Manuscripts and paper-based cultural heritage are among the most fragile historical materials, highly susceptible to degradation caused by acidity, environmental pollutants, biological activity, and ink–substrate interactions. Conventional conservation approaches, particularly polymer-based consolidants, often suffer from long-term incompatibility, leading to embrittlement, discoloration, and blocked porosity. In response, nanoscience and nanotechnology have emerged as transformative tools by enabling conservation treatments that operate at the same scale as the underlying degradation processes. This review critically examines nanoscience-based strategies for manuscript preservation, with emphasis on deacidification, consolidation, and ink stabilization. Key classes of nanomaterials including hydroxide nanoparticles, metal oxides, carbon-based nanostructures, and emerging biocompatible systems are analyzed in terms of their mechanisms of action, advantages, and limitations. The role of nanoscale analytical techniques such as Raman spectroscopy, electron microscopy, synchrotron-based methods, FTIR, and AFM in diagnosing degradation and evaluating treatment efficacy is also discussed. Selected manuscript-focused case studies, alongside comparative examples from wall paintings, illustrate how specific nanomaterial properties address defined degradation challenges. By integrating recent advances and mechanistic insights, this review highlights current challenges related to long-term stability, sustainability, and ethical application, and outlines future directions involving green nanotechnology and multifunctional materials for the responsible preservation of manuscript heritage.

Reduced graphene oxide (rGO) was synthesized via an eco-friendly green route using Azadirachta indica (neem) leaf extract as a natural reducing and stabilizing agent. Graphene oxide (GO) was first prepared using a modified Hummers’ method and subsequently reduced through the action of phytochemicals present in the neem extract, thereby eliminating the need for hazardous chemical reductants. Structural and morphological characterization using XRD, FTIR, Raman spectroscopy, and SEM confirmed the effective reduction of GO, partial restoration of the sp2-carbon network, and the formation of wrinkled, porous rGO structures suitable for adsorption applications. The adsorption performance of the green-synthesized rGO was evaluated using real industrial wastewater collected from the Kanpur industrial region, containing hexavalent chromium (Cr6+), lead (Pb2+), cadmium (Cd2+), and textile dyes.

Water pollution from industrial dyes like methylene blue (MB) presents significant environmental challenges due to their toxicity and persistence in aquatic ecosystems. This study investigates the effectiveness of polyvinyl alcohol (PVA)-alginate composite hydrogel beads for MB removal from aqueous solutions. The beads were synthesized using calcium chloride as a cross-linking agent and characterized via Scanning Electron Microscopy (SEM), Fourier-transform Infrared Spectroscopy (FTIR), and Thermogravimetric Analysis (TGA). Adsorption studies revealed optimal removal at pH 8 and 30 °C, with a maximum adsorption capacity of 36 mg of MB per gram of hydrogel beads. The process followed pseudo-second-order kinetics and the Langmuir isotherm model, indicating monolayer adsorption on a homogeneous surface. The hydrogel beads maintained over 85

Dye-sensitized solar cells (DSSCs) have garnered significant attention as a cost-effective and environment friendly alternative to traditional silicon-based photovoltaic systems. This study explores the use of carbon aerogel as a counter electrode material to improve DSSC performance. Carbon aerogels derived from waste newspaper have remarkable characteristics such as high porosity, large surface area, and excellent electrical conductivity, making them a viable and effective alternative to platinum. The use of a natural cocktail dye derived from mulberry, moss, and Cassia fistula flowers broadens the light absorption spectrum, while a polymer electrolyte composed of CMC and MWCNT provides stability and increased ionic transport. The carbon aerogel-based DSSC obtained a power conversion efficiency (PCE) of 4.52

Dye-sensitized solar cells (DSSCs) are being extensively researched to develop cost-effective and high performance photovoltaic cells, with the counter electrode material playing a crucial role in determining their overall cost. Carbon-based materials, particularly activated carbon derived from waste, have gained significant attention as viable alternatives to platinum due to their excellent electrical conductivity, high catalytic activity, and affordability. Incorporating composite materials alongside activated carbon further enhances DSSCs performance due to their multifunctionality. In this study, a composite paste of activated carbon derived from bamboo sticks and graphene in a 1:1 ratio was prepared as the counter electrode and evaluated in a solid-state DSSCs. Another critical strategy for improving DSSCs efficiency is enhancing the conductivity and stability of polymer electrolytes. To achieve this, multi-walled carbon nanotubes were employed as secondary fillers, while montmorillonite acted as a primary filler in poly(ethylene oxide)-based polymer electrolyte films, leading to improved electrical conductivity. The inclusion of a small amount of multi-walled carbon nanotubes facilitated the formation of conductive layers, increasing A.C. conductivity from 5.6 × 10⁻⁴ S cm⁻¹ to 6.63 × 10⁻³ S cm⁻¹. The combination of carbonized bamboo sticks with graphene as a counter electrode and an efficient solid polymer electrolyte resulted in the highest recorded solar efficiency of approximately 4.0

