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Self-assembled catalyst has the excellent selectivity and activity at low concentrations of CO 2. [Display omitted] • The self-assembled catalyst of CC3/Pd is synthesized. • Catalyst has the excellent selectivity and activity at low concentrations of CO 2. • The size effect of Pd nanoparticles has been systematically studied. • The mechanism of catalyst photoreduction CO 2 to CH 4 is studied. Porous heterogeneous photocatalysts containing both CO 2 adsorption and catalytically active sites can be might beneficial to achieve photoreduction of low concentrations of CO 2 to methane. Here, we show a self-assembled catalyst by combining catalytically-active Pd nanoparticles and porous organic cages for the CO 2 -to-CH 4 photoreduction reaction in the presence a molecular photosensitizer and a sacrificial reagent. The Pd nanoparticles is vital for the high CH 4 selectivity (over 97%) for the CO 2 photoreduction reaction, but they suffer from the low catalytic activity. When these Pd nanoparticles are equipped with an underneath support of porous organic cages, it dramatically boosts the catalytic activity with a high production rate of 78.5 μmol g-1h−1, while the CH 4 selectivity is up to ∼ 98% (electron basis). Importantly, when the photoreduction is performed under low concentration of CO 2 (10% concentration), over 98% of CH 4 selectivity and nearly 50% of the catalytic activity for the Pd-based catalysts retains. [ABSTRACT FROM AUTHOR]

Task-specific Py-Zn@IPOP X with multiple active sites are developed and exhibit durable high-activity for cycloaddition of CO 2 to epoxides under additive-free conditions. [Display omitted] • Novel task-specific Py-Zn@IPOP X are constructed in green ionic liquid medium. • Py-Zn@IPOP I with multiple active sites can activate CO 2 and epoxide simultaneously. • Py-Zn@IPOP I realizes efficient CO 2 cycloaddition under additive-free conditions. • The developed catalyst is easily separated and exhibits durable high-activity. Based on the Schiff base reaction and post-modification strategy, novel nanocomposites of pyridine-zinc-based ionic porous organic polymers (Py-Zn@IPOP X , X = Br, I, Ac) were constructed and structurally characterized. Various Py-Zn@IPOP X were applied to the transformation of CO 2 and epoxides into cyclic carbonates, and their catalytic activities were studied and discussed in detail. The results showed that Py-Zn@IPOP I possesses Lewis acid-base bifunctional features, and also modified with superior nucleophilic active groups, which exerted an important synergistic effect on activation of CO 2 and epoxide, and ring-opening of epoxide. Under co-catalyst/solvent-free conditions, Py-Zn@IPOP I could afford 96 % PC yield and 99 % selectivity at 120 °C and 2.0 MPa CO 2 pressure for 6 h, and turnover frequency (TOF) was high to 230 h−1. Moreover, the reusability and versatility of the catalyst were examined, and the catalytic mechanism was speculated according to the obtained results. Compared with previously reported porous polymer catalysts, Py-Zn@IPOP I requires much greener and milder reaction conditions while avoids the use of a co-catalyst, displaying bright prospects for the design and synthesis of ionic porous organic polymers for CO 2 activation and utilization. [ABSTRACT FROM AUTHOR]

Heterogeneous Co@PTPOFs with multiple Lewis acid/basic sites are developed and show excellent activity for cycloaddition of CO 2 and epoxides. [Display omitted] • Novel M@PPOFs with multiple Lewis acid/basic active sites are prepared facilely. • The M@PPOFs exhibit high specific surface area and good structural stability. • The 1.0Co@PPOFs-mediated CO 2 coupling reaction can conduct under mild conditions. • The optimum catalyst shows excellent reusability and broad substrate scope. • An insight into the M@PPOFs-catalyzed cycloaddition mechanism is proposed. A series of metal-decorated porous organic frameworks (M@PTPOFs) with cross-linked pyridyl and triazinyl were fabricated through a two-step method. The structures of the PTPOFs and M@PTPOFs were systematically characterized. As heterogeneous catalysts with Lewis acid/basic sites, the M@PTPOFs were applied to catalyze the model cycloaddition of CO 2 and epoxides. The optimal catalytic system and reaction parameters were investigated in detail. It was found that 1.0Co@PTPOF-400-15 cooperating with tetrabutylammonium iodide (TBAI) achieved the best catalytic performance, with a 96% product yield and 99% selectivity under mild conditions of 60 °C and 2.0 MPa CO 2 for 5.0 h. Moreover, 1.0Co@PTPOF-400-15 could be easily recycled by centrifugation and reused multiple times with nearly unchanged catalytic activity. Finally, the product yield and reaction parameters were compared with those of reported heterogeneous catalysts, and the possible synergistic catalytic mechanism of 1.0Co@PTPOF-400–15/TBAI was proposed. The multiple Lewis acid/basic active sites, robust structure and excellent catalytic performance are useful for the development of other high-efficiency heterogeneous catalysts. [ABSTRACT FROM AUTHOR]