Hydrogen evolution reaction (HER) under alkaline media plays a pivotal role in industrial electrocatalytic hydrogen production but even the platinum-based electrocatalysts suffer from high overpotential and low kinetics due to the high energy barrier of water dissociation. Here, by employing in-situ produced graphitic carbon nitride (g-C3N4) as template to induce the formation of a lamellar structure, we reported evenly dispersed Ru-doped Mo2C nanoparticles on ultrathin nitrogen-doped carbon nanosheets (RuMo2C/CN) as a highly efficient alkaline HER electrocatalyst. The optimal Ru-Mo2C/CN displays a remarkable activity with a low overpotential of only 34 mV to afford 10 mA cm(-2) and good stability of more than 30 h, which is much better than that of commercial Pt/C and recently reported electrocatalysts in the landmark literatures. Density functional theory (DFT) calculations show that the introduced Ru dopant on Mo2C significantly reduce the water dissociation energy barrier of HER and inhibit the competitive adsorption between H* and OH* on the surrounding Mo sites. This work highlights a simple yet effective strategy for designing electrocatalysts with excellent performance of hydrogen evolution reaction in alkaline media. (C) 2020 Elsevier Inc. All rights reserved.