A dye-sensitized solar cell (DSSC) consists of four crucial components: a photoanode, electrolyte, sensitizer, and photocathode. The stability, efficiency, and sustainability of a DSSC rely on these components. In this study, a biopolymer (chitosan) with graphite filler has been utilized as the electrolyte system to address sealing and leakage issues associated with liquid electrolytes. Chitosan, with its β(1–4) linked 2-amino-deoxy-D-glucopyranose units, exhibits a polycationic character that enhances anionic interactions, forming a polyelectrolyte complex. Furthermore, chitosan is biodegradable, eco-friendly, biocompatible, and non-toxic, making it a sustainable choice. The TiO₂ working electrode has been improved with CuO nanopowder to minimize the inherent energy barrier. A cocktail dye, prepared from beetroot and spinach dyes in a 1:1 ratio, is used as the sensitizer, replacing synthetic dyes and enhancing the eco-friendliness of the fabricated DSSC. The reported solar conversion efficiency is approximately 2.3

This study reports the development of a novel and eco-friendly dye-sensitized solar cell (DSSC) through the modification of its three major components: sensitizer, electrolyte, and photoanode. A natural cocktail dye was employed as the sensitizer, a polymer electrolyte with graphite filler as the electrolyte, and a TiO₂–CuO nanocomposite as the photoanode. Natural dyes extracted from Beta vulgaris (beetroot) and Spinacia oleracea (spinach) were mixed in a 1:1 v/v ratio to form a cocktail sensitizer, thereby enhancing the absorption properties and light-harvesting efficiency of the device. The polymer electrolyte was fabricated via the solution casting technique using polyethylene oxide (PEO) as the host matrix, lithium iodide/iodine (LiI/I₂) as the redox couple, ethylene carbonate (EC) and propylene carbonate (PC) as plasticizers, and graphite as a conductive nanofiller. Owing to its excellent electrical conductivity, thermal stability, and low cost, graphite significantly improved the ionic conductivity of the electrolyte to 10⁻³ S/cm. A TiO₂–CuO nanocomposite was synthesized using the sol–gel method and employed as the photoanode material, which improved electron transport and reduced recombination losses due to the synergistic effects between TiO₂ and CuO. Structural characterization was performed using Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Diffraction (XRD). The fabricated DSSC exhibited a power conversion efficiency of 3.3%, with a short-circuit current density (Jsc) of 9.0 mA/cm², an open-circuit voltage (Voc) of 0.68 V, and a fill factor of 57%. This multi-component modification combining sustainable natural dyes, a low-cost graphite-based solid polymer electrolyte, and a TiO₂–CuO nanocomposite photoanode offers a promising strategy for enhancing DSSC performance while maintaining both environmental and economic viability.

Carbon-based materials, particularly activated carbon generated from waste, have attracted much interest as ideal alternatives to platinum as a counter electrode in dye sensitized solar cells due to their high catalytic activity, and low cost. The use of composite materials in conjunction with activated carbon improves the performance due to its multi-functionality. A composite paste of activated carbon from corn cobs and Molybdenum disulfide nanospheres were used to prepare a counter electrode. The prepared counter electrode exhibits low charge transfer resistance at the electrolyte-electrode interface. The solution casting method was used to make nanocomposite polymer electrolyte films out of a blend of two polymers, polyvinyl alcohol and carboxymethyl cellulose, packed with various amounts of montmorillorite and graphene as primary and secondary nanofillers. Electrical impedance spectroscopy experiments at room temperature revealed that the addition of secondary nanofiller enhanced the electrical conductivity of the electrolyte films from 3.6 x 10-4 to 8.4 x 10-3 S cm-1 due to its capacity to form conductive layers in this polymer blend based electrolyte film. The fabricated synthetic dye based solar cell which uses an innovative counter electrode and nanocomposite polymer electrolyte outperformed platinum electrode with an efficiency of 4.34% and a fill factor of 61%.

