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

Abstract

Layered metal carbides, MAX phases, have gained significant interest in the scientific community due to their electrocatalytic and electrochemical properties. Among various MAX phases, Mo₂TiAlC₂ has driven much attention because of its enhanced electrochemical activity for the hydrogen evolution reaction (HER). So far, the macroscopic HER performance has been investigated by traditional electrochemical techniques such as voltammetry. However, the knowledge of the microscopic electrocatalytic behaviour, i.e., distribution and location of highly active sites for HER is still limited. Herein, the microscopic analysis of the MAX phase microparticles shows that their electrocatalysis is driven by a few particles with an outstanding catalytic activity towards hydrogen evolution. Such observation is of high importance for design and applications of electrocatalysts in general.