Contents lists available at ScienceDirect Materials Research Bulletin journal homepage: www.elsevier.com/locate/matresbu Ultrasensitive and selective non-enzymatic electrochemical glucose sensor based on hybrid material of graphene nanosheets/graphene nanoribbons/nickel nanoparticle L. Jothi a , N. Jayakumar a , S.K. Jaganathan b,c,d , G. Nageswaran a, ⁎ a Department of Chemistry, Indian Institute of space science and Technology, Thiruvananthapuram, Kerala, 695547, India b Department for Management of Science and Technology Development, Ton Duc Thang University, Ho Chi Minh City, Vietnam c Faculty of Applied Sciences, Ton Duc Thang University, Ho Chi Minh City, Vietnam d IJN-UTM Cardiovascular Engineering Centre, Faculty of Biosciences and Medical Engineering, Universiti Teknologi Malaysia, Skudai 81300, Johor, Malaysia ARTICLE INFO Keywords: Nickel nanoparticle Graphene sheet Graphene nanoribbon Non-enzymatic glucose sensor Amperometric ABSTRACT A fast, highly sensitive and selective non-enzymatic electrochemical glucose sensor based on graphene sheet/ graphene nanoribbon/nickel nanoparticles (GS/GNR/Ni) hybrid material modified electrode was fabricated. The hybrid material was synthesized via facile in-situ chemical reduction and characterized by X-ray diffraction, transmission electron microscopy, Raman spectroscopy, cyclic voltammetry and electrochemical impedance spectroscopy. The GS/GNR/Ni/GCE showed high electrochemical activity towards the oxidation of glucose in a 0.1 M NaOH solution. At an applied potential of +0.5 V, it displayed wide linear amperometric response to- wards glucose from the range of 5 nM–5 mM, with a detection limit of 2.5 nM and sensitivity of 2.3 mA/ mM cm 2 . Moreover, the modified electrode was relatively insensitive to commonly interfering species such as dopamine, ascorbic acid, sucrose, uric acid and Cl - ions. The fabricated sensor with better reproducibility, good long term stability, makes it a promising electrode for the development of effective glucose sensor. 1. Introduction Diabetes mellitus, a chronic disease related to glucose digestion caused by insufficient insulin secretion, causes increasing death rate worldwide. Therefore determination of glucose level in blood is of practical importance to reduce the complications associated with dia- betes. In recent years considerable research have been devoted in de- velopment of vast number of rapid, sensitive and accurate glucose sensors to monitor glucose which are not only relevant for determina- tion of glucose level in blood but also in the food industry, bioproces- sing, etc [1]. Among the various available analytical methods [2–5], electrochemical glucose sensor has been widely used due to its merits including high sensitivity, time efficiency, simplicity, excellent se- lectivity, rapid response, lowest detection limit and good reliability [6]. Since the development of the first ever enzymatic glucose sensor by Clark and Lyons in 1962 [7], the enzymatic glucose sensor based on glucose oxidase (GOD) developed for self-testing and continuous glu- cose monitoring dominates the biosensor industry. However, the in- trinsic flaws associated with enzyme based glucose sensors such as complicated immobilization procedures, critical operating conditions, poor reproducibility and poor long-term stability [8], have steered researchers to explore non-enzymatic detection. Over the past decades, tremendous efforts have been devoted in the development of reliable non-enzymatic glucose sensor which led to the utilization of metal, metal oxide and alloys, such as Pt, Au, Ag, Cu, Ni, Co, NiO, NiCo 2 O 4 , NiCoO 2 , Co 3 O 4 [9,10]. In spite of various catalytic materials available for glucose sensor, nickel (Ni) based nanomaterials [11,12] have captured more attention towards researchers, owing to wide linear range and excellent catalytic activity towards glucose oxi- dation in alkaline medium leading to Ni(OH) 2 and NiOOH species [13]. In spite of their high electrocatalytic activity, the surface fouling asso- ciated with glucose oxidation hinders its stability. Hence the need of a conductive nano structured substrate arises which can enhance the electrode stability and electron transfer toward oxidation of glucose of Ni. Carbon based nanomaterials such as carbon nanotube (CNT) [14], graphene sheet (GS) [15], graphene nanoribbon (GNR) [16] and full- erene [17] with excellent physico-chemical properties can be con- sidered as ideal supports for Ni catalyst nanoparticles. Graphene draws attention as an excellent catalyst support material due to its high spe- cific surface area, good conductivity, electrochemical stability and low manufacturing cost. However the excellent properties of graphene are http://dx.doi.org/10.1016/j.materresbull.2017.10.020 Received 23 March 2017; Received in revised form 7 September 2017; Accepted 13 October 2017 ⁎ Corresponding author. E-mail addresses: sivakumar.gomathi@gmail.com, gomathi@iist.ac.in (G. Nageswaran). Materials Research Bulletin 98 (2018) 300–307 Available online 28 October 2017 0025-5408/ © 2017 Elsevier Ltd. All rights reserved. T