Coherent-Interface-Assembled Ag2O-Anchored Nanofibrillated

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Coherent Interface Assembled Ag2O Anchored Nanofibrillated Cellulose Porous Aerogels for Radioactive Iodine Capture Yun Lu, Hongwei Liu, Runan Gao, Shaoliang Xiao, Ming Zhang, Yafang Yin, Siqun Wang, Jian Li, and Dongjiang Yang ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.6b10749 • Publication Date (Web): 06 Oct 2016 Downloaded from http://pubs.acs.org on October 8, 2016

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ACS Applied Materials & Interfaces

Coherent Interface Assembled Ag2O Anchored Nanofibrillated Cellulose Porous Aerogels for Radioactive Iodine Capture Yun Lu,1 Hongwei Liu,2 Runan Gao,3 Shaoliang Xiao,3 Ming Zhang,3 Yafang Yin,1 Siqun Wang,1,4 Jian Li3* and Dongjiang Yang5,6*

1.

Research Institute of Wood Industry, Chinese Academy of Forestry, Beijing

100091, China

2.

Australian Center for Microscopy & Microanalysis (ACMM), The University of

Sydney, Sydney, NSW 2006, Australia

3.

Material Science and Engineering College; Key Laboratory of Bio-based Material

Science and Technology, Ministry of Education, Northeast Forestry University, Harbin 150040, China. E-mail: [email protected]

4.

Center for Renewable Carbon, University of Tennessee, Knoxville, TN, 37996, US

5.

Queensland Micro- and Nanotechnology Centre (QMNC), Griffith University,

Nathan, Brisbane, Queensland 4111, Australia

6.

College of Chemistry, Chemical and Environmental Engineering; Laboratory of

Fiber Materials and Modern Textile, the Growing Base for State Key Laboratory, Qingdao University, Qingdao 266071, China. E-mail: [email protected] 1 ACS Paragon Plus Environment


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Abstract: Nanofibrillated cellulose (NFC) has received increasing attention in science and technology due not only to the availability of large amounts of cellulose in nature but also to its unique structural and physical features. These high aspect ratio nanofibers have potential applications as water remediation, reinforcing scaffold in composites, coatings, and porous materials due to their fascinating properties. In this work, highly porous NFC aerogels were prepared based on tert-butanol freeze-drying of ultrasonic isolated bamboo NFC with 20-80 nm diameters. Then non-agglomerated 2-20 nm silver oxide (Ag2O) nanoparticles (NPs) were grown firmly onto the NFC scaffold with a high loading content of ~500 wt% to fabricate Ag2O@NFC organic-inorganic composite aerogels (Ag2O@NFC). For the first time, it is explored the coherent interface and interaction mechanism between the cellulose Iβ nanofiber and Ag2O NPs by HRTEM and 3D electron tomography. Specifically, strong hydrogen between Ag2O and NFC makes them grow together firmly along coherent interface, where good lattice matching between specific crystal planes of Ag2O and NFC results in very small interfacial straining. The resulting Ag2O@NFC aerogels fully take the advantage of 3D organic aerogel framework and the inorganic NPs, such as large surface area, interconnected porous structures, and supreme mechanical properties. They open up a wide horizon for functional practical usages, for example, flexible super-efficient adsorbent to capture I- ions from contaminated water and trap I2 vapor for safe disposal, as presented in this work. The viable binding mode between many types of inorganic NPs and organic NFC established here highlights new ways to investigate cellulose-based functional nanocomposites. 2 ACS Paragon Plus Environment

