DOI: 10.1002/elan.201900194 Pulsed Deposited Manganese and Vanadium Oxide Film Modified with Carbon Nanotube and Gold Nanoparticle: Chitosan and Ionic Liquid-based Biosensor Seçil Akoğulları, [a] Seda Çιnar, [a] Kemal Volkan Özdokur, [b] Tülin Aydemir, [a] Fatma Nil Ertaş, [c] and Süleyman Koçak* [a] Abstract: Present study describes the synthesis of mixed oxide films of manganese and vanadium by electro- chemical pulsed deposition technique on a glassy carbon electrode (GCE) modified with multiwall carbon nano- tubes (MWCNT). The film was further decorated with gold nanoparticles to enhance the reduction signal of dissolved oxygen in pH 5.17 acetate buffer solution. All of the electrochemical synthesized modified electrodes have been characterized with Scanning electron microscopy (SEM), High-resolution transmission electron microscopy (HRTEM), X-Ray photoelectron spectroscopy (XPS), X- Ray diffraction (XRD) techniques. The electrode ob- tained (AuNPs/MnOx À VOx/CNT/GCE) was utilized as a platform for glucose biosensor where the glucose oxidase enzyme was immobilized on the composite film with the aid of chitosan and an ionic liquid. The electrochemical performance of the biosensor was investigated by cyclic voltammetry and the relative parameters have been optimized by amperometric measurements in pH 5.17 acetate buffer solution. The developed biosensor exhib- ited a linear range for glucose between 0.1–1.0 mM and the limit of detection was calculated as 0.02 mM. Keywords: Gold nanoparticles · manganese and vanadium oxide · pulsed deposition · oxygen · glucose 1 Introduction Transition metal oxides, molybdenum [1–3], manganese [4,5] and vanadium [6] oxides in particular, and their binary and ternary combinations have received much attention recently owing to their remarkable electro- catalytic and electrochromic properties. It was also reported that these properties largely depend on the synthesis procedure and among these techniques; electro- deposition offers an economic and practical way for producing uniform and thin oxide films on the electrode surface [6,7]. Repetitive cycling of the potential of a carbon based [8] or indium À tin oxide (ITO) electrodes [3] dipped into a cell containing a transition metal ions results in a mixed-valent metal oxide (MeO x ) formation which is most probably responsible from the catalytic activity of the oxide film [9]. Besides the cycling the potential, electrochemical pulsed deposition (PD) has become popular in the last decade, and it was revealed that the pattern of applied potential determines the compositions and morphologies of MeOx deposits [9,10]. The main goal of electrocatalysis is to minimize the overpotential, particularly for gas evolving or consuming electrode reactions including hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR). The mechanism of the latter reaction on a carbon based electrode modified with transition metal oxides has revealed that the different oxidation states of the transition metal was responsible from the reaction with dissolved oxygen adsorbed on carbon electrode [3,8,9]. Electrocatalytic activity of the electrode can be further enhanced by decorating the oxide film with noble metal nanoparticles and resulting combination of hypo- hyper-d electronic transition metal À metal oxides has displayed pronounced synergetic effect for both anode and cathode reactions [1,4,11]. This effect has been shown to improve by using binary or ternary oxide films decorated with metallic nanoparticles. As indicated in recent reviews, the electrode surfaces modified with carbon based nano- materials including carbon nanotubes (CNT), graphene etc., and ionic liquids have been mostly exploited in pursue of the synergic effect for ORR [1,4,5,11–13]. Electrochemical sensors developed by this means can also be applied for sensitive and selective detection of a variety of analytes. Gold nanoparticles have been greatly exploited in biosensor technologies [14,15] while transi- tion metal oxides have also been employed to construct [a] S. Akoğulları, S. Çιnar, T. Aydemir, S. Koçak Manisa Celal Bayar University, Faculty of Science and Art, Department of Chemistry, 45040 Manisa, Turkey Tel.: + 902362013162 Fax: + 902362412158 E-mail: suleyman.kocak@cbu.edu.tr [b] K. V. Özdokur Erzincan Binali Yıldırım University, Faculty of Science and Art, Department of Chemistry, Turkey [c] F. N. Ertaş Ege University, Faculty of Science, Department of Chemistry, İzmir, 35100, Turkey Supporting information for this article is available on the WWW under https://doi.org/10.1002/elan.201900194 Full Paper www.electroanalysis.wiley-vch.de © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Electroanalysis 2019, 31, 1 – 10 1 These are not the final page numbers! ��