Research Article Nanowires Nickel Oxide and Nanospherical Manganese Oxide Synthesized Via Low Temperature Hydrothermal Technique for Hydrogen Peroxide Sensor
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Hindawi Publishing Corporation Journal of Chemistry Volume 2016, Article ID 9138961, 6 pages http://dx.doi.org/10.1155/2016/9138961 Research Article Nanowires Nickel Oxide and Nanospherical Manganese Oxide Synthesized via Low Temperature Hydrothermal Technique for Hydrogen Peroxide Sensor Suriani Ibrahim,1,2 Tawatchai Charinpanitkul,3 Eiry Kobatake,4 and Mana Sriyudthsak1 1 Department of Electrical Engineering, Chulalongkorn University, Bangkok 10330, Thailand 2Department of Mechanical Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia 3Department of Chemical Engineering, Chulalongkorn University, Bangkok 10330, Thailand 4Department of Environmental Chemistry and Engineering, Tokyo Institute of Technology, Kanagawa 226-8501, Japan Correspondence should be addressed to Suriani Ibrahim; [email protected] and Mana Sriyudthsak; [email protected] Received 30 September 2015; Revised 11 December 2015; Accepted 18 January 2016 Academic Editor: Artur M. S. Silva Copyright © 2016 Suriani Ibrahim et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Binary catalyst nickel oxides (NiO) and manganese oxides (MnO) were prepared individually via hydrothermal route. The catalysts were characterized by scanning electron microscope (SEM), Brunauer-Emmett-Teller (BET) analysis, cyclic voltammetry (CV), and amperometry. Morphology studies revealed physical structure of nanowires nickel oxide and spherical manganese oxide with estimated length of 0.3–2.3 m and diameter of 0.2–0.8 m, respectively. Surface areas obtained for nickel oxide and manganese 2 −1 2 −1 oxide were 68.9 m g and 45.2 m g , respectively. Cyclic voltammetry exhibits electrochemical responses corresponding to the electrode surfaces. The linear responses of the binary catalyst modified gold electrodes with NiO-MnO were observed in the concentration range from 31.8 M to 0.5 mM with the detection limit of 62.5 M. 1. Introduction [12, 13]. Manganese oxide (MnOx) is a very attractive metallic oxide and widely used in fuel cells, sensor, catalyst, and metal Hydrogen peroxide was employed in many applications coating [14–17]. Moreover, MnOx wasalsousedasacocatalyst including pharmaceutical, food, and industry applications. It material in biosensor and fuel cells [18]. Binary catalysts can also be a biological marker for certain diseases like cancer, are very attractive materials for their unique properties, aging, and renal diseases [1–4]. Hence, rapid, sensitive, and when compared to single catalyst. For example, Ding et al. accurate determination of H2O2 is extremely important. fabricated NiO hybrid nanowires with uniformly distributed Amperometry is the most attractive techniques to detect Ag and Au NPs, enhancing glucose biosensing performance. hydrogen peroxide because of high sensitivity, low cost, and Polydopaminehasbeenwidelyusedasacoatingagentfor its simplicity [5]. Nanomaterials gained a lot of interest various inorganic and organic substrates [19, 20]. Dopamine among researchers due to their excellent mechanical and will self-polymerize at alkaline pH oxidizing and forming electrical properties. To increase the sensitivity of the sensor, thin polydopamine films. Some researchers are working on nanoparticles (NPs) are the best candidate due to their large binary catalyst NiO-MnO for various applications [21–24]. specific surface area and biocompatibility [6]. Nickel oxide For example, Zhang et al. synthesized MnO-NiO composite (NiOx) was intensively studied because of its high electron oxide catalyst for lean methane combustion at low tem- transfer capability and good biological compatibility [7–10]. perature.However,tothebestofourknowledge,thereare However,theperformanceoftheseelectrodescouldbelim- not many published reports on the binary catalyst NiO- ited by surface poisoning [11]. Some studies revealed that, by MnO for hydrogen peroxide detection. Therefore, this work using multicomponent surface compositions, especially the could be beneficial for researchers who make studies on metal composite can overcome surface poisoning problems catalyst for electrochemical sensors. We report on fabrication 2 Journal of Chemistry (a) (b) (c) Figure 1: (a) Precursor; (b) nickel hydroxide; (c) nickel oxide. of polydopamine-nickel oxide-manganese oxide composite Ni(OH)2 was obtained at this stage as shown in Figure 1(b). on gold electrode to detect low concentrations (31.8 Mto Theproductwasseparatedfromthesolutionbyfiltration 0.5 mM) of hydrogen peroxide. process, washed with deionized water and ethanol several ∘ times, and finally dried at 120 C in the air. The powder was ∘ 2. Experimental further heated to 400 Cfor2hours[25].Finally,thenickel oxide was obtained as shown in Figure 1(c). 