English

• While carbon dioxide (CO₂) is the primary driver of anthropogenic climate change [1], its role as a key C1 feedstock necessitates the capture and conversion of atmospheric CO₂ to value-added chemicals [2–4]. However, the inherent ultradilute atmospheric CO₂ concentration (~400 ppm) fundamentally limits the conversion efficiency [1]. Carbon capture, utilization and storage (CCUS) technologies are critical to this effort [5], with direct air capture (DAC) emerging as an essential negative emissions solution [6–9]. Among various conversion strategies, CO₂ photoreduction offers a promising solution with minimal carbon footprint and environmental compatibility versus enzymatic, thermal, or electrochemical routes [10–12]. This challenge motivates the discovery of novel materials for integration of CO₂ DAC with photoreduction in one body for practical CCUS [13].

  Porous materials are pivotal to DAC advancement through their tunable structures and functionalities [6,7]. The porous material systems, including porous carbons [14], zeolites [15], metal-organic frameworks (MOFs) [16–24], covalent-organic frameworks (COFs) [25,26], and porous organic polymers (POPs) [4,8,9], have been developed for integrated CO₂ capture-conversion [2–4]. Among them, the POPs exhibit exceptional structural diversity, featuring high surface areas, robust stability, tunable porosity, and facile functionalization [27], establishing them as ideal atmospheric CO₂ capture platforms [28]. Their customizable structures and pore environments further position POPs as scaffolds for integration of photocatalysts for CO₂ reduction [29–31]. To enhance CO₂ adsorption within POP materials, amine functionalization represents a key strategy where surface-grafted groups significantly boost CO₂ affinity [32–34]. The challenges in atmospheric CO₂ capture and conversion using POPs include [2,10,35–39]: (ⅰ) Intrinsically limited adsorption/conversion efficiency at ultradilute CO₂ concentrations due to poor interfacial contact; (ⅱ) Performance degradation from poor material stability hindering adsorption-conversion functionality; (ⅲ) System integration complexities involving adsorbent-catalyst coupling, CO₂ diffusion optimization, pore-blocking prevention, and incompatible operating conditions. Water-dispersible POPs, as an emerging class of porous materials [39], offer exceptional aqueous dispersibility, robust structural stability, and facile postsynthetic modification, which may resolve the integration challenges of CO₂ capture and conversion.

  Herein, we synthesized six novel water-dispersible POPs of POP-1~6 via polymerization of cyclen and tetrakis(4-(bromomethyl)phenyl)methane, followed by amine functionalization to enhance CO₂ affinity. The POP-1~6 possessed excellent aqueous-phase dispersibility for efficient CO₂ DAC, which can further integrate with an Fe-porphyrin catalyst (Fe-P) and Ru-photosensitizer for efficient atmospheric CO₂ photoreduction to CO with a yield up to 93%. This work establishes a dual-function material platform for integrated atmospheric CO₂ capture and photoreduction under ambient conditions.

  The 1,4,7,10-tetraazacyclododecane (cyclen, 1) is one kind of microcyclic tetramine that can be used as an excellent node molecule for constructing POPs due to its inexpensiveness, good water solubility, and the amine groups of cyclen can potentially endow the POP with CO₂ adsorption properties [40]. Aiming to achieve flexible adsorption due to the interaction of amine groups with CO₂ [41], we employed 1 as an amine-based structural linker and tetrakis(4-(bromomethyl)phenyl)methane (5) as a node molecule to synthesize the first cyclen-based POP-1 (Fig. 1, Figs. S1 and S2, and Method in Supporting information). As amine functionalization has been reported as an effective strategy to boost CO₂ affinity [32–34], we further introduced five selective primary and/or secondary amines to enhance the CO₂ adsorption capability. The POP-2~6 were synthesized based on the post-modification of POP-1 with a series of added amines (Fig. 1 and Fig. S1). Specifically, we introduced cyclen to construct POP-2, N, N-di(2-aminoethyl)ethylenediamine (TETA) to construct POP-3, polyamine N7 to construct POP-4, PAMAM-G0 to construct POP-5, and a cross-linked polymer derived from the polymerization reaction of PAMAM-G0 and 1,3-diiodopropane in situ to construct POP-6 (Fig. 1 and Fig. S1). To the best of our knowledge, these are the first examples of construction of cyclen-based POPs, and the resulting POP-1~6 exhibit excellent dispersibility in aqueous phase (Fig. S3 in Supporting information).

  Figure 1

  

  Figure 1.  Synthetic routes of designed POPs of POP-1~6 based on cyclen (1). (ⅰ) Reaction condition that was used to form POP-1 from cyclen (1) and tetrakis(4-(bromomethyl)phenyl)methane (5). (ⅱ) Two-step reaction conditions that contains (ⅰ) and subsequent reaction conditions to form POP-2~6 from POP-1 by introducing cyclen (1), TETA, polyamine N7, PAMAM-G0 and a cross-linked network of polymer derived from the reaction of PAMAM-G0 and 1,3-diiodopropane in situ, respectively. The porous structure is simulated by Materials Studio 7.0. Blue, grey, purple, reddish brown, and dark green represent the skeleton of 1, hydrogen atom of secondary amines of 1, skeleton of 5, bromine atom of 5, bromine residue and amines, respectively. The purple bond only represents one plausible connection between the amine groups and the POP skeleton.

