Space‐Confined One‐Step Growth of 2D MoO2/MoS2 Vertical Heterostructures for Superior Hydrogen Evolution in Alkaline Electrolytes

Abstract 2D material‐based heterostructures are constructed by stacking or spicing individual 2D layers to create an interface between them, which have exotic properties. Here, a new strategy for the in situ growth of large numbers of 2D heterostructures on the centimeter‐scale substrate is developed. In the method, large numbers of 2D MoS 2 , MoO 2 , or their heterostructures of MoO 2 /MoS 2 are controllably grown in the same setup by simply tuning the gap distance between metal precursor and growth substrate, which changes the concentration of metal precursors feed. A lateral force microscope is used first to identify the locations of each material in the heterostructures, which have MoO 2 on the top of MoS 2 . Noteworthy, the creation of a clean interface between atomic thin MoO 2 (metallic) and MoS 2 (semiconducting) results in a different electronic structure compared with pure MoO 2 and MoS 2 . Theoretical calculations show that the charge redistribution at such an interface results in an improved HER performance on the MoO 2 /MoS 2 heterostructures, showing an overpotential of 60 mV at 10 mA cm −2 and a Tafel slope of 47 mV dec −1 . This work reports a new strategy for the in situ growth of heterostructures on large‐scale substrates and provides platforms to exploit their applications.