Hello
Is there a certain value in m2/g for a nanomaterial to be considered of high surface area and thus good adsorption performance ?
Gabris Mahamid Over 60 m2/g (for unit density) will provide a good guide that the material is in the nano region (< 100 nm by ISO and ASTM definition). Values around 250 m2/g (for fumed silica) provide a high specific surface area but there can be handling difficulties with such materials. SSA's in this region can be achieved but I've never seen a material (in my practical experience) go into the 1000 m2/g + region.
Your only guide is 'fit for purpose'. If you're in catalysis then increased surface area means increased activity but, for example, there may be less resistance to poisoning.
Dear Prof. Alan Rawle
Thank you so much for sharing such information
I came across several papers reporting surface areas higher than 1000 m2 /g
May you please share more details on why it is hard to handled in what terms do you mean and do you think it is theoretically possible to have such very high surface area materials produced
Materials made up of nanoparticles have a relative larger surface area when compared to the same volume of material made up of bigger particles. It means that the surface area to volume ratio increases as the radius of the sphere decreases and vice versa. The tiny nature of nanoparticles results in some useful characteristics, such as an increased surface area to which other materials can bond in ways that make for stronger or more lightweight material. With a larger number of atoms on the surface, more atoms are available to interact with the atoms or ions of other substances. Therefore, materials made of nanoparticles have a much greater surface area per unit volume ratio compared with the materials made up of bigger particles. This leads to nano particles being more chemically reactive. surface area of the order of 2400 m2/g-2600 m2/g
That depends on what kind of material and the best option is always to compare to the same synthesis route. For example, a silica xerogel of 500 m²/g is a huge ssa, however some silica aerogel have more than 800 m²/g.
As a personal comment I add that sometimes i see people obsessed with high surface area, and neglecting other important properties at adsorption fenomena, like zeta potential, pore size distribution, sites of adsorption...
On your further question of 1000 m²/g, the surface tension on this kind of material is high, they tend to colapse/sinter the pores in order to reach a more stable state. That said, some people usually don't know how to use the methods of accessing surface area, as B.E.T., and report absurd SSA for some materials.. checking the methodology and the validity of the method used is always a good idea for trusting the article.
Dear Mr. Prem
What do you think can be done for one material to make its surface area higher without modifying its chemistry ?
Luiz Fernando de Sousa Lima Too much valuable comment
I came across some materials with low surface area but super adsorption performance
Don't know the reason but I assume it is related to the other factors you have mentioned
depending on your material and your route of synthesis, you can do a lot of techiniques leading to different porosity, surface area and pores morphology. On my thesis i’m mapping compositions on spinodal decomposition and soft templating using surfactants to get high surface area composites by sol-gel.
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