One-Step Synthesis of Carbon-Hybridized ZnO on Polymeric Foams

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One-step synthesis of carbon-hybridized ZnO on polymeric foams by atomic layer deposition for efficient absorption of oils from water Sen Xiong, Yang Yang, Zhaoxiang Zhong, and Yong Wang Ind. Eng. Chem. Res., Just Accepted Manuscript • DOI: 10.1021/acs.iecr.7b03939 • Publication Date (Web): 08 Jan 2018 Downloaded from http://pubs.acs.org on January 8, 2018

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Industrial & Engineering Chemistry Research

One-step synthesis of carbon-hybridized ZnO on polymeric foams by atomic layer deposition for efficient absorption of oils from water Sen Xiong, Yang Yang, Zhaoxiang Zhong, Yong Wang* State Key Laboratory of Materials-Oriented Chemical Engineering, Jiangsu National Synergetic Innovation Center for Advanced Materials, College of Chemical Engineering, Nanjing Tech University, Nanjing 210009 (P. R. China)

* Corresponding author. Tel.: +86-25-8317 2247; Fax: +86-25-8317 2292. E-mail: [email protected]

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Abstract: Reusable absorbents with high absorption capacity, good selectivity, and low cost are highly demanded for efficient removal of oil spills and organic leakages from water. We discover that ZnO produced by atomic layer deposition (ALD) is hybridized with carbon moieties, and consequently exhibits an appreciable hydrophobicity. By taking this advantage, we develop a “dry” process to produce high-performance oil absorbents. Originally amphiphilic polymeric foams are directly turned into strongly hydrophobic oil absorbents simply by ALD of ZnO and exhibit excellent absorption capacity, selectivity and reusability. Such absorption capacities and reusability are better than most foam-based oil absorbents. Surprisingly, we find that ALD-deposited ZnO can reverse the wettability of polymeric foams depending on the foam porosities. This ALD-enabled surface functionalization is expected to find important applications in the synthesis of many other interfacial materials.

KEYWORDS: Sustainable chemistry, Oil spills, Absorption, Zinc oxide, Atomic layer deposition

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Introduction Oil spills and organic leakages in water bodies frequently occur worldwide and efficient cleanup is required to avoid catastrophic consequences. Among different cleanup and remediation methods,1-6 absorption using porous media as oil absorbents is superior for the advantages such as environmentally friendly, easy-to-operate, energy-efficient, and the possibility of reusability of the absorbents and recovery of precious oil.7-15 A good oil absorbent needs to be 1) highly porous to accommodate oil spills as much as possible, 2) adequately hydrophobic to exclusively absorb oil from water, 3) strongly elastic to be regenerated and reused for multiple times. Also importantly, from the aspect of real applications, it is also highly desired that the absorbent can be produced in large scale through convenient processes at low costs. Natural absorbents such as raw cotton,16 kapok fibers17 are inexpensive and can be available at large quantities, however, they exhibit either limited absorption capacity or poor selectivity, and are incapable for efficient remediation. Recent studies on oil absorbents are focused on synthetic materials with a strong hydrophobicity.18-21 Notably, graphene (and its derivatives) and carbon nanotubes (CNTs) have recently emerged as interesting building blocks or coating materials for the fabrication of synthetic absorbents.8,11,22-25

These

nanocarbon-based

absorbents

could

absorb

oils >100 times of their own weights because of their high porosity and 3



inherent hydrophobicity. However, the extremely high costs of these nanocarbon materials significantly impair their scale-up and practical applications. Alternatively, significant interests are turned to absorbents using polymeric foams as substrates. In this regard, cheaply sourced, highly porous, and elastic polymeric foams are modified to obtain an adequate hydrophobicity, thus having a water-repelling and oil-absorptive function. A great number of methods have been explored to realize the hydrophobic modification to the foam substrates.22,26-30 However, these methods are generally tedious and usually require a surface activation or pretreatment prior to the grafting of the hydrophobic modifiers.20,31-33 Even worse, they are exclusively based on wet processes which require using copious organic solvents. The wet processes increase the complexity and cost on one hand, and pose potential environmental and safety issues on the other. Therefore, it is highly desired for a solvent-free and short process to modify polymeric foams for the production of high-performance oil absorbents. In this work, we propose a one-step, “dry” process to produce exceptional oil absorbents based on atomic layer deposition (ALD) of ZnO on polymeric foams. ALD is a solvent-free thin-film coating technique and uses vaporized precursors in a sequential, self-limiting reaction sequence to grow ultrathin metal oxide layers on substrates.34-35 We discover that ZnO produced by ALD is simultaneously hybridized by organic moieties and consequently exhibits an appreciable hydrophobicity. Simply by ALD-depositing ZnO on highly porous 4