  DownLoad: Full-Size Img PowerPoint

  Fourier transform infrared (FT-IR) spectroscopy was executed to examine the chemical structure of POP-1. As shown in Fig. S4 (Supporting information), no absorption band at 3327 and 3276 cm⁻¹ (N–H stretching vibration) manifests full conversion of secondary amine groups of 1. The absorption band at 1019 cm⁻¹ corresponding to C–N stretching vibration of tertiary amine group [42] further confirmed the formation of the new C–N bond in POP-1. Next, the absorption band at 2363 cm⁻¹ corresponding to N–H stretching vibration of tertiary ammonium salt (N⁺-H) was also observed, while the absorption at ~1500 and 900 cm⁻¹ (C–N⁺ stretching vibration) for quaternary ammonium salt was absent [43–45]. Consistently, solid-state ¹³C magic angle spinning nuclear magnetic resonance spectroscopy (¹³C MAS NMR) of POP-1 displayed a new peak assigned to the –CH₂– moieties at chemical shifts (δ) of 64.7 ppm, which further confirmed the formation of a new benzyl carbon (C–N) bond in POP-1 (Fig. S11 in Supporting information) [4,46–48]. The FTIR and ¹³C MAS NMR results confirmed the successful construction of POP-1. Notably, a week absorption peak at 615 cm⁻¹ corresponding to C-Br stretching vibration in POP-1 indicates that the residue of active benzyl bromide, which enables the post-modification with added amines (Fig. S4 in Supporting information). Next, elemental analysis was conducted to determine the residual amount of active benzyl bromide and the proportion of tertiary amine and tertiary ammonium salt in POP-1 by ion exchange (Fig. S12 and Method in Supporting information). The result shows that POP-1 contains 0.2% (mass fraction) of unreacted bromine residues (C-Br) and 11.8% (mass fraction) of ionic bond of bromine (Br⁻), and the molar proportion of tertiary amine in POP-1 is ca. 74% and the cationic tertiary ammonium salts is ca. 26% (Method in Supporting information). This cationic structure of POP-1 enables the loading of anionic catalysts through electrostatic interaction [49]. Nuclear magnetic resonance (NMR) spectroscopy was also used to analyze the structure of POP-1 and polyamines post-modified POPs of POP-2~6. Liquid-state ¹H NMR spectroscopy showed only solvent peaks of POPs of POP-1~6 (Figs. S5~S10 in Supporting information) due to their poor solubility, which is limited to structural verification of solid material, but ¹H NMR further confirmed no starting materials and no depolymerization products of 1 and 5 existed in POP-1 (Fig. S5) and no residual free amines from starting materials and no depolymerization products of 1 and 5 existed in POPs of POP-2~6 (Figs. S6~10).

  The predicted three-dimensional model of POP-1 with ideally ordered structure suggests that the pore size is approximately 1.0 nm as calculated by Materials Studio 7.0 (Fig. 1). Next, we performed the N₂ adsorption/desorption experiments to characterize the porosity of POP-1. The N₂ sorption isotherms displayed steep gas uptake at low relative pressures (Fig. S13a in Supporting information) with an adsorption capacity of 67.8 mg/g. The Brunauer-Emmett-Teller (BET) surface area of POP-1 was calculated to be 19.8 m²/g. Pore size distribution (PSD) analysis revealed that the aperture distribution of POP-1 is mostly at a range of 1–5 nm and contained both micropores (0.6–2 nm) and mesopores (2–35 nm) (Fig. S13b in Supporting information), the average pore width was calculated to be 1.8 nm with pore volume of 0.05 cm³/g (Fig. S13). The hierarchical porous structure is expected to accelerate mass transport during CO₂ adsorption processes [2,4,10]. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images showed that POP-1 has an irregular, cross-linked, sponge-like porous structure (Fig. 2 and Fig. S14 in Supporting information). And the POP-2~6 has the similar morphology as POP-1 as revealed by TEM (Fig. S14 in Supporting information). Moreover, the scanning transmission electron microscopy (STEM) and energy dispersive X-ray (EDX) mapping analysis also certified the colocalization of C, N, and Br elements within of POP-1~6 (Fig. 2, Figs. S14 and S15 in Supporting information). Small-angle X-ray scattering (SAXS) profile indicated an amorphous morphology of POP-1 (Fig. S16 in Supporting information). Thermal gravimetric analysis (TGA) suggested that POP-1~6 exhibited high thermal endurance that maintained structural integrity below 200 ℃ under inert conditions (Fig. S17 in Supporting information).

