Microenvironment\nControl over Electrocatalytic Activity\nof g‑C<sub>3</sub>N<sub>4</sub>/2H-MoS<sub>2</sub> Superlattice-like\nHeterostructures for Hydrogen Evolution

Microenvironments in heterogeneous catalysis have been\nrecognized\nas equally important as the types and amounts of active sites for\nregulating catalytic activity. Two-dimensional (2D) nanospaces between\nvan der Waals (vdW) gaps of layered materials provide an ideal microenvironment\nto create novel functionalities. Here, we explore a facile method\nfor fabricating g-C<sub>3</sub>N<sub>4</sub>/2H-MoS<sub>2</sub> superlattice-like\nheterostructures based on thermochemical intercalation and polymerization\nreactions of formamide within enlarged vdW gaps of 2H-MoS<sub>2</sub> nanosheets without any transfer process. DFT calculations demonstrate\nthat the interlayer electron–electron correlations due to the\nintercalation effect of g-C<sub>3</sub>N<sub>4</sub>, rather than\nhigh-κ dielectric environments, lead to the improvement of intrinsic\nconductivity of 2H-MoS<sub>2</sub> nanosheets. As the proof of concept\nin applications for the electrocatalysis field, the heterostructure\nfor hydrogen electrochemical reaction (HER) exhibits high stability\nand catalytic activity in both acid and alkaline media, such as a\nquite low onset overpotential of 98 mV, a high exchange current density\nof 77.6 μA cm<sup>–2</sup>, and a small Tafel slope (52.9\nmV dec<sup>–1</sup>) in an acid medium. The enhanced HER activity\nis attributed to the improved conductivity and nanoconfinement effect\nof 2D nanospaces that decrease the reaction activation energy and\nactivate the inert basal planes.