Dye-sensitized photoelectrochemical cells (DSPECs) are gaining growing interest as a viable alternative for visible-light-driven water electrolysis for hydrogen (H2) generation. The generated H2 has the potential to meet the energy needs of modern civilization while having minimal impact on the environment. DSPECs are made up of wide-bandgap nanostructured metal-oxide semiconductors (MOSs) and chromophore-catalyst assemblies designed to push the two halves of the water splitting process into physically isolated compartments. The two primary reactions in water oxidation and proton reduction occur at the photoanode and cathode, respectively, and are referred to as the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER), respectively. DSPECs have shown outstanding efficiency in converting sunlight into hydrogen in recent years, but they have not been commercially feasible due to high production costs. The present study encompasses state-of-the-art DSPECs and various advancements in DSPECs' functional architecture to improve their water splitting efficiency and stability. We further highlight the current challenges and prospects for the widespread adoption of DSPEC technology.

In the past three decades, dye-sensitized solar cells (DSSCs) have gained increased recognition as a potential substitute for inexpensive photovoltaic (PV) devices, and their maximum efficiency has grown from 7% to 14.3%. Recent developments in DSSCs have attracted a plethora of research activities geared at realizing their full potential. DSSCs have seen a revival as the finest technology for specific applications with unique features such as low-cost, non-toxic, colourful, transparent, ease of fabrication, flexibility, and efficient indoor light operation. Several organic materials are being explored and employed in DSSCs to enhance their performance, robustness, and lower production costs to be viable alternatives in the solar cell markets. This review provides a concise summary of the developments in the field over the past decade, with a special focus on the incorporation of organic materials into DSSCs. It covers all elements of the DSSC technology, including practical approaches and novel materials. Finally, the emerging applications of DSSCs, and their future promise are also discussed.

Water scarcity has emerged at the forefront of the world's most critical environmental concerns. In the future decades, the rapid population development in emerging regions will continue to raise the need for clean water from residential, agricultural, industrial, and energy perspectives. Clean drinking water is the most significant factor that influences the quality of life for humans. Nanomaterials are ideal for wastewater treatment due to their potential properties, which include small size, large surface area, high porosity, high catalytic activity, tailorable physical and chemical properties, ease of separation, and reproducibility. These favorable properties of nanomaterials make them an attractive candidate for wastewater treatment. This chapter comprehensively overviews a broad spectrum of nanomaterials in wastewater treatment, including different carbon allotropes (graphene, CNTs, MWCNTs, etc.) and metal oxide nanoparticles. Finally, the prospects of these new generation materials in water and wastewater treatment are also discussed.

Water scarcity has emerged at the forefront of the world's most critical environmental concerns. In the future decades, the rapid population development in emerging regions will continue to raise the need for clean water from residential, agricultural, industrial, and energy perspectives. Clean drinking water is the most significant factor that influences the quality of life for humans. Nanomaterials are ideal for wastewater treatment due to their potential properties, which include small size, large surface area, high porosity, high catalytic activity, tailorable physical and chemical properties, ease of separation, and reproducibility. These favorable properties of nanomaterials make them an attractive candidate for wastewater treatment. This chapter comprehensively overviews a broad spectrum of nanomaterials in wastewater treatment, including different carbon allotropes (graphene, CNTs, MWCNTs, etc.) and metal oxide nanoparticles. Finally, the prospects of these new generation materials in water and wastewater treatment are also discussed.

Vegetable crops grown in greenhouses have gained popularity across the world. Greenhouse technology fosters an atmosphere conducive to agricultural growth and development. This report thoroughly assesses solar energy-based temperature management and energy conservation strategies for greenhouses. A brief and succinct evaluation of current greenhouse systems has been provided regarding their contribution to overall energy consumption. This mini-review includes photovoltaic (PV) modules, solar thermal (T) collectors, hybrid PV/T collectors and systems, PCM-based heat storage methods,and novel techniques for enhanced thermal shielding and energy production.

