Sunlight harvesting for heat generation inside water using biosynthesized magnetite nanoparticles.

A low-cost, simple, inexpensive, and environmentally friendly method has been employed for synthesizing magnetite nanoparticles (Fe3O4 NPs). In this study, weeping willow (Salix babylonica L.) aqueous leaf extract has been utilized as a reducing, capping, and stabilizing agent. The synthesized Fe3O4 NPs were characterized by ultraviolet-visible (UV-Vis) spectroscopy, FT-IR spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), dynamic light scattering (DLS), zeta potential analysis, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The localized surface plasmon resonance (LSPR) performance of the Fe3O4 NPs was examined. It has been shown that the biosynthesized Fe3O4 NPs once dispersed in water can raise the temperature of water significantly when they absorb solar radiation through surface plasmon resonance (SPR). The impact of the pH value on the Fe3O4 NPs was also investigated. It has been shown that the optimum pH value among the examined pH values was pH 6. At this pH, the biosynthesized Fe3O4 NPs were able to increase the temperature of water from 25 °C to ∼36 °C. This dramatic increase in temperature was owing to the Fe3O4 NPs synthesized at pH 6 which acquired high crystallinity, monodispersity, high purity, minimum agglomeration, a small particle size, and high stability. In addition, the mechanism of converting solar energy to thermal energy has been discussed intensively. To the best of our knowledge, this study is unique and the novelty of this investigation is that Fe3O4 NPs acquire plasmonic-like properties under solar radiation. Also, they are anticipated to be an innovative photothermal adaptation material for solar-based water heating and heat absorption.

Biosynthesis of Silver Nanoparticles at Various pH values and their Applications in Capturing Irradiation Solar Energy.

BACKGROUND: Metallic nanoparticles (NPs), in general, are able, due to the high surface area per unit volume, to absorb the maximum incoming light flux through the vicinity of plasmonic structures and then provide local heating. Thus, silver (Ag) NPs has been used to generate heat and increase the temperature of water from solar radiation energy. The optimal plasmonic heating generation can be obtained as soon as the wavelength of the light source is close to the plasmonic resonance wavelength of Ag NPs. OBJECTIVE: Ag NPs have been fabricated through a straightforward, cheap, as well as environmentally friendly approach. In this study, Salix babylonica L., weeping willow leaf extract has been utilized as a reducing, capping, and stabilizing agent, without using any other toxic materials. The importance of this study lies in the generation of hot electrons, which can be obtained by collecting the solar spectrum near the infrared and infrared regions, which cannot be obtained by the conventional photocatalytic devices. METHODS: Numerous characterization techniques such as; UV-Vis, FT-IR spectroscopy, X-ray diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) analysis were used to study the optical, chemical, structural, morphological, properties of the Ag NPs. RESULTS: The impact of pH on the properties of Ag NPs and their performance to generate heat during solar irradiation have been investigated intensively. This study showed that the synthesized Ag NPs with pH value 12 is the optimum condition and can increase the temperature of water dramatically. CONCLUSION: An evaluation of the current patents displays that the field of green synthesis Ag NPs utilizing plant extracts is a vital field and produces rather stable, safe and effective Ag NPs. The novelty of this patent is that Ag NPs can be synthesized from a one-pot reaction without using any exterior stabilizing and reducing agent, which is not conceivable by means of the existing processes. This study, also, is rare and distinctive, and it demonstrates that even a slight quantity of the Ag NPs is significantly raising the temperature of water effectively.