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polymeric foams, the original nonselective foams are transformed to highly selective oil absorbents with excellent absorption capacity and reusability better than most foam-based absorbents. Moreover, by ALD deposition of ZnO, the wettability of polymeric foams can be reversed between hydrophobicity and hydrophilicity depending on their porosities. Except for oil absorbents fabrication, this solvent-free, “dry” process is expected to find interesting applications in the synthesis of other interfacial materials.

MATERIALS AND METHODS Materials The melamine foams (consisting of formaldehyde-melamine-sodium bisulfite copolymer), low-resilience polyurethane (LR PU) foams, and regular PU foams were purchased from local suppliers. Diethyl zinc (DEZ, 99.99%) was obtained from Nanjing University. Deionized water (conductivity: 8-20 µs/cm) was purchased from Wahaha Co. DEZ and deionized water were used as precursors for ZnO ALD processes. Acid orange 7 (AO7), a water-soluble dye, was purchased from Aladdin Chemicals. All oils and organic solvents including anhydrous ethanol, carbon tetrachloride (CCl4), lubricant oil, diesel oil, liquid paraffin, and vegetable oil were purchased from local suppliers and used as received.

Atomic Layer Deposition of ZnO on Polymeric Foams 5



The ZnO deposition was carried out in a home-made ALD reactor.36 The pristine foams were cut into blocks with the dimension of ~ 7 3 1 cm3 for ZnO deposition. Before ALD process, the foam blocks were washed with ethanol and dried in air. The ALD reaction chamber was pre-heated to 130°C, then the blocks were put into the chamber as substrates and kept at this temperature for 1 h under vacuum (~ 133 Pa) before deposition. Nitrogen (99.9%) was used as purge gas and ultrahigh purity nitrogen (99.999%) was used as carrier gas to pulse the precursors into the reaction chamber. DEZ and deionized water were alternately pulsed into the chamber to achieve self-limiting reaction. The pulse/exposure/purge time for each precursor was 0.03 s/10 s/60 s, respectively. Different deposition cycles up to 500 were adopted during the ALD process. To investigate the relationship between the porosity of the foam and the surface wettability after deposition, the melamine foams were pressed by a hot presser (R3202, Wuhan Qi-En) under 1 MPa for 3 h and 6 h at room temperature, and under 20 MPa for 3 h at 200°C, respectively. The thickness changes after compression were defined as press ratio because the changes in length and width of the foam after pressing were very slight and can be neglected. The pressed foams with different press ratios were also used as substrates for ALD process.

Characterizations 6


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Surface morphologies of the pristine and deposited foams were characterized by a field emission scanning electron microscope (S-4800, Hitachi) operated at 5 kV. A thin platinum layer was sputtered onto the sample surface to enhance conductivity. Fourier transformation infrared (FT-IR) spectra were obtained from a Nicolet 8700 FT-IR spectrometer in the attenuated total reflection mode. X-ray photoelectron spectroscopy (XPS) was performed on a Thermo ESCALAB 250XI X-ray photoelectron spectrometer applying a monochromatic Al Kα (hν = 1486.6eV). Atomic force microscopy (AFM) was carried out on a Park System XE-100 atomic force microscope. Water contact angles (WCAs) were measured at ambient temperature by a contact angle goniometer (Dropmeter A-100, Maist) to characterize the surface wettability of different specimens. Each specimen was measured for at least 3 times at different positions and the average values were recorded. Wide-angle X-ray diffraction (XRD) was performed on an X-ray diffractometer with a Cu Kα X-ray source (MiniFlex 600, Rigaku). Thermogravimetric (TG) analyses were performed within the range of 20°C to 800°C on a thermal analyzer (TA TG449F, Netzsch) in the atmosphere of O2 with a heating rate of 10 °C/min.