The rising demand for food and the unpredictable price of fossil fuels have led to the search for environmentally sustainable energy sources. Energy is one of the significant overhead costs for favorable climate control output of agriculture crops. Most farming machines are powered by fossil fuels, which leads to emissions of greenhouse gases and exacerbates climate change in turn. The concept of sustainable agriculture resides in a delicate balance between maximizing crop productivity and preserving economic stability while at the same time minimizing the use of natural resources and adverse environmental effects. Unlike fossil fuels, solar energy is one of the most abundant and cleanest renewable energy sources, with the capacity to meet the world's current energy demand with no adverse environmental effect. The use of solar energy systems in farm environments restricts fossil fuel consumption and increases farm production sustainability. This review provides a comprehensive overview focusing on key energy-saving strategies in agriculture farming. The technologies included in the research scope are mainly renewable and sustainable solutions, such as photovoltaic (PV) modules, solar thermal (T), hybrid PV/T collectors, energy-efficient pumping systems, various covering materials for improved thermal insulation, and energy generation.

The poor thermal conductivity of conventional base fluids limits their widespread applications and causes significant heat and mass losses. The thermal conductivity of traditional base fluids can be dramatically improved by suspending metal nanoparticles. The resultant nanofluids have excellent thermal conductivity than classical base fluids. Herein, the natural convection phenomenon in two vertical metallic cylinders at the same constant heat flux (180 W) containing silver nanofluid and deionized water (DI) has been experimentally investigated. The one-step method was used to prepare the silver nanofluid without using any surfactant. The prepared silver nanofluid is characterized by various modern scientific tools to assess its stability, evenness, and size distribution. The size of the prepared silver nanoparticles is observed in the range of 2 nm to 6 nm. The zeta potential analysis reveals a high value of zeta potential of − 38.5 mV, suggesting the superior stability of the prepared nanofluid. Furthermore, the variation in the silver nanofluid and DI water temperature with time, along the length of the cylinder, density, and the Grasshof number in two separate vertical fluid columns is also studied, and the results are compared. The experimental results show that the process of natural convection is highly improved in a vertical column containing silver nanofluid, encouraging rapid and optimized heat transfer applications in an inclined (45 °C) heat exchanger. This work will pave the way to further explore nanofluids for thermal applications.

In the present investigation, Copper/TiO2/graphene oxide (CuTGR) ternary nanocomposites have been prepared for the first time by the sol–gel-assisted hydrothermal method. The prepared CuTGR ternary composites have been investigated for their structural, surface morphological, and optical properties via X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), Energy-dispersive X-ray Spectroscopy (EDX), Transmission Electron Microscope (TEM), Brunauer, Emmett & Teller (BET) method, X-ray Photoelectron Spectroscopy (XPS), and UV–Vis spectroscopy (UV–Vis). The surface morphological and elemental analysis reveals graphene's presence in CuTGR ternary nanocomposite with uniform distribution and desired morphology. The addition of Cu and graphene further improves the CuTGR ternary nanocomposite's optical response by altering the electronic structure of TiO2. The bandgap of TiO2 was found to be lowered upon Cu and graphene inclusion. Results demonstrate that an optimal loading of Cu and graphene in TiO2 can significantly boost the surface and optical properties of CuTGR ternary nanocomposites, thereby allowing it to be a viable alternative for photocatalysis operations and dye-sensitized solar cell (DSSC) photoanode application.

Graphene (GR) demonstrates excellent photoelectrochemical properties, including its large specific surface area, unique structure, chemical stability, high conductance, and fast electron transfer. These parameters are crucial for the performance improvement and photoanode optimization of a dye-sensitized solar cell (DSSC). In this study, Cu-doped TiO2/graphene (CuTGR) composites have been prepared for the first time by the sol-gel-assisted hydrothermal method for the DSSC photoanode application. The prepared CuTGR composites have been coated on Fluorine-doped tin oxide (FTO) glass substrates using the doctor blade method. The surface morphological and elemental analysis reveals the presence of Cu and graphene into CuTGR nanocomposite with uniform distribution and desired morphology. The addition of graphene further improves the dye loading ability of the CuTGR photoanodes with improved current density and faster charge transport as observed in current-voltage (J-V) and intensity-modulated photocurrent spectroscopy (IMPS) measurements. Our findings demonstrate that an optimal loading of Cu and graphene can boost the power conversion efficiency (PCE) of the DSSC (9.81%) by 47% higher than undoped DSSC (6.66%).