  Figure 2

  

  Figure 2.  Characterization of the morphology and composition of POP-1. (a) SEM image of POP-1. (b) TEM image of POP-1 at 0.5 µm. (c) STEM image of POP-1 at 0.5 µm, and (d) EDX mapping analysis of C, N, and Br of POP-1. Samples were prepared by drop-casting ~10 µL of the POP dispersed solution onto a carbon-coated copper grid.

  DownLoad: Full-Size Img PowerPoint

  We first studied the solid-phase CO₂ adsorption capacities of POP-1~6 by collecting the CO₂ isothermals at 298 K. The solid-phase CO₂ adsorption capacities were determined to be 24.4, 31.2, 56.5, 71.4, 49.2, and 56.9 mg/g, respectively (Fig. 3a, Fig. S18, Table 1 and Table S1 in Supporting information). However, the CO₂ isothermals only reflect the adsorption capacity in solid phase; there is still a lack of methods to determine CO₂ adsorption capacity in solution [27]. Given that the designed potential application of POP-1~6 is to capture atmospheric CO₂ in aqueous phase, we developed a method to determine CO₂ adsorption capacity in water using gas chromatography (GC) (see Supporting information for details) [50]. The capacities of CO₂ adsorption of POP-1~6 were determined to be 263.9, 467.9, 527.2, 401.6, 505.1, and 569.1 mg/g, respectively (Fig. 3a, Table 1 and Table S1). We then explored the application of POP-1~6 for CO₂ DAC by continuously pumping air into well-dispersed POPs in aqueous phase for 1–5 days. The CO₂ DAC capacities of POP-1~6 over 5 days in aqueous phase were determined to be 10.8, 17.9, 19.5, 27.6, 34.3, and 48.5 mg g⁻¹ d⁻¹, respectively (Fig. 3b, Table 1, and Table S1). The significant difference in the ability of solid materials to adsorb CO₂ in air versus in aqueous environments may primarily be attributed to the distinct roles of water molecules in the adsorption process. The fundamental cause lies in the inherent differences in the physical state, concentration, mass transfer kinetics, and adsorption or reaction mechanisms of CO₂ across different media. In air, adsorption involves the interaction between low-concentration gaseous CO₂ and solid materials; in contrast, in aqueous solutions, it entails the interaction between dissolved CO₂ species, including carbonic acid, bicarbonate, and carbonate ions, and the solid material within a hydrated environment [51–53]. The enhanced CO₂ adsorption capacities of POP-2~6 compared to POP-1 may be attributed to the successful post-modification of additional amines, which the activated amine sites at aperture would draw more CO₂ molecules into the pores [54–56]. The comparisons of CO₂ capture performance of POP-1~6 with a range of benchmark materials are summarized in Tables S2 and S3 (Supporting information) [57].

  Figure 3

  

  Figure 3.  (a) Saturated CO₂ adsorption capacities of POP-1~6 in solid phase measured by CO₂ isothermal analysis (Fig. S17 and details in Supporting information) and in aqueous phase measured by GC (Table 1). (b) Atmospheric CO₂ adsorption capacities of POPs of POP-1~6 in aqueous phase measured by GC, see Table 1 and Supporting information.

  DownLoad: Full-Size Img PowerPoint

  Table 1

  

  Table 1.  Comparison of the CO₂ adsorption capacities of POP-1~6.

  DownLoad: CSV

  POPs	CO2 adsorption capacity (298 K, 1 atm CO2a, mg/g)			CO2 DAC capacity in aqueous phase (298 K, 1 atm air, mg/g)
  	Solid-phase	Aqueous-phase		1 db	3 d	5 d
  POP-1	24.4c	263.9 ± 14.7		10.8 ± 0.4	21.4 ± 1.2	32.5 ± 3.0
  POP-2	31.2	467.9 ± 12.9		17.9 ± 0.1	32.0 ± 1.7	39.6 ± 1.4
  POP-3	56.5	527.2 ± 10.5		19.5 ± 0.7	45.6 ± 2.5	73.2 ± 5.4
  POP-4	71.4	401.6 ± 44.3		27.6 ± 0.9	52.6 ± 1.8	84.9 ± 5.4
  POP-5	49.2	505.1 ± 17.1		34.3 ± 0.3	60.8 ± 2.2	83.0 ± 0.8
  POP-6	56.9	569.1 ± 16.8		48.5 ± 2.0	86.2 ± 0.6	134.9 ± 1.7
  a 1 atm refers to one standard atmosphere, which is defined as the pressure exerted by the weight of the Earth's atmosphere at sea level under standard conditions. b 1 day refers to 24 h. c The general formula for conversion between mg/g and mmol/g is: mg/g = mmol/g × 44.01, where 44.01 is the molar mass of CO2.

