Photocatalytic activity of NiZnAl hydrotalcite-like compound/carbon nitride composites for the degradation of methylparaben

The scope of this study is to improve the photocatalytic performance of C 3 N 4 for the degradation of methylparaben in solution, upon the immobilization of the semiconductor in the interlayer spacing of a NiZnAl-hydrotalcite like compound (LDH). The growth of LDH in the presence of a homogenous dispersion of increasing amounts of carbon nitride allowed the incorporation of this carbon-based semiconductor in the interlayer space of the LDH. The prepared photocatalysts exhibited light absorption features similar to those of the pristine semiconductor and displayed better photocatalytic performance for the degradation of methylparaben and intermediates (higher conversions and degradation rates). This is attributed to the improved separation of the photogenerated charge carriers boosted by the interfacial contact between the carbon nitride confined in the lamellar structure of the hydrotalcite-like compound. The best performing material containing 15 wt.% of carbon nitride showed good cycling stability over 20 hours of illumination. The confinement of C 3 N 4 affects the photodegradation mechanisms of methylparaben, with a hydroxylation-mediated reaction through the photogenerated holes as the main oxidation pathway and a minor impact of dissolved oxygen formed upon reaction of the photogenerated electrons. • NiZnAl-LDH/C 3 N 4 catalysts show faster degradation of methylparaben and intermediates. • Confinement of C 3 N 4 in the structure of NiZnAl-LDH does not hinder light absorption. • NiZnAl-LDH/C 3 N 4 catalysts show good catalytic performance upon 20 h illumination. • Hydroxylation-mediated oxidation is the main methylparaben degradation route.