A Novel CuxO Nanoparticles@ZIF-8 Composite Derived from Core

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A Novel CuxO Nanoparticles@ZIF-8 Composite Derived from Core-Shell Metal-Organic Frameworks for Highly Selective Electrochemical Sensing of Hydrogen Peroxide Juan Yang, Huili Ye, Faqiong Zhao, and Baizhao Zeng ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.6b06436 • Publication Date (Web): 19 Jul 2016 Downloaded from http://pubs.acs.org on July 24, 2016

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ACS Applied Materials & Interfaces

A Novel CuxO Nanoparticles@ZIF-8 Composite Derived from Core−Shell Metal−Organic Frameworks for Highly Selective Electrochemical Sensing of Hydrogen Peroxide Juan Yang, Huili Ye, Faqiong Zhao, Baizhao Zeng* Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, Hubei Province, P. R. China

ABSTRACT: A novel core−shell heterostructure of CuxO nanoparticles@zeolitic imidazolate framework (CuxO NPs@ZIF-8) was successfully prepared through facile pyrolysis of nanocrystalline copper-based metal−organic framework [nHKUST-1, i.e. Cu3(BTC)2 (BTC = 1,3,5-benzene-tricarboxylate)]@ZIF-8, based on the different thermal stability of the two metal−organic frameworks (MOFs). The small CuxO NPs derived from nHKUST-1 uniformly dispersed inside the host material and provided active sites, while ZIF-8 kept the original structure as molecular sieving shell. Owing to the proper pore shape and pore size of ZIF-8, H2O2 could diffuse through the shell, but bigger molecules could not pass. Thus the composite material exhibited high selectivity when it was used to construct a H2O2 sensor. In addition, the sensor showed extended linear detection range (from 1.5 to 21442 µM), low detection limit (0.15 µM) and high sensitivity, due to the good electrocatalysis of CuxO NPs and the

*

Corresponding author. Tel: 86-27-68752701, Fax: 86-27-68754067.

E-mail address: [email protected] 1 ACS Paragon Plus Environment


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synergistic effect of core−shell structure. KEYWORDS: metal−organic frameworks, core−shell structure, CuxO, ZIF-8, electrocatalysis, hydrogen peroxide 1. INTRODUCTION Metal−organic frameworks (MOFs), prepared by means of assembly of organic ligands and metal ions in appropriate solvents, have emerged as new porous crystalline materials due to their ordered structure, large internal surface area, uniform but tunable cavity, and tailorable chemical property.1-3 These characteristics make them very promising for a variety of applications, such as catalysis,4 separation,5 gas storage/capture,6 drug delivery7 and sensing.8-9 Recently, MOFs were used as unique host matrices for fabricating core-shell heterostructure by encapsulating metal nanoparticles (MNPs).10-14 The obtained MNPs@MOF exhibited novel chemical and physical properties and generated considerable interests in the field of selective catalysis because the MNP cores had catalytic activity and the MOF shells could act as recognition element like molecular

sieves.15-20

nanocubes@zeolitic

For

example,

imidazolate

HMIM=2-methylimidazole]

Yang

framework

core−shell

et

al.

(ZIF-8)

heterostructure

prepared [i.e. for

a

Pd

Zn(MIM)2,

the

selective

catalytic hydrogenation of 1-hexene in the presence of 1-octene and cyclohexene, because the ZIF-8 shell (aperture diameter: 3.4 Å) did not affect the diffusion of 1-hexene (molecular size: ca. 2.5 Å), but blocked the passing through of 1-octene (molecular size: ca. 4.0 Å) and cyclohexene (molecular size: 2 ACS Paragon Plus Environment

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ca. 4.2 Å).21 Xu et al. also applied Pd@ZIF-8 thin films to the selective catalytic hydrogenation of 1-hexene in the presence of cis-cyclooctene (molecular size: ca. 5.5 Å).22 Guo et al. prepared Pt@zirconium-based MOF (UiO-66-NH2) [i.e. Zr6O4(OH)4(BDC-NH2)6, BDC = 1,4-benzenedicarboxylate] catalyst for cinnamaldehyde hydrogenation, while the hydrogenation of coexistent 1,3-cyclooctadiene was completely inhibited because its size (6.7 × 6.2 × 4.2 Å) was slightly larger than the window size of UiO-66-NH2 (ca. 6 Å).20 Duan’s group successfully synthesized magnetic iron oxide nanoparticles (MagNP)@polydopamine

(PDA)@Au

NPs@ZIF-8

and

MagNP@PDA@AuNPs@UiO-66, and selected 4-nitrophenol (4-NPh) and methylene blue (MB) as the model reactants.16 They found that the small aperture of ZIF-8 prevented the diffusion of 4-NPh (molecular size: ca.∼4.8 Å) through the MOF shell to the Au nanocatalyst, while the UiO-66 MOF shell almost did not affect the reaction. But the MagNP@PDA@AuNPs@UiO-66 did not show catalysis for MB (∼7.6 Å) due to the molecular selectivity of the MOF layer. Similarly, the core−shell heterostructures of MOFs present promising

potential

in

electrochemical

field

due

to

their

size-/shape-selectivity.23 But the cores used are usually precious MNPs, and protective

agents

such

as

poly(vinylpyrrolidone)

(PVP),

cetyltrimethylammonium bromide and PDA are often needed. The modifying materials may greatly suppress the catalytic activity of MNPs. Therefore, it is worth trying to prepare non-noble metal based MNP@MOFs without protective 3 ACS Paragon Plus Environment


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agents. Recently, Tsung' group successfully prepared a UiO-66@ZIF-8 composite, which solved the problem of topology mismatch of two MOFs, leading to high interface energy.24 This research brings us a lot of inspiration. Herein, we choose ZIF-8 as shell and successfully synthesize a new copper-based

MOF

[nHKUST-1,

i.e.

