Nickel-Cobalt Layered Double Hydroxides for Photocatalytic Degradation under Visible Light Irradiation

Abstract

As large amount of dye has been discharged as wastewater and infiltrated into our water system, it is now affecting the aquatic life due to its carcinogenic nature. Although heterogenous photocatalytic process is found effective in mineralizing these organic pollutants into less harmful one through light irradiation, the most often explored TiO2 is active only under UV light, thus limits its real application such photocatalyst in environmental remediation. A new class materials with hydrotalcite like structure, layered double hydroxides (LDH) has been recently explored for their superior photocatalytic degradation property as their anionic intercalating layer boosts their absorption capabilities, thus yielding high active surface area for photo-degradation to proceed. Despite their band gap tunability, chemical versatility and high reproducibility in large quantities, they suffer from poor control over particles size and morphology. Here in this paper, three different Nickel-Cobalt LDH morphologies are uniformly produced by utilizing a facile and economical synthesis method and by adjusting the precursor, ammonium fluoride. It is shown that NH4F can act as a structural-mediating agent that transforms 1D to 2D structure as well as a crystal forming agent that boosts the photocatalyst’s crystallinity, which would essentially enhance its photocatalytic methyl orange degradation for almost 2-fold than those of poor crystallinity. In short, this paper demonstrates a facile control of morphology and crystallinity of LDH for better photocatalysis under visible light irradiation.