• Fe 2 O 3 , Sm 2 O 3 and Sm doped Fe 2 O 3 photocatalysts synthesized via sol-gel route • Sm-doped material showed good surface area of 1327 cm 2 /g • The doped materials showed excellent photodegration of 99.8% • The higher efficiency of the catalyst is owing to efficient charge separation/transportation. The growing population led to an increase in water contamination, which urged researchers to develop an efficient, eco-friendly, and safe catalyst to remove these pollutants from water bodies. Herein the present study, the Sm-doped Fe 2 O 3 photocatalyst was developed through a low-cost and facile sol-gel route to degrade methylene blue (MB) under sunlight. Various characterizations of the photocatalyst were performed by X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), photoluminescence (PL), and UV–vis spectrometry, current-voltage measurements (IV), and electrochemical impedance spectroscopy (EIS). The XRD confirmed the successful doping of Sm in Fe 2 O 3 lattices. Remarkably, the adsorption were 14%, 10%, 34%, photo-reduction efficiencies were 78.2%, 79.1%, 65.8%, while complete degradation of dyes were 91.2, 89.1 and 99.8% for Fe 3 O 3 , Sm 2 O 3 and Sm-doped Fe 2 O 3 , respectively, against methylene blue dye after 1.0 h under sunlight illumination. Moreover, the enhanced photocatalytic performance of the doped catalyst was found to be due to the structural variation, lower energy bandgap, hindered recombination, and the efficient charge carriers separation/transportation at the surface. The effective synergistic photocatalytic performance proved its potential in water remediation.