyes for photosensitization.•Twelve different DSSCs configurations consist of ZnO films, ...electrodes, and natural dye sensitizers.•Choices of dye, electrode material, and nanoparticle film provide rich options to calculate different DSSC configurations' efficiencies.•DSSC based on Capsicum annuum (as a dye), zinc oxide (as a charge transporter), and graphite as an electrode have an efficiency of 1.65%.
Twelve dye-sensitized solar cells (DSSCs) were fabricated using Capsicum annuum and Tamarindus indica seeds extract as natural photosensitizing dyes. Zinc oxide-based three different films were employed as charge transporters, whereas graphite and PEDOT:PSS were adopted as electrode materials. The optical character of natural dyes and zinc oxide-based layers was obtained by UV–vis spectroscopy. Structural information was achieved by X-ray diffraction and modes of vibrations were obtained by Fourier Transform IR spectroscopy. Different schemes of DSSCs were considered by choosing from metal oxide films, seed extract, and electrode material. J-V curves recorded for all the DSSCs-configurations revealed that the maximum power conversion efficiency of 1.65% was found in the case of DSSC which comprised Capsicum annuum (dye), zinc oxide, and graphite as an electrode. Minimum 0.43% efficiency was obtained for the DSSC based on Capsicum annuum as a dye, Al-doped zinc oxide film, and PEDOT:PSS as an electrode. This study is a way forward to using recyclable natural resources for sustainable and economical solar power conversion devices.
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•An alternative to traditional classification of bioactive compounds - phenolic and non-phenolic - was proposed.•Encapsulation and adsorption improve the thermal and chemical ...stability of bioactive compounds.•Adsorption of anthocyanin on eco-friendly materials showed promising.•There are drawbacks on encapsulation of bioactive compounds as spray-drying (thermal degradation), freeze-drying (costly and slow), ionic gelation (drying step), among others.
Bioactive compounds have remarkable biological activities for health, nutrition, and food preservation. However, these compounds are chemically unstable maily when exposure at high temperatures, light, and humidity. Several stabilization techniques have been used to protect these compounds, expanding their application range. Therefore, this review aims to show the main bioactive compounds currently studied and the use of stabilization techniques, such as encapsulation and adsorption, for food application. A broader systematic classification of bioactive compounds based on phenolic and non-phenolic sub-levels was suggested, which can assist in a deeper discussion of results, including the correlation of biological activities, their synergistic effects, and their enhanced stabilization on materials that promote a well-controlled delivery (higher bioavailability). Research on Scopus Database was used to identify the scientific trends for stabilization methods (2016–2020). This review article focused on analyzing bioactive encapsulation using cold processing techniques such as ionic gelation, emulsification, complex coacervation, and adsorption to expand production and application in the food sector.
•Cherry, blackberry, blueberry, raspberry and strawberry fruits used as sensitizers.•Performing blueberry dye, simply prepared, inexpensive and environmental-friendly.•Analytical characterisation of ...dyes.•New adsorption/desorption procedure to check the affinity of the dyes for the TiO2.•Better sensitizing performance of delphinidine derivatives compared to the other ANCs.
Natural dyes, extracted from cherry, blackberry, blueberry, raspberry and strawberry fruits, were used as sensitizers to fabricate dye-sensitized solar cells (DSSCs). The conversion efficiency (η%) ranged from 0.14 to 0.69. Specifically, the highest η% was obtained from the dye extracted with ethanol 70% from blueberry fruit and epicarp (1.13 and 0.75, respectively), without other chemicals, pH adjustments and thermal or purification processes. The absorbance spectra of the dyes and their photoelectrochemical performances demonstrated that anthocyanins (ANCs) were the most effectual component of the sensitizer for DSSC.
To check the affinity of the dyes for the TiO2 a new adsorption/desorption procedure was established. The comparison of the percentage distribution of each anthocyanin class in blueberry epicarp dye, before its adsorption and after its recovery from TiO2 powder, showed a better sensitizing performance of delphinidine derivatives compared to the other ANCs.
