Research Journal of Chemical Sciences ___ ______________________________ ______ ___ _ ___ ISSN 22 31 - 606X Vol. 3 ( 2 ), 31 - 34 , February (201 3 ) Res. J. Chem. Sci. International Science Congress Association 31 Characterization of Ruthenium Based Metal Complex Nanoparticles Decorated on Carbon Supported Surface Sudip Chakraborty 1 * and Nabakumar Pramanik 2 1 Department of Chemistry, Indian Institute of Technology, Kharagpur - 721302, INDIA 2 Department of Chemistry, National Institute of Technology, Arunachal Pradesh, INDIA Available online at: www.isca.in Received 17 th November 201 2 , revised 25 th November 201 2 , accepted 7 th January 201 3 Abstract The ruthenium oxide - hexacyanofer rate nanoparticles (RuOHCFNP) were prepared by an electroless deposition approach and the electrochemical, spectral and morphological behavior of RuOHCFNP modified electrode has been investigated. RuOHCFNP were well decorated on the walls of carbon nanotub es and shows stable voltammetric response. This electrode is highly stable with high reproducibility. Keywords: Carbon nanotubes , r uthenium oxide - hexacyanoferrate nanoparticles , v oltammetry . Introduction The deliberate tuning of electrochemical interf ace with nano - materials is one of the exciting developments in the field of electroanalytical sensor and biosensor. The nanostructured carbon such as carbon nanotubes (CNTs) has emerged as a new class of materials and received considerable interest since t heir discovery 1,2 as they have unique electrical, chemical and mechanical properties. They have been widely used for the fabrication of electroanalytical sensors and bio - sensors due to their excellent electrocatalytic activity 3 . The CNT assisted electroche mical oxidation of hydrogen peroxide; NADH, ascorbate and reduction of oxygen have been well documented 4 . The CNT tailored electrochemical interfaces have been shown useful to avoid surface fouling. The outstanding catalytic effect of CNT permits the utili zation of CNT for the development of highly sensitive nanoscale sensor devices and for different catalytic applications. Hexacyanoferrates of different transition metals display attractive redox chemistry and are find application in many different areas su ch as electrocatalysis, electrochromism, electrochemical sensors etc. 5 Among the metal hexacyanoferrates, ruthenium oxide hexacyanoferrate (RuOHCF) was studied for its interesting chemical and electrochemical properties. Ruthenium has ability to stabilize some polynuclear hexacyanometalates 6,7 , and preparation of stable thin films of these electroactive compounds is critical to their use in a functional capacity. We have prepared a composite thin film of RuOHCFNP using CNT based electrode according to the procedure mentioned in the literature 8 and used for the amperometric sensing of ethanol. Researchers have synthesized the modified film electrodes using repetitive cyclic voltammetry to form polynuclear mixed - valent ruthenium oxide/ ruthenocyanide films on various electrodes directly from solutions containing Ru +3 and Fe(CN) 6 3 - ions and various electrolyte 9 . Films have also been directly synthesized using repetitive cyclic voltammetry from Ru 3+ and Fe(CN) 6 3 - 10 . Herein we describe the spectral, morphological and electrochemical of the RuOHCFNP. Material and Methods Multi walled CNTs (  95% purity), Poly - diallyl dimethyl ammonium chloride (PDA), Ruthenium chloride (RuCl 3 ) and potassium ferricyanide [K 3 Fe(CN) 6 ] were purchased from Sigma - Aldrich. All other che micals used in this investigation were of analytical grade. All solutions were prepared using Milipore water. Instrumentation: Electrochemical measurements were performed using two - compartment three - electrode cell with a glassy carbon working electrode, a Pt wire auxiliary electrode and Ag/AgCl (3 M NaCl) reference electrode. Cyclic voltammograms were recorded using a computer controlled CHI643B electrochemical analyzer attached to a Picoamp Booster - Faraday cage. JEOL JEM 6700F field emission scanning elec tron microscope (FESEM) was used to obtain FESEM images of the PDDA dispersed CNT and RuOHCFNP deposited CNT. Electroless deposition of RuOHCFNP on CNT modified electrode: We have prepared a composite thin film of RuOHCFNP using CNT based electrode accord ing to the following procedure mentioned in the literature 8 . GC electrodes (0.07 cm 2 ) were used as substrate for making RuOCHFNP thin film. Before modification with the thin film, the GC electrodes were polished well with fine emery paper and alumina (0.05  m) slurry and then sonicated in Millipore water for 10 - 15 min. The polished electrode was thoroughly rinsed with Millipore water and used for modification. A 0.2 mg of purified CNT was dispersed in 100  L of PDA (1 % solution in water) and stirred in a m agnetic stirrer for about 30 min to obtain a homogeneous Research Journal of Chemical Sciences ___ _ _ _______________________________ ______________ _ _______ _ ISSN 22 31 - 606X Vol. 3 ( 2 ), 31 - 34 , February (201 3 ) Res. J. Chem. Sci. International Science Congress Association 32 suspension. An aliquot of 10  L of the suspension was coated on the GC electrode and allowed to dry at room temperature for 30 min. The RuOHCFNP modified electrode was been prepared by soaking the PD A/CNTcomposite electrode first in an aqueous solutions of 3mM K 3 Fe(CN) 6 for 5 min. and then the electrode was subsequently soaked in 3mM RuCl 3 for 30 min. Hereafter, the electrode modified with PDA, PDA - CNT and PDA - CNT - RuOHCFNP will be referred as PDA ele ctrode, PDA/CNT composite electrode and CNT/RuOHCFNP composite electrode. Results and Discussion Figure 1 shows the cyclic voltammograms obtained for RuOHCF film on CNT - modified electrode. Well - defined redox peaks at - 0.06 V, 0.8 V and 1.06 V were observ ed for the RuOHCF film on the electrode surface in 0.1(M) KNO 3 pH 1.5. The redox peaks I, IV and V for the RuOHCFNP film can be ascribed to the redox reactions of RuOHCFNP films (I: [Ru(II) - O/Fe(II) - CN]/ [Ru III - O/Fe II - CN] ; IV: [Ru III - O/Fe II - CN]/ [Ru III - O/ Fe III - CN] V: [Ru III - O/Fe III - CN]/ [Ru IV - O/Fe III - CN] ) whereas the redox couple III can be attributed to the redox reaction of [Ru III - NC - Fe II ]/ [Ru III - NC - Fe III ] couple 11 . The redox peak II corresponds to the redox reaction of surface adsorbed Fe(CN) 6 3 - /4 - redox couple. This was further confirmed by recording the voltammogram for the couple Fe(CN) 6 3 - /4 - on the CNT modified electrode (figure 2). Figure 2 displays the CV response of the adsorbed Fe(CN) 6 3 - /4 - onto the PDA/CNT composite electrode and PDA - electro de (figure 2 inset). It is interesting to note that in the presence of CNT current corresponding to the redox species is too high compared to the composite in absence of CNT. The adsorption of the redox species have been made by simple soaking the electrod e into the 3 mM aqueous solution of K 3 Fe(CN) 6 for 30 mins. As the polymer PDA is positively charged at the present experimental condition, the negatively charged Fe(CN) 6 3 - /4 - adsorbed on the electrode surface by the electrostatic interaction. The formatio n of the RuOHCFNP film is highly favorable due to the presence of CNT - PDA composite on the electrode surface. The FESEM image in Figure 3B confirmed the formation of RuOHCF nanoparticles displaying the diameter of the particle is ~70 nm. Figure 3A displays the typical FESEM image of the CNT with diameter between ~30 and 80 nm. It is notable that presence of PDA makes the well association of CNTs. According to the previous literature, shape of metal hexacyanoferrates are different because of their different synthetic procedure 12,13 , but we are reporting first time about the deposition of RuOHCF nanoparticles by a simple electroless method. Figure 4 displays the spectral behaviour of RuOHCF nanoparticles. UV - Visible absorption spectra for PDA - CNT - Fe(CN) 6 3 - co mposite coming ~ 420 nm whereas CNT/RuOHCFNP composite exhibits three peaks at 420, 480 and 595 nm respectively (figure 4a). This UV - visible absorption peak patterns are similar to the absorption spectra of RuOHCF (5). But the RuOHCFNP composite without C NT exhibits no well defined characteristic absorption peak (figure 4b), which indicates that presence of CNTs are critically essential for the electroless deposition of RuOHCFNP. Figure - 1 Cyclic voltammogram of the CNT/RuOHCF composite el ectrode in KNO 3 pH 1.5 at 100mV/s Research Journal of Chemical Sciences ___ _ _ _______________________________ ______________ _ _______ _ ISSN 22 31 - 606X Vol. 3 ( 2 ), 31 - 34 , February (201 3 ) Res. J. Chem. Sci. International Science Congress Association 33 Figure - 2 Cyclic voltammogram of the PDA/CNT/Fe(CN) 6 3 - /4 - electrode in 0.1M KNO 3 pH 1.5 at 100 mV/s. Inset shows Cyclic voltammogram of the PDA /Fe(CN) 6 3 - /4 - electrode in 0.1M KNO 3 pH 1.5 at 100 mV/s Fig ure - 3 (A) FESEM image of PDA/CNT composite and (B) FESEM image of CNT/RuOHCFNP composite. Figure 4 UV - visible absorption spectra of (a) CNT/RuOHCFNP composite (b) RuOHCFNP composite and (c) CNT/ Fe(CN) 6 3 - composite Research Journal of Chemical Sciences ___ _ _ _______________________________ ______________ _ _______ _ ISSN 22 31 - 606X Vol. 3 ( 2 ), 31 - 34 , February (201 3 ) Res. J. Chem. Sci. International Science Congress Association 34 Conclusion Electroless deposition of ruthenium oxide hexacyanoferrate nanoparticles on CNT - based electrode has been characterized. The electrochemical, spectral, and morphological behavior of RuOHCFNP modified electrode has been investigated. As the protocol for the preparation of electrode is very simple, it can be easily prepared daily. RuOHCFNP modified electrode can be used to bring new capabilities for electrochemical devices by utilizing synergic action of CNT and RuOHCFNP to facilitate electron - transfer process. Acknowled gements SC thanks IIT - Kharagpur, India and NP thanks NIT - Arunachal Pradesh for support. 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