Pt@UiO-66 Heterostructures for Highly Selective Detection of

Feb 20, 2015 - ... for Highly Selective Detection of Hydrogen Peroxide with an Extended ... triangular windows with a diameter of 6 Å. The transmissi...
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Pt@UiO-66 Heterostructures for Highly Selective Detection of Hydrogen Peroxide with an Extended Linear Range Zhaodong Xu, Lizi Yang, and Cailing Xu* State Key Laboratory of Applied Organic Chemistry, Key Laboratory of Special Function Materials and Structure Design Ministry of Education, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China S Supporting Information *

ABSTRACT: In this study, a good core−shell heterostructure of Pt NPs@UiO-66 was fabricated by encapsulating presynthesized platinum nanoparticles (Pt NPs) into the host matrix of UiO-66 which possesses the slender triangular windows with a diameter of 6 Å. The transmission electron microscopy images exhibited that the number of the encapsulated Pt NPs and the crystalline morphology of as-synthesized core−shell heterostructure samples had a series of changes with increasing the volume of the injected Pt NPs precursor solution. Among these samples, the Pt NPs@UiO-66-2 sample had a good crystalline morphology with several well-dispersed Pt NPs encapsulated in UiO-66 frameworks. But there were no obvious Pt NPs observed in the Pt NPs@UiO-66-1 sample, and for the Pt NPs@UiO-66-3 sample, the number of Pt NPs encapsulated in UiO-66 matrix notably reduced and the metal organic framework (MOF) crystals became small and aggregated. The electrochemical measurements showed that the Pt NPs@UiO-66-2 sample modified glass carbon electrode (GCE) presented a remarkable electrocatalytic activity toward hydrogen peroxide (H2O2) oxidation, including an excellent anti-interference performance even if the concentration of the interference species was the same as the H2O2, an extended linear range from 5 μM to 14.75 mM, a low detection limit, as well as good stability and reproducibility. The results indicate the superiority of MOFs in H2O2 detection. And more importantly, it will provide a new opportunity to promote the anti-interference performance of the nonenzyme electrochemical sensors.

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interfering substances based on the fact that these interferences can also generate redox reactions under the applied potential of H2O2 detection.20 Thus, designing the new sensing materials to improve the anti-interference performance of the nonenzymatic electrochemical H2O2 sensor becomes a challenging but urgent assignment these days. Metal organic frameworks (MOFs), a promising microporous material which was first defined by Yaghi and coworkers in 1995,21,22 have attracted widespread attention because of their ordered crystalline structure, controllable porosity, large internal surface area, and countless structural topologies.23,24 These unique features of MOFs have motivated researches for wide applications such as gas storage and separation,25,26 heterogeneous catalytic,27,28 and drug delivery.29 And recently, the application of MOFs in electrochemical areas including fuel cells, supercapacitors, solar cells, rechargeable Li-ion and Li−S batteries also attracts enormous scientific interest because of their good electrochemical activity.30−34 Moreover, very recently, there were also some reports on the application of different types of MOFs in nonenzymatic

he technology to quantitatively detect hydrogen peroxide (H2O2) attracts intensive attention of researchers due to the widespread applications of H2O2 in various fields such as the food industry,1 environmental protection,2 fuel cells,3 and so on. Besides, as one of the primary products of human metabolism,4 the accurate and fast detection of H2O2 also plays an important role in medical diagnosis. In the typical sensors, the electrochemical enzyme-based sensors have obtained a significant interest because of their advantages of high sensitivity and selectivity.5 However, the inferior stability and reproducibility of enzymes in different environmental effects such as temperature, oxygen, pH of solution, and toxic chemicals restrict their further application in H2O2 detection.6 Therefore, developing the nonenzymatic electrochemical sensors to improve the detection performance of H2O2 has been emphasized by more and more researchers. As a result, a variety of nanomaterials which possess the remarkable electrocatalytic activity toward H2O2 redox reaction were prepared and used for nonenzymatic electrochemical sensors in recent years, such as noble metals (Au, Pd, Pt) and their composites, 7−14 transition metals and their oxides or sulfides,15−18 carbon materials and their composites,19 and so on. However, although these systems can avoid the inherent defects of enzymes in some aspects, their electrochemical signals in detection process are easily influenced by a variety of © 2015 American Chemical Society

Received: December 19, 2014 Accepted: February 20, 2015 Published: February 20, 2015 3438