Novel sol-gel route was adopted for the synthesis of undoped and Cu/S co-doped TiO2 nanoparticles (NPs) with constant content 0.05 at% of non-metal Sulfur and diverse content from 0.1 to 0.5 at% of metal Copper. The formation of anatase TiO2 crystalline phase was observed from XRD results with the crystallite size less than 11 nm for all the synthesized samples. The UV-Vis analysis revealed that co-doping with Cu/S altered the optical properties of TiO2 and extended absorption in the visible light region with red shift in band gap energies. EDAX analysis confirmed the purity of Cu/S co-doped TiO2 nanoparticles and also the evident presence of titanium, oxygen, copper and sulfur atoms in stoichiometric ratio. In photovoltaic measurements, under simulated solar irradiation the DSSC based on Cu/S co-doped TiO2 with 0.3 at% Cu and 0.05 at% S has exhibited the best power conversion efficiency (PCE) of 10.44% with significantly improved short circuit current density (J(sc)) of 22.05 mA/cm(2). This enhanced PCE is attributed to the appropriate particle size, enhanced surface area, higher dye adsorption and hence improved short circuit current density (J(sc)). In contrast, the undoped TiO2 NPs based DSSC has displayed a PCE of 6.37% with J(sc) of 14.85 mA/cm(2).

Solar thermal energy storage unit anchored fatty acids as Phase Change Materials (PCMs) having narrow range of transition temperature and high latent heat of fusion. In this paper, a new novel eutectic PCM was developed by using a fatty acid (acetamide) and non-paraffin organic PCM (acetanilide) for a sharp melting point and high latent heat of fusion. The optimized eutectic PCM may be used for middle temperature range solar thermal energy storage systems. The binary mixture of acetamide and acetanilide at various compositions by mass ratio (wt%) was prepared and optimized experimentally for lowest value of melting point at a eutectic mixture composition of 60 wt% of acetamide and 40 wt% of acetanilide. Eutectic PCM was analyzed by Differential Scanning Calorimetry (DSC) and Field-Emission Scanning Electron Microscopy (FE-SEM). DSC results revealed that optimized eutectic PCM has a sharp melting point of 65.37°C and high latent heat of fusion of 224.67 kJ/kg. Accelerated thermal cycle testing of optimized eutectic PCM was performed for 100 melting and freezing cycles and change in melting temperature and latent heat of fusion was acceptable.

Titanium dioxide (TiO2) nanoparticles were synthesized using three different approaches successfully. These approaches were adopted as per different applications of TiO2 nanoparticles. These samples were characterized using X- ray diffraction (XRD) technique. XRD revealed nanocrystalline regime of TiO2 nanoparticles in each approach. The calculated size of nanoparticle was less than 11 nm in the used chemical approaches. Prominent and broad peaks were observed in XRD pattern for all samples, which showed all samples were in nanocrytalline form. The particle size was calculated for first three most intense prominent XRD peaks. By adopting sol gel method using Titanium tetra isopropoxide (TTIP) as precursor, the synthesized Titania particles were pure anatas and of size 7 to 11nm and using co-precipitation method using TiCl3 as precursor synthesized Titania were pure rutile and of size 3 to 7 nm. The co-precipitation method has been best suited for getting smaller nanoparticles. It was also observed that Solid state mechanical reduction root can be used to reduce the size of Titania micro-particles up to about 60 nm but phase of nanoparticles remains same as starting microparticles. It has been seen that the material properties of TiO2 can be tuned by proper method of synthesis. The work may play important role to choose particular synthesis method for specific application. These nano synthesized TiO2 materials may be used in a wide range of applications such as dye sensitized solar cell, photocatalysis, antibacterial, environment pollutant removal and photoactivated self cleaning properties etc.

In the present work, pure and copper/nitrogen (Cu/N) co-doped TiO2 nanoparticles (NPs) with various Cu concentrations have been synthesized via sol–gel route. The optical and electrical properties of the prepared pure and Cu/N-doped TiO2 NPs have been assessed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDX), scanning electron microscope, Brunauer, Emmett and Teller method and UV–Vis spectroscopy. The results show that the addition of suitable amounts of Cu and N content in TiO2 can alter its optical and electrical properties by extending absorption in the visible region and band gap reduction. XPS and XRD measurements suggest that some of the Ti sites are replaced by Cu atoms, while O sites are occupied by N atoms. An adequate addition of Cu/N in TiO2 could lead to smaller particle size, higher specific surface area, increased dye adsorption and retarded charge carrier recombination. An optimized 0.3 mol% Cu/N-doped sample shows a significant change in band gap value of TiO2 from 3.2 to 2.78 eV, enabling it to respond in the visible region. Hence, it can be used as a suitable alternative nanomaterial for dye-sensitized solar cell photoanode application and for photocatalysis operation as well.

