Developing noble-metal-free electrocatalysts for hydrogen evolution reaction (HER) is highly desirable to realize the hydrogen energy economy. Nanostructures and carbon-based hybrids are introduced to increase active-site abundance and to promote mass transportation. Herein, we reported a facile strategy for the in situ synthesis of bimetallic alloy-metal carbide heterostructures on ultra-fine chitin derived N-doped carbon nanofibers (NCNFs). The chitin nanofibers have abundant functional groups including hydroxyl (-OH) and amino (-NH2), which can strongly catch the metal ions. After the carbonization process, the Mo0.84Ni0.16-Mo2C nanoparticles were in situ formed throughout the whole NCNFs. Owing to the unique 3D nanofibers network structure, large specific surface area and synergistic effects between the Mo0.84Ni0.16 alloy and Mo2C, the Mo0.84Ni0.16-Mo2C/NCNFs electrocatalysts exhibit excellent HER activity with low overpotentials of 183 mV (10 mA cm(-2)) and Tafel slope of 71 mV dec(-1) in alkaline solution. Heterointerface engineering can optimize the chemical configurations of active sites toward intrinsically boosted HER kinetics. The Mo0.84Ni0.16-Mo2C/NCNFs display temperature-dependent HER activity and the 750 degrees C is the best carbonization temperature. In addition, the electrocatalysts exhibit outstanding stability during continuous HER electrolysis. This work provides a simple strategy to fabricate bimetal alloy metal carbide heterostructures. (C) 2020 Elsevier Ltd. All rights reserved.