Advanced catalysts with element-abundance, economic-cost and stability are desired for electrochemical hydrogen evolution reaction (HER) to scale-up the promising clean energy of hydrogen.[1] The discoveries in the (de)hydrogenation of petroleum chemicals have inspired several efficient and economic catalysts of metal non-oxides towards HER, such as Mo-based sulfides and carbides.[2] MoS2 possesses a layered structure exposing Mo- and S- edges, which are highly active for HER due to the moderate hydrogen bonding energy (ΔGH*).[3] However, its performance is still limited by the poor conductivity and the uncontrolled properties of active-sites. In our recent work, efforts have been made to synergically enhance the conductivity and active-site abundance of MoS2, achieving the high current densities and low onset overpotentials for HER.[4-6] For example, we proposed a new route to confine MoS2 growth within an in-situ formed polysaccharide matrix from glucose condensation during hydrothermal processes, and after the following carbonization, MoS2/C nanocomposites evenly integrating ultrathin MoS2 nanosheets (2 ~ 4 nm) with conducting carbon were successfully harvested (Fig. 1a).[6] The MoS2/C exhibited an excellent HER activity characterized by higher current densities and lower onset overpotentials than the conventional MoS2. In particular, the MoS2/C with a suitable MoS2 content of 14.8% showed a small onset overpotential of ~80 mV, a high current density of 88 mA cm-2 at η = 200 mV, which are ascribed to the abundant rim-sites on ultrathin MoS2 nanosheets and the improved conductivity by carbon. On the other hand, a facile microwave-assisted hydrothermal method was further introduced to fabricated active-site enriched MoS2 nanosheets employing reactant self-shelter, in which the excessive S source (e.g., thiourea) would cover the highly-active Mo-sites during MoS2 formation, and then be removed by following treatment with H2SO4, resulting in abundant active sites on MoS2. The electrocatalytic test well-confirmed the significantly improved active-sites (~3 orders) and conductivity as compared with the traditionally prepared MoS2. Thanks to the facile synthesis and outstanding electrochemical behaviors, our effort is expected to pave the way for earth-abundant, economic and efficient electrocatalysts used in energy conversion and storage.