The Potential of Nanostructured Electrode Materials in Analytical Sciences: A Short Commentary

Nanostructured materials are often employed in electrode manufacturing in order to enhance charge transfer kinetics as well as improve operational conditions in energy storage and electroanalytical devices. Considering the impact of modifying electrode surface with conductive nanostructured elements and the applicability of these modifications in pharmaceutical, biomedical, food, chemical and other sciences, this commentary is intended to briefly discuss the general characteristics and parameters underlying the uses of these devices, as well as foment the importance of nanostructured composites for analytical and electronic applications.

behavior in fluidic systems is often explored in analytical chemistry in order to promote analyte preconcentration, as well as understand electrode-solution interface features.
Although highly capacitive in nature due to double layer formation upon contact to electrolyte containing liquids, solid electrodes whose use is intended in sensing and biosensing technologies should also display lower charger transfer resistance [3]. This feature is largely pursued by materials scientists due to the influence of electron kinetics on device performance [3,4]. Moreover, when electrode materials showcase chemical affinity to oxidation or reduction products of analytes, a phenomenon known as electrode fouling may take place, which may hinder faradaic current output mid-analysis [5,6]. In this sense, many researchers focus on developing disposable lowcost electrodes whose surface is easily renewed [7].
Considering that most electroanalytical methods are conceived upon the premise that redox processes promote faradaic currents, therefore a stress must be applied in the system in order to render the thermodynamics of redox processes feasible.
In this context, analytical tools such as chronoamperometry and voltammetry make use of electric potential to promote redox processes whose current is used to determine analyte concentration, impurity, authenticity, etc [8,9,10].
In electroanalysis, the precise monitoring of the kinetics and thermodynamics of redox processes is essential to develop a reliable and reproducible method [3]. Given the representation of faradaic current as reactional kinetics, and the electric potential associated to these processes corresponding to the thermodynamic parameter, the efficiency of a method may be considered optimal if a minimal applied stress, i.e. electric tension applied to the system, is able to promote a massive  [13,14,15] .
Notwithstanding, depending on the analytic system to which these modified electrodes may be applied, reuse can be feasible. Regarding nanostructured electrode modifications applicability in pharmaceutical and chemical industries, several reports evidenced carbon-transition metal oxide electrodes being used in chronoamperometric techniques whose analytic parameters rivalled standard analytical approaches, such as high-performance liquid chromatography [10,13,15]. Moreover, when taking in consideration that liquid chromatography involves the expenditure of many liters of organic solvents, as well as high operational cost and time-consuming analysis, the appeal of electroanalytical tools employing nanostructured electrodes is remarkable.
Although the determination of substance concentrations is the first idea considered when nanostructured electrode use in electroanalysis is under the spotlight, their applicability is fairly diverse, being straight forward such as drug determination in pharmaceutical formulations [7,13], authenticity tests in raw mater assessment [5,8], emerging pollutants and industrial effluent monitoring [10], as well as other uses such as in decontamination systems for wastewater treatment [16,17], and operation and process monitoring in food and chemical industry [18]. In this sense, the sheer variety of applications provided by these compounds is noteworthy, and surely many more uses are yet to be unraveled.

CONCLUSION
Therefore, this commentary was intended to briefly discuss the general characteristics and parameters underlying the uses of nanostructured electrode materials, as well as foment the importance of nanostructured composites for analytical and electronic applications. It is safe to say that the use of nanostructured electrodes provides deep advances in electroanalytical area, and their versatility allows the use of these materials in several other fields.