Efficient surface Hydroxyl-to-Hydroxyl radical conversion on layered double hydroxide via High-Efficiency hydroxyl Transformer

Abstract

Promoting the activation of surface or edges hydroxyl groups in layered double hydroxides (LDHs) to facilitate its conversion to hydroxyl radicals (·OH) in photocatalytic process has received wider attention in research communities. However, the pristine LDHs are unable to convert surface or edges hydroxyl groups to ·OH with the energy of visible light illumination, so it is necessary to structurally modulate them to improve their conversion of surface hydroxyl groups to ·OH under light illumination. Herein, we innovatively combined nickel-iron layered double hydroxide (NiFe-LDHs, hydroxyl groups library) with bismuth carbonate oxide ((BiO)₂CO₃, BOC, ·OH generator), enabling a sustained and efficient transformation of hydroxyl groups on the surface or edges of NiFe-LDHs into ·OH. Mechanism studies supported by in-situ spectroscopic analyses and theoretical simulations, showed that under the visible light illumination the hot holes generated on energy band-matched BOC can capture OH^- located at the surface/edge of NiFe-LDHs nanosheets and further convert them into ·OH and efficiently promoted the oxidation of NO to NO₃^-. The NO removal efficiency of BOC/NiFe-LDHs composite material is about 54.5%, which was 2.23 times that of the original BOC.