Regular polyhedron α-Fe2O3 nanocrystals prepared from hot rolled sludge for photocatalytic degradation of organic pollutants: Optimization and mechanism

Abstract

Herein, a photocatalyst with the micromorphology of regular polyhedron (RP-α-Fe2O3 nanocrystals) was prepared via hot rolled sludge (HRS), and its preparation mechanism was investigated. The optical property test and DFT calculations exhibited the RP-α-Fe2O3 nanocrystals has strong visible light absorption and small electrochemical impedance, which indicated that it has excellent catalytic performance under visible light. The degradation efficiency of 100 mg/L Rhodamine B (RhB) solution could reach 99.2% within 60 min. Furthermore, the RP-α-Fe2O3 nanocrystals exhibited excellent reusability and stability. Meanwhile, hydroxyl radicals (·OH), superoxide radicals (·O2−) and photogenerated holes (h+) were the most significant active substances that affect the photocatalytic efficiency, due to they would synergically degrade RhB in the photocatalytic reaction system. Particularly, the diffraction peak of N1s was detected in the RP-α-Fe2O3 nanocrystals after reaction, and the intensity of CO and CO peaks increased, which proved that the photocatalyst has adsorption for RhB.