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Keywords: nanofibrillated cellulose; aerogel; Ag2O nanocrystals; iodine capture; coherent interface Introduction The abundant natural cellulose fibers (several micrometer thick) can be disintegrated stepwise,1,2 first into fibril bundles, then into separated native nanofibrils of tens of nanometers, called nanofibrillated cellulose (NFC). The abundant hydroxyl groups on the NFC offer tremendous opportunities for the self-assembly of a range of advanced micro- and nano-structures.3 or instance, highly porous and ultralight NFC aerogels can be fabricated from dilute aqueous suspensions whose excessive water can be removed or driven off by drying in processes, such as ultrafiltration,4 supercritical drying,5 freeze-drying,6 and tert-butanol freeze-drying.7 In this case, a deformable 3D framework is formed by the entangled long cellulose nanofibrils via strong hydrogen bonds.8 The morphology and 3D framework of NFC aerogels can be easily adjusted by different surface charge,9 freezing temperature,10 And dispersing medium.11 Compared with the synthetic polymer aerogels, the abundant and sustainable NFC aerogels are more environmental friendly and biocompatible.12,13 They also have superb mechanical stabilities8 and become an ideal precursors for carbonaceous nanofiber aerogels with facile pyrolysis treatment.14 In addition, with the existence of abundant hydroxyl groups within the structure of NFC aerogels, which is a unique platform for surface modification.15 All these superior properties make NFC aerogels into the most promising 3D scaffold materials.

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In comparison with pure NFC aerogels, nowadays, NFC-inorganic aerogels, a class of hybrid organic-inorganic composite aerogels (OICAs), processes remarkable features of multifunctional nature combining the organic NFC 3D framework and inorganic components. For example, with the growth of ferromagnetic cobalt ferrite nanoparticles on nanofibrils, the NFC-based magnetic aerogel can absorb and release water under compression for the hydrophilic and flexible nature of NFC.16 After combining with functional oxides like TiO2, SiO2, SnO2 etc., the advanced NFC-based OICAs have been applied as super capacitor,5 humidity sensor,17 photocatalysts,18 DSSC (dye-sensitized solar cells),18 super-absorbents,8 strong super-insulators.19 For these aerogels, NFC works as a novel framework due to their ultrafine nanostructures, rich surface chemistry and outstanding mechanical properties. These merits overcome the main drawback of the innovative functional metal oxide aerogels and therefore extend their applications. So the synthesis of NFC-based OICAs has attracted considerable and increasing attention. However, there is no any clear-cut proposal raised to explain the interactions between crystalline cellulose and inorganic NPs. This has greatly blurred the insight of design and syntheses of novel inorganic-cellulose materials.

In this work, in an effort to establish a viable binding mode between nanosized inorganic materials and NFC matrix, a new system was developed using 20~80 nm thick NFC aerogels as matrix for the non-agglomerated growth of 10~20 nm diameter silver

oxide

nanoparticles

(Ag2O

NPs),

thereby

forming

Ag2O

loaded

inorganic/organic composites (Ag2O@NFC). It was found that hydrogen bonds drive 4 ACS Paragon Plus Environment

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the assembly of Ag2O NPs on the nanofibers to form coherent interface. Specifically, the planar d-spacing of (001) of cellulose is exactly six time of that of (110) of Ag2O, which means there is a good atomic planar matching at the coherent interfaces. This ensures the Ag2O NPs are firmly attached on the cellulose nanofibers. Combining the merits of the porous NFC aerogel matrix and active Ag2O NPs, the Ag2O@NFC displays superior ability to capture iodine vapor and I- ions that are very toxic radioactive waste discharged from nuclear facilities as well as medical institutions.

Results and discussion Aqueous NFC dispersions were prepared from chemical purified bamboo cellulose under high-intensity ultrasound (step 1, Scheme 1). To determine optimum conditions for the formation of NFC, ultrasound treatment time and frequency were determined (for details see Figure S1 and associated discussion in SI). The ultrasound implosion of the cavity breaks the cellulose interfibrillar hydrogen bonding and van der Waal forces, and splits cellulose microfiber along the axial direction into NFC with diameter under 80 nm (step 2). After solvent exchange with tert-Butanol (t-BuOH), subsequent rapid freeze-drying led to highly porous NFC aerogel with high surface area (277 m2 g-1, see Figure S2) (step 3). The dried aerogel matrix is then immersed in an aqueous AgNO3/NH3•H2O solution at room temperature to deposit Ag(NH3)2+ on the matrix (step 4 and Eq. 1). Then the precipitated precursors converted into Ag2O NPs on immersion in aqueous NaOH solution at room temperature (step 5 and Eq. 2&3). The particle size and distribution can be controlled by adjusting concentration of starting