  We then investigated the catalytic activity of POP-1~6 when integrated with catalysts by a series of photocatalytic experiments. The CO₂ photoreduction experiments were conducted using 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin iron(III) chloride (Fe-P) as a catalyst, Ru(bpy)₃Cl₂ as a photosensitizer, and TEOA as a sacrificial reagent in the POP system (Fig. 4 and Fig. S19 and Table S4 in Supporting information for details). The Fe-P and Ru(bpy)₃Cl₂ were integrated with POP-1~6 to achieve the photocatalytic CO₂ conversion. The density functional theory (DFT) calculations confirmed that the energy levels of the Ru(bpy)₃Cl₂ photosensitizer matched with those of the Fe-P catalyst, and the electron transfer was allowed (Fig. S20 in Supporting information). The ¹³C isotope labelling experiment confirmed that the produced CO was from the photoreduction of CO₂ (Fig. S21 in Supporting information). The reaction conditions were then systematically studied and optimized for CO productivity and the turnover number (TON) using different contents of POP, the concentration of the Ru(bpy)₃Cl₂ photosensitizer, and the Fe-P catalyst (Fig. S22 and Tables S5~S7 in Supporting information for details). Next, we studied the atmospheric CO₂ photoreduction of POP-1~6 (1 mg/mL) using 0.01 mmol/L of Fe-P, 10 mmol/L of Ru(bpy)₃Cl₂, and 20 mmol/L TEOA, in water under an air atmosphere. The results showed that the POP-1~6 can achieved CO₂-to-CO conversion with a productivity of 1.4 µmol g⁻¹ h⁻¹ (TON = 335, yield = 29%), 2.6 µmol g⁻¹ h⁻¹ (TON = 622, yield = 53%), 3.9 µmol g⁻¹ h⁻¹ (TON = 928, yield = 80%), 3.9 µmol g⁻¹ h⁻¹ (TON = 927, yield = 79%), 4.2 µmol g⁻¹ h⁻¹ (TON = 1015, yield = 87%), and 4.5 µmol g⁻¹ h⁻¹ (TON = 1085, yield = 93%), respectively (Fig. 5, Table 2 and Table S8 in Supporting information). The high atmospheric CO₂ photoreduction performance of POP-3~6 may be owed to their high CO₂ adsorption capacities and the interactions, such as hydrophobic effect and electrostatic interactions, between the POP scaffolds and the Fe-P catalyst [58]. The cross-linked networks and hierarchical porous structure of POPs might also optimize the CO₂ mass transfer, electron transport, and the stability of intermediates [58]. We further performed photocatalytic recycling experiments of POP-1~6. The recycling results showed that these POPs have good recyclability with negligible activity loss after five catalytic cycles (Fig. S23 and Table S9 in Supporting information). The FT-IR experiments showed no obvious changes for POP-1 before and after five photocatalytic cycles, which indicated that its structural integrity was maintained (Fig. S24 in Supporting information).

  Figure 4

  

  Figure 4.  The model illustration of the POP catalytic platform for atmospheric CO₂ photoreduction using Fe-P as catalyst, Ru(bpy)₃Cl₂ as photosensitizer, and TEOA as a sacrificial reagent in water.

  DownLoad: Full-Size Img PowerPoint

  Figure 5

  

  Figure 5.  The atmospheric CO₂ photoreduction performance of POP-1~6 using 0.01 mmol/L of Fe-P, 10 mmol/L of Ru(bpy)₃Cl₂, and 20 mmol/L of TEOA in water under an air atmosphere (The atmospheric CO₂ concentration was determined to be 408.6 ± 2.9 ppm).

  DownLoad: Full-Size Img PowerPoint

  Table 2

  

  Table 2.  Comparison of atmospheric CO₂ photoreduction performance of POP-1~6 (see Supporting information and Table S5 for details).

  DownLoad: CSV

  POPs	CO2 conversion (%)a	CO productivity (µmol g−1 h−1)	TON
  POP-1	29	1.4 ± 0.1	335 ± 18
  POP-2	53	2.6 ± 0.4	622 ± 92
  POP-3	80	3.9 ± 0.0	928 ± 1
  POP-4	79	3.9 ± 0.1	927 ± 27
  POP-5	87	4.2 ± 0.4	1015 ± 90
  POP-6	93	4.5 ± 0.3	1085 ± 75
  a The percentage of atmospheric CO2 conversion is defined as the ratio of the output of CO to the initial amount of atmospheric carbon dioxide (CO2). The concentration of atmospheric CO2 was determined to be 408.6 ± 2.9 ppm.

