Facile preparation of AB-stacking graphene oxide/ZnAl-layered double hydroxide composites and enhanced visible-light photocatalytic performance of the calcined product

Mixed metal oxides (MMOs) are among the most important photocatalysts with heterogeneous structures and they have been used widely for environmental remediation. In this study, based on the memory effect of layered double hydroxides (LDHs), graphene oxide (GO) nanosheets were successfully intercalated into the ZnAl-LDH interlayer via rehydration to generate the AB-stacking (layer-by-layer ordered) GO/ZnAl-LDH (ABs-G-ZAL). A series of AB-stacking reduced GO (RGO)/ZnAl-MMO (ABs-R-ZAM) composite photocatalysts were then obtained by calcining ABs-G-ZAL at 700 degrees C. The prepared samples were characterized using powder X-ray diffraction, scanning electron microscopy, high-resolution transmission microscopy, X-ray photoelectron spectroscopy, ultraviolet visible diffuse reflectance spectroscopy, thermogravimetric analysis, photoluminescence spectroscopy, and electrochemical impedance spectroscopy. The photocatalytic degradation of methyl orange over the ABs-R-ZAM composites was highly dependent on the content of RGO in the composites, and the maximum removal efficiency of up to 90.2% was achieved with ABs-R-ZAM containing 3.30 wt% RGO. The excellent photocatalytic performance of the ABs-R-ZAM composites was mainly due to the enhanced visible light adsorption intensity and the effective separation of photogenerated electron hole pairs because of the excellent conductivity of the single-layered RGO within the AB-stacking structure of ABs-R-ZAM. These results suggest that ABs-R-ZAM photocatalysts have potential applications in water remediation.