Sunlight photobiocatalytic performance of LDH-Me2O nanocomposites synthesised in deep eutectic solvent (DES)

Abstract

This paper presents a method for the synthesis of a nanocomposite based on layered double hydroxide (Zn–Al LDH) on the surface of which Ag2O (LDH-Ag2O) and Cu2O (LDH-Cu2O) nanoparticles were deposited. A deep eutectic solvent (DES) (LDH-Ag2O-NDES, LDH-Cu2O-NDES) was used to obtain Ag/Cu metal oxides (Me2O). DES acted as a reaction medium and reductant, which allowed Me2O to be obtained in higher yields (>99 %), compared to the process carried out in water (75 % for Cu2O). The Ag2O or Cu2O-modified nanocomposite presented higher photocatalytic activity towards trypan blue under UV, visible artificial light and sunlight compared to Zn–Al LDH. The band gap energies changed from 3.36 eV for pure LDH to 2.52 and 2.69 eV for LDH-Ag2O and LDH-Cu2O obtained in water and 2.39 and 2.36 eV for their counterparts obtained in DES. The degradation efficiency of trypan blue by LDH-Cu2O-DES was the highest among the materials tested, with a degradation efficiency of 92.80 % after 120 min, at C0 = 200 mg/dm3. At the same time, the incorporation of Ag2O and Cu2O into the LDH structure gave the material bioactive properties (MIC = 39 and 156 mg/dm3), thus confirming the achievement of a multifunctional material that can be used in the future for the treatment of water from organic and bioactive contaminants.