The double-hole patch clamp is designed to measure the layer-dependent hydrogen evolution reaction performance of MoS₂. Increasing the MoS₂ layer from monolayer to trilayer, the bandgap decreases from 1.85 to 1.40 eV, but the onset potential increases. This could contribute to the ∼2.1 eV out-of-plane bandgap and corresponding high vertical resistance of MoS₂.

Conventional electrochemical experiments can only obtain the average contribution of all active sites in the catalyst. Hence, it is meaningful to distinguish the electrochemical contribution of the local active sites in single-crystal catalysts. Here, a double-hole patch clamp is designed to achieve a localized electrochemical measurement in a model catalyst, MoS₂. The double-hole patch clamp is further applied to measure the hydrogen evolution reaction of MoS₂. By increasing the MoS₂ thickness from monolayer to bilayer, the onset potential increases from 156 to 238 mV. There is no obvious electrocatalytic reaction by further increasing the MoS₂ thickness to the trilayer. This could contribute to the ≈2.1 eV out-of-plane bandgap and corresponding high vertical resistance of MoS₂. This double-hole patch clamp provides a new tool to understand the electrocatalysis activities of the local active sites.