A recent study published in the journal Scientific Reports focuses on the development of nanoscale lead sulfide (PbS) thin films using avocado leaf extracts using the chemical bath deposition technique.
Study: Synthesis of nanometric-sized lead sulfide thin films of avocado leaf extracts (Glycosmis cochinchinensis) to enhance contamination remediation. Image credit: Pixel-Shot / Shutterstock.com
A common trend is observed around the world regarding the use of avocado (Glycosmis cochinchinensis): its fruits are consumed while the leaves are left to pollute the environment.
Figure 1. A schematic set of the CBD method.
Nanomaterials have been widely used in energy, optoelectronics, drug delivery, and ecological remediation applications due to their unique physicochemical, structural, optical, and gas detection properties. However, traditional methods for producing nanomaterials have raised various environmental concerns due to the use of harmful chemicals.
Green synthesis of nanomaterials: why is it important?
The synthesis of green nanoparticles seeks to reduce waste and develop sustainable technologies. Ecological techniques that use moderate reaction conditions and non-toxic precursors have stood out in the development of nanotechnology in recent years to promote environmental sustainability.
In the green synthesis of nanomaterials bioactive agents such as plant materials, microbes and other biological wastes such as vegetable waste, fruit peel waste, eggshell and agricultural runoff are used. The use of natural bioactive agents to manufacture metal nanoparticles significantly minimizes the risk of environmental pollution.
Lead sulfide (PbS) thin films: synthesis methods and advantages
Lead sulfide (PbS) is a semiconductor with a direct narrow energy gap at room temperature. Lead sulfide also has a positive temperature coefficient of the energy gap, which makes it with many unique physicochemical characteristics. In addition, photosensitive constants such as the refractive index and extinction coefficients of lead sulfide thin films are optimal for optical detection applications.
Figure 2. Plant of avocado leaf extracts (Glycosmis cochinchinensis) and its fruits extracted from the local area of Dambi Dollo Town, Oromia, Ethiopia.
Chalcogenide nanomaterials such as lead sulfide (PbS) thin films can play an essential role in many optoelectronic applications such as solar cells, gas sensors, laser materials, thermoelectric devices and semiconductors.
PbS thin films have been prepared by various deposition methods such as spray pyrolysis, successive ion layer adsorption and reaction, solid vapor deposition, thermal evaporation, galvanic method, pulse electrodeposition, chemical bath deposition and atomic layer deposition.
Benefits of chemical bath deposition
Recently, the chemical bath deposition method has been used to produce PbS thin films.
The chemical bath deposition technique is a method of depositing thin films on a substrate from a solution containing metal, hydroxide, and sulfur or selenide ions. It has become an attractive technology for its simplicity of manufacture, low cost, suitability for large-scale deposition regions, ability to deposit thin films on various substrates and ease of adjusting the qualities of the thin film modifying the deposition settings.
The main advantage of this method is that it is feasible to ensure that the reaction that occurs in the deposition bath occurs slowly during the formation of a film on a substrate, resulting in the production of thin films with characteristics exceptional interfacials.
Figure 3. Scanning electron microscopic image of avocado lead sulfide thin films (Glycosmis cochinchinensis) The leaf extract at different pH values varied as (a) 2, (b) 4, (c) 6 and (d) 8.
Synthesis of PbS thin films using avocado leaf extracts
In the present study, nanocrystalline lead sulfide thin films were produced effectively by the chemical bath deposition approach from avocado plant leaf extracts. The thin films made were of exceptional quality. Various characterization techniques were used to explore the influence of concentration on the physical, structural, and optical aspects of PbS thin films.
The energy dispersed X-ray analysis (EDX) method was used to obtain the composition of the thin films. The X-ray photon spectroscopy (XPS) technique was then used to obtain the chemical composition of the prepared films. The X-ray diffraction (XRD) technique was also applied to study the structural properties of the prepared thin films.
XRD analysis revealed that the prepared nanomaterial is actually a cubic crystal and the average crystal size of the thin film is 0.5 nm. The prepared thin films showed remarkable absorbance and low reflectance, which made them suitable materials for use in solar cell applications.
The band gap of nanocrystalline lead sulfide thin films prepared from avocado leaf extracts was found to be 2.43 eV, which is higher than bulk films in due to quantum confinements of PbS nanocrystals. Samples prepared at pH = 4, in particular, showed remarkable optical performance.
From these results, it is safe to suggest that lead sulfide thin films deposited from avocado leaf extracts are a promising resource for future applications in pollution management and waste generation. sustainable energy.
Reference
Saka, A. et al. (2022). Synthesis of nanometric-sized lead sulfide thin films of avocado leaf extracts (Glycosmis cochinchinensis) to enhance contamination remediation. Scientific reports. Available at: https://www.nature.com/articles/s41598-022-15785-4
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