Cu3(BTC)2

(BTC

=

1,3,5-benzene-tricarboxylate)] @ZIF-8 composite. Based on the different thermal stability of the two MOFs, a perfect core−shell heterostructure of CuxO NPs@ZIF-8 is prepared by calcining nHKUST-1@ZIF-8 in air directly. As far as we know, it is the first example to use such a way to prepare non-noble metal based MNP@MOFs. This composite indeed exhibits many unusual merits: (1) the ZIF-8 shell acts as a protective layer to effectively prevent CuxO NPs from aggregation and migration during calcination process; (2) the ZIF-8 provides narrow penetration channels, which allow the transit of small molecules; (3) the large surface area and inherent porosity of ZIF-8 is beneficial for reactants rapidly arriving at the surface of CuxO NPs; (4) the CuxO NPs can maintain their catalytic activity and high dispersion inside the host materials during catalytic cycles. H2O2 was selected as the model molecule to examine the performance of the core−shell CuxO NPs@ZIF-8 heterostructure. The results showed that the CuxO NPs@ZIF-8 based electrochemical sensor had a broad linear detection range and high selectivity. It could effectively prevent the interference of uric acid (UA), DA, amino acid, ascorbic acid (AA), etc. 2. EXPERIMENTAL SECTION 4 ACS Paragon Plus Environment

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2.1. Chemical reagents. Cu(NO3)2·3H2O, NaOH, Zn(NO3)2·6H2O, H2O2, trimethylamine (TEA), sucrose, glucose, D-fructose, α-lactose, L-cysteine, acetic acid (HAc), AA, UA, DA, methanol and ethanol were obtained from Sinopharm Chemical Reagent Co. Ltd. (Shanghai, China); 1,3,5-benzene-tricarboxylic acid (H3BTC), PVP (Mw = 58 000) and 2-methyl imidazole were purchased from Aladdin Chemistry Co., Ltd. (Shanghai, China). 2.2. Apparatus. Electrochemical measurements were carried out on a model CHI 832C electrochemical workstation (Shanghai Chenhua Instrument, China). A conventional three-electrode system was adopted, including a modified glassy carbon electrode (GCE, diameter: 3 mm) as working electrode, a platinum wire as auxiliary electrode and a saturated calomel electrode (SCE) as reference electrode. . Scanning electron microscope (SEM) images were recorded with a field emission SEM (ZEISS, Germany), while transmission electron microscopy (TEM) images were gotten through a JEM-2100 transmission electron microscope with an accelerating voltage of 200 kV. X-ray diffraction (XRD) patterns were collected from a PANalytical X’Pert Pro diffractometer (Holland) using Cu Kα radiation (40 kV, 40 mA) with a Ni filter. Energy dispersive X-ray spectroscopy (EDS) was obtained using a Hitachi X-650 SEM (Hitachi Co., Japan). X-ray photoelectron spectroscopy (XPS) was recorded with a Thermo Fisher ESCALAB 250Xi X-ray photoelectron spectrometer with Al K X α-ray radiation for excitation. Thermo gravimetric analysis (TGA) was performed by using a diamond TG/DTA 6300 (PerkinElmer, USA) under air flow at a heating rate of 10 °C/min. N2 adsorption-desorption experiments were carried out on a 5 ACS Paragon Plus Environment


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Quantachrome Autosorb-iQ gas sorption analyzer. 2.3. Preparation of nHKUST-1. The nHKUST-1 was prepared according to previous report.25 Briefly, 0.435 g Cu(NO3)2·3H2O, 0.62 mL HAc, and 0.50 mL TEA were added into 12 mL ethanol. After stirring for 1 h, 0.210 g H3BTC was added. The mixture was stirred for additional 2 h to form a homogeneous solution and then transferred into a Teflon-lined autoclave. The mixture was kept at 25 °C for 24 h. Afterward, the solid was recovered by centrifuged at 8000 rpm for 3 min and washed with methanol for several times, and finally dispersed in 25 mL methanol. 2.4. Preparation of nHKUST-1@ZIF-8, nHKUST-1/ZIF-8 and ZIF-8. Firstly, 5 mL nHKUST-1 suspension (10 mg mL-1, in methanol) was diluted to 50 mL with methanol, and 10 mL PVP solution (0.350 g, in methanol) was added. After stirring for 12 h at room temperature the mixture was centrifuged and the PVP-stabilized nHKUST-1 was collected, which was washed with methanol for three times and dispersed in 5 mL methanol. Then the as-prepared PVP-stabilized nHKUST-1 suspension (0.5, 1 or 1.5 mL) and 0.372 g Zn(NO3)2·6H2O were dispersed in 50 mL methanol. After adding 50 mL 2-methylimidazole solution (0.103 g, in methanol), they were allowed to react at room temperature for 24 h without stirring. The products were collected by centrifuged, washed with methanol and dried overnight in an oven. They were denoted as nHKUST-1@ZIF-8-1, nHKUST-1@ZIF-8 and nHKUST-1@ZIF-8-2, corresponding to adding 0.5, 1 and 1.5 mL PVP-stabilized nHKUST-1 suspension, respectively. 6 ACS Paragon Plus Environment

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The pure ZIF-8 was synthesized by the same procedure as mentioned above except not adding PVP-stabilized nHKUST-1 suspension. The nHKUST-1/ZIF-8 was obtained by direct mixing ZIF-8 suspension and PVP-stabilized nHKUST-1 suspension, followed by centrifuging and drying in an oven. 2.5.