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AgNO3 and ammonia (with a fixed molar ratio of 1:2) (Table S1). At the same time, the color of NFC scaffold from white to brownish-black, and Ag2O nanocrystals were attached on NFC surfaces. The modified NFC composites brownish-grey aerogels (Ag2O@NFC) with 3D network was obtained by the second-step freeze-drying (step 6). AgNO3 + 2NH3•H2O ⇌ Ag(NH3)2+ + NO3- + 2H2O

(1)

Ag(NH3)2+ + NaOH ⇌ AgOH + 2NH3 + Na+ 2AgOH → Ag2O + H2O

(2)

(3)

The fabricated pure NFC is less than 80 nm thick and several micrometers long with smooth surface (Figure S1). After deposition of Ag2O NPs (10~20 nm), the nanofibers’ surface turns to very rough (Figure S2 and Figure S3). At the same time, with increasing the inorganic content, the composite scaffolds change from curly soft to straight hard (Figure S4). As shown in Figure S5, the size of Ag2O NPs increases from 10 to 16 and 21 nm, when the concentration of Ag(NH3)2OH raises from 5×10-3 M (Ag2O@NFC-005) to 5×10-2 M (Ag2O@NFC-010) and 1×10-2 M (Ag2O@NFC-050). The inorganic Ag2O species in the final product can be controlled to ~54, ~72, and ~92 wt%, respectively. The color of the final Ag2O modified NFC products also changes from light to dark. As depicted in the X-ray diffraction (XRD) patterns (Figure S5d and S6), the native cellulose Iβ and deposited Ag2O NPs (JCPDS no. 41-1104) are both observed for the Ag2O@NFC aerogels. The crystallite sizes of NPs determined from Scherrer equation range from 9 to 14 and 20 nm for Ag2O@NFC-005 to 6 ACS Paragon Plus Environment

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Ag2O@NFC-010 and Ag2O@NFC-050. This is in good agreement with the results obtained from TEM.

As mentioned above, it is hard to determine the interaction between crystalline cellulose and inorganic component, because the specific nucleation of inorganic species and subsequent condensation interaction with the hydroxyl groups on the nanofibres remain unclear. The FTIR was first used to disclose the possible combination between Ag2O NPs and NFC matrix. As shown in Figure S7 and Table S2, the wavenumber of the stretching band of the hydroxyl groups in Ag2O@NFC is located at 3,397 cm-1, which is lower than that of pure NFC (3,468 cm-1). The blue-shift indicates that Ag2O NPs were conjugated to the surface of NFC through the -OH group.20 It was also observed that the C-O bond stretching vibration (1,060 cm-1 and 1,037 cm-1) of NFC has a serious distortion after deposition of Ag2O NPs, which proves that a strong hydrogen bond has been formed between Ag2O and NFC. The 3D electron tomography was adopted to visualize the 3D morphological evolution of the Ag2O@NFC nanostructures. As depicted in Figure S8 and 3D Movie S1, the Ag2O NPs are decorated tightly on the surface rather than embedded into the inner part of NFC. How can hydrogen bond assemble the Ag2O NPs firmly onto the NFC matrix? Answer to this question is essential for understanding assembly of inorganic nanocrystals in NFC matrix, which is important for the fabrication of advanced materials. According to our previous study,21 bonding between two phases needs to minimize surface energy associated with unsaturated bonds to reduce overall energy,



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since such coherence is capable of decreasing Coulomb forces and of minimizing dangling bonds, and thus could create stable interfaces. In order to reveal the possible coherent interface between Ag2O and NFC, transmission electron microscopy (TEM) was used to investigate a single cellulose nanofiber loading a Ag2O NP. As shown in Figure 1a, the Ag2O NP portrays a typical co-axis five-fold twinning feature. In view of crystallography, nanocrystal with face-centred cubic (FCC) structure often exhibits such five-fold twinning phenomenon where each sub-grain boundary is {111} twinning plane, and the discrepancy angle between any two of planes {111} is 70.52°. The electron diffraction pattern (EDP) was collected from the selected area aperture containing cellulose nanofiber and Ag2O NPs. The diffraction rings could be indexed with lattice parameters of both Ag2O and NFC (see Figure 1b). Fast Fourier transformation (FFT) patterns were collected from the hollow square areas C, D and E in Figure 1a (see Figure S9 a, b, and c). They can be indexed as EDP viewed at zone axis of (110) of cellulose, [110] of Ag2O and [112] of Ag2O, respectively (see Figure S9 d, e, and f). Inverse FFT (IFFT) images are shown in Figure 1c and d to reveal the lattice fringes of both crystals. The orientation relationship (OR) between the two phases is summarized in Figure 1e as follows:

(002)s // (110)c

(110)s // (001)c

Where, the subscripts “s” and “c” denote Ag2O and cellulose respectively. It is also tested other areas of Ag2O and cellulose in terms of mutual orientation relationship and 8 ACS Paragon Plus Environment

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confirmed that the above mentioned orientation relationship is dominated although there is still some other orientation relationship which could be observed occasionally. By carefully checking the planar mis-matching between (002)s vs (110)c and (001)c vs (110)s, it was found that the mismatching is very small. This means the interfacial straining should be very small and there exists a good lattice matching between the two crystals (Figure 1f). The lattice matching makes the Ag2O NPs firmly attached on the NFC matrix, for instance, the studied nanocomposite is very stable under TEM service period (Figure 1g). The obtained Ag2O@NFC aerogels still exhibit high (Table S3) specific surface areas (153.0~256.5 m2g-1), large mesopore size distribution (15.1~25.2 nm), and large pore volume (0.38~0.52 cm3g-1). This 3D porous structure possesses three merits for efficient iodine capture. 1. The large mesoporous interconnected voids of 3D aerogel network allow high flux; 2. The exposed Ag2O NPs (capture centre) on the surface of the NFC are very accessible to I- ions or I2; 3. The Ag2O NPs are firmly fixed on the cellulose nanostructures via stable coherent interface, which makes them easy to be recovered from a solution or atmosphere. In this work, the Ag2O@NFC aerogels were used as sorbents to capture iodine vapor and I- ions (Eq. 4). Iodine capture/immobilization is of special interest because of the easy emission of radioactive iodine with low boiling point (bp.), and particularly the long-lived 129I (half-time life of 1.57×107 year) that is generated during the fission process.22 Ag2O@NFC + I2→2AgI@NFC+O2

(4)



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As shown in Figure 2a, when Ag2O@NFC-050 was exposed to iodine vapor, its color dramatically changed from brownish-black to light yellow due to the formation of AgI@NFC-050. The new-formed hexagonal β-AgI NPs (pdf 09-0374, ICDD) have been detected from its XRD pattern (Figure S10). When the exposure time extended to 5 and 15 min respectively, the samples were investigated by using thermogravimetric (TG) and derivative thermogravimetric (DTG) analysis. As shown in Figure 2b and 2c, besides the mass loss of NFC matrix after 387 °C,23 both samples give significant mass loss at 346 °C, which is corresponding to the decomposition of AgI NPs. More mass loss is observed from the specimen after 15 min I2 vapor treatment than that of the specimen treated 5 min, indicating more AgI formed during longer I2 vapor adsorption. In addition, a broad mass loss (~20%) from 170 to 230 °C appears in the curve of the AgI@NFC specimen after 15 min I2 vapor treatment, which is ascribed to physically adsorbed I2 vapor in the NFC matrix. The evolution from Ag2O@NFC to AgI@NFC was also detected by using X-ray Photoelectron Spectroscopy (XPS) measurement. Before I2 adsorption, the Ag 3d5/2 core level is located at 368.2 eV, a characteristic of Ag2O crystals.24 After I2 vapor capture, the Ag 3d5/2 and I 3d5/2 core levels are found to be located at binding energies of 368.6 eV and 619.4 eV, respectively, which can be indexed to AgI species (Figure 2d).25 In the circumstance of the core excitation of Ag 3d, the electronic state of different silver species represent minor difference in binding energy (BE). Hence, the X-ray Auger Electron Spectroscopy (XAES) measurements were employed to determine the electronic state of silver in the objective aerogel. In the case of Auger 10 ACS Paragon Plus Environment

