Solar Energy

New porous material promising for making renewable energy from water

Published

4 years ago

March 24, 2021

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New porous material promising for making renewable energy from water

One prospective source of renewable energy is hydrogen gas produced from water with the aid of sunlight. Researchers at Linkoping University, Sweden, have developed a material, nanoporous cubic silicon carbide, that exhibits promising properties to capture solar energy and split water for hydrogen gas production. The study has been published in the journal ACS Nano.

“”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 Linkoping University, who has led the new study.

Hydrogen has an energy density three times that of petrol. It can be used to generate electricity using a fuel cell, and hydrogen-fuelled cars are already commercially available. When hydrogen gas is used to produce energy, the only product formed is pure water. In contrast, however, carbon dioxide is created when the hydrogen is produced, since the most commonly used technology used today depends on fossil fuels for the process. Thus, 9-12 tonnes of carbon dioxide are emitted when 1 tonne of hydrogen gas is produced.

Producing hydrogen gas by splitting water molecules with the aid of solar energy is a sustainable approach that could give hydrogen gas using renewable sources without leading to carbon dioxide emissions. A major advantage of this method is the possibility to convert solar energy to fuel that can be stored.

“”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.

It is not, however, an easy task to split water using the energy in sunlight to give hydrogen gas. For this to succeed, it is necessary to find cost-efficient materials that have the right properties for the reaction in which water (H2O) is split into hydrogen (H2) and oxygen (O2) through photo-electrolysis. The energy in sunlight that can be used to split water is mostly in the form of ultraviolet radiation and visible light.

Therefore, a material is required that can efficiently absorb such radiation to create charges that can be separated and have enough energy to split the water molecules into hydrogen and oxygen gases. Most materials that have been investigated until now are either inefficient in the way they use the energy of visible sunlight (titanium dioxide, TiO2, for example, absorbs only ultraviolet sunlight), or do not have the properties needed to split water to hydrogen gas (for instance, silicon, Si).

Jianwu Sun’s research group has investigated cubic silicon carbide, 3C-SiC. The scientists have produced a form of cubic silicon carbide that has many extremely small pores. The material, which they call nanoporous 3C-SiC, has promising properties that suggest it can be used to produce hydrogen gas from water using sunlight.

The present study has been published in the journal ACS Nano, and in it the researchers show that this new porous material can efficiently trap and harvest ultraviolet and most of the visible sunlight.

Furthermore, the porous structure promotes the separation of charges that have the required energy, while the small pores give a larger active surface area. This enhances charge transfer and increases the number of reaction sites, thus further boosting the water splitting efficiency.

“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.

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Solar Energy

Scientists Probe Declining Earbud Battery Longevity

Published

2 days ago

February 5, 2025

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Scientists Probe Declining Earbud Battery Longevity

by Clarence Oxford

Los Angeles CA (SPX) Feb 05, 2025

Have you ever noticed how electronic devices, including wireless earbuds, seem to lose battery capacity faster the longer you use them? An international research team from The University of Texas at Austin set out to examine this familiar issue, known as battery degradation, by focusing on the earbuds that many people rely on daily. Through a series of x-ray, infrared, and other imaging approaches, the researchers investigated the hidden complexities behind these tiny devices and revealed why their battery life declines over time.

“This started with my personal headphones; I only wear the right one, and I found that after two years, the left earbud had a much longer battery life,” said Yijin Liu, an associate professor in the Cockrell School of Engineering’s Walker Department of Mechanical Engineering, who led the new research published in Advanced Materials. “So, we decided to look into it and see what we could find.”

Their analysis showed that crucial earbud features – like the Bluetooth antenna, microphones, and circuits – compete with the battery in a very confined space, producing a microenvironment that is less than ideal. This situation results in a temperature gradient that damages the battery over time, with different sections of the cell experiencing variable temperatures.

Real-world factors also complicate matters. Frequent changes in climate, shifts in air quality, and a host of other environmental variables challenge the battery’s resilience. While cells are generally designed to endure harsh conditions, constant fluctuations can take their toll.

These discoveries highlight the importance of considering how batteries interact with devices such as phones, laptops, and even electric vehicles. Packaging solutions, strategic design decisions, and adaptations for user habits may all play a role in extending battery performance.

“Using devices differently changes how the battery behaves and performs,” said Guannan Qian, the first author of this paper and a postdoctoral researcher in Liu’s lab. “They could be exposed to different temperatures; one person has different charging habits than another; and every electric vehicle owner has their own driving style. This all matters.”

In conducting this study, Liu and his team worked closely with UT’s Fire Research Group, led by mechanical engineer Ofodike Ezekoye. They paired infrared imaging methods with their in-house x-ray technology at UT Austin and Sigray Inc. To expand their scope, they then teamed up with some of the world’s most advanced x-ray facilities.

