A self-powered sensor based on molecularly imprinted polymer-coupled graphitic carbon nitride photoanode for selective detection of bisphenol A

Sensors and Actuators B 259 (2018) 394–401

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Sensors and Actuators B: Chemical journal homepage: www.elsevier.com/locate/snb

A self-powered sensor based on molecularly imprinted polymer-coupled graphitic carbon nitride photoanode for selective detection of bisphenol A Kai Yan, Yaohua Yang, Jingdong Zhang ∗ Key laboratory of Material Chemistry for Energy Conversion and Storage (Ministry of Education), School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan 430074, PR China

a r t i c l e

i n f o

Article history: Received 10 August 2017 Received in revised form 17 November 2017 Accepted 13 December 2017 Available online 14 December 2017 Keywords: Self-powered sensor Photofuel cell Graphitic carbon nitride Molecularly imprinted polymer Bisphenol A

a b s t r a c t A visible light-induced self-powered sensor for selective detection of bisphenol A (BPA) based on photofuel cell (PFC) was proposed. The PFC was constructed with a Pt cathode and a photoanode which was prepared by modifying fluoride doped tin oxide (FTO) electrode with graphitic carbon nitride (g-C3 N4 ) and molecularly imprinted polymer (MIP). The MIP/g-C3 N4 /FTO photoanode possessed high photoelectrocatalytic activity of g-C3 N4 and binding ability of MIP towards BPA. Under visible light illumination, the PFC generated different output power densities towards varied concentrations of BPA, and thus it was proposed as a self-powered sensor for BPA. The maximum output power density of the sensor was linearly proportional to the logarithm of BPA concentration ranging from 5 to 100 ␮mol L−1 . Moreover, the proposed self-powered sensor exhibited good selectivity, reproducibility and stability for BPA detection. © 2017 Elsevier B.V. All rights reserved.

1. Introduction Bisphenol A (BPA), namely 4,4 -(1-methylethylethylidene) bisphenol, is an important organic compound widely used as a monomer in the production of polycarbonate and epoxy resin [1,2]. However, the release of BPA from plastic products into the environment has threatened the human beings’ health [3]. It has been reported that BPA could interact with estrogen receptors [4] and act as a typical estrogenic endocrine interferon [5]. Human exposure to BPA is linked to cardiovascular diseases, liver abnormalities, adverse effects on the reproductive system, and obesity [6]. Thus, it is of great significance to develop highly sensitive and selective strategies to detect BPA in water samples. Different methods such as high performance liquid chromatography (HPLC) [7], gas chromatography coupled with mass spectrometry (GC–MS) [8], capillary electrophoresis [9], enzyme linked immunosorbent assays (ELISA) [10], electroanalysis [11] and photoelectrochemical sensing [12] have been developed for BPA detection. Photocatalysis is a representative advanced oxidation process for effective degradation of BPA and other organic pollutants

∗ Corresponding author. E-mail address: [email protected] (J. Zhang). https://doi.org/10.1016/j.snb.2017.12.075 0925-4005/© 2017 Elsevier B.V. All rights reserved.

[13–15]. Since photocatalytic oxidation process could generate electricity, photofuel cell (PFC) using organic compounds as fuel has been considered as a promising device for simultaneous pollutant removal and electricity generation [16–19]. Recently, our group has successfully fabricated PFC devices for developing self-powered sensors which could directly provide the responsive signal for sensing without using external electric source [20,21]. Compared to previously reported enzymatic self-powered sensors [22], the PFCbased sensor can effectively avoid the drawbacks of enzyme such as short durability and instability. However, unlike the high specificity of enzyme, photocatalyst can induce the reactions of many compounds [23], which limits the selectivity of PFC-based sensor. Molecularly imprinted polymers (MIPs) are artificial recognition materials which have been extensively introduced in various sensing platforms to improve the selectivity of detection [24–26]. Compared with biological recognition elements such as antibodies, aptamers and enzymes, MIPs have several advantages including low cost, high storage stability, easy preparation and applicability in harsh chemical media [27]. So far, BPA-binding MIPs have been successfully synthesized and employed to fabricate fluorescent [28], electrochemical [29], and photoelectrochemical [30] sensors for selective detection of BPA. In the present work, we proposed a novel self-powered sensor for selective detection of BPA based on MIP-coupled PFC.