  Meanwhile, the BET results showed that there is no obvious surface area loss in recycled POP-1 after photocatalytic recycling, possibly due to no pore collapse or blockage (Fig. S13). XRD analysis showed that POP-1~6 and recycled POP-1~6 both are amorphous materials and have no obvious structure change (Fig. S25 in Supporting information). The scanning transmission electron microscopy (STEM) and energy dispersive X-ray (EDX) mapping analysis also certified the incorporation of heteroatoms of N and Br elements within of POP-1~6 and of N, Br, Fe and Ru elements within recycled POP-1~6 (Fig. 2, Figs. S14, S15 and S26, and Table S10 in Supporting information). The quantitative EDS analysis (weight% and atomic%, Table S10) for all catalysts (POP-1~6) also confirmed their stability after reuse since the element contents of C and N remain basically unchanged. XPS analysis of recycled POP-1 confirmed the exist of C–C and C–N (Fig. S27 in Supporting information) [59–64], and there is no obvious signal of Fe and Ru may due to their trace amount (Figs. S15 and S26 and Table S10) [59–64]. The comparison of CO₂ reduction performance of these POP-1~6 platforms with a range of benchmark materials for integrated CO₂ DAC and photoreduction are summarized in Table S11 (Supporting information).

  In summary, we developed six amine-functionalized, water-dispersible cyclen-based POP platforms for atmospheric CO₂ capture and photoreduction. The POP-1~6 exhibit exceptional aqueous-phase CO₂ uptake 264–569 mg/g, with DAC capacities reaching 11–49 mg g⁻¹ d⁻¹ in water. When integrated with photocatalysts, the POP-1~6 can achieve atmospheric CO₂-to-CO conversion with a productivity of 1.4–4.5 µmol g⁻¹ h⁻¹ and CO₂ conversion rates up to 93% compared to free molecules while maintaining stability and recyclability (> 5 cycles). The design principles demonstrated herein provide insights for creating integrated capture-conversion systems based on POPs advancing carbon neutrality goals.

  CRediT authorship contribution statement

  Jiawei Hu: Writing – original draft, Formal analysis, Data curation. Qiao-Yan Qi: Data curation. Qingxuan Tang: Data curation. Wen-Zhuang Wang: Data curation. Zhan-Ting Li: Supervision, Conceptualization. Jia Tian: Writing – review & editing, Writing – original draft, Supervision, Project administration, Investigation, Funding acquisition, Conceptualization.

  Declaration of competing interest

  The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

  Acknowledgments

  We acknowledge the support from the National Key Research and Development Program of China (No. 2024YFA1510600), the National Natural Science Foundation of China (No. 22271306), the Strategic Priority Research Program of the Chinese Academy of Sciences (Nos. XDB0610000, XDA0540000), the Shanghai Rising-Star Program (No. 22QA1411200), the Shanghai Institute of Organic Chemistry and the Shanghai Branch, Chinese Academy of Sciences. We acknowledge the support from the National Key Research and Development Program of China (No. 2022YFA1206200). Jia Tian acknowledges the Shanghai Synchrotron Radiation Facility (SSRF) of BL16B1 (No. 31124.02.SSRF.BL16B1) and BL10U1 (No. 31124.02.SSRF.BL10U1) for the assistance on SAXS or USAXS and the SSRF Key Research Project (No. 2023-SSRF-ZD-503466). We thank Prof. Zhi Ma, Dr. Kun Cui and Qiaoling Zhao in Analysis and Testing Center of SIOC-CAS for assistance in SEM and TEM measurements. The AI-driven experiments, simulations and model training were performed on the robotic AI-Scientist platform of Chinese Academy of Sciences.

  Supplementary materials

  Supplementary material associated with this article can be found, in the online version, at doi:10.1016/j.cclet.2025.112222.

  
  
• 1. [1]

     R. Monastersky, Nature 497 (2013) 13–14. doi: 10.1038/497013a

  2. [2]

     Z. Zhong, X. Wang, B. Tan, Chem. Eur. J. 31 (2025) e202404089. doi: 10.1002/chem.202404089

  3. [3]

     Q. Cheng, M. Huang, Q. Ye, et al., Chin. Chem. Lett. 35 (2024) 109112. doi: 10.1016/j.cclet.2023.109112

  4. [4]

     J.K. Tang, C.Y. Zhu, T.W. Jiang, et al., J. Mater. Chem. A 8 (2020) 18677–18686. doi: 10.1039/D0TA07068H

  5. [5]

     H. Chu, Z. Huang, Z. Zhang, et al., Sep. Purif. Technol. 343 (2024) 127153. doi: 10.1016/j.seppur.2024.127153

  6. [6]

     X. Zhu, W. Xie, J. Wu, et al., Chem. Soc. Rev. 51 (2022) 6574–6651. doi: 10.1039/D1CS00970B

  7. [7]

     Y. Zhang, L. Ding, Z. Xie, et al., Chin. Chem. Lett. 36 (2025) 109676. doi: 10.1016/j.cclet.2024.109676

  8. [8]

     Y. Bao, J. Liu, Y. Zhang, et al., Fuel 331 (2023) 125909. doi: 10.1016/j.fuel.2022.125909

  9. [9]

     C. He, H. Yang, L. Fu, Chin. Chem. Lett. 34 (2023) 107581. doi: 10.1016/j.cclet.2022.06.004

  10. [10]