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spectra, the values of the X-ray induced Ag M4N45N45 and M5N45N45 Auger emissions and the Auger spectra shape (Figure 2e) also verified that AgI formed after I2 vapor adsorption. Evidence for the evolution from Ag2O to AgI is demonstrated in by the Ag (M5N45N45) kinetic energy of Ag2O@NFC-050 before and after iodine capture located at 351 eV and 350.2 eV, respectively.26,27 Furthermore, as shown in Figure 2f, the I 3d5/2 core level of physically adsorbed I2 (619.9 eV) is observed from the spectrum of exposure AgI@NFC-050 after 15 min I2 capture, which is in good agreement with TG-DTG results. The effective I2 capture and storage by Ag2O@NFC aerogels are facilitated by not only the intense dispersion of small size Ag2O nanocrystals but also the porous structure within the aerogels. The large macroporous interconnected voids of 3D aerogel network consent high flux iodine vapors to diffuse promptly and access the silver oxide phase. Besides, the hydrogen bonding with surface -OH of NFC skeleton may also beneficial for I2 absorption. Compared with conventional micro- or mesoporous adsorbents, facilitated diffusion of contaminated water containing I- ions is more easily achieved by the macroporous Ag2O@NFC aerogel due to its effective accessibility. As shown in Figure 3a, 10 mg Ag2O@NFC sorbent was used as sorption beds to catch I- ions from 50 mL NaI solutions with concentrations from 125 to 1000 ppm. The flow rate was kept at 5.0 mL/min. Apparently, at iodide ion concentrations below 500 ppm, over 90% of I- ions could be took away by the Ag2O@NFC-005, Ag2O@NFC-010, or Ag2O@NFC-050 adsorption bed (Figure 3b). The saturated I- anions adsorption capacity by Ag2O@NFC-050 is as high as 5.2 mmol g-1, which is higher than that of 11 ACS Paragon Plus Environment


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Ag2O@NFC-010 (4.7 mmol g-1) and Ag2O@NFC-005 (3.0 mmol g-1) due to the highest Ag2O loading. The uptake values are considerably higher than those of previously reported metallic compound sorbents (>1.0 mmol g-1).28

The additional valuable characteristic of aerogel adsorbents is their ultra-light weight and flexibility from the strong29 and highly entangled nanofibrils. As displayed in Figure 3c, the Ag2O@NFC aerogel is able to float in aqueous solution, even after the entire adsorption process with vigorous vibration. This makes the composite aerogel can be easily separated and collected from liquid-phase pollutants for ultimate safe disposal, which provides a cost effective solution for practical application. More importantly, the used aerogel can be compressed into a compact sheet to squeeze out most of the adsorbed water due to high flexibility of the NFC aerogel matrix. As shown in Figure 3d, a large amount of water, for example, 68.2 mg of the Ag2O@NFC aerogel can hold 12.3 g of an aqueous solution, was adsorbed by the Ag2O@NFC aerogel because of the high porosity and large surface area. However, it can be clearly seen from Figure 3e that more than 91.7% of the adsorbed water can be released after compression, and the Ag2O@NFC aerogel finally deforms into a 1.9 cm3 disk (Movie S2). The property makes it more feasible for safe disposal of radioactive waste.

Conclusions In summary, the NFC aerogel that was fabricated from bamboo fibers was employed as a versatile 3D scaffold to grow Ag2O NPs. It was observed that hydrogen bonds firmly bind Ag2O NPs on the nanofibers. The Ag2O@NFC aerogels display 12 ACS Paragon Plus Environment

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superior adsorption performance for iodine uptake due to the highly porous structure of the 3D aerogel. More importantly, it is disclosed the interaction between cellulose Iβ nanofiber and Ag2O NPs. In detail, it is figured out that the planar d-spacing of (001) of cellulose is exactly six time of that of (110) of Ag2O. The small atomic planar mis-matching makes them grow crosswise along a coherent interface. Thus, it is established a viable binding mode between many types of inorganic NPs and organic NFC. This mode can be extended to tremendous design and nanofabrication of cellulose-based functional nanocomposites.