Anthropogenic groundwater pollution poses a serious threat to both human health and environmental sustainability. In recent years, green synthesis methods have garnered considerable attention for their eco-friendly approach to nanoparticle production. Iron nanoparticles have emerged as promising materials for environmental remediation due to their high reactivity and low toxicity. This study focuses on the green synthesis of zero-valent iron (ZVI)/Cu nanoparticles using mulberry leaf extract and their application in groundwater treatment. Mulberry leaves are abundant in phytochemicals such as phenols, flavonoids, and tannins, which serve as effective reducing and stabilising agents in nanoparticle synthesis. The utilisation of mulberry leaves offers a sustainable and eco-friendly method for synthesising iron nanoparticles, eliminating the need for harsh chemicals and reducing environmental impact. The synthesised nanoparticles underwent comprehensive characterisation using UV-visible spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction to determine their size, morphology, and composition. The nanoparticles were subsequently evaluated for their efficacy in removing chromium from groundwater samples. The results demonstrated excellent adsorption capacity, achieving a removal efficiency of 94% under optimised conditions. Overall, the green synthesis of ZVI nanoparticles/Cu from mulberry leaves presents a promising approach for sustainable groundwater treatment, providing a viable and eco-friendly alternative to conventional methods.

Reduced graphene oxide (rGO) has proven to be a transformative material in dye-sensitized solar cells (DSSCs) due to its superior electrical conductivity and structural advantages. In this study, an rGO/TiO2 bilayer photoanode was developed to enhance charge transport and suppress recombination. The rGO layer, deposited on an indium tin oxide (ITO)-coated substrate, acts as an interfacial material, significantly improving photocurrent generation by providing efficient electron transport channels. The TiO2 layer, deposited over the rGO, offers a high surface area for dye adsorption and ensures optimal light harvesting. Electrochemical impedance spectroscopy confirmed that the rGO layer enhances charge transfer while minimizing recombination losses at the TiO2 interface. This improvement is attributed to rGO’s high electrical conductivity and its ability to create a favorable energy barrier, facilitating efficient charge movement through the photoanode. Additionally, the incorporation of a chitosan-based polymer electrolyte with multi-walled carbon nanotubes (MWCNTs) as filler provided enhanced ionic conductivity and mechanical stability. A natural cocktail dye derived from moss and mulberry was employed as the sensitizer for its broad-spectrum absorption and eco-friendly nature, while a platinum counter electrode ensured efficient redox reactions. This integration of materials highlights the potential of rGO/TiO2 bilayers in achieving high photovoltaic performance, offering a sustainable and cost-effective pathway for advancing DSSC technology.

The aim of the present study is to evaluate the potential of both the use of zinc oxide (ZnO) nanoparticles as primary filler and graphene as secondary filler in carboxy methyl cellulose based polymer electrolyte. The films were characterized structurally and morphologically by X-ray diffraction (XRD), Fourier-transform infra red spectroscopy (FT-IR), scanning electron microscopy (XRD). XRD results showed that ZnO nanoparticles inclusion reduced the crystallinity of the prepared biopolymer electrolyte. Addition of graphene as secondary filler further reduced the crystallinity of the prepared biopolymer electrolyte film. The FTIR technique and SEM images confirmed the complexation of salts with the polymer matrix. Due to graphene’s ability to create conductive layers, the inclusion of a little amount of it as a supplementary filler increased the A.C. conductivity from 1.63 × 10–5 to 2.6 × 10–4 S cm–1. The synergistic effects of both fillers contributed to raising the polymer electrolyte film’s electrical conductivity. Utilizing this polymer electrolyte layer enabled the creation of a solid state DSSC with an efficiency of 2.6

Dye-sensitized solar cells (DSSCs) based on redox electrolyte solution set the limitation and restriction on its fabrication. Moreover, when this redox electrolyte comes in contact with photoanode causes its corrosion. The finding of ionic conductivity in polymer material complex with salt has given a breakthrough in the formation of DSSC devices. Polymer electrolytes, especially Polyvinylidene fluoride (PVDF), have attained considerable interest due to its some exceptional properties like thermal stability, chemical resistance, and excellent mechanical strength. In the present work, dye-sensitized solar cell has been assembled using electrolyte system composed of PVDF as host polymer, Ethylene Carbonate as plasticizer, LiI: I2 as redox, and couple and graphite as filler; TiO2 modified with CuO photoanode in order to provide inherent energy barrier and natural cocktail dye as sensitizer. The obtained solar cell conversion efficiency was about 2.27% with using an irradiation of 100 mW/cm2 at 25 °C.