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Recently, we have proposed an enzyme-free self-powered sensor for glucose detection based on a glucose-H2 O2 PFC consisting of a Ni(OH)2 /CdS/TiO2 photoanode and a hemin-graphene nanocomposite coated cathode [20]. Furthermore, to simply the configuration of electrodes, we have designed a glucose-air PFC constructed with a Ni(OH)2 /TiO2 photoanode and a Pt cathode [21]. However, both sensors were developed for glucose sensing by utilizing the catalytic activity of Ni(OH)2 toward the oxidation of glucose. In the present work, in order to broaden the PFC-based self-powered sensors to detection of environmental pollutants represented by BPA, we synthesized graphitic carbon nitride (g-C3 N4 ), a metal-free semiconductor with narrow band gap, to serve as visible light-responsive material for construction of PFC. Actually, due to its eco-friendly preparation and superior photoelectric properties [31,32], g-C3 N4 has been intensively explored as outstanding photocatalyst for degradation of pollutants and photoelectrochemical sensing [33–35]. Herein g-C3 N4 was incorporated with MIP to fabricate a PFC possessing good selectivity, which could generate suitable power output under visible light illumination to drive the sensing process of BPA. 2. Experimental 2.1. Preparation of molecularly imprinted polymer MIP was prepared according to previous reports [36,37]. Briefly, 0.228 g BPA and 430 ␮L 4-vinylpyridine (4-VP) were dissolved in 30 mL acetonitrile. The mixture was sealed and stirred for 60 min to assure the fully reaction of template molecule and the functional monomer. Then, 3.8 mL ethylene glycol dimethacrylate (EGDMA) as cross liker and 50 mg 2,2-azo-bis-iso-butyronitrile (AIBN) as radical initiator were added successively to the solution. Meanwhile, nitrogen gas was purged into the system for removal of oxygen. Subsequently, the reaction vessel was sealed and transferred to water bath at 60 ◦ C. After polymerization for 24 h, the resulting polymer was dried and pulverized in a mortar. Regular-sized particles between 37.5 ␮m and 70.0 ␮m were obtained using different mesh sieves. Afterwards, the polymer particles were washed to remove template (BPA) molecules using an extraction solvent mixture of methanol and acetic acid (9:1 v/v) for 48 h in a Soxhlet apparatus. Then, the polymers were washed with methanol for 12 h and dried at 60 ◦ C in a vacuum oven. Non-imprinted polymer (NIP) was prepared in the same way without the addition of the template molecule. 2.2. Static adsorption experiments The static adsorption experiments were carried out in brown sample bottles containing 10 mL methanol solution of BPA at different initial concentrations (C0 ). Then, 50 mg MIP was added into the each solution. After shaking for 12 h, the adsorption equilibrium was reached and the residual concentration (Cs ) of BPA in the solution was determined using a TU-1900 UV–vis spectrophotometer (Beijing Purkinje General Instrument Company, China). The equilibrium adsorption capacity (Q) was calculated according to Q = V(C0 − Cs )/m, where m is the mass of MIP and V is the volume of reaction solution. The adsorption capacity test time was 12 h. All the adsorption experiments were repeated three times. For comparison, the static adsorption experiments for NIP were also carried out using NIP instead of MIP. 2.3. Electrode modification The water-dispersible g-C3 N4 was synthesized according to our previous reports [38,39], and a g-C3 N4 suspension was prepared by dispersing 6 mg g-C3 N4 in 3 mL water under sonication.

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Prior to modification, the fluoride doped tin oxide (FTO) glass substrate (NSG, Japan) was cleaned by sonication in acetone, mixed solution of ethanol and 2 mol L−1 NaOH (v/v, 1:1), and pure water for 20 min, respectively. After being dried with nitrogen gas, the electrode was sealed with Scotch tape with an exposed geometric area of 0.159 cm2 . Then, 20 ␮L of g-C3 N4 suspension was dropped onto the exposed surface of FTO and dried at 60 ◦ C to obtain a gC3 N4 /FTO electrode. For preparation of MIP/g-C3 N4 /FTO, 6 ␮L of MIP suspension (1.0 mg/mL in DMF) was coated on the g-C3 N4 /FTO electrode surface and dried at 60 ◦ C. The NIP/g-C3 N4 /FTO was prepared in the same procedure using the NIP suspension. 2.4. Construction of photofuel cell The PFC was constructed with a prepared photoanode and a Pt cathode (Pt foil, 1 cm × 1 cm) in a two-compartment photoelectrochemical cell separated by a Nafion 117 membrane. In both chambers, 0.1 mol L−1 PBS (pH 7.4) served as the supporting electrolyte; whereas the analyte of BPA was only present in anodic chamber. Moreover, the anodic chamber of the cell had a quartz window to allow the illumination from the light source on the anode. A portable violet laser pen with a power of 20 mW at 405 nm and a diameter of ca. 3 mm for the illumination area served as the visible light source. 2.5. Apparatus The surface morphology was characterized by a Quanta 200 field emission scanning electron microscope (FE-SEM) (FEI, The Netherlands). The crystalline phase was analyzed by X-ray diffraction (XRD, Bruker Instruments, Germany) using Cu K␣ radiation. The UV–vis diffuse reflectance spectrum (DRS) was collected on a UV-2550 spectrophotometer (Shimadzu, Japan). Cyclic voltammetric (CV) and electrochemical impedance spectroscopic (EIS) measurements were carried out on a CHI 660A electrochemical workstation (Chenhua Instrument Co., Shanghai, China) in a conventional three-electrode cell. A modified electrode, a saturated calomel electrode (SCE), and a platinum wire were employed as the working, reference and counter electrodes, respectively. 3. Results and discussion 3.1. Characterization of g-C3 N4 and MIP The morphology of the synthesized g-C3 N4 was characterized by SEM. As can be seen in Fig. 1A, g-C3 N4 displays a typical stacked layered structure, consistent with the previous observation [35,38]. Meanwhile, the crystalline nature of g-C3 N4 was analyzed by XRD. As shown in Fig. 1B, the prepared g-C3 N4 exhibits two characteristic diffraction peaks at 13.0◦ and 27.3◦ , which can be assigned to the in-plane structural packing motif of tris-triazine units and interlayer-stacking of the conjugated aromatic groups, respectively [40]. Moreover, the UV–vis diffuse reflectance spectrum of g-C3 N4 was recorded (Fig. 1C). The result indicates that the as-prepared g-C3 N4 exhibits an absorption edge at ca. 460 nm, demonstrating that g-C3 N4 could efficiently absorb visible light to induce photogenerated electron-hole pairs. On the other hand, the prepared MIP was also characterized by SEM. As can be seen, MIP exhibits a morphological structure of porous film consisting of many particles in the sizes between 200 nm and 400 nm (Fig. 2A.) By comparison, the NIP film looks more compact than MIP film, although their morphological structures are similar (Fig. 2B). Furthermore, we investigated the adsorption capacity of MIP for BPA at different initial concentrations ranging from 0.25 mmol L−1 to 5 mmol L−1 . As shown in Fig. 2C, the adsorption capacity of MIP increases as the initial