2.1. Chemical and Reagents. All chemicals were analyti- To prepare manganese oxide (MnO), 0.2 M Mn(CH3COO)2 cal grade reagents and employed as received without fur- and 0.2 M KMnO4 were individually dissolved in deionized ther purification. NiO and MnO were synthesized from water. These solutions were mixed together, with the molar Ni(CH3COO)2⋅4H2O(99%),Mn(CH3COO)2⋅4H2O(98%), ratio of 1 : 1 as shown in Figure 2(a). The mixed solution was loaded into the stainless steel mould. During the hydrother- and KMnO4 and obtained from Aldrich. Dopamine was ∘ obtained from Sigma. Hydrogen peroxide (50%) and ethylene mal reaction, the heating temperature setting was 125 Cfor3 glycol were obtained from domestic supplier. All solutions hours [26]. The black precipitates were obtained and collected through filtration and washed with deionized water and were prepared with deionized water. Phosphate buffer solu- ∘ tions (pH 8.4 and pH 7.4) were used for the modified finally dried at 120 Cfor10hours.Finally,themanganese electrodes preparation and measurement. oxide was obtained as shown in Figure 2(b). 2.2. Apparatus. A binary catalyst was individually prepared 2.4. Modified Gold Electrodes. For single catalyst modified by using Muffle Furnaces, P80-Series. The material charac- gold electrodes, dopamine solution was prepared by mixing terizations testing was performed using Brunauer-Emmett- 1mgdopaminewith1mLphosphatebuffer(pH8.4).Single Teller (BET) BELSORP-mini II, scanning electron micro- catalyst solutions were individually prepared by mixing 1 mg scope (SEM), and LEO 1450VPSE. For sensor fabrication, of each nickel oxide and manganese oxide in 1 mL ethanol 2-electrode system was used; both working and counter solution. Single catalyst modified electrodes were prepared by electrodes were made from gold. The electrode was obtained dropping 10 L of single catalyst suspension on the electrodes from Bioptik Company (Taiwan). The electrochemical tests surface and dried at room temperature (first layer). This type were performed by using home-made potentiostat. For of modified gold electrodes was used in cyclic voltammetry voltammetry testing, the potential was swept between −1V testing. Then, for amperometry testing, 6 Lofdopamine and +1 V with the scan rate of 50 mV/s. The solution for solution was dropped onto metal oxide layer and dried at voltammetry testing was 0.1 M phosphate buffer, pH 7.4. For room temperature with exposure to the room light for 7 hours amperometry testing, the applied potential was 0.7 V. The (second layer). concentration of hydrogen peroxide was varied from 31.8 M For binary catalyst modified gold electrode, 1 mg nickel to 0.5 mM. oxide and 1 mg manganese oxide were mixed in 1 mL of ethanol solution. Then 10 Lofthissuspensionwasdropped 2.3. Synthesis NiO and MnO. All experiments were con- on the electrode surface and dried at room temperature (first ducted under air atmosphere. Nickel oxide and manganese layer).Thistypeofmodifiedgoldelectrodeswasusedincyclic oxide were prepared by hydrothermal technique. To prepare voltammetry testing. Then, for amperometry testing, 6 Lof nickel oxide (NiO), 0.1 M of Ni(CH3COO)2⋅4H2Owere dopamine solution was dropped onto metal oxide layer and dissolved in a mixed solvent of deionized water and ethylene dried at room temperature with exposure to the room light glycol with a ratio (1 : 1) as shown in Figure 1(a). The solvent for 7 hours (second layer). was transferred into the stainless steel close mould. The fur- Schematic of modified electrode for amperometry testing ∘ nace was maintained at 200 C for 7 hours. Nickel hydroxide is shown in Figure 3. Journal of Chemistry 3 (a) (b) Figure 2: (a) Precursor; (b) manganese oxide. Polydopamine most oxides is related to the heating temperature during the Gold electrode Metal oxide preparation. Our nickel oxide shows higher crystallinity than ∘ manganese oxide because they were prepared at 400 Cand ∘ Figure 3: Schematic of modified gold electrode (layer by layer). 125 C, respectively. The electrochemical properties of modified gold elec- trodes without polydopamine were investigated using cyclic voltammetry (CV) as shown in Figure 6. The testing was −1 conductedin10mMphosphatebufferwith50mV/s scan 3. Results and Discussion rate. Both bare gold electrode and polydopamine modified gold electrode exhibit almost no voltammetric response. This Figure 4 presents SEM images taken from the synthesized implies that electron transfers at both of these electrodes nanoparticles. Figure 4(a) shows an image of the nickel surfaces are very slow. The current at the electrode with poly- oxides. The nanowires nickel oxides are in agglomerated dopamine