Preparation

of

CuxO

NPs@ZIF-8

and

CuxO

NPs.

The

nHKUST-1@ZIF-8 (0.10 g) was heated to 350 °C and kept at the temperature for 0.5 h under an air atmosphere. The obtained product was labelled as CuxO NPs@ZIF-8.

Similarly,

the

procedure

was

conducted

to

convert

nHKUST-1@ZIF-8-1 to CuxO NPs@ZIF-8-1, and convert nHKUST-1 to CuxO NPs. 2.6. Electrochemical measurements. Before the modification, the bare GCE was cleaned with alumina slurries of different grades (i.e. 1.0, 0.3 and 0.05 µm, respectively) to remove adsorbed impurities, and then washed successively using ethanol and ultra-pure water with the help of ultrasonication. To prepare the modified electrodes, 10 mg of the as-prepared sample was dispersed into 5 mL ethanol and 2 µL of the resulting homogeneous suspension was dropped onto the GCE. After it was dried, 2 µL Nafion ethanol solution (0.5 wt%) was dropped on the modified electrode and dried in air. Thus, CuxO NPs@ZIF-8/GCE, CuxO NPs@ZIF-8-1/GCE, CuxO NPs/GCE and ZIF-8/GCE modified electrodes were obtained, respectively. The cyclic voltammograms (CVs) of the modified electrodes (or sensors) in 0.10 M NaOH with definite concentration of H2O2 were recorded between 0 V 7 ACS Paragon Plus Environment


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and 1.0 V (vs. SCE) at 50 mV s-1. For the chronoamperometric tests, the response currents of the sensors were recorded along with the successive addition of H2O2 under magnetic stirring. The applied potential was 0.7 V (vs. SCE).

Scheme 1 Schematic diagram of the preparation of CuxO NPs@ZIF-8.

3. RESULTS AND DISCUSSION 3.1. Morphological and structural characterization. The fabrication process of the CuxO NPs@ZIF-8 polyhedra is schematically illustrated in Scheme 1. First of all, the nanosized HKUST-1 was prepared through solvothermal method with the modulator of TEA. Then the nHKUST-1@ZIF-8 templates with different nHKUST-1 contents (i.e. nHKUST-1@ZIF-8-1, nHKUST-1@ZIF-8 and nHKUST-1@ZIF-8-2, respectively) were synthesized by a surfactant-mediated overgrowth process. For preparing the new core-shell MOF@MOF heterostructures this strategy solved the problem of topology mismatch of two MOFs with the help of PVP. Here the morphologies of the prepared composites were characterized by SEM and TEM. As could be seen (Figure 1A, Figure S1 and Figure S2), the nHKUST-1 were irregular small particles with diameter between 20 nm and 50 nm, and they stacked together to 8 ACS Paragon Plus Environment

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form nano-porous structure (Figure S1A and Figure S2A); the rhombic dodecahedral ZIF-8 possessed smooth surface with uniform size of about 450 nm (Figure S1D and Figure S2B); the nHKUST-1@ZIF-8-x crystals were smaller in comparison with ZIF-8 crystals and they aggregated with each other. The nHKUST-1@ZIF-8-1 (Figure S1B) and nHKUST-1@ZIF-8 (Figure 1A) also showed smooth surface and they were angular, but no individual nHKUST-1

particles

nHKUST-1/ZIF-8

were

composite

observed (Figure

in S1E).

these The

composites, TEM

unlike

image

of

nHKUST-1@ZIF-8 was presented in Figure S2C, and clear core–shell structure was observed. The nHKUST-1 cores appeared to be irregular compared with the angular ZIF-8 shell. This indicated the successful synthesis of core-shell structure. But further increasing the amount of nHKUST-1, the resulting product nHKUST-1@ZIF-8-2 (Figure S1C) showed broken shell and some nHKUST-1 crystals could not be encapsulated by the ZIF-8. Thus nHKUST-1@ZIF-8-2 did not possess core-shell structure. In addition, the XRD patterns of these crystals were compared in Figure S3A. The nHKUST-1 sample showed clear reflections apart from peak broadening, which was attributed to the small grain size of the products.25 Other composites mainly showed the structural features of ZIF-826 and only two strong diffraction peaks (i.e. (220) and (222)) of nHKUST-1 were observed27 due to the low proportion of nHKUST-1, the peak overlapping of ZIF-8 and nHKUST-1 and/or core-shell heterostructure. With increasing the amount of nHKUST-1, the diffraction peak 9 ACS Paragon Plus Environment


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intensity of nHKUST-1 increased and the color of the obtained samples gradually became deep (Figure S3D). The Brunauer-Emmett-Teller (BET) surface areas of the nHKUST-1@ZIF-8-1 and nHKUST-1@ZIF-8 were calculated to be 1732 and 1611 m2 g−1, respectively, which located between those of ZIF-8 (1975 m2 g−1) and nHKUST-1 (673 m2 g−1) (Figure S3B). Moreover, the EDS of nHKUST-1@ZIF-8 exhibited the signals of oxygen, nitrogen, zinc, copper and carbon elements, indicating the existence of nHKUST-1 and ZIF-8 (Figure S3C). These confirmed the successful synthesis of core–shell nHKUST-1@ZIF-8 composite. To choose appropriate temperature for nHKUST-1@ZIF-8 template to transfer to CuxO NPs@ZIF-8, the thermal stability of various samples was investigated through TGA in air flow (Figure 2A). As could be seen, the nHKUST-1 sample displayed two steps of weight loss. It lost 23 wt% up to 200 °C due to the high adsorption amount of water, and a steep weight loss occurred at 280 °C, corresponding to the decomposition of the ligand in nHKUST-1. This was consistent with that reported.25 Nevertheless, ZIF-8 was stable up to 420 °C. The nHKUST-1@ZIF-8 exhibited two steps of weight loss. The first one occurred from 310 °C to 350 °C, resulting from nHKUST-1 decomposition. However, the decomposition temperature was higher than that of pure nHKUST-1 due to the protection of ZIF-8 shell. The another step of weight loss was assigned to the decomposition of ZIF-8, which was similar to that of pure ZIF-8. These results supported the contention that the nHKUST-1 10 ACS Paragon Plus Environment

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nanocrystals located in the interior of ZIF-8 crystals rather than on their surface. Based on the TGA result, 350 °C was chosen as the calcining temperature, where nHKUST-1 decomposed completely but ZIF-8 still kept the original structure.

