Construction of a three-dimensional nest-like lithium ferrite/reduced graphene oxide composite with enhanced visible-light photocatalytic activity

Abstract

A novel three-dimensional nest-like LiFe₅O₈/reduced graphene oxide (LiFe₅O₈/RGO) composite was prepared successfully via a one-pot hydrothermal method. The morphology and properties of the prepared composites were characterized by SEM, XRD, Raman spectroscopy, XPS, VSM, BET and UV-Vis DRS measurements. When compared with rod-like LiFe₅O₈, nest-like LiFe₅O₈ and rod-like LiFe₅O₈/RGO, the nest-like LiFe₅O₈/RGO composite displayed superior photocatalytic activity for the decomposition of dye under visible light irradiation. The first-order kinetic constant of photodegradation with nest-like LiFe₅O₈/RGO (0.03004 min⁻¹) was approximately 2.21, 4.52 and 6.04 times higher than that of rod-like LiFe₅O₈/RGO (0.01362 min⁻¹), nest-like LiFe₅O₈ (0.00665 min⁻¹) and rod-like LiFe₅O₈ (0.00497 min⁻¹). The improved photocatalytic activity was attributed to the higher visible-light harvesting capacity resulting from the multiple reflections of light, relatively high specific surface area, hierarchical porous structure and effective migration of photo-generated electrons. Based on free radicals trapping experiments, the superoxide radical played a major role during photocatalytic degradation. According to the estimated band structure and photo-electrochemical measurements, a possible mechanism for the photocatalytic degradation process was discussed in detail. Benefiting from its magnetic properties, the nest-like LiFe₅O₈/RGO can be easily separated and recycled, exhibiting outstanding stability.