Potassium-Functionalized Graphitic Carbon Nitride Supported on Reduced Graphene Oxide as a Sustainable Catalyst for Knoevenagel Condensation

A nanocomposite of potassium-functionalized graphitic carbon nitride (KGCN) and reduced graphene oxide (RGO) was fabricated by a facile hydrothermal method and used as a heterogeneous catalyst for Knoevenagel condensation and sustainable synthesis of aryl substituted chromenes. The prepared KGCN–RGO nanocomposite catalyst has been characterized by using various techniques, such as powder X-ray diffraction technique (PXRD), Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscope, thermogravimetric analysis, and BET surface area analysis. After detailed characterization, the nanocomposite was used as a heterogeneous catalyst to synthesize various aryl substituted chromenes in ethanol. The developed KGCN–RGO nanocatalyst also rendered good recyclability for the explored catalytic reactions. In addition, a high value of atom economy and a low value of E-factor are also key highlights of this green and sustainable catalytic protocol.