Advanced one pot photochemical surface modification approach towards graphene materials and their application in dye removal

Carbonaceous materials have shown undisputable promise as adsorbents and catalysts in various applications. The ability to tune key features such as specific surface area and functionality to improve the activity, represents a key advantage. However, this requires the development of general and versatile synthetic methods to deliver these multifunctional materials. This work reports a convenient general approach to prepare a series of graphene-chromophore systems. Two photochemical methods involving a step-by-step procedure and a one-pot method were compared. It was found that the two-step procedure is limited by the stability of the diazonium salts and thus has a limited application. The one-pot method allows preparation of a wide range of different composites in an easy and inexpensive manner. Synthesised samples were characterised by a range of methods including electron microscopy, X-ray diffraction, infra-red spectroscopy and gas adsorption. Transmission electron microscopy analysis revealed an ordered array of chromophores on the surface of the graphene nanoplatelets. The samples were tested as potential materials for dye removal; these studies revealed that most graphene-chromophore materials can successfully remove organic pollutants such as methylene blue, rhodamine B and methyl orange from aqueous media.