Intercalative hybridization of layered double hydroxide nanocrystals with mesoporous g-C3N4 for enhancing visible light-induced H2 production efficiency

Abstract

Efficient visible light active hybrid photocatalysts for H₂ production can be synthesized by the intercalative hybridization of Zn–Cr-layered double hydroxide (Zn–Cr-LDH) with a mesoporous g-C₃N₄ lattice. Small Zn–Cr-LDH nanocrystals with a size of ∼6 nm are immobilized in the mesopores of g-C₃N₄. Beyond an optimal LDH/g-C₃N₄ molar ratio of 0.3, a further increase in the LDH content leads to the surface deposition of LDH crystals on the g-C₃N₄ material as well as the intercalative immobilization of LDH into its mesopores, indicating the controllability of the LDH deposition site. The Zn–Cr-LDH−g-C₃N₄ nanohybrids exhibit smaller surface areas than the pristine g-C₃N₄, confirming the intercalative stabilization of Zn–Cr-LDH nanocrystals in the mesopore of g-C₃N₄. The hybridization between Zn–Cr-LDH and g-C₃N₄ is effective in enhancing visible light absorptivity and also in depressing electron−hole recombination, which is attributable to an efficient electronic coupling between both the hybridized components. The present Zn–Cr-LDH−g-C₃N₄ nanohybrid exhibits promising photocatalytic activities for visible light-induced H₂ production at a rate of 155.7 μmol g⁻¹ h⁻¹, which is much superior to that of the pristine g-C₃N₄ (21.7 μmol g⁻¹ h⁻¹). The present study underscores that the intercalative immobilization of Zn–Cr-LDH crystals in the limited space of a mesopore is quite useful in improving the visible light active photocatalyst functionality of mesoporous carbon nitride.