MoS2, TaS2, TiS2, WSe2 and TaSe2 nanobeltsdecorated with a PtAg alloy or Pt NPs have been successfully synthesized by etching 2D nanosheets under a mild reaction condition followed by a subsequent nanosheet-to-nanobelt transformation mediated by the PVP template. The PtAg-MoS2 hybrid nanobelt coated with PVP is used as the active material in a memory device, which exhibits hysteresis behavior with the function of dynamic random access memory.