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Fig. 1. (A) SEM image, (B) XRD and (C) UV–vis DRS of g-C3 N4 .

BPA concentration increased to 2.5 mmol L−1 . When the concentration of BPA further increases above 2.5 mmol L−1 , the adsorption of BPA on MIP tends to be saturated and balanced. Accordingly, the saturation adsorption capacity of MIP for BPA is calculated to be 64 ␮mol g−1 . Likewise, the saturation adsorption capacity of NIP for BPA is determined to be 38 ␮mol g−1 , obviously lower than that of MIP. This result demonstrates that the obtained MIP has much stronger binding ability for BPA adsorption than NIP. 3.2. Electrochemical and photoelectrochemical studies of modified electrodes In order to monitor the template removal of the prepared MIP, the CV curves for NIP/g-C3 N4 and MIP/g-C3 N4 modified electrodes were recorded in 0.1 mol L−1 PBS (pH 7.4). The result indicates that

Fig. 2. SEM images of (A) MIP and (B) NIP. (C) Adsorption curves of MIP and NIP. Error bars were derived from the standard deviation of three measurements.

NIP/g-C3 N4 electrode does not show noticeable Faradaic current in the potential range of 0.2–1.2 V (curve a in Fig. 3A), meaning the absence of electroactive compound in NIP. In contrast, when MIP before elution is used instead of NIP to modify the g-C3 N4 electrode, a strong anodic peak around 0.9 V assigned to electrochemical oxidation of BPA appears in the CV curve (curve b in Fig. 3A), indicating that BPA molecules are trapped in the polymer. While MIP after elution is employed to modify the electrode, the oxidation peak of BPA disappears (curve c in Fig. 3A), confirming that template BPA molecules are effectively removed from MIP using the proposed elution procedure. Moreover, we studied the electrochemical impedance spectra (EIS) of different modified electrodes in 0.1 mol L−1 KCl contain-

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of bare FTO is 601 . When g-C3 N4 is modified on the electrode surface, the Ret is increased to 890 , due to the poor conductivity of g-C3 N4 . After further assembly of MIP or NIP on the surfaces of g-C3 N4 electrode, the Ret value is increased to 1260  or 1600 , indicating that nonconductive MIP and NIP macromolecules hinder the electron transfer between the redox probe of [Fe(CN)6 ]3−/4− and electrode [41]. Furthermore, the Ret value of NIP modified electrode is higher than that of MIP modified electrode, ascribed to the fact that large numbers of imprinted cavities in MIP allow the diffusion and electron transfer of redox probe on the electrode surface [42]. Meanwhile, we recorded the CV curves for 0.2 mmol L−1 BPA on MIP/g-C3 N4 /FTO and g-C3 N4 /FTO electrodes in the dark and under visible light illumination to study the photoelectrochemical behaviors of BPA on the modified electrodes. As illustrated in Fig. 3C, in the dark, an anodic peak of BPA appears at ca. 0.9 V on the g-C3 N4 /FTO electrode while the peak current is enhanced on the MIP/g-C3 N4 /FTO electrode, indicating the enrichment of BPA on electrode surface by MIP. When the MIP/g-C3 N4 /FTO electrode is irradiated with light, a dramatic enhancement in the oxidation peak current of BPA is observed (curve c in Fig. 3C), similar to our previous reports on the photoelectrocatalytic oxidation of glucose [20] and p-phenylenediamine [43]. This phenomenon reveals high photoelectrocatalytic activity of the proposed MIP/gC3 N4 /FTO photoanode for oxidation of BPA, which provides the basis for construction of BPA-air PFC. 3.3. Construction of PFC

