Designing of low-cost and high efficient Pt-based catalysts is significant for clean and renewable energy applications. Combining Pt with transition metals and reducing the particle size of Pt-based catalysts are two effective strategies to improve their performances toward hydrogen evolution reaction (HER). Meanwhile, one-dimensional nanostructures with interconnected porous texture are ideal supports in electrocatalysis. Herein, ZIF-67 were embedded into electrospun polyacrylonitrile (PAN) to obtain hierarchical porous carbon nanofibers which were used as supports to anchor sub-5 nm octahedral Pt-Cu nanocrystals. The as-prepared nanocomposites exhibit outstanding HER performance in acidic medium with an overpotential of only 13 mV at the current density of 10 mA cm(-2) and superior stability over 10,000 cycles. This outperforms commercial Pt/C and most supported catalysts reported so far. The remarkable HER properties may be mainly attributed to the unique structures of nitrogen-doped porous carbon nanofibers and Pt-Cu nanocrystals. (C) 2019 Elsevier Inc. All rights reserved.