Absorption Capacity and Regeneration Tests Absorption capacities of the deposited foams towards different oils and organic solvents were tested as below. Before absorption, the original weight of the deposited foam was measured and recorded as m0 (g). Then the foam 7



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was put into a 1:1 (v:v) mixture of oils and water (total volume was 80 mL) to absorb oil or solvent until saturated, then the foam was hung in the air to scour the excess oil on the surface. Finally, the weight of the oil-absorbing foam was measured and recorded as mn (g), which meant the weight of the oil-absorbing foam at the n times recycling. The absorption capacity Qn (g/g) was defined by Eq.1: Qn =

mn - m0 m0

(1)

After absorption, the oil-absorbing foam was regenerated by squeezing the absorbed liquid out physically. Until no more liquid could be extracted out, the foam was used to absorb oil or solvent again. The weight change of the foam at each cycle was recorded and the absorption capacity was calculated by Eq.1. The absorption-regeneration process was repeated for 20 times to test the reusability of the prepared oil absorbent.

Adhesion test To test the adhesion between the ultrathin ZnO layer and the foam substrates, the deposited melamine foams were immersed into ethanol solution and challenged with ultrasonic treatment at the power of 180 W for 20 min. After ultrasonic treatment, the foam was removed from the ethanol and dried in air, then the hydrophobicity of the foam was tested.

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RESULTS AND DISCUSSION To exclude the effect of surface roughness on the wettability of ALD-deposited ZnO films, we first deposited ZnO on the smooth surfaces of silicon substrates. After 100 or 500 ALD cycles, the produced ZnO film exhibited a smooth surface with a roughness less than 0.7 nm, as revealed by SEM and AFM (Figure S2). Surprisingly, the WCA of the film was determined to be ~86° (Figure 1a), which falls in the weakly hydrophobic region. XRD characterization shows that the produced ZnO is moderately crystallized in the wurtzite phase (PDF #36-1451) (Figure 1b). Smooth wurtzite ZnO films are typically very hydrophilic with a WCA usually less than 20°,37-38 therefore, we anticipate that there should be some hydrophobic components incorporated into the deposited ZnO films. Indeed, FT-IR spectroscopy indicates that there are strong peaks of –CH2 (1457 cm-1) and C–O (1559 cm-1) in the spectrum of the deposited ZnO film (Figure 1c). The first speculation is that the carbon-containing groups are originated from contaminates absorbed on the ZnO film when exposed to air as described by Parsons.39 We etched the ZnO film with oxygen plasma for 10 min, however, we did not observe any noticeable change in WCA (Figure S1) and the film thickness. Therefore, we conclude that these carbon moieties in the ZnO film are not organic contaminants absorbed on the film surface as surface organic contaminants will be easily removed by plasma etching. During the ALD process, the ethyl groups (came from the DEZ precursor) or the generated ethane may 9



participate in the reaction to form chemical bonds.40-41 We further tried to remove the organic components from the ZnO films by calcination in air at 600°C. The calcined film exhibited a significantly reduced WCA of ~16° (Figure 1a), implying a moderate surface hydrophilicity. However, the XRD characterization reveals the emergence of crystalline phase of zinc carbide (ZnC) in the calcined film although the wurtzite phase ZnO remained.42 Therefore, we conclude that the organic components are hybridized in the ZnO film and ZnC is formed through the reaction between the organic components and ZnO in the process of calcination in air. XPS confirms the presence of carbon in the ZnO film before and after calcination (Figure 1d). It cannot be excluded that a portion of the organic components in the deposited ZnO film has been degraded by calcination at high temperature.

Figure 1. ZnO films ALD-deposited on the surface of a silicon substrate before and after calcination. (a) Photographs of a water droplet staying on the film captured during WCA tests; (b) XRD patterns; (c) FT-IR spectra; (d) XPS 10


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curves. In each panel, the lower and upper figures or curves correspond to the sample before and after calcination, respectively.

We then explore the use of the ALD-enabled hydrophobicity to prepare oil absorbents using highly porous melamine foams as the substrates. As shown in Figure 2a, the pristine foam exhibits a porous structure composed of 3D interconnected struts. This open porous structure allows the foam to accommodate both liquid and air with high capacity. No obvious changes could be observed after 30 cycles deposition (Figure 2b), and the surface of the melamine foam skeleton remained smooth. When the deposition cycles increased to 60, many grains appeared on the foam surface and these grains were randomly distributed on the foam skeletons (Figure S3). As shown in Figure 2c, after 150 cycles deposition, the deposited ZnO formed an intact layer on the foam skeletons. The fractures on the foam skeleton were caused by the strain generated in the sample preparation process, which also confirmed an intact layer on the foam skeletons.

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Figure 2. SEM images of the (a) pristine foam and the foam deposited with ZnO for (b) 30 and (c) 150 cycles. (d) WCAs of melamine foams with various deposition cycles.