Figure 1 SEM images of nHKUST-1@ZIF-8 (A) and CuxO NPs@ZIF-8 (B); TEM images of CuxO NPs@ZIF-8 (C) and its large visual scale (D); elemental mapping of CuxO NPs@ZIF-8 (E).

The morphology of CuxO NPs@ZIF-8 was also investigated by SEM and TEM. Obviously, its shape was similar to that of precursor (Figure 1B), some black particles were encapsulated by smooth, fracture-free and conformal ZIF-8 shell (Figure 1C), and almost no unencapsulated particles were observed 11 ACS Paragon Plus Environment


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(Figure 1D). Figure S4 showed the high-magnification TEM images of CuxO NPs@ZIF-8, which clearly displayed the core-shell structure. The fringe shell had no obvious lattice structure and the interlayer distances of the selected black particles were calculated to be 0.272 nm and 0.245 nm, which agreed well with the (110) and (111) lattice planes of CuO and Cu2O, respectively. Moreover, to further prove the embedment of CuxO NPs in the ZIF-8 crystals, the elemental mapping was recorded (Figure 1E). According to the distribution of Cu and Zn, it could be concluded that the CuxO NPs were embedded and well distributed in the ZIF-8 matrix, featuring with a typical core-shell structure. To explore the crystal structure of the annealed products, XRD measurement was performed (Figure 2B). All the peaks could be perfectly indentified as CuO/Cu2O (CuxO) after calcining nHKUST-1 because they were consistent with those of the simulated CuO (JCPDS No.45-0937) and Cu2O (JCPDS No.05-0067) (curve a-c).28-29 Compared with the diffraction peaks of nHKUST-1@ZIF-8, the annealed product well retained the diffraction peaks of ZIF-8 but did not exhibit the diffraction peaks of nHKUST-1, indicating the successful decomposition of nHKUST-1 and the unchanged phase of ZIF-8. However, the diffraction peaks of metallic oxides were not found, mainly due to their low proportion or weak crystallinity. The N2 adsorption−desorption isotherm of CuxO NPs@ZIF-8 was a typical type IV isotherm (Figure 2C). As can be seen, during the desorption branch the 12 ACS Paragon Plus Environment

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hysteresis loop gradually moved to higher relative pressure, indicating the presence of both micropores (< 2 nm) and mesopores (2–50 nm). The unique porous structure was beneficial to reactants to reach the encapsulated active sites and simultaneously facilitated

the catalytic process.30 The BET surface

area and total pore volume of CuxO NPs@ZIF-8 were 1680 m2 g−1 and 0.88 cm3 g-1, respectively.

Figure 2 (A) TGA curves of nHKUST-1 (a), nHKUST-1@ZIF-8 (b) and ZIF-8 (c); (B) XRD patterns of simulated CuO (a), simulated Cu2O (b), CuxO NPs (c), nHKUST-1@ZIF-8 (d) and CuxO NPs@ZIF-8 (e); (C) nitrogen-adsorption/desorption isotherms of CuxO NPs@ZIF-8.

In addition, XPS measurement was conducted (Figure 3), and the atomic ratio of Cu/Zn was 0.046. Inductively coupled plasma optical emission spectroscopy (ICP-OES) was also applied to the precise determination of Cu and Zn contents. The result indicated that the atomic ratio of Cu/Zn was 0.058, 13 ACS Paragon Plus Environment


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which was basically consistent with the result of XPS analysis. As shown in Figure 3, the Cu 2p spectrum included a doublet at binding energy (BE) of 932.7 and 952.6 eV, assigned to Cu 2p3/2 and Cu 2p1/2 lines, respectively. Two specific peaks with BEs of 932.4 and 952.2 eV corresponded to Cu2O, and the other two distinctive peaks with BEs of 933.6 and 953.6 eV corresponded to CuO.31 The molar ratio of CuO/Cu2O was 0.63, based on the XPS result.

Figure 3 The survey XPS data of CuxO NPs@ZIF-8 (A) and high resolution Cu 2p XPS data of CuxO NPs@ZIF-8 (B).

3.2. Electrocatalytic Detection of H2O2. The electrocatalytic activity of CuxO NPs@ZIF-8/GCE toward H2O2 oxidation was studied using cyclic voltammetry. Upon the addition of H2O2 to 0.10 M NaOH solution, an obvious increase of oxidation current could be seen and it constantly increased with increasing H2O2 concentration (Figure 4A), implying that the ZIF-8 shell did not affect the diffusion of H2O2. According to previous literatures,32-35 the reaction mechanism could be thought as follows: first, Cu+ (i.e. Cu2O) was converted to Cu2+ (i.e. Cu(OH)2, CuO), and then to Cu3+ (i.e. CuOOH) by

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electrochemical oxidation in alkaline media. Subsequently, H2O2 was oxidized by Cu3+ (i.e. CuOOH), and Cu2+ was regenerated. For comparison, bare GCE, CuxO NPs @ZIF-8-1/GCE, ZIF-8/GCE and CuxO NPs@ZIF-8/GCE were also investigated (Figure S5A). For these electrodes the oxidation current of H2O2 followed such order as: CuxO NPs@ZIF-8/GCE > CuxO NPs@ZIF-8-1/GCE > ZIF-8/GCE > bare GCE. The different current responses could be attributed to the following factors: the specific surface area and the catalytic activity as well as the amount of encapsulated CuxO NPs. The CuxO NPs@ZIF-8 possessed large specific surface area and more CuxO NPs which exhibited good electrocatalysis towards the oxidation of H2O2. Hence the CuxO NPs@ZIF-8/GCE presented higher current response than other electrodes.