      K.S. Song, P.W. Fritz, A. Coskun, Chem. Soc. Rev. 51 (2022) 9831–9852. doi: 10.1039/D2CS00727D

  11. [11]

      Y. Li, Y. Wei, W. He, et al., Chin. Chem. Lett. 34 (2023) 108417. doi: 10.1016/j.cclet.2023.108417

  12. [12]

      J. Zhou, H. Liu, H. Wang, Chin. Chem. Lett. 34 (2023) 107420. doi: 10.1016/j.cclet.2022.04.018

  13. [13]

      X. Gao, G. Yan, M. Li, et al., Fuel 378 (2024) 132960. doi: 10.1016/j.fuel.2024.132960

  14. [14]

      L. Shao, S. Wang, M. Liu, et al., Chem. Eng. J. 339 (2018) 509–518. doi: 10.1016/j.cej.2018.01.145

  15. [15]

      C. Chen, D.W. Park, W.S. Ahn, Appl. Surf. Sci. 292 (2014) 63–67. doi: 10.1016/j.apsusc.2013.11.064

  16. [16]

      F.F. Yang, Y.K. Ding, L.K. Wu, et al., Chin. Chem. Lett. 36 (2025) 110550. doi: 10.1016/j.cclet.2024.110550

  17. [17]

      J. Liu, C. Chen, K. Zhang, et al., Chin. Chem. Lett. 32 (2021) 649–659. doi: 10.1016/j.cclet.2020.07.040

  18. [18]

      X.D. Zhang, J.M. Huang, X. Zhu, et al., Chin. Chem. Lett. 36 (2025) 109937. doi: 10.1016/j.cclet.2024.109937

  19. [19]

      X. Wu, J. Lu, Z. Zhu, et al., Chin. Chem. Lett. 36 (2025) 110151. doi: 10.1016/j.cclet.2024.110151

  20. [20]

      L. Chen, Q. Liu, J. Yang, et al., Chin. Chem. Lett. 34 (2023) 107335. doi: 10.1016/j.cclet.2022.03.058

  21. [21]

      X. Zhang, Y. Zhang, W. Zhou, et al., Chin. Chem. Lett. 34 (2023) 107368. doi: 10.1016/j.cclet.2022.03.091

  22. [22]

      A.A. Zhang, R. Wang, H.B. Huang, et al., Chin. Chem. Lett. 34 (2023) 107311. doi: 10.1016/j.cclet.2022.03.034

  23. [23]

      X. Dong, Z. Xie, D. He, et al., Chin. Chem. Lett. 34 (2023) 107459. doi: 10.1016/j.cclet.2022.04.057

  24. [24]

      X. Kang, G. Fu, X.Z. Fu, et al., Chin. Chem. Lett. 34 (2023) 107757. doi: 10.1016/j.cclet.2022.107757

  25. [25]

      Z. Zhou, T. Ma, H. Zhang, et al., Nature 635 (2024) 1–6.

  26. [26]

      Z. Gu, Z. Shan, Y. Wang, et al., Chin. Chem. Lett. 35 (2024) 108356. doi: 10.1016/j.cclet.2023.108356

  27. [27]

      H. Gao, Q. Li, S. Ren, Curr. Opin. Green Sustain. Chem. 16 (2019) 33–38. doi: 10.1016/j.cogsc.2018.11.015

  28. [28]

      N. Huang, G. Day, X. Yang, et al., Sci. China Chem. 60 (2017) 1007–1014. doi: 10.1007/s11426-017-9084-7

  29. [29]

      J. Li, K. Ma, Y. He, et al., Catal. Sci. Technol. 11 (2021) 7300–7306. doi: 10.1039/D1CY01311D

  30. [30]

      W.J. Wang, K. Chen, Chin. Chem. Lett. 36 (2025) 109998. doi: 10.1016/j.cclet.2024.109998

  31. [31]

      G. Xu, Q.L. Hong, Y. Sun, et al., Chin. Chem. Lett. 33 (2022) 2915–2918. doi: 10.1016/j.cclet.2021.10.061

  32. [32]

      T. Shi, Z. Wu, Z. Wu, et al., J. Polym. Sci. 62 (2024) 1554–1568. doi: 10.1002/pol.20230469

  33. [33]

      R. Wang, S. Wang, C. Zhu, et al., Chin. Chem. Lett. 36 (2025) 111547.

  34. [34]

      X. Kong, S. Li, M. Strømme, et al., Nanomaterials 9 (2019) 1020. doi: 10.3390/nano9071020

  35. [35]

      M. He, H. Zhao, J. Jia, et al., Environ. Res. 267 (2025) 120701. doi: 10.1016/j.envres.2024.120701

  36. [36]

      Q.H. Zheng, C. Chen, S.M. Cao, et al., Chin. Chem. Lett. 34 (2023) 107273. doi: 10.1016/j.cclet.2022.02.078