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FEI Tecnai G2F30 microscope. All of the electrochemical measurements were performed on a CHI760E electrochemical workstation (Chenhua, Shanghai, China) equipped with a conventional three-electrode system: a platinum plate and Hg/ HgO electrode were used as counter and reference electrode, respectively, the modified glass carbon electrode (GCE) was used as the working electrode, and 0.1 M NaOH was used as the electrolyte. Synthesis of Poly(vinylpyrrolidone)-Stabilized Pt Nanoparticles. Poly(vinylpyrrolidone) (PVP)-stabilized Pt nanoparticles were prepared following the procedure of the previous report with minor modifications.48 In a typical synthesis, 66.7 mg of PVP (MW ∼ 58 000) was fully dissolved in a mixed solution of H2PtCl6 (6.0 mM, 10 mL) and ethyl alcohol (90 mL) under vigorous magnetic stirring. Then the mixture was refluxed in a flask at 80 °C. After 3 h, ∼10 mL of concentrated suspension of PVP-stabilized Pt NPs was obtained by evaporating the solvent at 80 °C under air. Synthesis of Pt NPs@UiO-66 Heterostructures. Pt NPs@UiO-66 heterostructures were synthesized on the basis of the previous report with minor modifications.48 An 8.75 mM dimethylformamide (DMF) solution of ZrCl4 was first prepared by mixing the 0.2039 g of ZrCl4 and 100 mL of DMF under ultrasonication for 5 min. Subsequently, 5 mL of the above solution was mixed with 5 mL of DMF solution of benzenedicarboxylic acid (H2BDC; 8.01 mM) in a glass vial. And then 1.2 mL of acetic acid and the as-prepared PVPstabilized Pt NPs suspension (0.05, 0.1, or 0.2 mL) were quickly injected. Afterward, the reaction mixture was kept in an oven for 48 h at 120 °C without stirring and then cooled to room temperature. The product was collected by centrifugation and washed with DMF three times. After that, the obtained gray powder was soaked in alcohol at 60 °C for 3 days with replacing the soaking solvent every 24 h to exchange DMF. Finally, the product was washed three times with alcohol and dried at 80 °C in an oven. The obtained samples with different content of Pt NPs are denoted as Pt NPs@UiO-66-1, Pt NPs@ UiO-66-2, and Pt NPs@UiO-66-3, respectively. Synthesis of Pure UiO-66. Pure UiO-66 was synthesized following the same procedure as above except for not adding the PVP-stabilized Pt NPs suspension. Preparation of Pt NPs@UiO-66 Modified Electrode. A glassy carbon electrode (GCE) was polished using 0.05 μm alumina slurry on a polishing cloth to create a mirror finish. After that, the electrode was sonicated with absolute ethanol and double-distilled water for about 2 min, respectively. And then it was rinsed thoroughly with double-distilled water and dried under ambient temperature. At the same time, catalyst ink was prepared by mixing 2 mg of Pt NPs@UiO-66 powder and 1 mL of ethanol under sonication for 10 min. Then the asprepared catalyst ink was dropped on the GCE surface. Here, 5, 10, or 15 μL of catalyst ink was used for optimizing the mass loading of Pt NPs@UiO-66 heterostructures. After the electrode was dried in air, 3 μL of Nafion solution (0.5 wt %) was cast onto the surface of the Pt NPs@UiO-66 modified GC electrode and dried at room temperature.

