Sol–Gel Assisted Synthesis of Ca‐Modified α‐ Fe2O3 Films for Enhanced Dye Photodegradation

Abstract

This study investigates the synthesis of Ca‐modified hematite (CaX‐Fe2O3) films via a sol–gel dip‐coating method for visible‐light‐driven photocatalytic applications. The properties of the films were systematically characterized using comprehensive analytical techniques. XRD analysis confirmed the formation of a rhombohedral phase with a (104) preferred orientation and a maximum crystallite size of 65 nm, while SEM revealed increased grain agglomeration at higher Ca contents. Optical analyses showed a reduction in the bandgap from 2.10 to 1.96 eV with increasing Ca content, whereas photoluminescence revealed a marked decrease in emission intensity for the 5 wt.% Ca‐modified film, indicating suppressed electron–hole recombination. The 5 wt.% Ca‐modified hematite exhibited significantly enhanced photocatalytic performance, achieving 97% dye degradation within 120 min compared with 64.1% for Fe2O3. This enhanced activity is attributed to the combined effects of improved visible‐light absorption and efficient charge separation arising from Ca‐induced defect states within the bandgap. Reusability tests demonstrated that the photocatalyst retained approximately 85% of its degradation efficiency after three consecutive monthly photocatalytic cycles, while post‐reaction analyses further confirmed its structural stability after repeated use. These results demonstrate that Ca‐modified Fe2O3 is a promising visible‐light photocatalyst for the sustainable removal of organic pollutants from wastewater.