We investigated the use of graphite as primary filler and multi-walled carbon nanotubes (MWNTs) as secondary filler in chitosan-based polymer electrolyte film which aided in increasing the electrical conductivity of the prepared film. The addition of a small amount of MWNTs as secondary filler increased the A.C. conductivity from 2.6 × 10–4 to 1.4 × 10−3 S/cm due to the formation of conductive layers by it. The co-sensitized dye obtained from pomegranate and moss (1:1) is evaluated for the fabrication of dye-sensitized solar cells. In place of nanostructured TiO2-based photoanode, we admixed TiO2 with indium oxide (In2O3) to improve the spectral response of TiO2 for obtaining better efficiency. The use of this polymer electrolyte film along with co-sensitized natural dye and admixed photoanode helped in the fabrication of a highly efficient dye-sensitized solar cell (DSSC) with around 3.8

Graphite nanopowder is synthesized by mechanical method using ball mill and used as filler in polymer electrolyte film based on Polyvinyl alcohol (PVA) for application in natural dye sensitized solar cell (DSSC). In the present work dye sensitized solar cell has been assembled using electrolyte system composed of PVA as host polymer, ethylene carbonate as plasticizer, LiI: I2 as redox couple and graphite as filler; TiO2 modified with Copper oxide (CuO) photoanode in order to provide inherent energy barrier and natural cocktail dye as sensitizer. The obtained solar cell conversion efficiency was about 3.2 % with fill factor 52% using an irradiation of 100 mW/cm2 at 25º C.

Current studies on dye-sensitized solar cells focus on using low cost materials with high efficiency. Platinum is the most desirable material for the counter electrode of dye-sensitized solar cells but it is an expensive material that limits its use. To reduce the cost, carbon-based materials are focused on as it proves to be the best material as far as cost is concerned. We investigated the use of composite paste of multiwall carbon nanotubes and activated carbon based on coconut fiber (1:1) for the preparation of counter electrodes. In place of liquid electrolyte, we have prepared solid polymer electrolyte based on Polyvinylidene fluoride (PVDF) due to its exceptional properties with graphite as filler. The obtained conductivity was found to be 5.63 × 10−3 S cm− 1. Anthocyanin pigment obtained from mulberry is being used as a natural dye. The addition of indium oxide (In2O3) to titanium dioxide (TiO2) increased the spectrum response of TiO2, which led to greater efficiency. The obtained efficiency was found to be 3.3 which is excellent in the case of natural dye-sensitized solar cells.

Out of the main challenge facing dye sensitized solar cells (DSSCs) is the leakage and vaporization of liquid electrolyte limiting the long term durability of these cells. Therefore, solidification of electrolyte in DSSCs is a crucial research direction. In this work, DSSC was assembled using electrolyte system composed of Chitosan as host polymer, ethylene carbonate as plasticizer, LiI: I2 as redox couple and TiO2 as filler; TiO2 modified with WO3 photoanode to provide inherent energy barrier and anthocyanin as sensitizer. The obtained solar cell conversion efficiency was about 1.8% with fill factor 53% using an irradiation of 100 mW/cm2 at 25 °C. The prepared DSSC is not only stable but also eco friendly due to use of natural polymer and dye. © 2018 American Institute of Chemical Engineers Environ Prog, 38: 630–634, 2019

Present paper deals with the study of dielectric properties in polyethylene oxide (PEO)—based polymer electrolytes subsequent to dispersal of graphite filler particles synthesized by hot press and solution cast technique. The formation of nanocomposites and changes in the structural and microstructural properties of the materials were investigated by X-ray diffraction, Infrared measurements and optical microscopy. A decrease in crystanillity or increase in amorphousity was found to be more for solution cast film in comparison to hot press film. Electrical and thermal properties of PEO based polymer electrolyte film are found to be enhanced with the addition of graphite powder not only by solution cast method but also by hot press method. The conductivity for film prepared by solution cast method was found be in the range of 10−2 S/cm whereas for film prepared by hot press method the conductivity was found to be in the range of 10−4 S/cm at increasing temperature. The dielectric behavior is analyzed using the dielectric permittivity (ε’ and ε’’) and tangent loss (tan δ). It is found that the dielectric permittivity (ε’ and ε’’) rises sharply towards low frequencies and maxima of tangent loss shifts towards higher frequencies for both the films.

The motivation of the present work was to obtain improved TiO2 photoelectrode by admixing CeO2 through sol gel process. The surface morphology, structural and PEC characterization of the TiO2 overland with CeO2 admixtures have been investigated in relation to hydrogen production through semiconductor septum photo-electro-chemical (SC-SEP PEC) solar cell. UV Vis absorption spectra show a clear enhancement in the absorption range caused by admixing CeO2. The CeO2 admixed ns TiO2 exhibited a high photocurrent and photovoltage of 14.6 mA cm(-2) and 920 mV. The ns TiO2 CeO2 electrode showed high hydrogen gas evolution rate of 13.8 1 h(-1) m(-2) in comparison to bare ns- TiO2 photoelectrode which showed 8.6 1 h(-1) m(-2) hydrogen gas evolution rates. (C) 2015 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.