In-situ polymerization for PPy/g-C3N4 composites with enhanced visible light photocatalytic performance

Abstract

Polypyrrole-modified graphitic carbon nitride composites (PPy/g-C3N4) are fabricated using an in-situ polymerization method to improve the visible light photocatalytic activity of g-C3N4. The PPy/g-C3N4 is applied to the photocatalytic degradation of methylene blue (MB) under visible light irradiation. Various characterization techniques are employed to investigate the relationship between the structural properties and photoactivities of the as-prepared composites. Results show that the specific surface area of the PPy/g-C3N4 composites increases upon assembly of the amorphous PPy nanoparticles on the g-C3N4 surface. Owing to the strong conductivity, the PPy can be used as a transition channel for electrons to move onto the g-C3N4 surface, thus inhibiting the recombination of photogenerated carriers of g-C3N4 and improving the photocatalytic performance. The elevated light adsorption of PPy/g-C3N4 composites is attributed to the strong absorption coefficient of PPy. The composite containing 0.75 wt% PPy exhibits a photocatalytic efficiency that is 3 times higher than that of g-C3N4 in 2 h. Moreover, the degradation kinetics follow a pseudo-first-order model. A detailed photocatalytic mechanism is proposed with ·OH and ·O2− radicals as the main reactive species. The present work provides new insights into the mechanistic understanding of PPy in PPy/g-C3N4 composites for environmental applications.