electrochemical sensors, such as Cu(tpa)−MOF, Cu−BTC, Co−MOCP, and MIL-101.35−38 However, for pure MOFs, they are still faced with the problem of narrow linear range, low sensitivity, and insufficient anti-interference performance, especially for the interference species with high concentrations. Compared with pure MOFs, MOFs with other functional material heterostructures which were synthesized through incorporating different functional guest species into MOFs host matrixes provide the opportunity to achieve desired properties in different research areas, which largely expands the MOF-based applications.39−41 Especially, in the past few years, the core−shell heterostructure of metal nanoparticles and MOFs has been generating a considerable interest in the field of selective catalysis42,43 because the permeable channels and coordination nanospace of MOFs endow them with recognition effects like molecular sieves for the size-selective catalytic reactions.24 For example, Lu et al. synthesized the Pt@ZIF-8 core−shell composites by encapsulating the presynthesized Pt nanoparticles into the ZIF-8 host matrixes, which showed a good size catalytic performance for the liquid-phase hydrogenation of n-hexene and cis-cyclooctene.44 Zhan et al. prepared a ZnO@ZIF-8 core−shell heterostructure by the typical hydrothermal method and found its selective photoelectrochemical response to the ascorbic acid and H2O2 molecule.45 So far, controllable molecular-size selectivity as well as other valuable functions has been introduced into the core−shell nanostructural catalysis based on the tunable cavities and tailorable chemistry of the host matrix of MOFs.46 And the core−shell heterostructure of MOFs presents a promising potential in size-/shape-selective catalytic reactions. But there is extremely rare work on encapsulating noble metal NPs into the cavities of MOFs for the nonenzymatic electrochemical detection of small molecules with high selectivity. Herein, a good core−shell heterostructure of Pt NPs@UiO66 was fabricated through encapsulation of presynthesized Pt nanoparticles (Pt NPs) in the host matrix of UiO-66. As a zirconium-based MOF, the UiO-66 has high chemical and thermal stability based on the strong Zr−O bonds as well as the compact structure;47 besides, its triangular windows provide the narrow penetration channels with a diameter of 6 Å,24 which would allow the transit of small molecules only. Thus, UiO-66 was selected as the raw material to synthesize core−shell heterostructure for the selective detection of H2O2. The sensing performances of the Pt NPs@UiO-66 heterostructure toward H2O2 oxidation were investigated. The electrochemical measurements showed that the Pt NPs@UiO-66 heterostructure could be well-utilized as a nonenzymatic sensing material for the H2O2 detection with a wide linear range and high selectivity, providing a new opportunity to design the nonenzymatic sensor with enhanced anti-interference performance.

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EXPERIMENTAL DETAILS Reagents and Apparatus. All reagents were of analytical grade which were purchased from Tianjin Guangfu Fine Chemical Research Institute and used as received without further purification. The H2O2 disinfectant (3% H2O2, RunKang Pharmacy Limited Company, Lanzhou China) was used as real samples. The X-ray powder diffraction (XRD, a Rigaku D/Max-2400 diffractometer, Japan; monochromated Cu Kα radiation, k = 1.548 Å; 40.0 kV, 60.0 mA) was used to characterize the crystalline structure of the samples. Transmission electron microscopy (TEM) images were taken by a

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RESULTS AND DISCUSSION The XRD patterns of pure UiO-66, Pt NPs@UiO-66-1, Pt NPs@UiO-66-2, and Pt NPs@UiO-66-3 samples are shown in Figure 1. It can be seen that the peak positions of the experimental and simulated patterns of pure UiO-66 sample are in good agreement with each other except the peak at 12° 3439

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Figure 1. XRD patterns of pure UiO-66, Pt NPs@UiO-66-1, Pt NPs@ UiO-66-2, and Pt NPs@UiO-66-3 samples.

which could be also observed in other synthetic UiO-66.47,49,50 And the intensity of this peak weakens when the synthesis temperature is increased;51 it could be inferred that this peak is assigned to the DMF solvent molecules in the UiO-66 cavities. For the Pt NPs@UiO-66-1, Pt NPs@UiO-66-2, and Pt NPs@ UiO-66-3 samples, no visible reflections of Pt NPs were detected due to the low content of Pt NPs, while they showed the same reflections as the pure UiO-66 sample, which illustrated that the encapsulation of Pt NPs did not disrupt the crystal structure of UiO-66. The morphological character and microstructure of the assynthesized samples are shown in Figure 2. Figure 2a shows the TEM image of the Pt NPs. It can be seen that the Pt NPs are almost spherical and the diameter is about 2−3 nm. As can be observed from Figure 2b−e, the obtained UiO-66 MOFs resembled a squarelike shape with no or several Pt NPs residing at the center and no aggregation or morphological variation of the Pt NPs is observed after being encapsulated. And the number of Pt NPs encapsulated in each UiO-66 crystal is very different when the different amount of Pt NPs is added during synthesis process. In Figure 2b, no obvious Pt NPs could be observed for the Pt NPs@UiO-66-1 sample when 0.05 mL of Pt NPs suspension was added. With the volume of Pt NPs suspension being added up to 0.1 mL, it can be clearly observed that some well-dispersed Pt NPs were encapsulated in UiO-66 frameworks as shown in Figure 2c. Nevertheless, when the volume of Pt NPs suspension was further increased to 0.2 mL, not only the amount of Pt NPs has a sharp decline in UiO-66, but the diameter of UiO-66 crystal becomes small and the crystals are also aggregated with each other, as shown in Figure 2d. A possible reason for this change is that large amounts of Pt NPs will provide superabundant nucleation centers to result in the formation of many small UiO-66 crystals which encapsulated a few Pt NPs. And the large quantity of small crystals have not enough mother solution to grow into large regular octahedron crystals and gradually aggregate together because of the high surface energy compared to the large particles. Further studies on the fine microstructure of the Pt NPs were accomplished by means of high-resolution transmission electron microscopy (HRTEM).52 As shown in Figure 2e, the HRTEM image of Pt NPs encapsulated in UiO-66 crystal demonstrated that the 0.224 nm interplanar distance