Supporting Information

Supporting Figures S1−S13, Tables S1−S3, and Movie S1 and S2. Diameter distributions of bamboo cellulose with different ultrasonication time (Figure S1); nitrogen adsorption and desorption isotherms for the NFC aerogel (Figure S2); SEM images of the NFC aerogel and Ag2O@NFC aerogel (Figure S3); SEM images of Ag2O@NFC aerogels with different Ag2O contents (FigureS4); TEM images, photos and XRD of Ag2O@NFC aerogels with different Ag2O contents (Figure S5); the XRD pattern of the pure NFC aerogel (Figure S6); FT-IR spectrum of pure NFC aerogels and Ag2O@NFC aerogels (Figure S7); the 3D representation of the Ag2O@NFC-100 obtained by electron tomography (Figure S8); FFT images of the TEM of Ag2O@NFC and corresponding indexed results (Figure S9); the XRD of the AgI@NFC after capturing iodine vapor (Figure S10); XRD patterns for the AgI@NFC aerogels after 13 ACS Paragon Plus Environment


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adsorption of I- ions (Figure S11); SEM images of AgI@NFC aerogels (Figure S12); The schematic illustration of the Ag2O formation on cellulose Iβ (10∑1) planes (Figure S13); Characteristics of the Ag2O-based nanocomposites (Table S1); FTIR assignments of Ag2O@NFC (Table S2); BET surface area and BJH pore diameter of the aerogel samples (Table S3); the electron tomography 3D representation of the Ag2O@NFC-100 (Movie S1); and the Ag2O@NFC aerogel under compressive strains (Movie S2).

Acknowledgements This work was financially supported by Special Fund for Forest Scientific Research in the Public Welfare (grant no. 201504603), the Fundamental Research Funds for the central Non-profit Research Institution of CAF (grant no. CAFYBB2016QB012), and the National Natural Science Foundation of China (grant no. 31500468 and 21207073).

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(6) Sehaqui, H.; Salajková, M.; Zhou, Q.; Berglund, L. A., Mechanical Performance Tailoring of Tough Ultra-high Porosity Foams Prepared from Cellulose I Nanofiber Suspensions. Soft Matter 2010, 6 (8), 1824-1832. (7) Sehaqui, H.; Zhou, Q.; Berglund, L. A., High-porosity Aerogels of High Specific Surface Area Prepared from Nanofibrillated Cellulose (NFC). Compos. Sci. Technol. 2011, 71 (13), 1593-1599. (8) M. K.; Silvennoinen, R. J.; Houbenov, N.; Nykänen, A.; Ruokolainen, J.; Sainio, J.; Pore, V.; Kemell, M.; Ankerfors, M.; Lindström, T., Photoswitchable Superabsorbency Based on Nanocellulose Aerogels. Adv. Funct. Mater. 2011, 21 (3), 510–517. (9) Sehaqui, H.; Zhou, Q.; Ikkala, O.; Berglund, L. A., Strong and Tough Cellulose Nanopaper with High Specific Surface Area and Porosity. Biomacromolecules 2011, 12 (10), 3638-3644. (10) Heath, L.; Thielemans, W., Cellulose Nanowhisker Aerogels. Green Chem. 2010, 12 (8), 1448-1453. (11) Saito, T.; Uematsu, T.; Kimura, S.; Enomae, T.; Isogai, A., Self-aligned Integration of Native Cellulose Nanofibrils Towards Producing Diverse Bulk Materials. Soft Matter 2011, 7 (19), 8804-8809. (12) Klemm, D.; Heublein, B.; Fink, H. P.; Bohn, A., Cellulose: Fascinating Biopolymer and Sustainable Raw Material. Angew. Chem.Int. Edit. 2005, 44 (22), 3358-93. (13) Klemm, D.; Heublein, B.; Habil., H. P. F.; Bohn, A., Cellulose: Faszinierendes Biopolymer und Nachhaltiger Rohstoff. Angew. Chem. 2005, 117 (22), 3422-3458. (14) Wu, Z. Y.; Li, C.; Liang, H. W.; Chen, J. F.; Yu, S. H., Ultralight, Flexible, and Fire‐Resistant Carbon Nanofiber Aerogels from Bacterial Cellulose. Angew. Chem. Int. Edit. 2013, 52 (10), 2925-2929. (15) Habibi Y. Key Advances in the Chemical Modification of Nanocelluloses[J]. Chem. Soc. Rev. 2014, 43(5): 1519-1542. (16) Olsson, R. T.; Azizi Samir, M. A.; Salazaralvarez, G.; Belova, L.; Ström, V.; Berglund, L. A.; Ikkala, O.; Nogués, J.; Gedde, U. W., Making Flexible Magnetic Aerogels and Stiff magnetic Nanopaper Using Cellulose Nanofibrils as Templates. Nat. Nanotechnol. 2010, 5 (8), 584-8. (17) Ivanova, A.; Fravventura, M. C.; Fattakhovarohlfing, D.; Rathousky, J.; Movsesyan, L.; Ganter, P.; Savenije, T. J.; Bein, T., Nanocellulose-templated Porous Titania Scaffolds Incorporating Pre-Synthesized Titania Nanocrystals. Chem.of Mater. 2015, 27 (18). (18) X. W.; X. L.; Liu, B.; Chen, D.; Tong, Y.; Shen, G., Flexible Energy-storage Devices: Design Consideration and Recent Progress. Adv. Mater. 2014, 26 (28), 4763-4782. (19) Zhao, S.; Zhang, Z.; Sèbe, G.; Wu, R.; Virtudazo, R. V. R.; Tingaut, P.; Koebel, M. M., Multiscale Assembly of Superinsulating Silica Aerogels Within Silylated Nanocellulosic Scaffolds: Improved Mechanical Properties Promoted by Nanoscale Chemical Compatibilization. Adv. Funct. Mater. 2015, 25 (15), 2326–2334. 15 ACS Paragon Plus Environment