Fig. 3. (A) CV curves recorded in 0.1 mol L−1 PBS (pH 7.4) on (a) NIP/g-C3 N4 /FTO and MIP/g-C3 N4 /FTO (b) before and (c) after elution. (B) Experimental (symbols) and fitted (solid lines) EIS data of (a) FTO electrode, (b) g-C3 N4 /FTO electrode, (c) MIP/gC3 N4 /FTO, and (d) NIP/g-C3 N4 /FTO electrode in 0.1 mol L−1 KCl solution containing 5 mmol L−1 [Fe(CN)6 ]3−/4− . The frequency range is between 0.1 and 100 000 Hz with applied voltage of 0.2 V. The inset represents the corresponding equivalent circuit (Rs = solution resistance, Ret = electron transfer resistance, W = Warburg impedance, CPE = constant phase element). (C) CV curves recorded in 0.1 mol L−1 PBS (pH 7.4) containing 0.2 mmol L−1 BPA on (a) g-C3 N4 /FTO and (b, c) MIP/g-C3 N4 /FTO (a, b) in the dark and (c) under light illumination. Scan rate: 50 mV/s.

ing 5 mmol L−1 [Fe(CN)6 ]3−/4− to characterize the electron transfer properties at the electrode-solution interfaces. Fig. 3B shows the experimental and fitted Nyquist plots of various electrodes and the corresponding equivalent circuit. According to the semicircle diameter in the Nyquist plot, the electron transfer resistance (Ret )

Prior to construction of PFC, the polarization curves for MIP/gC3 N4 /FTO photoanode and Pt cathode were studied to examine the thermodynamic feasibility of the proposed PFC. As shown in Fig. 4A, an onset anodic potential appears at ca. −0.024 V on MIP/gC3 N4 /FTO photoanode in the presence of BPA under illumination, while the electrocatalytic reduction of oxygen at Pt cathode starts at 0.25 V. That is, the photoanode oxidizes BPA promptly at a low potential while the cathode catalyzes the reduction of O2 at a high potential, confirming the feasibility of the establishment of the PFC [44]. The output performances of PFCs fabricated with different photoanodes were evaluated by recording the dependences of power density on the cell current (P–I curves, Fig. 4B), using 50 ␮mol L−1 BPA as fuel in anodic chamber. As illustrated in Fig. 4B, the maximum output power density (PMax ) for g-C3 N4 /FTO photoanode-based PFC reaches 0.091 ␮W cm−2 (curve a in Fig. 4B). When MIP/g-C3 N4 /FTO is employed instead of g-C3 N4 /FTO as the photoanode, the PMax of the PFC decreases slightly (curve b in Fig. 4B). This should be attributed to the hindrance of nonconductive MIP to electron transfer and light transmission, despite that the introduction of MIP is favorable to the adsorption of BPA on the photoanode surface. While NIP/g-C3 N4 /FTO is employed to construct PFC, the PMax decreases obviously (curve c in Fig. 4B), owing to the fact that NIP provides few cavities for BPA binding. Accordingly, considering that MIP had the specificity to bind BPA and MIP/gC3 N4 /FTO photoanode-based PFC could generate higher output, we explored such a MIP-coupled PFC to develop a self-powered sensor for selective detection of BPA. 3.4. Self-powered sensing of BPA Fig. 5A illustrates the P-I curves of the MIP/g-C3 N4 /FTO-based PFC with different BPA concentrations in anodic chamber. The PMax is found to increase linearly with the logarithm of BPA concentration from 5 to 100 ␮mol L−1 (Fig. 5B). The linear regression equation can be expressed as PMax /␮W cm−2 = 0.0095lgc/␮mol L−1 –0.0018 (correlation coefficient R = 0.998). According to the standard deviation of the blank (SDblank ) derived from six measurements of blank

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Table 1 Comparison of different electrochemical BPA sensors. Sensor a

Tyrosinase/poly(thionine)/GCE Tyrosinase/BDDb carbon nanohorns-Nafion/GCE Graphene-Ionic Liquid/GCE Au/Gr–AuCu/gold electrode MIP/g-C3 N4 /FTO a b

Linear range (␮mol L−1 )

Limit of detection (␮mol L−1 )

Ref.

23–400 1–100 2–1000 20–1000 0.1–20 5–200

23 1 1.8 0.19 1.91 1.3

[51] [52] [53] [54] [55] This work

GCE is abbreviated from glass carbon electrode. BDD is abbreviated from boron-doped diamond electrode.

Fig. 4. (A) Polarization curves for (a) photoanode recorded in 0.1 M PBS (pH 7.4) containing 0.1 mmol L−1 BPA on MIP/g-C3 N4 /FTO under illumination and (b) cathode in air-saturated 0.1 M PBS (pH 7.4) on Pt. Scan rate: 2 mV/s. (B) P–I curves of PFCs constructed with (a) g-C3 N4 /FTO, (b) MIP/g-C3 N4 /FTO, and (c) NIP/g-C3 N4 /FTO photoanodes using 50 ␮mol L−1 BPA as fuel in anodic chamber.