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Figure 4 (A) CV curves of Cux O NPs@ZIF-8/GCE in H2O2 solutions. H2O2 concentrations: 0 mM (a), 1.0 mM (b), 3.0 mM (c) and 5.0 mM (d); supporting electrolyte: 0.10 M NaOH. (B) Amperometric response curves of CuxO NPs@ZIF-8/GCE upon successively adding H2O2 at 0.7 V. Left inset: amperometric response of H2O2 at lower concentration; right inset: the relationship between current signal and H2O2 concentration. Current response of CuxO NPs@ZIF-8/GCE (C) and CuxO NPs/GCE (D) to 50 µM H2O2, glucose, D-fructose, sucrose, α-lactose, L-cysteine, AA, UA and DA.

Moreover, the current response was closely related to the applied potential. As Figure S5B showed, with the operated potential increasing from 0.4 V to 0.7 V, the current response continuously increased. Although the current response still increased when the potential was up to 0.8 V, the noise also became large due to the supererogatory redox reactions (such as water splitting). Thus 0.7 V was chosen for determination. Besides, the influence of modifying amount of CuxO NPs@ZIF-8 was investigated and 2 µL of CuxO NPs@ZIF-8 suspension was selected for preparing modified electrode (Figure S5C). Figure 4B showed the chronoamperometric curves of H2O2 at the CuxO NPs@ZIF-8 under optimized conditions. The response current increased upon the increase of H2O2 concentration, and the linear detection range was 1.5−21442 µM. The linear regression equation was I (µA)= 0.0126c (µM) – 1.93 (R2= 0.999), with a sensitivity of 178 µA mM-1 cm-2. The limit of 16 ACS Paragon Plus Environment

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detection (LOD) was 0.15 µM (S/N= 3). Compared with other H2O2 sensors, the CuxO NPs@ZIF-8/GCE presented excellent performance, especially the broad linear range (Table 1). Table 1. Comparison of the performance of the CuxO NPs@ZIF-8/GCE with that of other H2O2 sensors H2O2 sensors

Linear

Limit of

Sensitivity

range (µM)

detection (µM)

(µA mM-1 cm-2)

Cu-MOF/MPCa

10-11600

3.2

2.97 (µA mM-1 )

36

Pt NPs@UiO-66

5-14750

3.06

75.33

37

Cu2O/rGOb

30-12800

21.7

20.7 (µA mM-1 )

38

Ni(II)-MOF/CNTsc

10-51600

2.1

8.2 (µA mM-1 )

39

Cu-MOF

0.1-2.75

0.068

78220 (µA mM-1 )

32

Cu2O/GNsd

300-7800

20.8

-

40

CuO/ silicon nanowire

10-13180

1.6

22.27 (µA mM-1 )

41

5-3750

0.8

26.67 (µA mM-1 )

42

Cu-CoTCPP/MWCNTsf

0.5-1800

0.24

168

43

CuxO NPs@ZIF-8

1.5-21442

0.15

178

This work

Cu2O NPs/N-GNe

a

Cu-based MOF/macroporous carbon

b

Cu2O/reduced graphene oxide

c

Ni-based MOF/carbon nanotubes

d

Cu2O/graphene

e

Cu2O NPs/N-doped graphene

f

Co, Cu-bimetallic metalloporphyrinic framework/multi-walled carbon nanotubes

Reference

3.3. Selectivity, reproducibility and stability. As we known, many species such as AA, UA, amino acid and some carbohydrate compounds can generate 17 ACS Paragon Plus Environment


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interfering electrochemical signals during H2O2 oxidation, which is a big challenge for a H2O2 electrochemical sensor.44-45 As shown in Figure 4C, in this case glucose, D-fructose, sucrose, α-lactose, L-cysteine, AA, UA and DA also presented weak current responses at the CuxO NPs@ZIF-8/GCE. This was related to the gaps/pores formed by the modified materials. But their current responses were negligible even if their concentration was as high as that of H2O2, indicating that these species had no obvious interference. But CuxO NPs (without MOF shell) suffered serious interference from them (Figure 4D). Apparently, the high anti-interference performance of CuxO NPs@ZIF-8 was related to the size exclusion of ZIF-8 shell. The aperture of ZIF-8 was too small to allow bigger molecules (such as AA and UA) to pass through, thus they could not reach the encapsulated CuxO NPs surface. In order to discuss the repeatability and reproducibility of the H2O2 sensor, eight different CuxO NPs@ZIF-8/GCEs were independently fabricated by the same way. The amperometric responses of these electrodes to 50 µM H2O2 were recorded. As a result, the relative standard deviation (RSD) of the response current was 4.6% (n=8). Moreover, eight repetitive measurements using a sensor gave an RSD of 4.1% (n=8). This manifested that the sensor had good reproducibility and repeatability for the H2O2 detection. The stability of the sensor was examined by comparing the corresponding TEM images for before and after six cycles of consecutive CV runs. As shown in Figure S6, the CuxO NPs@ZIF-8 still exhibited intact morphology 18 ACS Paragon Plus Environment

