• Zn doping in hematite enhances coercivity, remanence, oxygen vacancy concentration, and reduces crystallite size. • Zn incorporation alters the electronic structure of hematite, reducing the band gap and improving light absorption. • Zn doping significantly improves the photocatalytic degradation of RhB dye, with optimal performance observed at 10% Zn concentration, following pseudo-first-order kinetics. The widespread occurrence of organic dye pollutants poses serious environmental concerns, demanding efficient treatment strategies. This study reports the photocatalytic degradation of the cationic dye Rhodamine B (RhB) using Zn-doped hematite synthesized by a cost-effective sol-gel method, with Zn concentrations ranging from 2% to 10%. Structural analyses confirmed the retention of the rhombohedral hematite phase (R-3c) without secondary phases, along with lattice expansion, a decrease in crystallite size from 17.1 to 13.1 nm, and a slight shift of the (104) peak toward lower diffraction angles, confirming substitutional Zn incorporation, while FTIR and XPS results verified Fe-O bonding, successful Zn incorporation, mixed Fe 2+ /Fe 3+ states, and increased oxygen vacancies with higher Zn content. SEM revealed notable morphological variations and enhanced particle aggregation. Band-gap narrowing from 2.01 to 1.91 eV was observed with increasing Zn doping. Magnetic measurements indicated weak ferromagnetic behavior with Zn-dependent modulation of coercivity and saturation magnetization. The 10% Zn-doped sample achieved 95% RhB degradation within 160 min, with superior performance under mildly basic conditions (pH 10). Enhanced photocatalytic performance of Zn-doped α-Fe 2 O 3 , achieving nearly complete degradation of Rhodamine B dye within 160 minutes under visible-light irradiation at pH 10.
Samadder et al. (2026) studied this question.