Molecular intercalation of transition metal dichalcogenide nanosheets to enhance electrocatalytic activity toward hydrogen evolution reaction

The novel two-dimensional nanostructures of transition metal dichalcogenides (TMDs) have motivated extensive studies on the control of electronic structures via sandwiching of foreign species. Herein, we review our recent works on TMD nanosheets that intercalated with various molecules (i.e., amine, cobaltocene, porphyrin, phthalocyanine, etc.). They were mainly synthesized by a one-step solvothermal reaction. The intercalation expanded the interlayer spacing significantly and induced the phase conversion from semiconducting 2H to metallic 1T ' (distorted 1T), accompanied by the charge transfer from the intercalants to the TMDs. The intercalated TMD nanosheets exhibit excellent catalytic performance in water-splitting hydrogen evolution reaction (HER). First-principles calculations suggest that the 2H-1T ' phase transition via intercalation can be driven by a significant charge transfer to TMD. The intercalation increased carrier concentration, which leads to enhanced catalytic performance. The present work illustrates how the intercalation of molecules can stabilize the metastable 1T ' phase and effectively enhance the HER performance.