Graphitic-carbon nitride system (C₃N₅) was functionalized with Pd nanoparticles as a result of in situ reduction of Pd²⁺ through a prepared N-rich system. The obtained composite demonstrates excellent photocatalytic activity in the Suzuki-Miyaura coupling reaction.

Utilizing sunlight as a driving force in chemical reactions is a great benefit for a sustainable future. Metal-based composites are basic components in various catalytic reactions. However, few researches reported carbon nitride-supported Pd nanoparticles in photocatalytic coupling reactions. This study reports the preparation of a graphitic-carbon nitride system (C₃N₅) followed by modification with various amounts of Pd nanoparticles. The C₃N₅ was synthesized by thermal deammoniation of melem hydrazine precursor and then modified by Pd cations to create a metallic composite. Regarding the N-rich surface of C₃N₅, Pd²⁺ cations are rapidly reduced to Pd nanoparticles in mild conditions, which is strongly supported by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) analyses. Moreover, field emission scanning electron microscopy (FESEM) and high-resolution transmission electron microscopy (HRTEM) analyses clearly depicted the formation of 20 nm Pd nanoparticles on the surface of C₃N₅. The obtained Pd/C₃N₅ composite exhibited prominent photocatalytic performance for Suzuki-Miyaura coupling reactions (91% during 25 min at room temperature). This study also compares the effect of various amounts of Pd cation in the progress of Suzuki-Miyaura coupling reactions.