Activity of MXene Single Flakes in situ using SECCM

MXene are 2D carbides of transition metals, which are studied for their application in different fields, including electrocatalysis and energy storage. Ti3C2 is a MXene, which has shown activity for the hydrogen evolution reaction. We study the activity of Ti3C2 singles flakes, mixed single layer and multilayer, using SECCM and ex situ AFM. SECCM studies reveal differences in activity for different flakes. Our results show that multilayer flakes have a larger overpotential, possibly because of more difficult insertion of ions between layers compared to the reaction on the basal plane. We develop an in situ method for evaluating electrochemical surface area using known redox chemistry of Ti3C2. Contrary to AFM-derived surface area, it takes into account insertion between layers to properly understand the activity of multilayer flakes.