Evaluation of graphene surface area is important for energy storage and sensor applications. The specific surface area of dry materials is commonly evaluated through Brunauer–Emmett–Teller (BET) analysis technique, based on nitrogen physisorption. However, the BET method is inaccurate for surface area measurements of graphene materials in powder form, due to graphene flakes overlapping and making a significant amount of surface area unavailable for nitrogen adsorption. As an alternative approach, a simple reproducible method is developed to measure specific surface area of dispersed non-agglomerated graphene materials in methylene blue (MB) solution. This technique is more accurate than the BET method and more time efficient than the traditional MB titration technique requiring multiple sampling/centrifugation cycles. Current analytical method relies on the adsorption of MB molecules to the surface of graphene materials dispersed in water with different concentrations of dye. When the adsorption of MB onto graphene has reached its maximum capacity, the excess MB in solution is determined by UV-Vis spectroscopy. The concentration of MB left in solution is in the linear domain of the Beer-Lambert law. The developed MB method was used to measure specific surface area of various graphene materials including graphene nanoplatelets, graphene oxide, reduced graphene oxide, single-layer graphene, and graphite. A linear relation was observed between BET and MB surface areas.

Analytical method to measure surface area of graphene materials in solution

2019 Spring National Meeting

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