The pristine melamine foams have no absorption selectivity to water and oil, both water and oil droplets were immediately absorbed by the pristine foam (Figure S4a). After 30 cycles of ZnO deposition, the WCAs varied a lot at different positions on the foam (Figure S4b). As shown in SEM images, the ZnO layer did not completely grow at the early ALD stage, thus producing unstable WCAs. When the deposition exceeded 60 cycles, the WCA was stabilized around 135° (Figure 2d). Moreover, the water droplet could seat on the cross section of the 100-cycle-deposited foam as spherical shape (Figure 12


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S4c), which further confirmed the uniformity of the ALD-based hydrophobic modification. According to this observation, foams with 100 cycles of ZnO deposition were chosen for further investigations.

Figure 3. (a) XRD patterns of the pristine foam and ZnO-deposited melamine foams with different ALD cycles; (b) TG curves of the pristine foam and the 100-cycle-deposited foam.

We investigated the deposited foams with XRD and TG analysis. As shown in Figure 3a, both the pristine and slightly deposited foams exhibited no detectable characteristic XRD peaks between 30-90°. With rising cycle numbers, the characteristic peaks with strengthening intensity of the wurtzite phase of ZnO appeared. TG analysis was employed to investigate the mass of ZnO deposited on the melamine foam. As shown in Figure 3b, the pristine foam was totally decomposed at 710°C, while the 100-cycle-deposited foam remained a 4.6% residual mass. Both XRD and TG characterizations demonstrate that ZnO had been successfully deposited on the foam, while only very limited amount of ZnO was deposited as ultrathin layers. Therefore, 13



the high porosity of the foams will be reserved to the largest extent after ZnO deposition as a consequence of the ultrathin nature of the deposited ZnO. The wettability of a solid surface was determined by two factors: surface chemical compositions and topological structures.43 Therefore, it is expected that the porosity of foams, which significantly influences the surface topology of the foams, would play a role in determining their wettability after ZnO deposition. We pressed pristine melamine foams to decrease their porosities. No wettability changes occurred after pressing with moderate press ratios of 21% and 34.5%. After 100 cycles of ZnO deposition, the pressed foams exhibited strong hydrophobicity similar to that of the pristine one subjected to ZnO deposition for 100 cycles. As shown in Figures 4a-b, the water droplet could sit on the foam surface and maintained a near-spherical shape. Although the porosity of the foams was reduced after pressing, it is still large enough to support the water droplet after ZnO deposition. We further pressed the foam at elevated temperature to significantly reduce the porosity to < 2% (Figure S5a), and the distance between the foam skeletons was also decreased sharply (Figure S5b-c). This highly pressed foam maintained its amphiphilic surface nature as both water and oil can easily wet it (Figure S6). After ZnO deposition, the highly pressed foam exhibited greatly different wettability than the moderately pressed foams. As shown in Figure 4c, water droplets readily penetrated into the highly pressed foam after ZnO deposition, implying a relatively hydrophilic surface. The SEM image shows that the pores in this 14


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highly pressed foam was significantly diminished (Figure 4d). Therefore, we understand that the high porosity of the foam is essential to realize a strong hydrophobicity.

Figure 4. Photographs of water droplets on the (a) 21%, (b) 34.5%, and (c) nearly 99% pressed melamine foams after 100 cycles of ZnO deposition. The water was dyed yellow for easy visualization; (d) The SEM image of (c). The schematic of the water wettability of the (e) pristine and (f) ZnO-coated foams.

According to the Cassie equation, the apparent contact angle (θ*) for a composite surface was determined by the solid fraction (fs), air fraction (fa) (the sum of fs and fa is 1), and the intrinsic contact angle (θ).44 The Cassie equation was given in Eq. 2: cosθ*=fscosθ-fa

(2)

where the θ* and θ are 135° and 86°, respectively. The fs calculated by Eq.1 was 27%, which implies that the water droplet on the deposited foam surface was mainly supported by air. In our present case, the open porous structure of 15



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the melamine foam provides large volume to accommodate air thus forming “air cushions” under the droplet.45 The “air cushions” act as the support layer and work against the capillary force which would suck the droplet into the foam. Considering the water-air interface in the pore, there are two forces controlling the penetration of water into the pore: the capillary force (Fc) and the gravity force. The capillary force is related to the Young’s CA and is defined as Eq.3: Fc = πγdcosθ