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(compared with Figure 1D). Moreover, the stability of the H2O2 sensor was also tested by recording chronoamperometric curves. It was found that the response current of CuxO NPs@ZIF-8/GCE retained 99.3% of its original value after 15 days-storage in air, and it still retained 97.8% after a month-storage. These reflected the long-term stability of CuxO NPs@ZIF-8/GCE. 4. CONCLUSION In conclusion, a novel template-engaged strategy was developed for the preparation of CuxO NPs@ZIF-8 core−shell heterostructure, and the strategy was based on calcining nHKUST-1@ZIF-8 core−shell composite and making use of the different thermal stability of two MOFs. The CuxO NPs@ZIF-8 composite possessed good crystalline structure and well-dispersed CuxO NPs; the encapsulated CuxO NPs presented good electrocatalysis for H2O2 oxidation. The resulting CuxO NPs@ZIF-8/GCE showed remarkable performance in H2O2 detection, such as excellent anti-interference capacity, extended linear range, low detection limit and satisfactory stability. This study provides a new avenue for improving the selectivity of non-enzyme electrochemical sensors. ASSOCIATED CONTENT Supporting Information Additional SEM, XRD, BET, EDS, photographs, amperometric results. This material is available free of charge via the Internet at http://pubs.acs.org.



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AUTHOR INFORMATION Corresponding Author ∗ ∗

Tel: 86-27-68752701; Fax: 86-27-68754067; E-mail address: [email protected]

Notes The authors declare no competing financial interest.

ACKNOWLEDGMENT This work was supported by the National Natural Science Foundation of China (Grant Nos. 21075092, 21277105). REFERENCES (1) Yaghi, O. M.; Li, H.; Groy, T. L., Construction of Porous Solids from Hydrogen-Bonded Metal Complexes of 1,3,5-Benzenetricarboxylic Acid. J. Am. Chem. Soc. 1996, 118, 9096-9101. (2) Furukawa, S.; Reboul, J.; Diring, S.; Sumida, K.; Kitagawa, S., Structuring of Metal-Organic Frameworks at the Mesoscopic/Macroscopic Scale. Chem. Soc. Rev. 2014, 43, 5700-5734. (3) Furukawa, H.; Cordova, K. E.; O’Keeffe, M.; Yaghi, O. M., The Chemistry and Applications of Metal-Organic Frameworks. Science 2013, 341, 1230444. (4) Nguyen, H. G. T.; Schweitzer, N. M.; Chang, C. Y.; Drake, T. L.; So, M. C.; Stair, P. C.; Farha, O. K.; Hupp, J. T.; Nguyen, S. T., Vanadium-Node-Functionalized UiO-66: A Thermally Stable MOF-Supported Catalyst for the Gas-Phase Oxidative Dehydrogenation of Cyclohexene. ACS Catal. 2014, 4, 2496-2500. 20 ACS Paragon Plus Environment

Page 20 of 28

Page 21 of 28

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(5) Huang, L.; He, M.; Chen, B.; Hu, B., A Designable Magnetic MOF Composite and Facile Coordination-Based Post-Synthetic Strategy for the Enhanced Removal of Hg2+ from Water. J. Mater. Chem. A 2015, 3, 11587-11595. (6) Zhao, Y.; Seredych, M.; Zhong, Q.; Bandosz, T. J., Superior Performance of Copper Based MOF and Aminated Graphite Oxide Composites as CO2 Adsorbents at Room Temperature. ACS Appl. Mater. Interfaces 2013, 5, 4951-4959. (7) Horcajada, P.; Serre, C.; Maurin, G.; Ramsahye, N. A.; Balas, F.; Vallet-Regí, M.; Sebban, M.; Taulelle, F.; Férey, G., Flexible Porous Metal-Organic Frameworks for a Controlled Drug Delivery. J. Am. Chem. Soc. 2008, 130, 6774-6780. (8) Bhardwaj, S. K.; Bhardwaj, N.; Mohanta, G. C.; Kumar, P.; Sharma, A. L.; Kim, K. H.; Deep, A., Immunosensing of Atrazine with Antibody-Functionalized Cu-MOF Conducting Thin Films. ACS Appl. Mater. Interfaces 2015, 7, 26124-26130. (9) Zhang, Y.; Bo, X.; Nsabimana, A.; Han, C.; Li, M.; Guo, L., Electrocatalytically Active Cobalt-Based Metal–Organic Framework with Incorporated Macroporous Carbon Composite for Electrochemical Applications. J. Mater. Chem. A 2015, 3, 732-738. (10) Lu, G.; Li, S.; Guo, Z.; Farha, O. K.; Hauser, B. G.; Qi, X.; Wang, Y.; Wang, X.; Han, S.; Liu, X.; DuChene, J. S.; Zhang, H.; Zhang, Q.; Chen, X.; Ma, J.; Loo, S. C.; Wei, W. D.; Yang, Y.; Hupp, J. T.; Huo, F., Imparting Functionality to a Metal-Organic Framework Material by Controlled Nanoparticle Encapsulation. Nat. Chem. 2012, 4, 310-316. (11) Li, G.; Kobayashi, H.; Taylor, J. M.; Ikeda, R.; Kubota, Y.; Kato, K.; Takata, M.; 21 ACS Paragon Plus Environment


