Ultrathin magnetic Mg-Al LDH photocatalyst for enhanced CO₂ reduction: Fabrication and mechanism

The two-dimensional (2D) ultrathin Mg-Al layered double hydroxide modified by magnetic Fe₃O₄ (Fe₃O₄/Mg-Al LDH) was successfully synthesized via the co-precipitation method. The Fe₃O₄/Mg-Al LDH not only exhibits superior separation efficiency of charge carriers but also possesses signally enhanced photocatalytic activity for CO₂ reduction than Mg-Al LDH. The as-prepared Fe₃O₄/Mg-Al LDH affords the CO and CH₄ generation rate of 442.2 µmol g⁻¹ h⁻¹ and 223.9 µmol g⁻¹ h⁻¹. The enhanced reduction CO₂ activity mainly comes from synergetic effect of Fe₃O₄ and ultrathin Mg-Al LDH. And Fe₃O₄ can increase the separation efficiency of photogenerated electron-hole pairs, and ultrathin Mg-Al LDH can reduce the transmission resistance of charge carriers. Moreover, a detailed mechanism insight of Fe₃O₄/Mg-Al LDH for CO₂ reduction is also investigated by a series of characterization methods and activity experiments. This work offers a simple and environment-friendly approach to develop recycled photocatalysts in CO₂ reduction treatment.