(3)

where γ and d are the surface tension and pore diameter, respectively. Compared with the capillary force, the gravity force is relatively small and can be neglected. The penetration of water into the pore is resisted by the “air cushions” trapped in the foam pores, and the resistance force (Fr) can be expressed as Eq.4:46 Fr = P0aπd2/4(L-a)

(4)

where P0, a, and L are the atmospheric pressure, water displacement into the pore, and pore depth, respectively. The capillary force is balanced by the air resistance, and the displacement of water into the pore can be termed as Eq.5:46 a = 4Lγcosθ/(P0d+4γcosθ)

(5)

After ZnO deposition θ is increased from nearly zero for the pristine foam to 86°. Due to the small value of cosθ (0.07), the capillary force in the deposited 16


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foam is much weaker than that in the pristine foam. Thus the a value (calculated from Eq.5) of the deposited foams would be dozens of times smaller than that of the pristine foams, the water droplet hardly permeates into the deposited foams and a macroscopically hydrophobic surface achieved. The schematics of wettability on the pristine and deposited foam are shown in Figures 4e-f.

Figure 5. The SEM images of (a) the LR PU foam and (b) the regular PU foam after 100 cycles of ZnO deposition. Insert in (b) is the photograph of a water droplet staying on the regular PU foam taken during the WCA test.

To further confirm the correlation between foam porosity and the wettability, we deposited ZnO on two other different polymeric foams, namely hydrophobic LR PU foams and hydrophilic regular PU foams. Interestingly, after ZnO deposition the originally hydrophobic LR PU foam became hydrophilic whereas the hydrophilic regular PU foam turned into hydrophobic. With ZnO deposition the original surfaces of the two foams were covered by ZnO and their wettabilities were then determined by the porous structures of specific foams. The LR PU foams (Figure 5a) composed of wide struts exhibit much lower 17



porosity than regular PU foams (Figure 5b) and melamine foams we used above. As a result of the relatively high surface energy of deposited ZnO and low porosity, the LR PU foams were shifted from its initial hydrophobic to hydrophilic after ZnO deposition. In contrast, deposition of ZnO on regular PU foam led to a transition from hydrophilic to hydrophobic. The deposited regular PU foam gives a WCA of ~137° (insert in Figure 5b), comparable to that of ZnO-deposited melamine foams. These control experiments imply that ALD deposition of ZnO, which has a moderate surface energy, is a generic method to render hydrophobicity to initially hydrophilic porous foams on one hand, and confirms that ALD deposition of ZnO is a versatile approach to switch the surface wettability of porous substrates depending on their specific surface structures.

Figure 6. Absorption of oil/organics of the ZnO-deposited foams. Photographs of the deposited melamine foams absorbing (a-c) diesel oil floating on the 18


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water surface and (d-f) CCl4 underwater. Both organics were dyed blue for easy visualization. (g) The absorption capacity of deposited melamine foams for different organics; (h) The absorption capacity at different recycle times towards diesel oil of the deposited melamine foam.

Considering the strong hydrophobicity and high porosity, the ZnO-deposited melamine foams are expected to work as an excellent absorbent to selectively absorb oil spills and organic leakages from water. As shown in Figure 6, the deposited melamine foams are able to quickly absorb both diesel oil floated on the water surface (Figures 6a-c) and CCl4 precipitated into the bottom of water (Figures 6d-f). After absorption, there were no residual organics (dyed blue) left behind. A number of organics were used to test the absorption capacity of the deposited melamine foams. As shown in Figure 6g, the Q (g/g) values of the deposited foams are ranged from 85 to 162 g/g for different organics. We also investigated the reusability of the deposited foams. As shown in Figure 6h, the initial Q value to diesel oil is 86 g/g and decreases to 76 g/g after reused for 20 times. Nearly 90% of the initial absorption capacity is maintained after 20 times reuse, indicating the excellent recyclability of the ZnO-deposited foams. This high absorption capacity and excellent reusability should be ascribed to the ultrathin ZnO layer that hardly consumes any porosity of the pristine foams. In addition, the adhesion between the ultrathin ZnO layer and the foam substrates was very strong. The ZnO-deposited foams survive a harsh 19



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ultrasonication challenge (Figure S7) and their strong hydrophobicity and the ability to selectively absorption oil from water are maintained for at least eight months when they are stored in ambience. To further confirm the adhesion strength, we conducted 20 times press-release test on the foam and no morphology changes could be seen in the SEM images (Figure S8). Also importantly, our ALD method is a “dry” and one-step process which involves no solvent and is very convenient and highly controllable. Compared to oil absorbents prepared by other methods, our ZnO-deposited foams are among the best in terms of absorption capacity, reusability, stability, cost, and preparation processes (Table 1). Table 1. Comparison of the oil absorbents prepared by different methods Method

Absorption capacity*

Reusability

Cost of raw materials

Process

Ref.

