A Review: Scanning Electrochemical Microscopy (SECM) for Visualizing the Real-Time Local Catalytic Activity

Abstract

Scanning electrochemical microscopy (SECM) is a powerful scanning probe technique for measuring the in situ electrochemical reactions occurring at various sample interfaces, such as the liquid-liquid, solid-liquid, and liquid-gas. The tip/probe of SECM is usually an ultramicroelectrode (UME) or a nanoelectrode that can move towards or over the sample of interest controlled by a precise motor positioning system. Remarkably, electrocatalysts play a crucial role in addressing the surge in global energy consumption by providing sustainable alternative energy sources. Therefore, the precise measurement of catalytic reactions offers profound insights for designing novel catalysts as well as for enhancing their performance. SECM proves to be an excellent tool for characterization and screening catalysts as the probe can rapidly scan along one direction over the sample array containing a large number of different compositions. These features make SECM more appealing than other conventional methodologies for assessing bulk solutions. SECM can be employed for investigating numerous catalytic reactions including the oxygen reduction reaction (ORR), oxygen evolution reaction (OER), hydrogen evolution reaction (HER), water oxidation, glucose oxidation reaction (GOR), and CO2 reduction reaction (CO2RR) with high spatial resolution. Moreover, for improving the catalyst design, several SECM modes can be applied based on the catalytic reactions under evaluation. This review aims to present a brief overview of the recent applications of electrocatalysts and their kinetics as well as catalytic sites in electrochemical reactions, such as oxygen reduction, water oxidation, and methanol oxidation.

Layered MAX phase electrocatalyst activity is driven by only a few hot spots

“…Recently, the scanning probe techniques such as scanning electrochemical microscopy (SECM), have been employed to study the electrochemical activity of different electrocatalytic surfaces. 31–35 The SECM has been used for investigation of the catalytic surfaces by reflecting the surface morphology, conductivity and electrochemical activity as well as the location of the HER active sites on the electrocatalytic surfaces. 36–42…”

Designing Cu-Based Tandem Catalysts for CO2 Electroreduction Based on Mass Transport of CO Intermediate

“…128 Therefore, SERS mapping and model catalysts with micrometer-scale patterns can be combined to reveal the correlation between the spatial distribution of different species and the catalytic performance of tandem catalysts. To gain higher spatial resolution and detect a finer distribution of different species, scanning electrochemical microscopy (SECM) 129 and tip-enhanced Raman spectroscopy (TERS) 130 are suitable techniques.…”

Elucidating Electrocatalytic Oxygen Reduction Kinetics via Intermediates by Time Resolved Electrochemiluminescence

“…[17][18] Alternatively, thanks to ultramicroelectrodes (UME) giving hemispherical diffusion, scanning electrochemical microscopy (SECM) provides another intriguing way to achieve useful steady-state conditions, but the scanning area and probe types require specialized topography of electrocatalysts, restricting its broad application. [19][20][21][22] Despite unprecedented advances, notably, few of them use the reactive oxygen species (ROS) intermediates to establish reaction rate equations. [22][23][24] Indeed, ROS are produced in the diffusion layer at a much lower concentration than O2 and of short life, making the mass diffusion resistance in the bulk solution negligible.…”