Combining MgNiAl-LDH nanoflower with AlBi-MOF nanosheets to construct a S-scheme heterojunction for enhancing CO2 photoreduction

The thoughtful construction of highly efficient, tiered photocatalysts has become a focal point of interest. Herein, in this context, the step-scheme (S-scheme) AlBi-MOF/MgNiAl-LDH heterojunction is specifically engineered to facilitate the photocatalytic reduction of CO 2 . The CO 2 photocatalytic reduction experiments of three samples, AlBi-MOF, MgNiAl-LDH and AlBi-MOF/MgNiAl-LDH, were conducted for 5 h using triethanolamine as the sacrificial agent, the optimized sample demonstrates significantly enhanced CO 2 photoreduction efficiency compared to the control without treatment, i.e., AlBi-MOF and MgNiAl-LDH. The optimized AlBi-MOF/MgNiAl-LDH exhibited a CO 2 reduction rate of 86.84 μmol g −1  h −1 , which was 25.85 times higher than that of MgNiAl-LDH alone and 20.15 times higher than that of AlBi-MOF alone. The improved photocatalytic efficiency is mainly attributed to the decreased recombination of photogenerated charge carriers, facilitated by S-scheme heterojunction. Additionally, the large specific surface areas and abundant active sites also contribute to the improvement. Meanwhile, the S-scheme photocarrier transfer mechanism was verified by in situ X-ray photoelectron spectrum (XPS) and femtosecond transient absorption spectroscopy (fs-TA). This research outlines an effective methodological for advancing highly efficient heterojunction photocatalysts dedicated to the transformation of solar energy into fuel.