The direct Z-scheme provide a potential strategy for high efficient CO2 photoreduction, whereas the heterointerface contact resistance is significantly limited the interfacial electron transfer kinetic. Herein, we build the directional charge-transfer channels in a direct Z-scheme system over metal−organic frameworks (MOFs), that is the lattice-guided MOF-on-MOF hybrids, to facilitate CO2 photoreduction. The heteroepitaxial lattice growth along the c-axis of MIL-88B(Fe) via the high-activity (001) facet over the stable (111) facet of UiO-66-NH2. Theoretical calculations and experimental results provide the direct evidence that engineering direct Z-scheme of these MOFs hybrids can induce the electrons migration from UiO-66-NH2 to the holes of MIL-88B(Fe) by directional charge-transfer channels owing to their lattice match. This can dramatically boosts photocatalytic CO2-to-CO selectivity up to nearly 100%, with a rate of 2.26 μmol·g-1·h-1. This work demonstrates that the efficiently selective CO2 photoreduction processes can be achieved by engineering Z-scheme via lattice intergrown of MOF hybrids strategy.

Efficient and economical separation of 1,3-butadiene (C4H6) from C4 hydrocarbons is imperative yet challenging in industrial separation processes. Herein, a guest-induced flexible Mn-bpdc MOF has been employed to separate C4H6 from C4 hydrocarbons, including n-butene (n-C4H8), iso-butene (iso-C4H8), n-butane (n-C4H10) and iso-butane (iso-C4H10). Significantly, C4H6 can instantaneously induce gate-opening of Mn-bpdc MOF at 0.13 bar and 298 K, thus significant amounts of C4H6 can be adsorbed, while other C4 hydrocarbons cannot induce the gate-opening even at 1 bar. The uptake selectivities of Mn-bpdc MOF for C4H6/n-C4H8 and C4H6/iso-C4H8 are up to 40.0 and 45.0 at 298 K and 1 bar, respectively, both surpassing all the reported adsorbents. In addition, breakthrough experiments verified that C4H6/n-C4H8, C4H6/iso-C4H8, C4H6/n-C4H10 and C4H6/iso-C4H10 mixture can be efficiently separated. More importantly, Mn-bpdc possesses excellent water stability and outstanding regeneration ability for C4H6 separation, making it a new benchmark for C4H6 purification.

The introduction of mesoporosity into the microporous metal-organic frameworks (MOFs) is expected to expand their applications. Herein, we report a green and facile method to obtain hierarchically porous MOF structures by using an air-steam etching process. By virtue of the protonation reaction between the imidazole moiety and water vapor, the protonated imidazole related linkers leave the framework, resulting in the formation of mesopores in the zeolitic imidazolate frameworks (ZIFs), as exemplified by ZIF-8. Given the mild etching process, the materials’ structural integrity and crystallinity are well maintained. Remarkably, the proposed steam etching approach is generally applicable, which can be readily extended to other ZIFs, such as ZIF-14, ZIF-69, and ZIF-71, thus representing a powerful strategy to construct hierarchically porous MOF materials.