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 22 of 28

Yamamoto, T.; Toh, S.; Matsumura, S.; Kitagawa, H., Hydrogen Storage in Pd Nanocrystals Covered with a Metal-Organic Framework. Nat. Mater. 2014, 13, 802-806. (12) Tsuruoka, T.; Kawasaki, H.; Nawafune, H.; Akamatsu, K., Controlled Self-Assembly of Metal–Organic Frameworks on Metal Nanoparticles for Efficient Synthesis of Hybrid Nanostructures. ACS Appl. Mater. Interfaces 2011, 3, 3788-3791. (13) Liu, H.; Chang, L.; Bai, C.; Chen, L.; Luque, R.; Li, Y., Controllable Encapsulation of “Clean” Metal Clusters within MOFs through Kinetic Modulation: Towards Advanced Heterogeneous Nanocatalysts. Angew. Chem. Int. Ed. 2016, 55, 5019-5023. (14) Vilian, A. T.; Puthiaraj, P.; Kwak, C. H.; Hwang, S. K.; Huh, Y. S.; Ahn, W. S.; Han, Y. K., Fabrication of Palladium Nanoparticles on Porous Aromatic Frameworks as a Sensing Platform to Detect Vanillin. ACS Appl. Mater. Interfaces 2016, 8, 12740−12747. (15) Yang, Y.; Wang, F.; Yang, Q.; Hu, Y.; Yan, H.; Chen, Y. Z.; Liu, H.; Zhang, G.; Lu, J.; Jiang, H. L.; Xu, H., Hollow Metal-Organic Framework Nanospheres Via Emulsion-Based Interfacial Synthesis and Their Application in Size-Selective Catalysis. ACS Appl. Mater. Interfaces 2014, 6, 18163-18171. (16) Zhou, J.; Wang, P.; Wang, C.; Goh, Y. T.; Fang, Z.; Messersmith, P. B.; Duan, H., Versatile

Core–Shell

Nanoparticle@Metal–Organic

Framework

Nanohybrids:

Exploiting Mussel-Inspired Polydopamine for Tailored Structural Integration. ACS Nano 2015, 9, 6951-6960. 22 ACS Paragon Plus Environment

Page 23 of 28

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(17) Saikia, M.; Bhuyan, D.; Saikia, L., Facile Synthesis of Fe3O4 Nanoparticles on Metal Organic Framework MIL-101(Cr): Characterization and Catalytic Activity. New J. Chem. 2015, 39, 64-67. (18) Ding, S.; Yan, Q.; Jiang, H.; Zhong, Z.; Chen, R.; Xing, W., Fabrication of Pd@ZIF-8 Catalysts with Different Pd Spatial Distributions and Their Catalytic Properties. Chem. Eng. J. 2016, 296, 146-153. (19) Zhang, M.; Yang, Y.; Li, C.; Liu, Q.; Williams, C. T.; Liang, C., PVP–Pd@ZIF-8 as Highly Efficient and Stable Catalysts for Selective Hydrogenation of 1,4-Butynediol. Catal. Sci. Technol. 2014, 4, 329-332. (20) Guo, Z.; Xiao, C.; Maligal-Ganesh, R. V.; Zhou, L.; Goh, T. W.; Li, X.; Tesfagaber, D.; Thiel, A.; Huang, W., Pt Nanoclusters Confined within Metal–Organic Framework Cavities for Chemoselective Cinnamaldehyde Hydrogenation. ACS Catal. 2014, 4, 1340-1348. (21) Yang, Q.; Xu, Q.; Yu, S.; Jiang, H., Pd Nanocubes@ZIF-8: Integration of Plasmon-Driven Photothermal Conversion with a Metal–Organic Framework for Efficient and Selective Catalysis. Angew. Chem. Int. Ed. 2016, 55, 1-6. (22) Xu, Z.; Zhang, W.; Weng, J.; Huang, W.; Tian, D.; Huo, F., Encapsulation of Metal Layers within Metal–Organic Frameworks as Hybrid Thin Films for Selective Catalysis. Nano Res. 2015, 9, 158-164. (23) Kuo, C. H.; Tang, Y.; Chou, L. Y.; Sneed, B. T.; Brodsky, C. N.; Zhao, Z.; Tsung, C. K., Yolk–Shell Nanocrystal@ZIF-8 Nanostructures for Gas-Phase Heterogeneous Catalysis with Selectivity Control. J. Am. Chem. Soc. 2012, 134, 14345-14348. 23 ACS Paragon Plus Environment


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 24 of 28

(24) Zhuang, J.; Chou, L. Y.; Sneed, B. T.; Cao, Y.; Hu, P.; Feng, L.; Tsung, C. K., Surfactant-Mediated

Conformal

Overgrowth

of

Core–Shell

Metal–Organic

Framework Materials with Mismatched Topologies. Small 2015, 11, 5551-5555. (25) Cao, Y.; Ma, Y.; Wang, T.; Wang, X.; Huo, Q.; Liu, Y., Facile Fabricating Hierarchically Porous Metal–Organic Frameworks Via a Template-Free Strategy. Cryst. Growth Des. 2016, 16, 504-510. (26) Huang, Y.; Zhang, Y.; Chen, X.; Wu, D.; Yi, Z.; Cao, R., Bimetallic Alloy Nanocrystals Encapsulated in ZIF-8 for Synergistic Catalysis of Ethylene Oxidative Degradation. Chem. Commun. 2014, 50, 10115-10117. (27) Schafer, P.; van der Veen, M. A.; Domke, K. F., Unraveling a Two-Step Oxidation Mechanism in Electrochemical Cu-MOF Synthesis. Chem. Commun. 2016, 52, 4722-4725. (28) Hu, L.; Huang, Y.; Zhang, F.; Chen, Q., CuO/Cu2O Composite Hollow Polyhedrons Fabricated from Metal–Organic Framework Templates for Lithium-Ion Battery Anodes with a Long Cycling Life. Nanoscale 2013, 5, 4186-4090. (29) Wang, Y.; Lu, Y.; Zhan, W.; Xie, Z.; Kuang, Q.; Zheng, L., Synthesis of Porous Cu2O/CuO Cages Using Cu-Based Metal-Organic Frameworks as Templates and Their Gas-Sensing Properties. J. Mater. Chem. A 2015, 3, 12796-12803. (30) Mao, C.; Kong, A.; Wang, Y.; Bu, X.; Feng, P., MIL-100 Derived Nitrogen-Embodied Carbon Shells Embedded with Iron Nanoparticles. Nanoscale 2015, 7, 10817-10822. (31) Lee, K. Y.; Hwang, H.; Shin, D.; Choi, W., Enhanced Thermopower Wave Via 24 ACS Paragon Plus Environment

