MOF-aided topotactic transformation into nitrogen-doped porous Mo2C mesocrystals for upgrading the pH-universal hydrogen evolution reaction

Molybdenum carbide (Mo2C) is one type of promising noble-metal-free electrocatalyst for the hydrogen evolution reaction (HER), but the synthesis of highly crystalline Mo2C is usually accompanied by particle coarsening and/or carbon residues, resulting in low exposed active sites and decreased mass activity. Herein, we developed a metal-organic framework (MOF)-aided topotactic transformation strategy for the fabrication of N-doped porous Mo2C mesocrystals on carbon fiber paper (N-Mo2C/CFP). The optimized N-Mo2C/CFP requires the overpotentials of only 45, 80 and 37 mV to deliver the current density of 10 mA cm(-2)in acidic, neutral and alkaline media, respectively. The pH-universal HER activities are competitive with those of commercial 20 wt% Pt/C. This work provides the advanced metal carbide mesocrystals as noble-metal-free electrocatalysts for HER in all pH ranges.