Photocatalytic H2 production under visible-light irradiation based on covalent attachment of manganese phthalocyanine to graphene

In this paper, a manganese phthalocyanine (MnPc) covalently functionalized graphene nanohybrid (MnPcG) has been successfully synthesized via 1,3-dipolar cycloaddition, and used as a photocatalyst after modifying it with platinum nanoparticles via photodeposition. The nanocomposite was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV-vis, Fourier transform infrared (FTIR), and Raman spectroscopy. These characterization results confirmed the grafting of MnPc moiety onto the graphene sheets. The intermolecular electron transfer was facilitated and the photoexcited charges recombination was suppressed as confirmed by the fluorescence quenching and enhanced photocurrent density in MnPcG nanohybrid. In comparison to graphene, the MnPcG nanohybrid shows a substantial improvement in the photocatalytic hydrogen evolution. The yields of hydrogen production of MnPcG/Pt reached to 8.59 and 1.45 μmol mg−1 under 10 h of UV-vis and visible light (λ > 400 nm) irradiation, respectively. This work demonstrates that metallophthalocyanines covalently functionalized graphene is a novel photocatalyst for solar energy conversion to produce hydrogen from water.