Accessibility to potentiostats is crucial for research development in electrochemistry, but their cost is the principal drawback for their massive use. With the aim to provide an affordable alternative for resource-constrained communities, we present a low-cost, portable electrochemical workstation that integrates an open-source potentiostat based on Arduino and a smartphone application. This graphical user interface allows easy control of electrochemical parameters and real-time visualization of the results. This potentiostat can perform the most used electrochemical techniques of cyclic and linear voltammetry and chronoamperometry, with an operating range of AE225 μA and AE1.50 V, and results that are comparable with those obtained with commercial potentiostats. Three applications reported here demonstrate the capacity and the good performance of this low-cost potentiostat as a teaching tool: identification of redox pairs, electrochemical characterization of pencil graphite electrodes, and detection of heavy metals using an electrodeposited film of bismuth on the pencil graphite electrode. Furthermore, detailed schemes of the device and its software are entirely available, expecting to provide an open-source potentiostat easy to replicate to further support education in electrochemical fundamentals and instrumentation.
Graphite is the most commercialized electrode active compound for lithium-ion batteries (LIB). However, its limited theoretical capacity (372 mAh/g) and relatively poor rate performance make it unsuitable for LIB with higher energy density and fast charge ability. Therefore, alternative carbon-based materials, like graphene, have also been explored due to their attractive electrochemical properties.1 Despite having these properties, the low density and the high specific surface area of graphenic materials result in a low coulombic efficiency when it is used in LIB. To solve this, the physical and electrochemical properties of graphenic materials can be modified during the process of obtention of this material. This work presents a methodology with unique advantages in terms of low cost, stability, scalability, and non-use of hazardous conditions for obtaining an N-doped graphene-like graphite material. This procedure consists of the electrochemical oxidation of graphite rods and a subsequent hydrothermal reduction of the oxidated graphene. First, the electrochemical exfoliation of graphite rods was carried out under constant potential in a basic solution. Due to the exfoliation process, this graphenic material was characterized by having oxygenated functional groups and a graphite-like structure. The structural properties of this material were investigated at room temperature using X-ray diffraction (XRD), infrared spectroscopy (FTIR), and Raman spectroscopy. To reduce the oxygenated functional groups on the graphenic material, a hydrothermal method was used. Simultaneously to the reduction, heteroatom doping was carried out to enhance the electrochemical properties of the obtained reduced graphenic material. To further control the doping process of the rGO and the final properties of the material, a pre-reduction treatment was also introduced. This low-cost, pre-reduction process allowed the controlled introduction of defects in the material to enhance the doping percentage of the N-rGO. Besides the structural characterization techniques previously indicated, electrochemical impedance spectroscopy (EIS) and voltammetric methods were used to characterize the final N-doped electrochemical properties fully. The observed features of the samples indicate that the graphenic material possesses a graphite-like graphene structure, which allows the material to act like independent graphene layers that maintain a highly regulated orientation between the sheets, which can increase the charge/discharge capacity if used in LIB.2 Furthermore, it was shown that the pre-reduction treatment allowed an increase in the doping percentage of the graphenic material. This increased doping led to an increased charge-transfer conductivity, as indicated by the electrochemical characterization methods. Overall, this low-cost, scalable procedure allows the obtention of graphenic materials with properties suitable for their applications in LIB. Al Hassan, M. R., Sen, A., Zaman, T. & Mostari, M. S. Emergence of graphene as a promising anode...
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