## 1 Introduction  
Sunset yellow (SY) is a dye extensively used in the preparation of several types of food including soft drinks, candies, cheese, cake, ice-cream, canned juice, sauce, etc. It is a synthetic dye composed of an azo group with aromatic rings that can cause mutagenic and carcinogenic risks in humans [1, 2, 3]. Its use in foods is already banned in a few countries such as the USA, Norway and Finland. An effective method for SY determination is highly necessary for improving food safety control. For conventional techniques used to quantify SY analysis, one can refer to UV-VIS absorption [4, 5] fluorescence [6], Raman [7] spectroscopies, and liquid chromatography [8, 9] with varying levels of complexity and accuracy. In this context, electrochemical techniques offer the advantage that they can be used directly in the medium to test, with little preparation, thus simplifying the detection protocol in order to offer a rapid response and portable analysis. The challenge is therefore to develop electrodes enabling high sensitivity and accuracy. Graphene appears as an excellent supporting material owing to its unique electronic properties and large specific surface area [10]. Therefore, it has attracted great attention for various fields such as electronics [11], supercapacitors [12], nanocomposite materials [13] and especially in electrochemical/biosensors [14; 15; 16]. Prior to the fabrication of graphene-based sensors, a direct electrochemical reduction exhibits a straightforward route to reduce graphene oxide (GO) into electrochemically reduced GO (ERGO) from GO suspensions [17]. However, graphene nanosheets tend towards the formation of irreversible agglomerates that could cause dramatic deterioration of the sheet's properties due to strong planar stacking of graphene layers. These will impede the continuous pathway for electron/photon transport and thus restrict widespread applications [18; 19]. In recent years, effective strategies have been proposed to separate graphene sheets by adding stabilizers such as surfactants [20; 21], ionic liquids [22; 23], and polymers [24]. Inorganic nanoparticles based on metals and metallic oxides, being relatively stable and robust with respect to the above agents, have become promising candidates as stabilizers for improving the electrochemical performance of graphene-modified sensors. Furthermore, the fabrication of metallic nanoparticle-graphene nanohybrids can benefit from the synergic effect of both nanomaterials for applications [25; 26]. Various metallic species have been successfully proposed for incorporation into graphene-based materials for electroanalytical applications, varying from the precious metals AuNPs [27; 28; 29], Au-Pd [30], Pt [31], and Ag [32] to the transition metal oxides Cu\({}_{2}\)O [33; 34], CuO [35; 36], Mn\({}_{3}\)O\({}_{4}\)[37], Fe\({}_{3}\)O\({}_{4}\)[38], TiO\({}_{2}\)[39; 40], CeO\({}_{2}\)[41], ZnO [42], and ZrO\({}_{2}\)[43]. However, graphene-based sensors are usually elaborated using Reduced Graphene Oxide (RGO) obtained via chemical reduction using toxic reducing agents, thus causing serious problems for human health and the environment. Therefore, effective and eco-friendly techniques enabling the preparation of graphene-based hybrid nanocomposites are highly recommended. In this context, electrochemical techniques exhibit several advantages for the preparation of graphene-metal nanocomposites with various benefits: (i) it can be achieved via a one-step process from a graphene oxide-ion metal mixture; it is green and fast without the use of any toxic chemical agents; (ii) the method is easily controllable by fine-tuning of electrochemical parameters; and (iii) it enables the direct preparation of a nanocomposite directly deposited onto a substrate and ready to use as an electrode.