▎ 摘　　要

Hematite alpha-Fe2O3 nanoparticle synthesis via a facile and eco-friendly hydrothermal method has been hybridized by different loading of graphene obtained by the pyrolysis of biopolymers (alginate, chitosan and carrageenan). The resulting alpha-Fe2O3-Gr catalyst shows a high catalytic activity of -98% toward RhB degradation under visible light irradiation. The existence of N and S heteroatoms on the surface of the graphene affects the size of nanoparticles and the specific surface area in the alpha-Fe2O3-Gr, with a negative effect on catalytic performance. Electron Spin Resonance (ESR) studies showed that the hydroxyl radical center dot OH was the main reactive species responsible for the degradation of RhB. The reusability of alpha-Fe2O3-Gr was studied and the catalyst kept good stability and high activity over four cycles with no change in the morphology of the catalysts. Interestingly, incorporation of graphene into hematite nanoparticles resulted in superior photocatalytic activity compared to alpha-Fe2O3 loaded on carbon nanotubes, active carbons and biochar. (C) 2020 The Authors. Published by Elsevier Ltd.