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Captions of Schemes and Figures Scheme 1. Procedure for the synthesis of Ag2O@NFC aerogel. 1) Purified bamboo cellulose under high-intensity ultrasonication to prepare 2) the NFC. 3) After t-BuOH assistant freeze-drying, the NFC aerogel is processed, and 4) first immersed into AgNO3/NH3 solution, 5) then transferred into dilute NaOH solution to form Ag2O nanoparticles. 6) The Ag2O@NFC aerogel is obtained after drying Figure 1. TEM investigation of Ag2O@NFC. a) HRTEM image and b) electron diffraction rings of Ag2O@NFC. The IFFT images give lattice fringes of c) cellulose (110) and (002), and d) Ag2O (111) and (002). e) The composited electron diffraction patterns of cellulose and Ag2O. f) Scheme of interface structure (001)s//(110)c. g) The high density distribution of Ag2O on NFC surface. c)~e) corresponding to the selected areas marked in Panel A with the same label. Figure 2. a) Ag2O@NFC-050 before and after I2 vapor capture. b) The TG analysis and c) the DTG analysis of Ag2O@NFC-050 after 5 min and 15 min iodine capture. The XPS of d) Ag 3d core level spectra and e) Ag Auger spectra of Ag2O@NFC-050 and AgI@NFC-050. f) The XPS I 3d core level spectra of AgI@NFC-050 with 15 min iodine capture. Figure 3. a) The apparatus for the high flux I- capture, and b) the removal different Iconcentrations by Ag2O@NFC-005, -010, and -050 adsorbents. c) A Ag2O@NFC aerogel (diameter: 33.4 mm, height: 20.9 mm) float on the aqueous solution, d) and swell to 53 mm diameter and 33.4 mm height to absorb ~ 73.6 g water. e) the sample without the surrounding solution (diameter: 33.1 mm, height: 16.5 mm). f) 11.3 g water (11.3 g) is released by compression, and g) the aerogel turn to a compressed disk (diameter: 34.9 mm, height: 2 mm).



