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Metal–organic frameworks (MOFs) provide an ideal platform for loading various guests owing to their available space, and can be developed as a class of multifunctional materials. Herein, we cover the design and synthesis of two kinds of exchanged frameworks with multifunctional applications based on H3ImDC and In(NO3)3·2H2O through guest exchange inside the framework. The guest ammonium ion (NH4+) and [Ru(2,2′-bipyridine)3]2+ (Rubpy) are selected to exchange the dimethylammonium cation (Me2NH2+) encapsulated within In-MOF, giving birth to two kinds of new MOFs, named NH4+@In-MOF and Rubpy@In-MOF respectively. The proton conduction of NH4+@In-MOF and the CO2 photoreduction of Rubpy@In-MOF are investigated. Under different test conditions, the proton conductive behaviors of NH4+@In-MOF are evaluated and the best proton conductive value can reach up to 9.81 × 10−3 S cm−1. Compared to the original In-MOF, Rubpy@In-MOF exhibits a significantly enhanced CO2 photoreduction performance under a pure CO2 atmosphere. Furthermore, its photocatalytic activity is retained even under a 10% CO2 gas atmosphere, displaying a synergistic effect between Rubpy and In-MOF24 within Rubpy@In-MOF. [ABSTRACT FROM AUTHOR]

A family of heterojunction photocatalysts C 60 /TpPa have been constructed from fullerenes (C 60) and TpPa-1 via in-situ solvothermal method firstly. The photocatalytic activity toward CO 2 of C 60 /TpPa has been evaluated through the gas-solid reaction system under pure CO 2 and low concentration CO 2 (10 %) atmosphere, respectively. The results show that the maximum CO formation rates for C 60 /TpPa are as high as 48.16 μmol·g−1·h−1 and 90.25 μmol·g−1·h−1 under pure CO 2 and 10 % CO 2 environment, respectively. The attractive experimental phenomenon is assigned to the existence of C O groups in TpPa-1. Due to the presence of Z-scheme heterojunction, the separation of photoexcited electrons and holes is effectively enhanced, and the photocatalytic performances are significantly improved. This work suggests that the construction of COF-based photocatalysts with heterojunction for efficient photoreduction of CO 2 is a promising strategy. [Display omitted] • It is the first work that combining C 60 with TpPa-1 build Z-scheme heterojunction photocatalysts. • Due to the presence of C O groups, C 60 /COF achieve higher performance in 10 % CO 2 environment. • Z-scheme heterojunction enhances the performances by improving the efficient separation of photo-excited electrons and holes. [ABSTRACT FROM AUTHOR]

• MOF/COF hybrid photocatalysts are prepared through the simple grinding method. • TpPa/ZIF-8 photocatalysts exhibit excellent performances in pure and diluted CO 2. • The role of –OH groups on photocatalytic performances is proposed and verified. It remains challenging to design and synthesize porous crystalline photocatalysts for photocatalytic reduction CO 2 with high efficiency. Herein, a Schiff-based covalent organic framework (TpPa-1) is explored to combine with a metal–organic framework (ZIF-8) via a simple and fast method (the grinding method) firstly, generating a series of photocatalysts TpPa/ZIF-8. The photocatalytic performances of the as-synthesized photocatalysts TpPa/ZIF-8 are evaluated through a gas–solid reaction mode without photosensitizers and sacrificial agents, exhibiting excellent photocatalytic activities toward CO 2 in pure CO 2 and 10% CO 2 atmosphere, especially in 10% CO 2 environment. Therefore, the experimental result presents that TpPa/ZIF-8 can obtain the CO formation rates of 43.94 μmol·g−1·h−1 at a pure CO 2 environment and 84.87 μmol·g−1·h−1 in 10% CO 2 atmosphere, approximately 2 times and about 6 times larger than those of TpPa-1 in the pure CO 2 and 10% CO 2 atmosphere, respectively. The interesting phenomenon inspires us to investigate the structural factors affecting the photocatalytic activity, and hydroxyl groups from TpPa-1 are suspected to play an important role in the significantly improved photoreduction performance of CO 2 in 10% CO 2 atmosphere. The controlling examples TFPa/ZIF-8 without hydroxyl groups have also been prepared and evaluated their photoreduction performances in order to validate this hypothesis. The results clearly prove the hydroxyl groups tend to enhance CO 2 photoreduction. Additionally, it is noted that TpPa/ZIF-8 could maintain certain photocatalytic activity under the irradiation of sunlight. Summarily, the superior photocatalytic performances of TpPa/ZIF-8 may result from the high charge separation efficiency and increased photocatalytic active sites as well as the CO 2 adsorption capacity. The reported work sheds light on the construction of MOFs/COFs hybrid materials and expands their applications. [ABSTRACT FROM AUTHOR]