Investigation of the electrocatalytic activity of sensors based on graphene oxide decorated with PT, AU or Ag nanoparticles by scanning electrochemical microscopy

Abstract

Aiming at an assortment of applications ranging from selective catalysts to biosensors, understanding the processes that take place on the surface/interface of an electrocatalyst and determining its electrocatalytic activity at different regions are very important. Scanning Electrochemical Microscopy (SECM) provides direct images of heterogeneous systems and also yields a local modification of substrates due to electrochemical reactions. In this internship project, the electrocatalytic activity of graphene oxide-based sensors modified with Pt, Au or Ag nanoparticles will be investigated by SECM, to fundamentally understand their catalytic properties. Furthermore, we will investigate the roles of the graphene oxide preparation method and deposition conditions of the noble metals on the electrocatalytic activity of the sensors. This correlation could provide the knowledge to improve the analytic performance of the sensors or even the electrocatalysis for specific reactions as oxygen reduction reaction (ORR), and hydrogen evolution reaction (HER). The SECM is a technique still in development in Brazil, but it holds great promise for the advancement of many interdisciplinary applications, such as biosensors, catalysts, fuel cells, interfaces, etc. The knowledge of this technique is of high interest since it can provide specific information about a substrate's reactivity that is properly designed for novel bioanalytical interfaces as the modified graphene oxide. Moreover, the understanding of localized processes can enhance the applicability, sensitivity, and detection limits of several sensors including H2O2, NH3 or even NO2 sensors. Throughout the internship, I will gain SECM knowledge in microelectrode/nanoelectrode fabrication, SECM measurements, and data treatment thereof. The protocols developed in Mauzeroll's group at McGill University are well respected, including the development of patents about microelectrodes/nanoelectrodes fabrication. The expertise of the group in electrochemical reactive imaging and detection of biological systems, such as drug delivery, multidrug resistance, and biosensors development, will also allow the progress of the technique in the biological field, especially at Kubota's group.