  37. [37]

      C. Cui, G. Li, Z. Tang, Chin. Chem. Lett. 32 (2021) 3307–3321. doi: 10.1016/j.cclet.2021.04.001

  38. [38]

      S.B. Yu, F. Lin, J. Tian, Chem. Soc. Rev. 51 (2022) 434–449. doi: 10.1039/D1CS00862E

  39. [39]

      X. Hong, Y. Fang, D. Chao, Mol. Catal. 549 (2023) 113476.

  40. [40]

      M. Meyer, V. Dahaoui-Gindrey, C. Lecomte, Coord. Chem. Rev. 178-180 (1998) 1313–1405.

  41. [41]

      Q.M. Sun, J.H. He, J.M. Lu, Energy Sci. Eng. 11 (2023) 952–973. doi: 10.1002/ese3.1334

  42. [42]

      R. Gomes, A. Bhaumik, J. Solid State Chem. 222 (2015) 7–11. doi: 10.1016/j.jssc.2014.10.032

  43. [43]

      M.E. Atlaskina, A.A. Atlaskin, O.V. Kazarina, Environments 8 (2021) 134. doi: 10.3390/environments8120134

  44. [44]

      Z. Xiao, D. Kong, J. Liang, Carbon 116 (2017) 633–639. doi: 10.1016/j.carbon.2017.02.041

  45. [45]

      Z.H. Ping, Q.T. Nguyen, S.M. Chen, Polymer 42 (2001) 8461–8467. doi: 10.1016/S0032-3861(01)00358-5

  46. [46]

      L. Zhang, N. Di, Z. Wang, et al., J. Membr. Sci. 688 (2023) 122129. doi: 10.1016/j.memsci.2023.122129

  47. [47]

      W. Cao, Z. Wang, Q. Zeng, et al., Appl. Surf. Sci. 389 (2016) 404–410. doi: 10.1016/j.apsusc.2016.07.095

  48. [48]

      K. Zhang, X.J. Chen, AIP Adv. 8 (2018) 025004. doi: 10.1063/1.5016876

  49. [49]

      Z.W. Liu, B.H. Han, Curr. Opin. Green Sustain. Chem. 16 (2019) 20–25. doi: 10.1016/j.cogsc.2018.11.008

  50. [50]

      R.M. Enick, S.M. Klara, Chem. Eng. Commun. 90 (1990) 23–33. doi: 10.1080/00986449008940574

  51. [51]

      S.J. Datta, C. Khumnoon, Z.H. Lee, et al., Science 350 (2015) 302–306. doi: 10.1126/science.aab1680

  52. [52]

      N.L. Drenchev, K.K. Chakarova, O.V. Lagunov, et al., J. Vis. Exp. 156 (2020) e60285.

  53. [53]

      J. Wang, L. Huang, R. Yang, et al., Energy Environ. Sci. 7 (2014) 3478–3518. doi: 10.1039/C4EE01647E

  54. [54]

      R. Ahmadi, M.S. Alivand, N.H. Mohammad Hossein Tehrani, et al., Chem. Eng. J. 415 (2021) 129076. doi: 10.1016/j.cej.2021.129076

  55. [55]

      H. Jung, S. Jeon, D.H. Jo, et al., Chem. Eng. J. 307 (2017) 836–844. doi: 10.1016/j.cej.2016.09.005

  56. [56]

      L. Zou, Y. Sun, S. Che, et al., Adv. Mater. 29 (2017) 1700229. doi: 10.1002/adma.201700229

  57. [57]

      M.G. Darmayanti, K.L. Tuck, S.H. Thang, Adv. Mater. 36 (2024) 2403324. doi: 10.1002/adma.202403324

  58. [58]

      H. Daglar, H.C. Gulbalkan, G.O. Aksu, et al., Adv. Mater. 36 (2024) 2405532.

  59. [59]

      M.C. Biesinger, B.P. Payne, A.P. Grosvenor, et al., Appl. Surface Sci. 257 (2011) 2717–2730. doi: 10.1016/j.apsusc.2010.10.051

  60. [60]

      N.S. McIntyre, M.G. Cook, Anal. Chem. 47 (1975) 2208–2213. doi: 10.1021/ac60363a034

  61. [61]

      A. Taylor, J. Chem. Technol. Biotechnol. 53 (1992) 215.

  62. [62]

      S. Kumar, P. Chakrabortty, R.V. Singh, et al., ACS Appl. Energy Mater. 7 (2024) 4429–4444. doi: 10.1021/acsaem.4c00360

  63. [63]

      S. Kumar, P. Chakrabortty, B. Banerjee, et al., ACS Appl. Nano Mater. 8 (2025) 12946–12956. doi: 10.1021/acsanm.5c01423

  64. [64]