Figure 2. TEM images of Pt NPs (a), Pt NPs@UiO-66-1 (b), Pt NPs@UiO-66-2 (c), and Pt NPs@UiO-66-3 (d), and HETEM image of Pt NPs in Pt NPs@UiO-66-2 sample (e).

matched well with the {111} lattice plane spacing of Pt crystal.53,54 The electrocatalytic activity of pure UiO-66 and different Pt NPs@UiO-66 modified GC electrodes (denoted by UiO-66/ GCE and Pt NPs@UiO-66/GCE) toward H2O2 oxidation was studied using the typical cyclic voltammetry (CV). For the pure UiO-66/GCE, as shown in Figure 3, there is a small current

Figure 3. Cyclic voltammetry curves (CVs) of the pure UiO-66 (a), Pt NPs@UiO-66-1 (b), Pt NPs@UiO-66-2 (c), and Pt NPs@UiO-66-3 (d) modified GC electrode in the absence (dotted line) and presence (solid line) of 2 mM H2O2 in 0.1 M NaOH solution recorded at scan rate of 20 mV/s. 3440

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Figure 4. (a) Amperometric response of the Pt NPs/UiO-66-2/GCE with successive addition of different concentrations of H2O2 at the potential of 0.85 V. Inset: a partial magnification of the current response toward a low concentration of H2O2 solution. (b) The calibration curves obtained from panel a.

increase after the addition of 2.0 mM H2O2 solution, indicating its limited electrocatalytic activity for H2O2 oxidation. Compared with the UiO-66/GCE, a remarkable increase of the anodic current could be observed for different Pt NPs@ UiO-66 sample modified GC electrodes. However, the highest oxidation current increase and the smallest onset potential of 0.32 V are observed for the Pt NPs@UiO-66-2/GCE, demonstrating its superior electrocatalytic activity and kinetics toward H2O2 oxidation compared with the other two sample modified GC electrodes. Additionally, upon the injection of H2O2 solution, the oxidation current increase presented in Pt NPs@UiO-66-3/GCE is only a bit higher than that of pure UiO-66/GCE. The different current responses presented in different samples could be mainly attributed to the two factors: the amount of encapsulated Pt NPs and the crystal morphology of the samples. Increasing the number of encapsulated Pt NPs would generate more catalytic centers toward H2O2 oxidation and thus be in favor of generating the higher current response.55,56 So the best electrocatalytic performance for H2O2 oxidation was obtained from Pt NPs@UiO-66-2/GCE because of its maximum amount of the encapsulated Pt NPs, which has been observed in TEM images. Besides, the crystal morphology of UiO-66 also has an important effect on current increase of H2O2 oxidation. For the Pt NPs@UiO-66-3/GCE, the crystal aggregation leads to some obstruction of the UiO-66 channels; as a result, the transmission of the H2O2 molecule from electrolyte solution to active sites of Pt NPs was disturbed or interdicted. Considering that the current response of the electrode is closely related to the applied potential,57 the potential optimization was performed using the Pt NPs@UiO-66-2/ GCE through a typical current−time (I−t) technique. As shown in Supporting Information Figure S-1, it can be seen that, with the applied potential being increased from 0.6 to 0.85 V, the current response was continuously increased and a sharp current response was obtained at 0.85 V. Subsequently, the current response continued increasing with the applied potential enhanced to 1.0 V; however, the background current also turned very large because of the supererogatory redox reactions such as the water splitting. So 0.85 V was adopted as the optimum potential in the following experiments. Compared with the pure Pt nanoparticles modified electrode on which the optimum potential is about 0.7 V for the oxidation of H2O2,58