Fig. 5. (A) P–I curves of the proposed MIP/g-C3 N4 /FTO-based PFC in the presence of BPA at different concentrations (curve a–e: 5, 10, 20, 50, 100 ␮mol L−1 ) in anodic chamber. (B) Linear relationship between PMax and the logarithm of BPA concentration. Error bars were derived from the standard deviation of three measurements.

signal and the slope of linear regression equation, the limit of detection (LOD) calculated as (3 × SDblank )/slope [45] is 1.3 ␮mol L−1 . Compared with most of previously reported electrochemical methods for BPA determination (Table 1), the present self-powered sensor shows a lower LOD with acceptable linear range. The selectivity of the proposed self-powered sensor for detection of 50 ␮mol L−1 BPA was examined by adding 20-fold concentration of some common inorganic ions that might be present in water such as K+ , Ca2+ , Mg2+ , Al3+ , Zn2+ , CO3 2− , NO3 − , SO4 2− and Cl− . The results indicate that these inorganic species have no influence on BPA determination. Moreover, the responses of

the sensor toward 50 ␮mol L−1 BPA in the presence of several organic compounds with similar molecular structures such as phenol, hydroquinone (HQ), tetrabromobisphenol A (TBBPA) and o-aminophenol (o-AMP) at 100 ␮mol L−1 were also studied. As can be seen in Fig. 6A, these species do not cause obvious interference in the sensing of BPA, showing that the sensor has a good selectivity, which can be attributed to the recognition ability of MIP towards BPA. Nevertheless, the PMax value of the sensor toward 50 ␮mol L−1 BPA was increased by ca. 20% after all of these four organic compounds were mixed with BPA solution in the electrolyte. This

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Table 2 Determination of BPA in real bottled water using the proposed method. Sample

Spiked (␮mol L−1 )

Found (␮mol L−1 )

Recovery (%)

RSD (%)

Bottled water

0 10.00 20.00

– 9.57 20.44

– 95.7 102.2

– 1.8 1.4

after 15 days, showing a high stability. Compared with a previously reported enzyme-based sensor which remains ca. 88% of its original signal after the storage of 15 days [50], the present PFC-based sensor shows higher stability, attributed to the fact that PFC can efficiently avoid the short durability and instability originating from the intrinsic nature of enzymes. Additionally, the applicability of the proposed BPA sensor was assessed in real sample using the standard addition method. Since BPA could spread into water from plastics, mineral water samples in plastic bottles were analyzed using the standard addition method. Table 2 shows the analytical results of the proposed method for BPA sensing in spiked water samples. The recoveries of BPA are in the range of 95.7%–102.2%. The average recovery of 98.9% reveals that the developed method is of good accuracy and reliability in practical applications. 4. Conclusions A novel self-powered sensor for selective detection of BPA was proposed based on a visible light-induced PFC consisting of a MIP/gC3 N4 /FTO photoanode and a Pt cathode. In such a sensor, BPA molecules were specifically recognized by MIP and oxidized on MIP/g-C3 N4 /FTO photoanode under photoirradiation to generate electricity. The maximum output power density of the constructed PFC was found to provide a responsive signal to the concentration of BPA from 5 to 100 ␮mol L−1 , without using external electric source. Moreover, the proposed sensor exhibited good selectivity, demonstrating the potential of MIP-coupled PFC in the development of self-powered sensors for selective detection of pollutants. Acknowledgements

−1 Fig. 6. (A) NormalizedPMax of  the proposed PFC towards 50 ␮mol L BPA obtained

0 ’ ) and after PMax before (PMax

adding 100 ␮mol L−1 phenol, HQ, TBBPA and o-AMP.

(B) Normalized PMax of the proposed PFC towards 50 ␮mol L−1 BPA obtained before 0 ” ) and after (PMax ) storing the photoelectrodes in 4 ◦ C for different days. Error (PMax bars were derived from the standard deviation of three measurements.

should arise from the non-specific adsorption of organic species on the photoanode. Therefore, these interfering compounds should be separated from BPA prior to analysis if they coexist in water sample. Alternatively, the selectivity of the sensor can be further improved by coupling molecularly imprinted technology with solid phase extraction [46–48], ascribed to the specific preconcentrating process. Moreover, some biological recognition elements such as aptamer [12] and enzyme [49] that have specific interactions with the analyte can also be used to improve the selectivity. The reproducibility of the self-powered sensor was evaluated. The relative standard deviation (RSD) of the responses for detection of 50 ␮mol L−1 BPA using six independently prepared PFC is 5.7%, suggesting a good reproducibility. Moreover, we investigated the stability of the developed sensor by checking the PMax response of the fabricated PFC towards 50 ␮M BPA every 3 days. The MIP/gC3 N4 /FTO photoanodes were stored at 4 ◦ C before test. As shown in Fig. 6B, the PFC still retains 94.6% of its original PMax response

