Scrutinizing Intrinsic Oxygen Reduction Reaction Activity of a Fe−N−C Catalyst via Scanning Electrochemical Cell Microscopy

Abstract

Carbon-based nanomaterials are renowned for their exceptional properties, making them propitious candidates for oxygen reduction reaction (ORR) electrocatalysis. However, their intrinsic activity is often challenging to investigate unambiguously with conventional methodologies due to the inherent complexities of such systems and the material itself. Zooming into the material and gaining electrochemical information with high resolution is a way to get rid of many experimental factors that influence the catalytic activity in macro-scale measurements.Herein, we employ nano-scale scanning electrochemical cell microscopy (SECCM) to investigate individual catalyst agglomerates with and without Nafion content. The intrinsic ORR activity of the catalyst was unravelled by using a unique approach of normalizing the data of all measured points by their distinctive electrochemical surface area (ECSA). When coupling with scanning electron microscopy (SEM), the structure and morphology of the catalytically active agglomerates were visualized.

Au Micro‐ and Nanoelectrodes as Local Voltammetric pH Sensors During Oxygen Evolution at Electrocatalyst‐Modified Electrodes

“…Concordantly, the water activity was determined previously to be less than unity in concentrated HClO 4 solutions. [22] To demonstrate the capability of Au microprobes for local pH sensing in acid conditions, the OER reaction at an IrO 2 catalyst deposited on a flat boron-doped diamond (BDD) surface [23] was initially studied as a model case representing a catalyst with high OER activity. The SECM tip was positioned close to the surface to guarantee that the SECM tip was probing the diffusion layer in front of the working catalyst surface, as described in the experimental section.…”

“…The mixture was treated with tip sonication for 40 min, and then 5 μL of a 5 wt% Nafion solution was added. After being treated with bath sonication for 40 min, 10 μL of the obtained ink was drop cast onto a boron-doped diamond substrate [23] with an exposed surface area of 0.196 cm 2 and dried at room temperature (RT).…”

Spatially Confined Microcells: A Path toward TMD Catalyst Design

“…Since then, there has been a notable surge in the development of SECCM instrumentation, specifically emphasizing pipet design by reducing meniscus size and refining measurement methodologies . Furthermore, SECCM has found extensive application in the study of diverse materials, including but not limited to highly oriented pyrolytic graphite (HOPG), metal–organic framework (MOF), metal particles, TMD, and polycrystalline metals and alloys. − …”

Recent Developments in Single-Entity Electrochemistry

“…A trend in SEE with SECCM is the study of single nanocrystals with controlled size, shape, facet, and surface area. ,− Jeong et al employed SECCM to resolve activity for electrochemical CO 2 reduction (eCO 2 RR) at faceted single-crystalline Au nanocrystals . Three differently faceted nanocrystals were designed to have the same surface area.…”