In recent years, photocatalytic solar energy conversion has become the focus of several research projects due to its potential to help end human dependency on fossil fuels. Now, a paper published in Applied Nano Materials has explored the use of MgB4 nanosheets for this purpose.
Study: MgB4 MXene-like Nanosheets for Photocatalytic Hydrogen Evolution. Image Credit: LukVFX/Shutterstock.com
Moving Away from Fossil Fuels
Fossil fuels have been human society’s main source of energy since the industrial revolution. However, this has come at a cost, with rising global temperatures threatening the stability of planetary ecosystems and vulnerable communities and resource depletion raising the real possibility of future energy crises.
The exploitation of fossil fuel resources also causes physical damage to ecosystems and pollution of water bodies from industrial runoff, and disasters such as oil spills compound the issues with fossil fuels.
Wind power, hydroelectric power, wave, and tidal power, and solar power are all increasingly being used in the renewable energy mix to replace carbon dioxide emitting oil, gas, and coal power generation. Focus has been placed on the rapid development and deployment of these technologies to help governments meet their net-zero carbon emissions targets by 2050.
Solar energy has become an attractive proposition to provide clean, limitless energy that will replace fossil fuels. Research over the last few decades has provided new technologies and advanced materials for the field of solar energy generation and conversion that has made utilizing the abundant energy from the sun commercially viable.
Photocatalytic Solar Energy Conversion
This field of energy research has garnered a lot of attention recently due to its potential to provide clean, renewable energy storage and environmental protection. Photocatalysis converts solar into chemical energy, whilst simultaneously providing storage solutions.
Aside from green energy generation, photocatalytic solar energy conversion has many applications for important environmentally friendly technologies and fields such as pollutant removal, artificial photosynthesis, and green fuel production. Photocatalysis enhances important energy conversion-related reactions such as carbon dioxide reduction, light-driven water splitting, nitrogen fixation, and so forth.
A key requirement of a photocatalyst is that its conduction band bottom should be more negative than the reduction potential of hydrogen. This enables the generation of H2 molecules. To realize the potential of the technology, research into advanced materials with superior photocatalysis properties has been carried out by different teams. Now, one team has explored the use of boron-based MXene-like nanomaterials.
Using MXene-like Nanosheets for Photocatalysis
A paper published online in November 2021 has explored the use of these 2D nano-scaled materials as photocatalysts. MXenes are comprised of early transition metal carbides, carbonitrides, or nitrides. They are prepared by removing certain atomic layers from precursor materials via etching. MXenes display several interesting and unusual electronic and structural properties that make them attractive for use in applications such as photocatalysis.
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Properties of MXenes that make them useful for photocatalytic H2 evolution from water (a potential approach that makes possible full utilization of solar energy) and pollutant removal include their hydrophilic functionalities and the presence of exposed transition metal sites on their surface. Other molecules such as water, dye, metals, and even semiconductors can connect to these sites, giving MXenes superior reactive activities.
In the research paper, the team explored boron-based magnesium tetraboride (MgB4) MXene-like nanosheets for use as photocatalysts. General MXene preparation procedures were used in the study. A single Mg layer was etched from magnesium dibromide (MgB2) to create the novel material. The etching agent chosen was an aqueous solution of hydrochloric acid. The team explored the material’s photocatalytic, optical, chemical, and structural properties.
Metal-layered MXenes transfer and separate photogenerated carriers and harvest higher levels of photonics, which generates more active electron-hole pairs. The presence of boron-boron and boron-metal bonds in the magnesium tetrabromide gives the material superior mechanical, thermal, and chemical stability as well as high levels of thermal and electrical conductivity.
Results of the study showed that these nanosheets exhibited stable, efficient photocatalysis of H2 generation from water molecules. This was due to the presence of numerous exposed metal sites on the surface of the material, as well as superior conductivity. Superior solar energy absorbing and harvesting capabilities were observed. The research paper paves the way for developing more efficient catalysts based on boron for energy conversion and storage applications.
Research into advanced materials is benefitting multiple industries, providing better, more efficient technology that helps to solve critical problems facing humanity in the 21st century. Boron-based magnesium tetrabromide MXene-like nanosheets have several interesting properties that make them an attractive material for use in next-generation energy storage and photocatalysis applications that could prove revolutionary for the future of solar energy and, by extension, the end of fossil fuel dependency.
Xiao, L et al. (2021) MgB4 MXene-like Nanosheets for Photocatalytic Hydrogen Evolution [online] ACS Appl. Nano Mater. | pubs.acs.org. Available at: https://pubs.acs.org/doi/pdf/10.1021/acsanm.1c03497
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