This work was supported by the National Natural Science Foundation of China (Grant No. 61571198), the opening fund of Hubei Key Laboratory of Bioinorganic Chemistry & Materia Medica (Grant No. BCMM201704), and Graduates’ Innovation Fund of Huazhong University of Science and Technology (Grant No. 5003013001). We also thank the Analytical and Testing Center of Huazhong University of Science and Technology for help in materials characterization. References [1] J. Im, F.E. Löffler, Fate of bisphenol A in terrestrial and aquatic environments, Environ. Sci. Technol. 50 (2016) 8403–8416. [2] A. Schecter, N. Malik, D. Haffner, S. Smith, T.R. Harris, O. Paepke, L. Birnbaum, Bisphenol A (BPA) in U.S. food, Environ. Sci. Technol. 44 (2010) 9425–9430. [3] F. Wang, J. Yang, K. Wu, Mesoporous silica-based electrochemical sensor for sensitive determination of environmental hormone bisphenol A, Anal. Chim. Acta 638 (2009) 23–28. [4] D. Khan, S.A. Ahmed, Epigenetic regulation of non-lymphoid cells by bisphenol A, a model endocrine disrupter: potential implications for immunoregulation, Front. Endocrinol. 6 (2015) 91. [5] J.A. Rogers, L. Metz, V.W. Yong, Review endocrine disrupting chemicals and immune responses: a focus on bisphenol-A and its potential mechanisms, Mol. Immunol. 53 (2013) 421–430. [6] A. Myridakis, G. Chalkiadaki, M. Fotou, M. Kogevinas, L. Chatzi, E.G. Stephanou, Exposure of preschool-age greek children (RHEA Cohort) to bisphenol A parabens, phthalates, and organophosphates, Environ. Sci. Technol. 50 (2016) 932–941.

400

K. Yan et al. / Sensors and Actuators B 259 (2018) 394–401

[7] M. Rezaee, Y. Yamini, S. Shariati, A. Esrafili, M. Shamsipur, Dispersive liquid–liquid microextraction combined with high-performance liquid chromatography-UV detection as a very simple, rapid and sensitive method for the determination of bisphenol A in water samples, J. Chromatogr. A 1216 (2009) 1511–1514. [8] Z. Kuklenyik, J. Ekong, C.D. Cutchins, L.L. Needham, A.M. Calafat, Simultaneous measurement of urinary bisphenol A and alkylphenols by automated solid-phase extractive derivatization gas chromatography/mass spectrometry, Anal. Chem. 75 (2003) 6820–6825. [9] S. Alsudir, Z. Iqbal, E.P. Lai, Competitive CE-UV binding tests for selective recognition of bisphenol A by molecularly imprinted polymer particles, Electrophoresis 33 (2012) 1255–1262. [10] W. Miao, B. Wei, R. Yang, C. Wu, D. Lou, W. Jiang, Z. Zhou, Highly specific and sensitive detection of bisphenol A in water samples using an enzyme-linked immunosorbent assay employing a novel synthetic antigen, New J. Chem. 38 (2014) 669–675. [11] J.Y. Wang, Y.L. Su, B.H. Wu, S.H. Cheng, Reusable electrochemical sensor for bisphenol A based on ionic liquid functionalized conducting polymer platform, Talanta 147 (2016) 103–110. [12] Y. Qiao, J. Li, H. Li, H. Fang, D. Fan, W. Wang, A label-free photoelectrochemical aptasensor for bisphenol A based on surface plasmon resonance of gold nanoparticle-sensitized ZnO nanopencils, Biosens. Bioelectron. 86 (2016) 315–320. [13] Y. Kanigaridou, A. Petala, Z. Frontistis, M. Antonopoulou, M. Solakidou, I. Konstantinou, Y. Deligiannakis, D. Mantzavinos, D.I. Kondarides, Solar photocatalytic degradation of bisphenol A with CuOx/BiVO4: insights into the unexpectedly favorable effect of bicarbonates, Chem. Eng. J. 318 (2017) 39–49. [14] M.E. Taheri, A. Petala, Z. Frontistis, D. Mantzavinos, D.I. Kondarides, Fast photocatalytic degradation of bisphenol A by Ag3PO4/TiO2 composites under solar radiation, Catal. Today 280 (Part 1) (2017) 99–107. [15] Y. Ma, X. Wang, Y. Jia, X. Chen, H. Han, C. Li, Titanium dioxide-based nanomaterials for photocatalytic fuel generations, Chem. Rev. 114 (2014) 9987–10043. [16] P. Lianos, Production of electricity and hydrogen by photocatalytic degradation of organic wastes in a photoelectrochemical cell: the concept of the photofuelcell: a review of a re-emerging research field, J. Hazard. Mater. 