Alternatingly stacked 2D/2D hybrid via preferential intercalation of nitrate ions between layered double hydroxide and graphene oxide

Abstract

In this study, zinc-aluminum layered double hydroxide (LDH) with nitrate ion intercalation was developed to form a 2D/2D nanostructured hybrid composite on graphene oxide (GO) thin layers. Differing from ordinary LDH/GO composites where carbonate ion intercalation took place in LDH, the hybrid was achieved with exchangeable nitrate anion, hence allowing the subsequent GO and LDH interaction at the nanoscale level. Highly exfoliated GO product was introduced to the co-precipitation of zinc and aluminum ions at 10–30 %wt. compositions. Properties of the prepared hybrid were characterized by several techniques. This hybrid setup offered a synergistic effect of the two materials and benefitted the physicochemical properties including size-control of LDH particles on GO sheet, higher surface area with mesoporosity, and increased carbon combustion temperature making it heat resistant. The efficient adsorption property was then proven by the removal of both cationic and anionic dyes, i.e., methylene blue and methyl orange, up to 81 and 83 mg/g, respectively, and still recoverable due to its improved stability. The fast-forming mechanism of LDH, with and without GO participation, was revealed by the wide-angle x-ray diffraction, suggesting the initial formation of LDH intermediate that later re-structured to a more uniform nanohybrid. The findings of the study suggest that the 2D/2D hybrid system can be formed under facile precipitation. It is promising for water decontamination, controlled release, and delivery system.