ALD of Al2O3 and silanization

119.0

117.0

Medium

Two steps; use of organic solvents

47

Dip-coating rGO and silanization

62.2

62.2

Very high


22

Dip-coating GO and reduction

103.6

101.5

Very high


8

Thermal curing of PDMS

23.0

23.0

Medium

One step; use of organic solvents

48

Suspension polymerization of β-CD

54.2

54.2

Medium

One step; use of organic solvents

49

Hard template fabricated PDMS sponge

10.6

10.6

Medium


50

Polymerization and cross-linking

49.7

\

High


51

20


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Dip-coating GO, reduction and silanization

60.4

54.4 (8 times)

Very high

Three steps; use of organic solvents

52

Eugenyl methacrylate synthesis and suspension polymerization

~64.8

~64.8 (5 times)

Medium


53

Hydrothermal, casting and silicon coating

~ 22.2

\

Medium

Three steps; Time-consuming

54

ALD of ZnO

102.4

97.3

Low

One step; Without organic solvents

This work

*The absorption capacity was calculated as Qmax absorption capacity/ρabsorbed solvent.

CONCLUSIONS In summary, we discover that in the ALD-deposited ZnO films using diethyl zinc and water as the precursors there is a significant amount of organic moieties originated from DEZ, offering the deposited ZnO a stable surface hydrophobicity. By taking the advantages of the moderate surface energy of the ALD-deposited ZnO layers and the high porosity of polymeric foams, we produce stable oil absorbents with better absorption capability and reusability than any other foam-based oil absorbents. Considering the ease in depositing oxide layers virtually on any substrate and the flexibility in tuning the surface wettability of the deposited substrates, this ALD-induced hydrophobicity is expected to find important applications in many other fields where the surface wettability of the materials plays a role.

SUPPORTING INFORMATION 21



The WCA on the O2 plasma treated Si wafer (Figure S1). The SEM and AFM images of 500-cycle-deposited silicon substrate (Figure S2); SEM image of the melamine foam with 60 cycles deposition (Figure S3); photographs of the 100-cycle-deposited melamine foam, pristine melamine foam and WCA test of the melamine foam with 30 cycles deposition, and water droplet seated on the cross section of deposited foam (Figure S4); the digital photo and SEM images of the pristine foam and highly compressed foam (Figure S5). the nonselectivity of the highly pressed melamine foam (Figure S6); the floating foam after ultrasonic treatment (Figure S7); the 100-cycle-deposited melamine foams before and after 20 times press-release test (Figure S8). .

ACKNOWLEDGMENTS Financial support from the National Basic Research Program of China (2015CB655301), the Natural Science Research Program of the Jiangsu Higher Education Institutions (13KJA430005), the Natural Science Foundation of Jiangsu Province (BK20150063), and the Program of Excellent Innovation Teams of Jiangsu Higher Education Institutions is gratefully acknowledged. REFERENCES (1). Ge J.; Ye Y. D.; Yao H. B.; Zhu X.; Wang X.; Wu L.; Wang J. L.; Ding H.; Yong N.; He L. H.; Yu S. H. Pumping through porous hydrophobic/oleophilic materials: an alternative technology for oil spill remediation. Angew. Chem. 2014, 126, 3686-3690. (2). Chen Q.; de Leon A.; Advincula R. C. Inorganic–organic thiol–ene coated mesh for oil/water separation. ACS Appl. Mater. Inter. 2015, 7, 18566-18573. (3). Wang B.; Liang W.; Guo Z.; Liu W. Biomimetic super-lyophobic and super-lyophilic 22


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One-step synthesis of carbon-hybridized ZnO on polymeric foams by atomic layer deposition for efficient absorption of oils from water Sen Xiong, Yang Yang, Zhaoxiang Zhong, Yong Wang*

Oil absorbents with exceptional absorption capability and reusability were produced by atomic layer deposition of carbon-hybridized ZnO on low-cost polymeric foams

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One-Step Synthesis of Carbon-Hybridized ZnO on Polymeric Foams

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