Covalent edge-functionalization of graphene oxide with porphyrins for highly efficient photoinduced electron/energy transfer and enhanced nonlinear optical performance

Covalent modification of graphene oxide (GO) with functional chromophores plays an important role in constructing various kinds of advanced optoelectronic materials for applications in molecular diagnosis, light-harvesting, photodynamic therapy, and optical limiting. Herein, a new approach to functionalizing GO with meso-substituted formylporphyrins at GO’s edge sites via imidazole condensation is developed, which affords a novel GO-imi-Por nanohybrid covalently-linked by imidazole rings between two components. The structure of the GO-imi-Por nanohybrid was thoroughly characterized by scanning electron microscopy (SEM), attenuated total reflectance-Fourier transform infrared (ATR-FTIR), Raman, and X-ray photoelectron spectroscopy (XPS). The red-shifted steady-state absorption, 95% quenched fluorescence, and largely enhanced nonlinear optical (NLO) properties through Z-scan studies at lower input energies demonstrate that this GO-imi-Por nanohybrid exhibits a more effective photoinduced energy/electron transfer between the intrahybrid two components and can be flexibly applied as an optical limiter candidate. This covalent edge-functionalization approach provides a new paradigm for constructing various edge-expanding GO nanohybrids with an efficient energy/electron transfer process and improved nonlinear optical effects, which would draw inspiration for engineering more adaptable optoelectronic devices.