the higher optimum potential on the Pt NPs@UiO-66-2/GCE may be due to the slower diffusion rate of H2O2 in the UiO-66. Moreover, the influence of the mass loading of Pt NPs@UiO66-2 sample on the current response was also investigated. As shown in Supporting Information Figure S-2, with the mass loading changing from 10 to 30 μg, the current response increased and reached a maximum at 20 μg. Thus, the mass loading of 20 μg was determined as the optimum experiment condition. Figure 4a shows the stable amperometric response of Pt NPs@UiO-66-2/GCE with successive addition of different concentrations of H2O2 into the stirring 0.1 M NaOH at the applied potential of 0.85 V with a time interval of 50 s. An arrestive tendency of the I−t curve is noted in that 95% of the steady-state current was obtained about 3 s after each of the addition of H2O2. It shows that the H2O2 molecule needs a certain time to move from electrolyte solution to active sites of encapsulated Pt NPs in the penetration process, which indirectly demonstrates that the Pt NPs were embedded into the inside rather than attached on the surface of the UiO-66 shell. The corresponding calibration curve of Pt NPs@UiO-662/GCE is shown in Figure 4b; it can be seen that this electrode displayed an extended linear range from 5 μM to 14.75 mM and the linear regression equation was I (μA cm−2) = 75.33C + 7.63 with a coefficient of determination of 0.999, which revealed the preeminent leaner relationship between the concentration of H2O2 and the responding current. The sensitivity of 75.33 μA mM−1 cm−2 was obtained, and the detection limit was calculated as 3.06 μM (S/N = 3). Compared with other nanocatalyst which were reported previously to detect H2O2, such as PtRu/3D graphene foam,58 Pt−MnO2/rGO paper,59 PtNP/AuNWs,60 the nanoporous alloy of PtAu13 or PdCr,61 etc., the Pt NPs@UiO-66-2 heterostructure presents an excellent sensing performance, especially the broader linear range with a high fitting degree, demonstrating its superiority to detect H2O2. The anti-interference performance toward other physiological species such as ascorbic acid (AA), uric acid (UA), and some carbohydrate compounds, which are possibly oxidized along with H2O2 molecules on the electrode surface to form interfering electrochemical signals during H2O2 oxidation, is one of the biggest concerns for a H2O2 electrochemical sensor. Thus, it is essential to investigate the effects of interferences on 3441

DOI: 10.1021/ac5047278 Anal. Chem. 2015, 87, 3438−3444

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Analytical Chemistry the current response of sensing materials for H2O2 oxidation. However, it is still a great challenge to find a good H2O2 sensing material which possesses an excellent anti-interference performance, especially when the concentration of interfering species is closed to that of H2O2. Attractively, as shown in Figure 5, the current responses of all the interferences were

Figure 6. I−t curve of Pt NPs@UiO-66-2/GCE in a stirring 0.1 M NaOH solution containing 1 mM H2O2 at 0.85 V.

evaluate the recovery capability of the Pt NPs@UiO-66-2/ GCE. As shown in Table 1, most of the recovery ratios for the Table 1. Determination of H2O2 in Disinfectant Sample by the Pt NPs@UiO-66-2/GCE Figure 5. Current response of Pt NPs@UiO-66-2/GCE to 0.5 mM H2O2 in the presence of 0.5 mM glucose, lactose, fructose, UA, and AA.

negligible compared with the sharp current increase of H2O2 even if the concentration proportion of H2O2 and interferences was adjusted to 1:1, demonstrating the inspiring antiinterference performance of Pt NPs/UiO-66-2/GCE. The high anti-interference performance is mainly benefited from the slender triangular channels being present in UiO-66, the pore size of which is too small to allow the permeation of big molecules, such as AA and UA, to the encapsulated Pt NPs surface. Therefore, the function of different chapters of the Pt NPs@UiO-66 heterostructure could be expounded that the core Pt NPs encapsulated in UiO-66 matrix provide plentiful active sites to catalyze the H2O2 oxidation reaction, so Pt NPs@ UiO-66 heterostructure presents much more stronger current response than the pure UiO-66 sample in electrochemical measurements, and the shell UiO-66 matrix avoids the aggregation of Pt NPs and could act as a sieve to selectively penetrate H2O2 molecules, so the Pt NPs@UiO-66 heterostructure presents a remarkable anti-interference performance in the H2O2 detection. The stability of the Pt NPs@UiO-66-2/GCE was investigated by monitoring its steady-state current response over a period of 1000 s in a stirring 1.0 mM H2O2 solution. As shown in Figure 6, 88% of the initial current is still retained after 1000 s, showing the good stability. In addition, three electrodes prepared with the same method for the reproducible measurement were investigated to compare the current response to 1 mM H2O2 in the same conditions and a relative standard deviation (RSD) of 4.5% was acquired, indicating a good reproducibility of the H2O2 sensor. In order to testify the feasibility of the proposed Pt NPs@ UiO-66-2/GCE for practical analysis, it was used in the recovery measurements to detect the H2O2 content in a disinfectant. After addition of some disinfectant samples in the electrolyte solution, the standard H2O2 solutions were spiked into the testing systems two times with an interval of 50 s to

sample of disinfectant

content c/(μM)

added c/(μM)

total after addition c/(μM)

recovery (%)

