Twist-Angle-Dependent Electrocatalytic Activation of Basal Plane MoS2 in Twisted Bilayer Structures.

The electrocatalytic performance of transition metal dichalcogenides (TMDs) is often hindered by their basal planes. Although defect engineering and heteroatom doping are employed, improving the electrocatalytic activity of the basal plane without disrupting the in-plane lattice structure remains a challenge. The interlayer twist serves as an effective strategy to preserve the in-plane lattice integrity of TMDs and tune their electrocatalytic performance. In this work, high-quality twisted bilayer MoS2 (TBL-MoS2) was fabricated through polydimethylsiloxane (PDMS)-assisted mechanical exfoliation and dry transfer stacking. On-chip electrochemical nanodevices were subsequently constructed to investigate hydrogen evolution reaction (HER) performance at different twist angles. This demonstrates that bilayer MoS2 with a twist angle of 15° (TBL-15°) exhibits superior hydrogen evolution reaction performance with a Tafel slope of 63 mV/dec, significantly lower than the value of 202 mV/dec of the pristine bilayer. This work paves the way for twist angle engineering in designing high-performance 2D electrocatalysts.