Carbon spheres - small spherical structures that have found large applications in carbon capture and energy storage - can now be created faster and more sustainably in a novel technique developed by researchers.
A team from Swansea University in the United Kingdom has devised a way for fast, green, and one-step production of porous carbon spheres. Additionally, spheres produced from this method supposedly have good carbon capture capacities and retain efficiency even at larger scales.
The new technique is built upon and significantly improves on the chemical vapor deposition - a commonly-used technique in fabricating 2D nanomaterials, as well as carbon spheres. The Swansea University team published their report in the journal Carbon, included in its Volume 171, January 2021 issue.
Carbon Spheres: The Future of Carbon Capture Techs
Carbon spheres are so named because of their shape and composition, generally ranging in size from micrometers down to nanometers. Improvements over the last years have emphasized the role of this man-made micro-and nanostructures in fields of energy capture, storage, and conversion, as well as catalysis, gas adsorption and storage, delivery of necessary enzymes and proteins, and in water and sewage treatment operations.
These small balls have also seen a significant increase in carbon capture technology - a strategy for capturing and locking carbon emissions instead of releasing them into the atmosphere, reducing carbon footprints, and helping in the fight against climate change.
However, the current production of carbon spheres has technical constraints and drawbacks. Existing practices can either be expensive, impractical or result in carbon spheres with poor carbon-capturing capabilities. While some methods now employ biomass as more environmentally friendly raw materials, it still requires a catalyst or other chemical agent to activate them as carbon spheres.
Swansea University's CVD Improvement
To overcome some of the existing limitations, the Swansea University researchers, based in the institution's Energy Safety Research Institute, adapt an existing production strategy and make adjustments in order to develop a better, cleaner, and greener method of creating carbon spheres.
Researchers used CVD - chemical vapor deposition - which involves the application of heat to apply, or deposit, a chemical to an existing surface or substrate. In this novel method, they used pyromellitic acid as both the carbon and oxygen source before conducting CVD at varying temperatures ranging from 600 to 900 degrees Celsius (1112 - 1652 degrees Fahrenheit). The team then observed the resulting carbon spheres' efficiency in terms of carbon dioxide capture under different pressure and temperature conditions.
Among the significant findings in the experiment was that 800 degrees Celsius was the optimum temperature for forming their carbon spheres. Additionally, the ultramicropores formed on these porous spheres' surface provided the products with higher carbon capture capacity - both at atmospheric and at lower pressures.
With this novel method, the production of carbon spheres is now alkali-free and no longer needs an external catalyst to encourage the formation of the ball-like structures. Researchers also managed to use feedstock as raw material - a cheap and readily available resource. Also, in the Swansea University method, no solvent is used to purify the raw materials, cutting down on lead time, and reducing safety risks.
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