1

19.96

2

21.60

3

21.01

20.0 20.0 20.0 20.0 20.0 20.0

40.60 61.52 42.76 63.82 42.44 64.36

101.6 102.6 102.8 103.6 103.5 105.5

different disinfectant samples are between 100% and 104%. The low deviations indicate that this electrode is effective for the determination of H2O2 and enough to resist the interference effects in real sample analysis. On the basis of these results, this new Pt NPs@UiO-66-2/GCE shows a good potential in nonenzymatic detection of H2O2 in real samples.

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CONCLUSION In summary, the Pt NPs@UiO-66 core−shell heterostructure was fabricated through encapsulating presynthesized Pt NPs into the host matrix of UiO-66. The results showed that the Pt NPs@UiO-66-2 sample possessed a good crystalline structure with several well-dispersed Pt NPs being encapsulated in octahedron-like UiO-66 frameworks, which can provide multiple electroactive sites for redox reaction. The Pt NPs@ UiO-66-2 modified GC electrode showed remarkable electrocatalytic performance toward H2O2 oxidation, such as an excellent anti-interference performance and an extended linear range. Additionally, it also presented the good stability and reproducibility as well as a low detection limit. These characters indicate the superiority of MOFs in H2O2 detection, and it will create a new avenue to promote the anti-interference performance of the nonenzyme electrochemical sensors.

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ASSOCIATED CONTENT

S Supporting Information *

Additional information as noted in text. This material is available free of charge via the Internet at http://pubs.acs.org. 3442

