Hydrogen gas, which is created from water with the help of sunshine, is one potential renewable energy source. Researchers at Linköping University in Sweden have created a material called nanoporous cubic silicon carbide that has the potential to collect solar energy and split water to produce hydrogen gas. The research was reported in the ACS Nano journal.
“New sustainable energy systems are needed to meet global energy and environmental challenges, such as increasing carbon dioxide emissions and climate change,” says Jianwu Sun, senior lecturer in the Department of Physics, Chemistry, and Biology at Linköping University, who has led the new study.
Hydropower is used to create electricity by utilities all over the world because it is inexpensive, easy to store and dispatch, and produced without the use of fossil fuels, which means it does not emit carbon dioxide or pollutants as power plants that burn coal or natural gas do.
The energy density of hydrogen is three times that of gasoline. It can be used to create power using a fuel cell, and hydrogen-fueled automobiles are already on the market. The sole product created when hydrogen gas is utilized to generate electricity is clean water.
New sustainable energy systems are needed to meet global energy and environmental challenges, such as increasing carbon dioxide emissions and climate change.
Jianwu Sun
However, because the most widely utilized technology today relies on fossil fuels for the process, carbon dioxide is generated when hydrogen is produced. When 1 tonne of hydrogen gas is generated, 9-12 tonnes of carbon dioxide is released.
Producing hydrogen gas by splitting water molecules with solar radiation is a sustainable method for producing hydrogen gas from renewable sources without emitting carbon dioxide. The ability to transform solar energy into fuel that can be stored is a key benefit of this approach.
“Conventional solar cells produce energy during the daytime, and the energy must either be used immediately or stored in, for example, batteries. Hydrogen is a promising source of energy that can be stored and transported in the same way as traditional fuels such as petrol and diesel,” says Jianwu Sun.
The majority of watersheds throughout the world, including those that have relied on hydropower for over a century, are severely damaged, with filthy streams and obsolete infrastructure. Because traditional reservoirs are generally stagnant bodies of water, harmful algal blooms, or HABs, are common. HABs are dangerous to humans, fish, shellfish, marine animals, and birds.
However, splitting water to produce hydrogen gas using the energy in the sunshine is not a simple operation. To be successful, cost-effective materials with the correct characteristics for the photo-electrolysis reaction in which water (H2O) is divided into hydrogen (H2) and oxygen (O2) are required.
UV radiation and visible light make up the majority of the energy in the sunshine that may be utilized to split water. As a result, a material must be able to absorb such radiation efficiently in order to form charges that can be separated, as well as have enough energy to split water molecules into hydrogen and oxygen gases.
The majority of materials studied thus far are either inefficient in their utilization of visible light energy (titanium dioxide, TiO2, for example, absorbs only ultraviolet light) or lack the characteristics required to split water into hydrogen gas (for instance, silicon, Si).
The research group of Jianwu Sun has looked on cubic silicon carbide, or 3C-SiC. The researchers created a cubic silicon carbide with a large number of exceedingly tiny holes. They name the material nanoporous 3C-SiC, and it has intriguing features that suggest it may be utilized to create hydrogen gas from water using sunlight.
The researchers show in this work, which was published in the journal ACS Nano, that this novel porous material can successfully capture and collect UV and most visible sunlight.
Furthermore, the porous structure encourages the separation of high-energy charges, while the tiny holes provide a greater active surface area. This improves charge transfer and expands the number of reaction sites, increasing the efficiency of water splitting even more.
“The main result we have shown is that nanoporous cubic silicon carbide has a higher charge-separation efficiency, which makes the splitting of water to hydrogen much better than when using planar silicon carbide,” says Jianwu Sun.
Financial funding for the study came from the Swedish Research Council, FORMAS, and the Swedish Foundation for International Cooperation in Research and Higher Education, among others.