185 (2011) 575–590. [17] Y. Liu, J. Li, B. Zhou, H. Chen, Z. Wang, W. Cai, A TiO2 nanotube-array-based photocatalytic fuel cell using refractory organic compounds as substrates for electricity generation, Chem. Commun. 47 (2011) 10314–10316. [18] Q. Chen, J. Li, X. Li, K. Huang, B. Zhou, W. Cai, W. Shangguan, Visible-light responsive photocatalytic fuel cell based on WO3/W photoanode and Cu2O/Cu photocathode for simultaneous wastewater treatment and electricity generation, Environ. Sci. Technol. 46 (2012) 11451–11458. [19] Z. Li, W. Luo, M. Zhang, J. Feng, Z. Zou, Photoelectrochemical cells for solar hydrogen production: current state of promising photoelectrodes, methods to improve their properties, and outlook, Energy Environ. Sci. 6 (2013) 347–370. [20] K. Yan, Y. Yang, O.K. Okoth, L. Cheng, J. Zhang, Visible-light induced self-powered sensing platform based on a photofuel cell, Anal. Chem. 88 (2016) 6140–6144. [21] Y. Yang, K. Yan, J. Zhang, Dual non-enzymatic glucose sensing on Ni(OH)2/TiO2 photoanode under visible light illumination, Electrochim. Acta 228 (2017) 28–35. [22] M. Zhou, J. Wang, Biofuel cells for self-powered electrochemical biosensing and logic biosensing: a review, Electroanalysis 24 (2012) 197–209. [23] X. Shen, L. Zhu, G. Liu, H. Yu, H. Tang, Enhanced photocatalytic degradation and selective removal of nitrophenols by using surface molecular imprinted Titania, Environ. Sci. Technol. 42 (2008) 1687–1692. [24] L. Chen, X. Wang, W. Lu, X. Wu, J. Li, Molecular imprinting: perspectives and applications, Chem. Soc. Rev. 45 (2016) 2137–2211. [25] J. Wackerlig, P.A. Lieberzeit, Molecularly imprinted polymer nanoparticles in chemical sensing–synthesis, characterisation and application, Sens. Actuators B 207 (2015) 144–157. [26] L. Uzun, A.P.F. Turner, Molecularly-imprinted polymer sensors: realising their potential, Biosens. Bioelectron. 76 (2016) 131–144. [27] L. Zhu, Y. Cao, G. Cao, Electrochemical sensor based on magnetic molecularly imprinted nanoparticles at surfactant modified magnetic electrode for determination of bisphenol A, Biosens. Bioelectron. 54 (2014) 258–261. [28] Y.T. Wu, Y.J. Liu, X. Gao, K.C. Gao, H. Xia, M.F. Luo, X.J. Wang, L. Ye, Y. Shi, B. Lu, Monitoring bisphenol A and its biodegradation in water using a fluorescent molecularly imprinted chemosensor, Chemosphere 119 (2015) 515–523. [29] F. Tan, L. Cong, X. Li, Q. Zhao, H. Zhao, X. Quan, J. Chen, An electrochemical sensor based on molecularly imprinted polypyrrole/graphene quantum dots composite for detection of bisphenol A in water samples, Sens. Actuators B 233 (2016) 599–606. [30] B. Lu, M. Liu, H. Shi, X. Huang, G. Zhao, A Novel photoelectrochemical sensor for bisphenol A with high sensitivity and selectivity based on surface molecularly imprinted polypyrrole modified TiO2 nanotubes, Electroanalysis 25 (2013) 771–779. [31] S. Cao, J. Low, J. Yu, M. Jaroniec, Polymeric photocatalysts based on graphitic carbon nitride, Adv. Mater. 27 (2015) 2150–2176. [32] W.-J. Ong, L.-L. Tan, Y.H. Ng, S.-T. Yong, S.-P. Chai, Graphitic carbon nitride (g-C3N4)-based photocatalysts for artificial photosynthesis and environmental remediation: are we a step closer to achieving sustainability? Chem. Rev. 116 (2016) 7159–7329.