Cheap and efficient dye sensitized solar cells (DSSCs) can be prepared using natural dyes responding in the visible region of solar spectrum. Localized surface plasmon resonance (LSPR) plays a very important role for the improvement in the efficiency of DSSCs by using Plasmonic nanoparticles (PNPs) for exploiting the visible portion of the solar radiation by transferring the energy from dye to PNP. This energy transfers from dye to semiconductor TiO2 through PNP which increases the overall photo catalytic activity. In the present study, Al-doped TiO2 photoanodes were prepared via sol–gel route and used for DSSC application. Various natural and synthetic dyes are prepared and the optical transmittance and absorbance of the dyes are measured in the wavelength range of 250–850[Formula: see text]nm using UV-Vis spectroscopy and they are used in DSSC. Natural dyes extracted from fruits and synthetic dye based on Ruthenium (Ru) metal complex is used as sensitizers. Power conversion efficiency (PCE) of solar cells utilizing different dyes is compared. Out of the various natural dyes, beetroot and strawberry extracts based dyes show good absorbance in the visible range of electromagnetic spectrum. On the other hand, synthetic dyes based on Ru complex show strong absorbance over a wide range of visible spectrum. The absorbance increases with increase in concentration of Ru in ethanol. The extracts of beetroot, strawberry and mixed fruits show a peak in absorbance spectra at 501nm, 416nm and 332nm, respectively, indicating the absorption over a wide range of visible spectrum. Maximum efficiency of DSSCs utilizing PNPs sensitized with beetroot and strawberry dyes are found to be 1.5% and 1.3%, respectively.

The present investigation reports the sol-gel synthesis of novel Aluminium/Nitrogen (Al/N)-codoped TiO2 nanoparticles (NPs) and their successful incorporation in dye-sensitized solar cells (DSSCs). The impact of Al doping on the operation of Al/N-doped TiO2 DSSCs has been systematically investigated by varying Al content, while keeping N content constant. The prepared samples have been examined for their crystallite size, surface morphology, chemical state, surface area, optical response and electrical response using various characterization techniques such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-Visible spectroscopy (UV-Vis), Scanning electron microscopy (SEM), Tunnelling electron microscopy (TEM) and Electrochemical impedance spectroscopy (EIS). The photovoltaic measurement of all the prepared cells has been performed using solar simulator under 100 mW cm(-2) light intensity. A DSSC with 2 wt% Al/N-doped TiO2 NPs shows the best power conversion efficiency (PCE) of 11.08% about 40.78% enhancement in the PCE relative to Degussa P25 based DSSC. The experimental results show that an adequate inclusion of Al and N in TiO2 nanostructure lead to smaller particle size, stabilized structure, increased specific surface area, elevated dye loading, smooth charge carrier separation, enhanced short circuit current density (J) and hence improved PCE of DSSC.

In the present investigation novel Aluminium/Nitrogen (Al/N)-codoped TiO2 nanoparticles (NPs) have been prepared via sol–gel route under mild conditions. The structural, optical, morphological and compositional properties of all the prepared samples have been characterized by X-Ray Diffraction (XRD), X-Ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscope, Transmission Electron Microscopy, UV–Vis spectroscopy (UV–Vis) and Photoluminescence Spectroscopy (PL). XRD results reveal that the doping of Al in TiO2 nanostructure hinders its crystal growth and stabilizes the crystal structure. XPS result confirms the successful incorporation of Al and N in TiO2 structure. UV–Vis measurement shows a distinct alteration in the optical properties of TiO2 resulting in red shift i.e. lower band gap values relative to undoped TiO2 NPs. Moreover, PL spectra reveal prolonged electron–hole pair lifetime for efficient photocatalytic performance. Thus, Al/N co-doped samples exhibit enhanced absorption, retarded charge carrier recombination and hence excellent photocatalytic activity for degradation of methylene blue (MB) solution under visible light irradiation. A sample doped with 2 wt% Al/N-doped TiO2 NPs shows best photocatalytic activity among all other samples.

