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Electrochemical sensors present a wide range of interesting applications in the areas of environmental, industrial, and chemical analysis. This review presents an overview of two types of sensors: electrocatalytic ones, which involve oxidation and reduction reactions through electron transfer, and photoelectrocatalytic ones, which involve a current response due to the incidence of light and redox reactions. Another point discussed was how these sensors’ detection capacity and behavior can be affected by several factors related to the material used to make the electrode. In this way, inorganic, organic, and hybrid materials were compared in electrocatalytic and photoelectrocatalytic sensors. The use of inorganic materials is interesting due to the fact of their abundance, low cost, and good electroactivity. Among organics, conductive polymers and carbonaceous materials are often cited due to the fact of their conductivity and their different possibilities for synthesis, being possible to mold their shape. Finally, hybrid materials unite these two classes, presenting different properties not found in a single substance.

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This work shows the synthesis and characterization of graphite-like materials produced from the pyrolysis of biomass, obtained from industrial waste. The product has shown interesting electrochemical characteristics for application in the formation of a composite material with polyaniline, creating a perspective of application in a so-called “waste” helping to avoid environmental issues associated with this industrial disposal. The raw pyrolyzed material was further separated into nanosized structures by applying high-potency ultrasonic radiation, which was used in the modification of flexible electrodes of polyaniline, resulting in a composite material. Thermogravimetric analysis, electrochemical experiments, electrochemical impedance spectroscopy, Raman spectroscopy, and electronic microscopy were used for the characterization of the material itself and the composite electrode. The interaction between the modified graphite-like materials and polyaniline produced a high superficial area electrode, in a one-step synthesis. Such composite material favors the intrinsic conductivity of the conducting polymer, which was confirmed by the enhancement of its electrochemical and interfacial properties even in milder electrolytes, generating good perspectives for other electrochemical applications. These results demonstrate the potential of developing this composite material in energy storage electrodes.