Development of photocatalysts with both high CO 2 adsorption capacity and robust CO 2 reduction performance is promising toward carbon capture and utilization (CCU). Herein, a porous organic polymer (POP) based on molecular monomers 1,2,3,5–Tetrakis(carbazol–9–yl)–4,6–dicyanobenzene (4CzIPN) and 9–(4–([2,2′:6′,2′'–terpyridin]–4′–yl)phenyl)–9H–carbazole (CzTPY) has been prepared for metal–free photocatalytic reduction of CO 2 to CO with 94.7% selectivity in 100% aqueous medium. The POP displays a yield of CO up to 265.7 mmol g –1 , which is among the highest yields for POPs–based photocatalytic systems. More importantly, the POP also shows a high CO 2 uptake of 109.1 cm 3 g –1 (21.4 wt%) at 273 K and 1 atm. External photosensitizers or catalysts are not required in this photocatalytic system. Mechanistic studies indicate the introduction of CzTPY improved the electron transfer and charge separation. These results show a feasible way to construct POP–based photocatalysts not only capturing CO 2 efficiently but also catalyzing CO 2 reduction with a high yield by rational regulation of molecular monomers.
Traditional fluorescence switching molecules achieving the state change between on and off states commonly based on UV irradiation. However, it is worth noting that UV irradiation is harmful to both the cancer cells and the normal cells. To achieve fluorescence switching under visible wavelength and avoid complicate molecular design, a fluorophore of 2,4,5,6-tetrakis(carbazol-9-yl)-1,3-dicyanobenzene (4CzIPN) and a quencher of diarylethene (DAE) were physically incorporated within the biocompatible block copolymer poly(lactic-co-glycolic acid)- b -poly(ethylene glycol) (PLGA- b -PEG) to form 4CzIPN-DAE nanoparticles (NPs) through flash nanoprecipitation (FNP). By using the FNP method, the NPs were prepared within milliseconds in a confined impingement jets dilution (CIJ-D) mixer. Quenching and recovery of fluorescence could achieve in the presence of DAE under 475 nm and 560 nm irradiation. Appropriate structure and fluorescent properties of the nanoparticles can be tuned by external conditions for their efficient fluorescence resonance energy transfer (FRET) in a kinetic stabilization process. This NPs formation process was further optimized by varying the dilution ratio, Reynolds number ( Re ) and polymer concentration to modulate the mixing and particle nucleation and growth process. The size and fluorescence switching properties of the NPs were systematically investigated in solution and in cellular uptake experiments. This work is anticipated to provide a simple and highly effective engineering strategy for the modulation of fluorescence switching nanoparticles and beneficial to its engineering application.
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