Pure and Copper/Nitrogen (Cu/N)-codoped TiO2 photoanodes with various Cu concentrations are prepared via sol–gel route for the photoanode application in dye-sensitized solar cells (DSSCs). All the prepared samples are characterized by X-Ray Diffraction (XRD), X-Ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscope (SEM), Transmission Electron Microscopy (TEM), UV–Vis spectroscopy (UV–VIS) and Electrochemical Impedance Spectroscopy (EIS). Addition of suitable amount of Cu and N content in TiO2 can alter its optical and electrical properties by extending absorption in the visible region and band gap reduction. The results show that some of the Ti sites are replaced by Cu atoms while O sites are occupied by N atoms. Upon adequate addition of Cu/N could lead to smaller particle size, higher specific surface area, increased dye adsorption and retarded charge carrier recombination. A significant improvement in the power conversion efficiency is observed in case of optimized 0.3 mol% Cu/N-doped TiO2 nanoparticles (NPs) based DSSC. This optimized 0.3 mol% Cu/N-doped photoanode accomplished a best power conversion efficiency of 11.70% with a short circuit current density of 23.41 mA cm−2 which is 41% higher than that of the pure TiO2 photoanode based DSSC (6.82%).

Pure and copper doped titanium dioxide nanoparticles (TiO2 NPs) for Dye Sensitized Solar Cell (DSSC) photo anodes with different doping amounts of copper (Cu) 0.1, 0.3 and 0.5 mole% are synthesized using modified sol-gel route. Addition of Cu in TiO2 matrix can enhance absorption towards visible spectrum and can reduce the charge carrier recombination due to Localized Surface Plasmon Resonance (LSPR). The samples are characterized by X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), UV-vis spectroscopy (UV-VIS), X-ray Photoelectron Spectroscopy (XPS), Electro Chemical Impedance Spectroscopy (EIS). The crystallite size is measured by XRD and surface morphology of the samples is analyzed using SEM. UV-vis measurement shows that the influence of Cu in TiO2 lattice altered its optical properties and extended absorption in the visible region. The resistances between different junctions of the cell are measured by EIS. The J-V measurement of the cell prepared using pure and Cu-doped TiO2 NPs is carried out by solar simulator. The optimized Cu doped DSSC with 0.3 mole% Cu in TiO2 shows the best power conversion efficiency of 8.65% which is approximately 26% greater than the efficiency of undoped DSSC (6.41%). (C) 2017 Elsevier Ltd. All rights reserved.

Pure and doped titanium dioxide (TiO2) nano particles have been prepared using acid tailored novel sol-gel method based on the use of new chemicals using different doping concentration of metal aluminum (Al) at annealing temperature of 450 degrees C. Powder XRD and UV-Vis have been used to investigate the effect of Al doping in pure TiO2. Particle size analysis using X-ray line broadening shows marginally increasing trend with increasing Al impurity. Results show that all samples prepared by this method having particle size in the range of 11 nm to 23.9 nm. UV-Vis analysis indicates decrease in energy band gap due to Al doping which means there is a shift in the solar spectrum towards the lower wavelength region in case of doped TiO2 and hence absorption is increased as compared to pure TiO2. Metal doping of Al enhances electrical conductivity due to plasmonic effect and improves optical transparency of TiO2 semiconductor at a low cost. The value of band gap for pure TiO2 is 3.1 eV and decreases to 2.8 eV for 0.03 mole % of Al in Pure TiO2. Versatile, cheap and easy novel method has been reported for preparation of pure and doped TiO2 nano particles, which can be used for making photo anode for solar cells.

Nanofluid is a new class of heat transfer fluid in the area of energy research and engineering. In the present work, silver/water nanofluid is synthesized and it is characterized. One step method was developed for the preparation of silver nanofluid without using any surfactant. Silver nitrate was used as precursor and sodium citrate as reducing agent. Investigation of sample was carried out to study the particle size, pH value, absorption spectra and zeta potential. Nanofluid with particle size 2nm to 6nm was achieved at 80°C temperature. Zeta potential was measured and has value of -38.5mV. Transmission electron micrograph showed the presence of uniform size of particles in the base fluid. The silver nanoparticles as prepared nanofluid found to have an uniform dispersion, narrow size distribution with good stability over ageing.