Revealing the Heterogeneity of Large‐Area MoS(2) Layers in the Electrocatalytic Hydrogen Evolution Reaction

The electrocatalytic activity concerning the hydrogen evolution reaction (HER) of micrometer‐sized MoS(2) layers transferred on a glassy carbon surface was evaluated by scanning electrochemical cell microscopy (SECCM) in a high‐throughput approach. Multiple areas on single or multiple MoS(2) layers were assessed using a hopping mode nanocapillary positioning with a hopping distance of 500 nm and a nanopipette size of around 55 nm. The locally recorded linear sweep voltammograms revealed a high lateral heterogeneity over the MoS(2) sheet regarding their HER activity, with currents between −40 and −60 pA recorded at −0.89 V vs. reversible hygrogen electrode over about 4400 different measured areas on the MoS(2) sheet. Stacked MoS(2) layers did not show different electrocatalytic activity than the single MoS(2) sheet, suggesting that the interlayer resistance influences the electrocatalytic activity less than the resistances induced by possible polymer residues or water layers formed between the transferred MoS(2) sheet and the glassy carbon electrode.