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(24) Liu, J.; Chen, L.; Cui, H.; Zhang, J.; Zhang, L.; Su, C.-Y. Chem. Soc. Rev. 2014, 43, 6011−6061. (25) Farha, O. K.; Eryazici, I.; Jeong, N. C.; Hauser, B. G.; Wilmer, C. E.; Sarjeant, A. A.; Snurr, R. Q.; Nguyen, S. T.; Yazaydın, A. O.; Hupp, J. T. J. Am. Chem. Soc. 2012, 134, 15016−15021. (26) Huang, A.; Liu, Q.; Wang, N.; Zhu, Y.; Caro, J. J. Am. Chem. Soc. 2014, 136, 14686−14689. (27) Ranocchiari, M.; van Bokhoven, J. Phys. Chem. Chem. Phys. 2011, 13, 6388−6396. (28) Lee, J.; Farha, O. K.; Roberts, J.; Scheidt, K. A.; Nguyen, S. T.; Hupp, J. T. Chem. Soc. Rev. 2009, 38, 1450−1459. (29) Horcajada, P.; Chalati, T.; Serre, C.; Gillet, B.; Sebrie, C.; Baati, T.; Eubank, J. F.; Heurtaux, D.; Clayette, P.; Kreuz, C. Nat. Mater. 2010, 9, 172−178. (30) Yang, L.; Kinoshita, S.; Yamada, T.; Kanda, S.; Kitagawa, H.; Tokunaga, M.; Ishimoto, T.; Ogura, T.; Nagumo, R.; Miyamoto, A. Angew. Chem., Int. Ed. 2010, 122, 5476−5479. (31) Mao, J.; Yang, L.; Yu, P.; Wei, X.; Mao, L. Electrochem. Commun. 2012, 19, 29−31. (32) Bhaumik, A.; Wu, K. C.-W. Energy Environ. Sci. 2014, 7, 3574− 3592. (33) Vinogradov, A. V.; Zaake-Hertling, H.; Hey-Hawkins, E.; Agafonov, A. V.; Seisenbaeva, G.; Kessler, V.; Vinogradov, V. V. Chem. Commun. 2014, 50, 10210−10213. (34) Morozan, A.; Jaouen, F. Energy Environ. Sci. 2012, 5, 9269− 9290. (35) Wang, X.; Wang, Q.; Wang, Q.; Gao, F.; Gao, F.; Yang, Y.; Guo, H. ACS Appl. Mater. Interfaces 2014, 6, 11573−11580. (36) Zhang, Y.; Bo, X.; Luhana, C.; Wang, H.; Li, M.; Guo, L. Chem. Commun. 2013, 49, 6885−6887. (37) Yuan, B.; Zhang, R.; Jiao, X.; Li, J.; Shi, H.; Zhang, D. Electrochem. Commun. 2014, 40, 92−95. (38) Li, Y.; Huangfu, C.; Du, H.; Liu, W.; Li, Y.; Ye, J. J. Electroanal. Chem. 2013, 709, 65−69. (39) Liu, Y.; Zhang, W.; Li, S.; Cui, C.; Wu, J.; Chen, H.; Huo, F. Chem. Mater. 2014, 26, 1119−1125. (40) Sabo, M.; Henschel, A.; Fröde, H.; Klemm, E.; Kaskel, S. J. Mater. Chem. 2007, 17, 3827−3832. (41) Li, H.; Zhu, Z.; Zhang, F.; Xie, S.; Li, H.; Li, P.; Zhou, X. ACS Catal. 2011, 1, 1604−1612. (42) Yang, Y.; Wang, F.; Yang, Q.; Hu, Y.; Yan, H.; Chen, Y.-Z.; Liu, H.; Zhang, G.; Lu, J.; Jiang, H.-L. ACS Appl. Mater. Interfaces 2014, 6, 18163−18171. (43) Aijaz, A.; Xu, Q. J. Phys. Chem. Lett. 2014, 5, 1400−1411. (44) Lu, G.; Li, S.; Guo, Z.; Farha, O. K.; Hauser, B. G.; Qi, X.; Wang, Y.; Wang, X.; Han, S.; Liu, X. Nat. Chem. 2012, 4, 310−316. (45) Zhan, W.-w.; Kuang, Q.; Zhou, J.-z.; Kong, X.-j.; Xie, Z.-x.; Zheng, L.-s. J. Am. Chem. Soc. 2013, 135, 1926−1933. (46) Kuo, C.-H.; Tang, Y.; Chou, L.-Y.; Sneed, B. T.; Brodsky, C. N.; Zhao, Z.; Tsung, C.-K. J. Am. Chem. Soc. 2012, 134, 14345−14348. (47) Zhao, Q.; Yuan, W.; Liang, J.; Li, J. Int. J. Hydrogen Energy 2013, 38, 13104−13109. (48) Zhang, W.; Lu, G.; Cui, C.; Liu, Y.; Li, S.; Yan, W.; Xing, C.; Chi, Y. R.; Yang, Y.; Huo, F. Adv. Mater. 2014, 26, 4056−4060. (49) Cavka, J. H.; Jakobsen, S.; Olsbye, U.; Guillou, N.; Lamberti, C.; Bordiga, S.; Lillerud, K. P. J. Am. Chem. Soc. 2008, 130, 13850−13851. (50) Katz, M. J.; Brown, Z. J.; Colón, Y. J.; Siu, P. W.; Scheidt, K. A.; Snurr, R. Q.; Hupp, J. T.; Farha, O. K. Chem. Commun. 2013, 49, 9449−9451. (51) Shearer, G. C.; Chavan, S.; Ethiraj, J.; Vitillo, J. G.; Svelle, S.; Olsbye, U.; Lamberti, C.; Bordiga, S.; Lillerud, K. P. Chem. Mater. 2014, 26, 4068−4071. (52) Chen, L.; Peng, Y.; Wang, H.; Gu, Z.; Duan, C. Chem. Commun. 2014, 50, 8651−8654. (53) Yu, W.; Porosoff, M. D.; Chen, J. G. Chem. Rev. 2012, 112, 5780−5817. (54) Bragaru, A.; Vasile, E.; Obreja, C.; Kusko, M.; Danila, M.; Radoi, A. Mater. Chem. Phys. 2014, 146, 538−544.

AUTHOR INFORMATION

Corresponding Author

*Phone: +86-931-891-2589. Fax: +86-931-891-2582. E-mail: [email protected]. Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS This work was supported by grants from the National Science Foundation for Fostering Talents in Basic Research of the National Natural Science Foundation of China (Grant No. J1103307), the Basic Scientific Research Business Expenses of the Central University and Open Project of Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University (LZUMMM2014001 and LZUMMM2014014), the Fundamental Research Funds for the Central University (lzujbky-2014-189), and the Science and Technology Program of Gansu Province of China (145RJZA176).

