Surface area measurements of graphene and graphene oxide samples: Dopamine adsorption as a complement or alternative to methylene blue?

The possible use of dopamine, monitored spectroscopically, as a probe molecule for surface area measurements is investigated. Using high surface area carbon materials, including both graphene and graphene oxide (GO), the method is established as a complement or alternative to methylene blue or conventional N-2 (BET) adsorption. The molecular reorientation (flat to vertical) of dopamine on the graphene and GO surface provides a direct indication of the monolayer coverage and the rapid adsorption (within 10 min to saturation) offers high convenience. The smaller dopamine molecule size and less self-repulsion compared to methylene blue can be considered to yield a more closely-packed surface coverage on the materials of interest. Especially for materials with complex morphologies and internal structures, the dopamine adsorption will therefore lead to a more 'correct' measurement. (C) 2019 Elsevier Ltd. All rights reserved.