**3. The electrochemistry of quantum dots**

It is important to note that the influence of the core diameter, protective shell size, and functional groups on the QDs concerning their redox activity is not yet well understood. However, it is recognized that the quality of the nanomaterial plays a fundamental role in determining the photocurrent potential [26].

In the generation of current induced by light, some criteria are known to be significant in the process. For efficient electronic transfer, factors such as the distances and the nature of the connections between QD-electrode and QD-analyte are crucial. The redox rate can also be affected by the properties of the Quantum dots and their surface ligands. Moreover, the light induction can generate charge recombination events in the system, involving the electronic transfer [27].

Several investigations on the electrochemical behavior of QDs have been carried out using aqueous solutions as a basis or deposited on electrodes. Although there are few studies on the correlation between their structure and their redox potential, some works compare the optical performance concerning the electroche mical activity of these nanocrystals [28, 29].

Of the main challenges associated with the electrochemical behavior of these semiconductors, the main ones are related to the low solubility and the low diffusion coefficient, which makes the measurement of current intensity little distinguishable

from interference. Furthermore, the occurrence of electronic removal or injection within the particle, resulting from redox processes, often leads to chemical irreversibility. This chemical irreversibility can contribute to less reproducible measurements [30].

One study evaluated the correlation between the electrochemical band gap and the Luminous electronic spectrum. In quantum dots based on CdS, it is evident that these nanoparticles actively participate by fuctioning as both multiple electron donors and acceptors, owing to their confinement within the particle [28].

In order to gain a deeper understanding of the electrochemical properties of CdTe-based QDs, a comprehensive evaluation of multiple parameters was conducted. These parameters included particle size, solution pH, and surface stabilizing agents. The technique of cyclic voltammetry was employed to investigate these aspects. The results of the study revealed that the reduction and oxidation events observed in the QDs could be attributed to the positions of the energy bands, which were influenced by the quantum size effect [31].

The so-called traps are energy states formed by breaking the surface symmetry of the QDs that occur within the valence and conduction bands. These traps are closely linked to changes generated in the direction of the polarization potential, which affects the behavior of the QDs [32–34].
