In Situ Construction of MIL-100@NiMn-LDH Hierarchical Architectures for Highly Selective Photoreduction of CO 2 to CH 4 .

Layered double hydroxides (LDHs) are considered a promising catalyst for photocatalytic CO 2 reduction due to their broad photoresponse, facile channels for electron transfer, and the presence of abundant defects. Herein, we reported for the first time the fabrication of a novel photocatalyst MIL-100@NiMn-LDH with a hierarchical architecture by selecting MIL-100 (Mn) as a template to provide Mn 3+ for the in situ growth of ultrathin NiMn-LDH nanosheets. Moreover, the in situ growth strategy exhibited excellent universality toward constructing MIL-100@LDH hierarchical architectures. When applied in the photocatalytic CO 2 reduction reaction, the as-prepared MIL-100@NiMn-LDH exhibited excellent CH 4 selectivity of 88.8% (2.84 μmol h -1 ), while the selectivity of H 2 was reduced to 1.8% under visible light irradiation (λ > 500 nm). Such excellent catalytic performance can be attributed to the fact that (a) the MIL-100@NiMn-LDH hierarchical architectures with exposed catalytic active sites helped to enhance the CO 2 adsorption and activation and (b) the presence of rich oxygen vacancies and coordinately unsaturated metal sites in MIL-100@NiMn-LDH that optimized the band gap and accelerated the separation/transport of photoinduced charges.