Their collaborators included researchers from SLAC National Accelerator Laboratory’s Stanford Synchrotron Radiation Lightsource, Brookhaven National Laboratory’s National Synchrotron Light Source II, Argonne National Laboratory’s Advanced Photon Source, and the European Synchrotron Radiation Facility (ESRF) in France. These partnerships allowed them to observe battery behavior under more authentic operating conditions.

“Most of the time, in the lab, we’re looking at either pristine and stable conditions or extremes,” said Xiaojing Huang, a physicist at Brookhaven National Laboratory. “As we discover and develop new types of batteries, we must understand the differences between lab conditions and the unpredictability of the real world and react accordingly. X-ray imaging can offer valuable insights for this.”

Looking ahead, Liu says his team will continue analyzing battery performance in the settings people experience every day. They plan to expand their approach to larger batteries, such as those in smartphones, laptops, and electric vehicles, to learn more about their degradation patterns.

Research Report:In-device Battery Failure Analysis

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Solar Energy

Quantum factors elevate plant energy transport efficiency

Published

2 days ago

February 5, 2025

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Quantum factors elevate plant energy transport efficiency

by Robert Schreiber

Munich, Germany (SPX) Feb 05, 2025

For countless engineers, converting sunlight into easily stored chemical energy stands as an enduring goal. Yet nature perfected this challenge billions of years ago. A recent study reveals that quantum mechanics, once thought to be limited to physics, is also essential for key biological processes.

Green plants and other photosynthetic organisms draw on quantum mechanical mechanisms to capture the sun’s energy. According to Prof. Jurgen Hauer: “When light is absorbed in a leaf, for example, the electronic excitation energy is distributed over several states of each excited chlorophyll molecule; this is called a superposition of excited states. It is the first stage of an almost loss-free energy transfer within and between the molecules and makes the efficient onward transport of solar energy possible. Quantum mechanics is therefore central to understanding the first steps of energy transfer and charge separation.”

Classical physics alone cannot completely describe how this phenomenon unfolds throughout green plants and in certain photosynthetic bacteria. Although the exact details remain only partly understood, Prof. Hauer and first author Erika Keil consider their new findings an important step toward uncovering how chlorophyll, the pigment behind leaf coloration, functions. Applying these insights to engineered photosynthesis devices could unlock unprecedented solar energy conversion efficiencies for both power production and photochemical applications.

In their investigation, the researchers focused on two portions of the light spectrum absorbed by chlorophyll: the low-energy Q band (yellow to red) and the high-energy B band (blue to green). In the Q region, two electronic states are quantum mechanically coupled, promoting virtually loss-free energy movement. The system subsequently relaxes via “cooling”, i.e. by releasing energy in the form of heat. These observations demonstrate that quantum mechanical processes can play a major role in shaping key biological functions.

Research Report:Reassessing the role and lifetime of Qx in the energy transfer dynamics of chlorophyll a

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Solar Energy

HZB sets new efficiency record for CIGS perovskite tandem solar cells

Published

2 days ago

February 5, 2025

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HZB sets new efficiency record for CIGS perovskite tandem solar cells

by Robert Schreiber

Berlin, Germany (SPX) Feb 05, 2025

Researchers at Helmholtz Center Berlin for Materials and Energy (HZB) and Humboldt University Berlin have developed a CIGS-perovskite tandem solar cell that has set a new world record for efficiency, achieving 24.6%. The performance of the cell has been officially certified by the Fraunhofer Institute for Solar Energy Systems.

Thin-film solar cells, such as those based on copper, indium, gallium, and selenium (CIGS), require minimal material and energy to manufacture, making them an environmentally friendly alternative to conventional silicon-based solar cells. CIGS thin films can also be applied to flexible substrates, expanding their potential applications.

The new tandem solar cell developed by HZB and Humboldt University combines a CIGS bottom cell with a perovskite top cell. By optimizing the contact layers between these two components, the research team successfully increased efficiency to a record-breaking 24.6%. This milestone was confirmed by the Fraunhofer Institute for Solar Energy Systems ISE in Freiburg, Germany.

This achievement was made possible through a collaborative effort among researchers. The top cell was developed by Thede Mehlhop, a master’s student at TU Berlin, under the supervision of Stefan Gall. The perovskite absorber layer was created in the joint laboratory of HZB and Humboldt University Berlin, while the CIGS sub-cell and contact layers were fabricated by HZB researcher Guillermo Farias Basulto. Additionally, the KOALA high-performance cluster system at HZB was used to deposit the perovskite and contact layers in a vacuum.

“At HZB, we have highly specialized laboratories and experts who are top performers in their fields. With this world record tandem cell, they have once again shown how fruitfully they work together,” said Prof. Rutger Schlatmann, spokesman for the Solar Energy Department at HZB.

HZB has a strong track record in achieving world records in solar cell efficiency, including past accomplishments in silicon-perovskite tandem cells and now in CIGS-perovskite tandem technology.

“We are confident that CIGS-perovskite tandem cells can achieve much higher efficiencies, probably more than 30%,” said Prof. Rutger Schlatmann.