Page 25 of 28

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Nanowire Bonding and Grain Boundary Fusion in Combustion of Fuel/CuO-Cu2O-Cu Hybrid Composites. J. Mater. Chem. A 2015, 3, 5457-5466. (32) Zhang, C.; Wang, M.; Liu, L.; Yang, X.; Xu, X., Electrochemical Investigation of a New Cu-MOF and Its Electrocatalytic Activity Towards H2O2 Oxidation in Alkaline Solution. Electrochem. Commun. 2013, 33, 131-134. (33) Huo, H.; Guo, C.; Li, G.; Han, X.; Xu, C., Reticular-Vein-Like Cu@Cu2O/Reduced Graphene Oxide Nanocomposites for a Non-Enzymatic Glucose Sensor. RSC Adv. 2014, 4, 20459-20465. (34) Lu, W.; Sun, Y.; Dai, H.; Ni, P.; Jiang, S.; Wang, Y.; Li, Z.; Li, Z., Direct Growth of Pod-Like Cu2O Nanowire Arrays on Copper Foam: Highly Sensitive and Efficient Nonenzymatic Glucose and H2O2 Biosensor. Sens. Actuators, A 2016, 231, 860-866. (35) Lin, X.; Jing, Z., Cuo Crystalline Modified Glassy Carbon Electrodes for Anodic Amperometric Determination of Hydrogen Peroxide. Chin. J. Chem. 2010, 28, 2501-2506. (36) Zhang, Y.; Bo, X.; Luhana, C.; Wang, H.; Li, M.; Guo, L., Facile Synthesis of a Cu-Based MOF Confined in Macroporous Carbon Hybrid Material with Enhanced Electrocatalytic Ability. Chem. Commun. 2013, 49, 6885-6887. (37) Xu, Z.; Yang, L.; Xu, C., Pt@UiO-66 Heterostructures for Highly Selective Detection of Hydrogen Peroxide with an Extended Linear Range. Anal. Chem. 2015, 87, 3438-3444. (38) Xu, F.; Deng, M.; Li, G.; Chen, S.; Wang, L., Electrochemical Behavior of Cuprous Oxide–Reduced Graphene Oxide Nanocomposites and Their Application in 25 ACS Paragon Plus Environment


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Nonenzymatic Hydrogen Peroxide Sensing. Electrochim. Acta 2013, 88, 59-65. (39) Wang, M. Q.; Zhang, Y.; Bao, S. J.; Yu, Y. N.; Ye, C., Ni(II)-Based Metal-Organic Framework Anchored on Carbon Nanotubes for Highly Sensitive Non-Enzymatic Hydrogen Peroxide Sensing. Electrochim. Acta 2016, 190, 365-370. (40) Liu, M.; Liu, R.; Chen, W., Graphene Wrapped Cu2O Nanocubes: Non-Enzymatic Electrochemical Sensors for the Detection of Glucose and Hydrogen Peroxide with Enhanced Stability. Biosens. Bioelectron. 2013, 45, 206-212. (41) Huang, J.; Zhu, Y.; Zhong, H.; Yang, X.; Li, C., Dispersed CuO Nanoparticles on a Silicon Nanowire for Improved Performance of Nonenzymatic H2O2 Detection. ACS Appl. Mater. Interfaces 2014, 6, 7055-7062. (42) Jiang, B. B.; Wei, X. W.; Wu, F. H.; Wu, K. L.; Chen, L.; Yuan, G. Z.; Dong, C.; Ye, Y., A Non-Enzymatic Hydrogen Peroxide Sensor Based on a Glassy Carbon Electrode Modified with Cuprous Oxide and Nitrogen-Doped Graphene in a Nafion Matrix. Microchim. Acta 2014, 181, 1463-1470. (43) Shi, L. M.; Pan, J. X.; Zhou, B.; Jiang, X., A New Bifunctional Electrochemical Sensor for Hydrogen Peroxide and Nitrite Based on a Bimetallic Metalloporphyrinic Framework. J. Mater. Chem. B 2015, 3, 9340-9348. (44) Janyasupab, M.; Liu, C. W.; Zhang, Y.; Wang, K. W.; Liu, C. C., Bimetallic Pt–M (M=Cu, Ni, Pd, and Rh) Nanoporous for H2O2 Based Amperometric Biosensors. Sens. Actuators, A 2013, 179, 209-214. (45) Gao, W.; Tjiu, W. W.; Wei, J.; Liu, T., Highly Sensitive Nonenzymatic Glucose and H2O2 Sensor Based on Ni(OH)2/Electroreduced Graphene Oxide−Multiwalled 26 ACS Paragon Plus Environment

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Carbon Nanotube Film Modified Glass Carbon Electrode. Talanta 2014, 120, 484-490.



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A Novel CuxO Nanoparticles@ZIF-8 Composite Derived from Core

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