      P. Sarkar, A.H. Chowdhury, S. Biswas, et al., Mat. Today Chem. 21 (2021) 100509. doi: 10.1016/j.mtchem.2021.100509

• 

  Figure 1  Synthetic routes of designed POPs of POP-1~6 based on cyclen (1). (ⅰ) Reaction condition that was used to form POP-1 from cyclen (1) and tetrakis(4-(bromomethyl)phenyl)methane (5). (ⅱ) Two-step reaction conditions that contains (ⅰ) and subsequent reaction conditions to form POP-2~6 from POP-1 by introducing cyclen (1), TETA, polyamine N7, PAMAM-G0 and a cross-linked network of polymer derived from the reaction of PAMAM-G0 and 1,3-diiodopropane in situ, respectively. The porous structure is simulated by Materials Studio 7.0. Blue, grey, purple, reddish brown, and dark green represent the skeleton of 1, hydrogen atom of secondary amines of 1, skeleton of 5, bromine atom of 5, bromine residue and amines, respectively. The purple bond only represents one plausible connection between the amine groups and the POP skeleton.

  下载: 全尺寸图片 幻灯片
  

  Figure 2  Characterization of the morphology and composition of POP-1. (a) SEM image of POP-1. (b) TEM image of POP-1 at 0.5 µm. (c) STEM image of POP-1 at 0.5 µm, and (d) EDX mapping analysis of C, N, and Br of POP-1. Samples were prepared by drop-casting ~10 µL of the POP dispersed solution onto a carbon-coated copper grid.

  下载: 全尺寸图片 幻灯片
  

  Figure 3  (a) Saturated CO₂ adsorption capacities of POP-1~6 in solid phase measured by CO₂ isothermal analysis (Fig. S17 and details in Supporting information) and in aqueous phase measured by GC (Table 1). (b) Atmospheric CO₂ adsorption capacities of POPs of POP-1~6 in aqueous phase measured by GC, see Table 1 and Supporting information.

  下载: 全尺寸图片 幻灯片
  

  Figure 4  The model illustration of the POP catalytic platform for atmospheric CO₂ photoreduction using Fe-P as catalyst, Ru(bpy)₃Cl₂ as photosensitizer, and TEOA as a sacrificial reagent in water.

  下载: 全尺寸图片 幻灯片
  

  Figure 5  The atmospheric CO₂ photoreduction performance of POP-1~6 using 0.01 mmol/L of Fe-P, 10 mmol/L of Ru(bpy)₃Cl₂, and 20 mmol/L of TEOA in water under an air atmosphere (The atmospheric CO₂ concentration was determined to be 408.6 ± 2.9 ppm).

  下载: 全尺寸图片 幻灯片

  Table 1.  Comparison of the CO₂ adsorption capacities of POP-1~6.

  POPs	CO2 adsorption capacity (298 K, 1 atm CO2a, mg/g)			CO2 DAC capacity in aqueous phase (298 K, 1 atm air, mg/g)
  	Solid-phase	Aqueous-phase		1 db	3 d	5 d
  POP-1	24.4c	263.9 ± 14.7		10.8 ± 0.4	21.4 ± 1.2	32.5 ± 3.0
  POP-2	31.2	467.9 ± 12.9		17.9 ± 0.1	32.0 ± 1.7	39.6 ± 1.4
  POP-3	56.5	527.2 ± 10.5		19.5 ± 0.7	45.6 ± 2.5	73.2 ± 5.4
  POP-4	71.4	401.6 ± 44.3		27.6 ± 0.9	52.6 ± 1.8	84.9 ± 5.4
  POP-5	49.2	505.1 ± 17.1		34.3 ± 0.3	60.8 ± 2.2	83.0 ± 0.8
  POP-6	56.9	569.1 ± 16.8		48.5 ± 2.0	86.2 ± 0.6	134.9 ± 1.7
  a 1 atm refers to one standard atmosphere, which is defined as the pressure exerted by the weight of the Earth's atmosphere at sea level under standard conditions. b 1 day refers to 24 h. c The general formula for conversion between mg/g and mmol/g is: mg/g = mmol/g × 44.01, where 44.01 is the molar mass of CO2.

  下载: 导出CSV

  Table 2.  Comparison of atmospheric CO₂ photoreduction performance of POP-1~6 (see Supporting information and Table S5 for details).

  POPs	CO2 conversion (%)a	CO productivity (µmol g−1 h−1)	TON
  POP-1	29	1.4 ± 0.1	335 ± 18
  POP-2	53	2.6 ± 0.4	622 ± 92
  POP-3	80	3.9 ± 0.0	928 ± 1
  POP-4	79	3.9 ± 0.1	927 ± 27
  POP-5	87	4.2 ± 0.4	1015 ± 90
  POP-6	93	4.5 ± 0.3	1085 ± 75
  a The percentage of atmospheric CO2 conversion is defined as the ratio of the output of CO to the initial amount of atmospheric carbon dioxide (CO2). The concentration of atmospheric CO2 was determined to be 408.6 ± 2.9 ppm.

  下载: 导出CSV
•