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Scheme 1. Procedure for the synthesis of Ag2O@NFC aerogel. 1) Purified bamboo cellulose under high-intensity ultrasonication to prepare 2) the NFC. 3) After t-BuOH assistant freeze-drying, the NFC aerogel is processed, and 4) first immersed into AgNO3/NH3 solution, 5) then transferred into dilute NaOH solution to form Ag2O nanoparticles. 6) The Ag2O@NFC aerogel is obtained after drying


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Figure 1. TEM investigation of Ag2O@NFC. a) HRTEM image and b) electron diffraction rings of Ag2O@NFC. The IFFT images give lattice fringes of c) cellulose (110) and (002), and d) Ag2O (111) and (002). e) The composited electron diffraction patterns of cellulose and Ag2O. f) Scheme of interface structure (001)s//(110)c. g) The high density distribution of Ag2O on NFC surface. c)~e) corresponding to the selected areas marked in Panel A with the same label.



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Figure 2. a) Ag2O@NFC-050 before and after I2 vapor capture. b) The TG analysis and c) the DTG analysis of Ag2O@NFC-050 after 5 min and 15 min iodine capture. The XPS of d) Ag 3d core level spectra and e) Ag Auger spectra of Ag2O@NFC-050 and AgI@NFC-050. f) The XPS I 3d core level spectra of AgI@NFC-050 with 15 min iodine capture.


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Figure 3. a) The apparatus for the high flux I− capture, and b) the removal different I− concentrations by Ag2O@NFC-005, -010, and -050 adsorbents. c) A Ag2O@NFC aerogel (diameter: 33.4 mm, height: 20.9 mm) float on the aqueous solution, d) and swell to 53 mm diameter and 33.4 mm height to absorb ~ 73.6 g water. e) the sample without the surrounding solution (diameter: 33.1 mm, height: 16.5 mm). f) 11.3 g water (11.3 g) is released by compression, and g) the aerogel turn to a compressed disk (diameter: 34.9 mm, height: 2 mm).



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TOC

The Ag2O nanocrystal anchored to the NFC nanostructure by coherent interfaces and the subsequent deposition of iodine.


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Scheme 1. Procedure for the synthesis of Ag2O@NFC aerogel. 1) Purified bamboo cellulose under highintensity ultrasonication to prepare 2) the NFC. 3) After t-BuOH assistant freeze-drying, the NFC aerogel is processed, and 4) first immersed into AgNO3/NH3 solution, 5) then transferred into dilute NaOH solution to form Ag2O nanoparticles. 6) The Ag2O@NFC aerogel is obtained after drying 109x71mm (300 x 300 DPI)

ACS Paragon Plus Environment


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Figure 1. Procedure for the synthesis of Ag2O@NFC aerogel. 1) Purified bamboo cellulose under highintensity ultrasonication to prepare 2) the NFC. 3) After t-BuOH assistant freeze-drying, the NFC aerogel is processed, and 4) first immersed into AgNO3/NH3 solution, 5) then transfered into dilute NaOH solution to form Ag2O nanoparticles. 6) The Ag2O@NFC aerogel is obtained after drying 106x142mm (300 x 300 DPI)


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Figure 2. a) Ag2O@NFC-050 before and after I2 vapor capture. b) The TG analysis and c) the DTG analysis of Ag2O@NFC-050 after 5 min and 15 min iodine capture. The XPS of d) Ag 3d core level spectra and e) Ag Auger spectra of Ag2O@NFC-050 and AgI@NFC-050. f) The XPS I 3d core level spectra of AgI@NFC-050 with 15 min iodine capture. 98x57mm (300 x 300 DPI)



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Figure 3. a) The apparatus for the high flux I- capture, and b) the removal different I- concentrations by Ag2O@NFC-005, -010, and -050 adsorbents. c) A Ag2O@NFC aerogel (diameter: 33.4 mm, height: 20.9 mm) float on the aqueous solution, d) and swell to 53 mm diameter and 33.4 mm height to absorb ~ 73.6 g water. e) the sample without the surrounding solution (diameter: 33.1 mm, height: 16.5 mm). f) 11.3 g water (11.3 g) is released by compression, and g) the aerogel turn to a compressed disk (diameter: 34.9 mm, height: 2 mm). 88x49mm (300 x 300 DPI)


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The Ag2O nanocrystal anchored to the NFC nanostructure by coherent interfaces and the subsequent deposition of iodine. 22x6mm (300 x 300 DPI)


Coherent-Interface-Assembled Ag2O-Anchored Nanofibrillated

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