Nanotechnology researchers and physicists from Kafrelsheikh University, Egypt, recently fabricated a promising nanocomposite material that they say is well-suited for applications in solar energy.
Image Credit: foxbat/Shutterstock.com
The study was published in the Journal of Alloys and Compounds, showing how the team fabricated a novel CO@CuO.γ-Al2O3 nanocomposite with graphene and copper oxide and characterized the material.
The researchers then demonstrated how the new nanocomposite material exhibits enhanced thermal conductivity performance for novel nanofluids. This feature makes it a good candidate for high-performance solar energy applications, according to the paper's authors.
Graphene In Solar Energy Production
Graphene's textural and electronic properties have been enhanced in recent years by adding metal oxide photocatalyst materials, enabling its composite to be used in solar energy cells.
Metal oxide-based nanocomposites are currently a key focus of research. This is due to their high corrosion stability and nontoxicity, in addition to their ready availability and photocatalytic properties.
Achieving a suitable architecture to minimize electron loss at the connections within the material's nanostructure has been a challenge. This step is required to control the high efficiency of graphene composite-based photoanode and counter electrode materials.
Harnessing the features of graphene nanocomposites has significant applications in solar energy technology. Photon absorption, charge separation, and charge carrier transport all benefit from graphene-based nanocomposites.
Fabrication of a New Graphene-Based Nanocomposite
The team fabricated the new graphene nanocomposite by loading a graphene oxide (GO) nanosheet with quantum dots of other nanomaterials. They used copper oxide (CuO) nanorods and aluminum oxide (γ-Al2O3) nanoparticles to form a graphene oxide-based nanocomposite (GO@CuO.γ-Al2O3).
Compositing these materials required advanced nanotechnology techniques X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM).
Zeta potential was employed to characterize the fabricated nanomaterials, and results confirmed that nanorods and nanoparticles had been successfully loaded onto the graphene oxide's surface.
Enhancing Thermal Conductivity
To test the material's thermal conductivity, the team processed them with water to create novel nanofluids. Researchers investigated different concentrations of nanofluids at temperatures ranging from 20 to 50 °C.
The researchers found thermal conductivity in GO@CuO.γ-Al2O3 nanofluid was enhanced up to 22.56% compared with water. This effect was achieved with the greatest concentration tested, 0.2% nanomaterial.
Suitability for High-Performance Solar Energy Applications
According to the paper's authors, these results mean that the GO@CuO nanocomposite was better at producing photocurrent than other nanocomposites used in solar energy today.
GO@CuO also had the lowest photoluminescence (PL) intensity tested. PL is the emission of absorbed light as photons; a low PL intensity enables lower charge carrier recombination and higher light harvesting.
Charge carrier generation and recombination enable mobile charge carriers (electrons and electron holes) to be created and eliminated in semiconductors' solid-state physics. These processes are fundamental to optoelectronic semiconductor devices' operation.
The study's authors said that the PL results for GO@CuO nanocomposites showed them to be well suited for solar cell applications. Consequently, the team said, GO@CuO.γ-Al2O3 and GO@CuO are good candidates for improving solar energy performance.
Graphene in Solar Cells
This latest study is part of a growing body of research examining the many applications of graphene in advanced technologies. Graphene, an allotrope of carbon made of a single layer of atoms arranged in a lattice nanostructure, is a transparent conductor used in various materials and devices.
Solar cell technology has been one of the most promising applications for the novel material.
It prevents high local electric fields with its unique 2D surface nanostructure. This slows down the electric transport of charge on the surface, making it easier to control.
Graphene also performs better than indium tin oxide – traditionally used in solar cell manufacture – due to being transparent to a particular partition of infrared light.
In silicon or gallium arsenide – conventional semiconductors – a freely moving electron is created for each photon absorbed. However, this only absorbs some of the photon's energy, while the rest is lost heating up the semiconductor's crystal lattice. Graphene can overcome this issue, making it potentially a much more efficient solar cell material.
Graphene's unique 2D structures make it ideally suited for use in solar cell devices as a transparent electrode, hole/electron transport material, and interfacial buffer layer.
As well as extracting and transporting charge to the electrodes, graphene can also play a part in solar energy production by protecting equipment against environmental degradation. This is due to its solid-state 2D network structure, providing long-term environmental durability for photovoltaic devices.
Recent advances in graphene-based solar cells include bulk heterojunction (BHJ) organic devices, dye-sensitized technology, and perovskite solar cells. The latter technology has received significant attention in industry and research, with record-breaking conversion efficiency for commercial photovoltaics.
Continue reading: Minimizing Solar Cell Surface Reflectance with Photonic Quasi-Crystal Nano-Structuring.
References and Further Reading
El Shafai, N.M., and W. Ismail (2021) Investigation of a novel (GO@CuO.γ-Al2O3) hybrid nanocomposite for solar energy applications. Journal of Alloys and Compounds. Available at: https://doi.org/10.1016/j.jallcom.2020.157463
Low, F.W., C.W. Lai, and S.K. Tiong (2019) Graphene-Based Nanocomposites for Renewable Energy Application. Handbook of Polymer and Ceramic Nanotechnology. https://doi.org/10.1007/978-3-030-10614-0_26-1
Mahmoudi, T., and Y-B. Haha (2018) Graphene and its derivatives for solar cells application. Nano Energy. Available at: https://doi.org/10.1016/j.nanoen.2018.02.047
Zhong, M. et al. (2016) Interface coupling in graphene/fluorographene heterostructure for high-performance graphene/silicon solar cells. Nano Energy. Available at: https://doi.org/10.1016/j.nanoen.2016.08.031