Effect of covalent and non-covalent linking of zinc(II) phthalocyanine functionalised carbon nanomaterials on the sensor response to ammonia

Abstract

In this work, a comparative study of the sensor response of single walled carbon nanotubes (SWCNTs) and reduced graphene oxide (rGO) covalently and non-covalently functionalised with1-[N-(2-ethoxyethyl)-4-pentynamide]-8(11),15(18),22(25)-tris-{2-[2-(2-ethoxyethoxy) ethoxy]-1-[2-((2-ethoxy ethoxy)-ethoxy)methyl]ethyloxy}zinc(II) phthalocyanine (ZnPc) to ammonia is carried out. It was shown that in the case of SWCNT-based materials both covalent and non-covalent functionalisation with zinc(II) phthalocyanine leads to the increase of the sensor response toward NH3, while functionalisation of reduced graphene oxide causes a decrease in the response. At the same time both covalent and non-covalent linking of zinc(II) phthalocyanine leads to twofold decrease of the sensor recovery times. The sensor response of the carbon nanomaterial (single walled carbon nanotubes or reduced graphene oxide) hybrids covalently functionalised with zinc(II) phthalocyanine is several times higher than in the case of non-covalent linking of zinc(II) phthalocyanine to these nanomaterials, which is in good correlation with the number of zinc(II) phthalocyanine molecules adsorbed onto the SWCNT and rGO walls.