Recent advances in high-crystalline conjugated organic polymeric materials for photocatalytic CO₂conversion

Abstract

Photocatalytic carbon dioxide (CO2) conversion to high-value-added fuels is a meaningful strategy to assist achieve carbon neutrality and alleviate energy crisis. However, the low efficiency, poor selectivity, and insufficient of...

Donor–Acceptor-Conjugated Porous Polymer for Photopromoted N–H Formylation of Secondary Amines: Efficient In Situ N-Heterocyclic Carbene Catalysis in Radical Manner

“…As shown in Figure S3, powder X-ray diffraction indicates the amorphous structures of Im-PCPPs, and the broad diffraction peak at 15−30°reveals the existence of π−π stacking in Im-PCPPs. 39 The bulk Im-PCPPs materials exhibit stacking of overlapping slices as observed by scanning electron microscopy, and the transmission electron microscopy images confirm the porous layer aggregate of Im-PCPPs with abundant, clearly visible flaky wrinkles (Figure S4). 69 In N 2 isotherm measurements at 77 K, the adsorption behaviors of Im-PCPP-1 and Im-PCPP-2 are weak at lower relative pressures but strong at high relative pressures, and the hysteresis loops of isotherms demonstrate that they possess mesoporous structures.…”

“…Thermogravimetric analysis (Figure S2) of the as-prepared porous polymers under O 2 unveils modest-to-high thermal stability. As shown in Figure S3, powder X-ray diffraction indicates the amorphous structures of Im-PCPPs, and the broad diffraction peak at 15–30° reveals the existence of π–π stacking in Im-PCPPs . The bulk Im-PCPPs materials exhibit stacking of overlapping slices as observed by scanning electron microscopy, and the transmission electron microscopy images confirm the porous layer aggregate of Im-PCPPs with abundant, clearly visible flaky wrinkles (Figure S4).…”

“…Conjugated porous polymers (CPPs), − including covalent organic frameworks (COFs), − crystalline covalent triazine frameworks, − or conjugated microporous polymers, − have emerged as promising heterogeneous photocatalysts due to large conjugated system, tailor-made functions, adjustable energy level, and remarkable stability. − The predesign strategy by selecting well-arranged electron donor–acceptor (D–A) building blocks is an ideal way for precisely adjusting the photocatalytic performance of CPPs at the molecular level. ,,,, The push–pull effect of D–A pairs can effectively enhance the light absorption range and improve the transport and separation efficiency of photogenerated carriers (e – –h + ). ,,,, Facts proved that the photogenerated electrons or holes showed effectively reductive or oxidative activities in organic conversion reactions through a radical mechanism, such as oxidative amine coupling, reductive dehalogenation reaction, trifluoromethylated ketones, and radical polymerization. − Wang and co-workers introduced pyrene and benzothiadiazole cores into conjugated D–A Py-BSZ-COF COFs, which showed good photocatalytic activity for oxidative amine coupling because of its improved charge separation. Under visible light irradiation, photogenerated h + oxidized amine to give amine radical anion and ROS O 2 · – to oxidize amine radical anion to form the key imine intermediate .…”

Manipulation of interfacial charge dynamics for metal–organic frameworks toward advanced photocatalytic applications

“…The incorporation of heterojunctions that combine the desirable properties of individual constituents into an integrated whole was a significant step in achieving advanced photocatalysis for semiconductor nanostructures. 60,61 Four types of heterojunctions have been incorporated to design sophisticated photocatalysts, 17,60–62 including metal–semiconductor, graphene–semiconductor, semiconductor–semiconductor, and Z-scheme (or S-scheme) heterojunctions. Metal–semiconductor heterojunctions are characteristic of pronounced charge separation and peculiar plasmonic effect.…”

Strategies to improve the photocatalytic performance of covalent triazine frameworks

“…Generally, high crystallinity in materials is associated with reduced defect density and trapping centers for photogenerated electron–hole trapping and recombination, which in turn promote efficient charge separation and minimize recombination. 106,107 Improving the crystallinity of CTFs is an effective approach to enhance their photocatalytic performance. 35 Crystalline CTFs offer several advantages over amorphous counterparts, including few defects, 18 tunable bandgaps, 25,108 uniform porosity 109 and regular crystal planes.…”