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REFERENCES

(1) Toniolo, R.; Dossi, N.; Pizzariello, A.; Susmel, S.; Bontempelli, G. Electroanalysis 2011, 23, 628−636. (2) Tang, D.; Yuan, R.; Chai, Y. Electroanalysis 2006, 18, 259−266. (3) Marimuthu, T.; Mahmoudian, M.; Mohamad, S.; Alias, Y. Sens. Actuators, B 2014, 202, 1037−1043. (4) Gaynor, J. D.; Karakoti, A. S.; Inerbaev, T.; Sanghavi, S.; Nachimuthu, P.; Shutthanandan, V.; Seal, S.; Thevuthasan, S. J. Mater. Chem. B 2013, 1, 3443−3450. (5) Wu, H.; Fan, S.; Jin, X.; Zhang, H.; Chen, H.; Dai, Z.; Zou, X. Anal. Chem. 2014, 86, 6285−6290. (6) Meng, L.; Jin, J.; Yang, G.; Lu, T.; Zhang, H.; Cai, C. Anal. Chem. 2009, 81, 7271−7280. (7) Jou, A. F.-j.; Tai, N.-H.; Ho, J.-a. A. Electroanalysis 2014, 26, 1816−1823. (8) Zheng, M.; Li, P.; Yang, C.; Zhu, H.; Chen, Y.; Tang, Y.; Zhou, Y.; Lu, T. Analyst 2012, 137, 1182−1189. (9) You, J.-M.; Jeong, Y. N.; Ahmed, M. S.; Kim, S. K.; Choi, H. C.; Jeon, S. Biosens. Bioelectron. 2011, 26, 2287−2291. (10) Su, J.; Gao, F.; Gu, Z.; Pien, M.; Sun, H. Sens. Actuators, B 2013, 181, 57−64. (11) Li, Y.; Lu, Q.; Wu, S.; Wang, L.; Shi, X. Biosens. Bioelectron. 2013, 41, 576−581. (12) Noh, H.-B.; Lee, K.-S.; Chandra, P.; Won, M.-S.; Shim, Y.-B. Electrochim. Acta 2012, 61, 36−43. (13) Wang, J.; Gao, H.; Sun, F.; Xu, C. Sens. Actuators, B 2014, 191, 612−618. (14) Li, Z.; Li, R.; Mu, T.; Luan, Y. Chem.Eur. J. 2013, 19, 6005− 6013. (15) Xu, F.; Deng, M.; Li, G.; Chen, S.; Wang, L. Electrochim. Acta 2013, 88, 59−65. (16) Yang, Y. J.; Zi, J.; Li, W. Electrochim. Acta 2014, 115, 126−130. (17) Dantas, L.; Castro, P.; Peña, R.; Bertotti, M. Anal. Methods 2014, 6, 2112−2116. (18) Ensafi, A. A.; Abarghoui, M. M.; Rezaei, B. Sens. Actuators, B 2014, 196, 398−405. (19) Lin, K.-C.; Tsai, T.-H.; Chen, S.-M. Biosens. Bioelectron. 2010, 26, 608−614. (20) Wang, J.; Wang, Z.; Zhao, D.; Xu, C. Anal. Chim. Acta 2014, 832, 34−43. (21) Yaghi, O.; Li, H. J. Am. Chem. Soc. 1995, 117, 10401−10402. (22) Yaghi, O. M.; Li, G.; Li, H. Nature 1995, 378, 703−706. (23) Hod, I.; Bury, W.; Karlin, D. M.; Deria, P.; Kung, C. W.; Katz, M. J.; So, M.; Klahr, B.; Jin, D.; Chung, Y. W. Adv. Mater. 2014, 26, 6295−6300. 3443

DOI: 10.1021/ac5047278 Anal. Chem. 2015, 87, 3438−3444

Article

Analytical Chemistry (55) Huo, H.; Guo, C.; Li, G.; Han, X.; Xu, C. RSC Adv. 2014, 4, 20459−20465. (56) Karam, P.; Halaoui, L. I. Anal. Chem. 2008, 80, 5441−5448. (57) Guo, C.; Huo, H.; Han, X.; Xu, C.; Li, H. Anal. Chem. 2013, 86, 876−883. (58) Kung, C.-C.; Lin, P.-Y.; Buse, F. J.; Xue, Y.; Yu, X.; Dai, L.; Liu, C.-C. Biosens. Bioelectron. 2014, 52, 1−7. (59) Xiao, F.; Li, Y.; Zan, X.; Liao, K.; Xu, R.; Duan, H. Adv. Funct. Mater. 2012, 22, 2487−2494. (60) Jamal, M.; Xu, J.; Razeeb, K. M. Biosens. Bioelectron. 2010, 26, 1420−1424. (61) Zhao, D.; Wang, Z.; Wang, J.; Xu, C. J. Mater. Chem. B 2014, 2, 5195−5201.

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DOI: 10.1021/ac5047278 Anal. Chem. 2015, 87, 3438−3444