In recent years, the photocatalytic conversion of solar energy has become the subject of several research projects because of its potential to help end human dependence on fossil fuels. Now an article published in Nanomaterials applied explored the use of MgB4 nanosheets therefor.
To study: MgB4 MXene-type nanosheets for the photocatalytic evolution of hydrogen. Image Credit: LukVFX / Shutterstock.com
Move away from fossil fuels
Fossil fuels have been the main source of energy for human society since the industrial revolution. However, it has come at a cost, with rising global temperatures threatening the stability of planetary ecosystems and vulnerable communities, and resource depletion increasing 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 exacerbate fossil fuel problems.
Wind power, hydroelectric power, wave and tidal power and solar power are all increasingly used in the renewable energy mix to replace the production of electricity from oil, gas and coal. emitting carbon dioxide. Emphasis 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 power has become an attractive proposition to provide clean, unlimited energy that will replace fossil fuels. Research over the past decades has provided new technologies and advanced materials for the field of solar power generation and conversion that have made the use of the sun’s abundant energy commercially viable.
Photocatalytic solar energy conversion
This area of energy research has recently received a lot of attention because of its potential for storing clean, renewable energy and protecting the environment. Photocatalysis converts solar energy into chemical energy, while simultaneously providing storage solutions.
Besides the production of green energy, the photocatalytic conversion of solar energy has many applications for important environmentally friendly technologies and fields such as the removal of pollutants, artificial photosynthesis and the production of green fuel. Photocatalysis improves important reactions related to energy conversion such as reduction of carbon dioxide, water splitting by light, nitrogen fixation, etc.
A key requirement of a photocatalyst is that the bottom of its conduction band be more negative than the reduction potential of hydrogen. This allows the generation of H2 molecules. To realize the potential of the technology, research into advanced materials with superior photocatalytic properties has been carried out by different teams. Today, a team explored the use of boron-based MXene-type nanomaterials.
Use of MXene-type nanosheets for photocatalysis
An article published online in November 2021 explored the use of these 2D nanoscale materials as photocatalysts. MXenes are composed of carbides, carbonitrides or nitrides of early transition metals. They are prepared by removing certain atomic layers from the precursor materials by etching. MXenes exhibit 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 H photocatalysis2 the evolution of water (a potential approach that makes the full use of solar energy possible) and the removal of pollutants include their hydrophilic functionalities and the presence of transition metal sites exposed on their surface. Other molecules such as water, dyes, metals, and even semiconductors can connect to these sites, giving MXenes higher reactive activities.
In the research paper, the team explored boron-based magnesium tetraboride (MgB4) MXene type nanosheets for use as photocatalysts. General MXene preparation procedures were used in the study. A single layer of Mg was etched from magnesium dibromide (MgB2) to create the new material. The selected etchant was an aqueous solution of hydrochloric acid. The team explored the photocatalytic, optical, chemical and structural properties of the material.
Metal-coated MXenes transfer and separate photogenerated carriers and harvest higher levels of photonics, resulting in more active electron-hole pairs. The presence of boron-boron and boron-metal bonds in magnesium tetrabromide gives the material superior mechanical, thermal and chemical stability as well as high levels of thermal and electrical conductivity.
The results of the study showed that these nanosheets exhibited stable and efficient photocatalysis of H2 generation from water molecules. This was due to the presence of many exposed metal sites on the surface of the material, as well as higher conductivity. Higher capacities for absorption and recovery of solar energy have been observed. The research paper paves the way for the development of more efficient boron-based catalysts for energy conversion and storage applications.
Research into advanced materials benefits many industries, providing better and more efficient technology that helps solve critical issues facing humanity in the 21st century. MXene boron-based magnesium tetrabromide nanosheets have several interesting properties that make them an attractive material for use in next-generation energy storage and photocatalysis applications that could prove to be revolutionary for the future of solar energy and, by extension, the end of fossil fuel dependence.
Xiao, L et al. (2021) MgB4 MXene-type nanosheets for the photocatalytic evolution of hydrogen [online] ACS Appl. Nano-matter. | pubs.acs.org. Available at: https://pubs.acs.org/doi/pdf/10.1021/acsanm.1c03497