Synthesis and multifaceted use of phosphorylated graphene oxide: growth of titanium dioxide clusters, interplay with gold nanoparticles and exfoliated sheets in bioplastics

Abstract

Five different functional phosphorus motifs were trivially installed within graphene oxide (GO) sheets to provide water-dispersible and thermally-stable phosphorus graphene oxide materials (PGO). The presence of exogenous phosphorus heteroatoms on the surface of the tiny carbon sheets was harnessed for the anchoring and growth of metal oxide clusters, exemplified herein by titanium dioxide, and for the chelation and stabilization of small gold nanoparticles. Unexpectedly, both GO and PGO promoted crystallization in a low-temperature liquid-phase medium without thermal annealing treatment. However, the fingerprint of the surface chemistry is illustrated through the formation of different species; while discrete anatase nanoparticles were selectively formed on the surface of GO sheets, a biphasic mixture of anatase and rutile was grown on PGO. The latter provides a more stable material owing to the robustness of the interfacial P–O–Ti bridges. Strong coordination to gold nanoparticles was also observed for PGO due to the presence of PO(OH)₂ fragments, compared to the weakly coordinating oxygenated functions in GO. Lastly, the possible delamination of PGO sheets associated with their improved thermal stability renders them promising nanosized fillers for carbohydrate-based bioplastics.