[33] J. Zhuang, W. Lai, M. Xu, Q. Zhou, D. Tang, Plasmonic auNP/g-C3N4 nanohybrid-based photoelectrochemical sensing platform for ultrasensitive monitoring of polynucleotide kinase activity accompanying DNAzyme-catalyzed precipitation amplification, ACS Appl. Mater. Interfaces 7 (2015) 8330–8338. [34] H. Yin, Y. Zhou, B. Li, X. Li, Z. Yang, S. Ai, X. Zhang, Photoelectrochemical immunosensor for microRNA detection based on gold nanoparticles-functionalized g-C3N4 and anti-DNA:RNA antibody, Sens. Actuators B 222 (2016) 1119–1126. [35] P. Niu, L. Zhang, G. Liu, H.M. Cheng, Graphene-Like carbon nitride nanosheets for improved photocatalytic activities, Adv. Funct. Mater. 22 (2012) 4763–4770. [36] E. Herrero-Hernández, R. Carabias-Martínez, E. Rodríguez-Gonzalo, Use of a bisphenol-A imprinted polymer as a selective sorbent for the determination of phenols and phenoxyacids in honey by liquid chromatography with diode array and tandem mass spectrometric detection, Anal. Chim. Acta 650 (2009) 195–201. [37] T. Jing, H. Xia, J. Niu, Y. Zhou, Q. Dai, Q. Hao, Y. Zhou, S. Mei, Determination of trace 2,4-dinitrophenol in surface water samples based on hydrophilic molecularly imprinted polymers/nickel fiber electrode, Biosens. Bioelectron. 26 (2011) 4450–4456. [38] Y. Liu, K. Yan, J. Zhang, Graphitic carbon nitride sensitized with CdS quantum dots for visible-light-driven photoelectrochemical aptasensing of tetracycline, ACS Appl. Mater. Interfaces 8 (2016) 28255–28264. [39] R. Li, Y. Liu, L. Cheng, C. Yang, J. Zhang, Photoelectrochemical aptasensing of kanamycin using visible light-activated carbon nitride and graphene oxide nanocomposites, Anal. Chem. 86 (2014) 9372–9375. [40] S. Martha, A. Nashim, K.M. Parida, Facile synthesis of highly active g-C3N4 for efficient hydrogen production under visible light, J. Mater. Chem. A 1 (2013) 7816–7824. [41] B. Wang, O.K. Okoth, K. Yan, J. Zhang, A highly selective electrochemical sensor for 4-chlorophenol determination based on molecularly imprinted polymer and PDDA-functionalized graphene, Sens. Actuators B 236 (2016) 294–303. [42] H. Yang, L. Li, Y. Ding, D. Ye, Y. Wang, S. Cui, L. Liao, Molecularly imprinted electrochemical sensor based on bioinspired Au microflowers for ultra-trace cholesterol assay, Biosens. Bioelectron. 92 (2017) 748–754. [43] Y. Zhu, K. Yan, Y. Liu, J. Zhang, Photovoltammetric behavior and photoelectrochemical determination of p-phenylenediamine on CdS quantum dots and graphene hybrid film, Anal. Chim. Acta 884 (2015) 29–36. [44] L. Zhang, M. Zhou, S. Dong, A self-powered acetaldehyde sensor based on biofuel cell, Anal. Chem. 84 (2012) 10345–10349. [45] N. Ben Messaoud, M.E. Ghica, C. Dridi, M. Ben Ali, C.M.A. Brett, Electrochemical sensor based on multiwalled carbon nanotube and gold nanoparticle modified electrode for the sensitive detection of bisphenol A, Sens. Actuators B 253 (2017) 513–522. [46] M.N.H. Rozaini, N. Yahaya, B. Saad, S. Kamaruzaman, N.S.M. Hanapi, Rapid ultrasound assisted emulsification micro-solid phase extraction based on molecularly imprinted polymer for HPLC-DAD determination of bisphenol A in aqueous matrices, Talanta 171 (2017) 242–249. [47] X. Wu, Y. Li, X. Zhu, C. He, Q. Wang, S. Liu, Dummy molecularly imprinted magnetic nanoparticles for dispersive solid-phase extraction and determination of bisphenol A in water samples and orange juice, Talanta 162 (2017) 57–64. [48] T.A.V. Brigante, L.F.C. Miranda, I.D. de Souza, V.R. Acquaro Junior, M.E.C. Queiroz, Pipette tip dummy molecularly imprinted solid-phase extraction of bisphenol A from urine samples and analysis by gas chromatography coupled to mass spectrometry, J. Chromatogr. B 1067 (2017) 25–33. [49] M. Portaccio, D. Di Tuoro, F. Arduini, D. Moscone, M. Cammarota, D.G. Mita, M. Lepore, Laccase biosensor based on screen-printed electrode modified with thionine–carbon black nanocomposite, for bisphenol A detection, Electrochim. Acta 109 (2013) 340–347. [50] L. Sun, Y. Ma, P. Zhang, L. Chao, T. Huang, Q. Xie, C. Chen, S. Yao, An amperometric enzyme electrode and its biofuel cell based on a glucose oxidase-poly(3-anilineboronic acid)-Pd nanoparticles bionanocomposite for glucose biosensing, Talanta 138 (2015) 100–107. [51] E. Dempsey, D. Diamond, A. Collier, Development of a biosensor for endocrine disrupting compounds based on tyrosinase entrapped within a poly(thionine) film, Biosens. Bioelectron. 20 (2004) 367–377. [52] H. Notsu, T. Tatsuma, A. Fujishima, Tyrosinase-modified boron-doped diamond electrodes for the determination of phenol derivatives, J. Electroanal. Chem. 523 (2002) 86–92. [53] G. Xu, L. Gong, H. Dai, X. Li, S. Zhang, S. Lu, Y. Lin, J. Chen, Y. Tong, G. Chen, Electrochemical bisphenol A sensor based on carbon nanohorns, Anal. Methods 5 (2013) 3328–3333. [54] Y. Ma, X. Chen, L. Zhuo, Z. Lin, Z. Huang, X. Chen, Functional graphene-ionic liquid composites for the fabrication of a rapid and facile bisphenol A electrochemical sensor, J. Nanosci. Nanotechnol. 17 (2017) 1908–1914. [55] P. Florina, R.B. Alexandru, S. Crina, C. Maria, M. Lidia, R. Marcela-Corina, D.L. Mihaela, B. Gheorghe, P. Stela, Graphene–bimetallic nanoparticle composites with enhanced electro-catalytic detection of bisphenol A, Nanotechnology 27 (2016) 484001.

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Biographies Kai Yan is currently a Ph.D. Student in School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, P.R. China. His research interests include electrochemical sensors and biosensors. Yaohua Yang received her master degree from School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, P.R. China in 2017. Her research interests include electrochemical sensors and chemically modified electrodes.

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Jingdong Zhang is a professor in School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, P.R. China. He received his PhD degree from Hunan University, P.R. China in 2000. His research interests include bioelectrochemistry, electrochemical sensors, nanomaterials and photoelectrochemistry.