(ORDO NEWS) — If we’re going to work with renewable energy, we need to find ways to efficiently store that energy until it’s needed – and scientists have identified new material that can do just that.
This material is known as an organometallic framework (MOF), in which carbon-based molecules form structures by binding metal ions. It is important to note that MOFs are porous, so they can form composites with other small molecules.
The scientists added molecules of a light-absorbing compound, azobenzene. The finished composite material could store UV energy for at least four months at room temperature before releasing it again – a big improvement in days or weeks that most light-sensitive materials can handle.
“The material is a bit like the phase change materials used to provide heat in hand warmers,” says materials chemist John Griffin of Lancaster University in the UK.
“However, while hand warmers need to be heated to recharge, the advantage of this material is that it captures free energy directly from the sun.”
Azobenzene acts as a photo switch – a molecular machine that responds to external stimuli such as light or heat. Under the influence of ultraviolet radiation, the molecules change their shape, remaining in the structure of the MOF pores, effectively conserving energy.
Applying heat to the MOF composite material causes a rapid release of energy, generating heat, which can then potentially be used to heat other materials or devices.
While the material still needs some work to make it commercially viable, it can ultimately be used to de-ice car windshields, to provide additional heating to homes and offices, or as a heat source for off-grid installations. Photo switches like these are also used for data storage and drug delivery.
“It also has no moving or electronic parts, so there is no waste associated with storing and releasing solar energy,” says Griffin. “We hope that with further development we will be able to produce other materials that conserve even more energy.”
More work is now required to prepare this MOF material for widespread use. Although tests have shown that it can store energy for months, the material’s energy density is relatively low, and the researchers hope to improve this area.
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