Spinel ferrites and their composites photocatalysts for CO₂ conversion to solar fuels: A review

Spinel ferrite (MFe₂O₄, M= Fe, Co, Ni, Cu, Zn, Sn, Mn, Ca, and Mg) nanomaterials have attracted enormous attention for CO₂ photoreduction due to their superparamagnetic properties, narrow band gap, and suitable band position. However, a review about MFe₂O₄ and its composites for CO₂ photoconversion is still absent. In this study, the conventional preparation processes of MFe₂O₄ are summarized, and the recent advances in the modification of MFe₂O₄ catalysts for efficient CO₂ photoreduction are first discussed systematically with respect to microstructure regulation, defect introduction, and MFe₂O₄-based composite construction. Additionally, the enhancement mechanisms, including CO₂ adsorption, light harvesting, and promotion of charge separation, are analyzed in depth. Finally, the major challenges and possible perspectives for the development of MFe₂O₄-based heterojunctions are proposed, hoping to provide insight for designing highly efficient and selective MFe₂O₄-based photocatalysts for CO₂ photoconversion.