Hierarchical Nitrogen‐doped Mo 2 C Nanoparticle‐in‐microflower Electrocatalyst: in Situ Synthesis and Efficient Hydrogen‐evolving Performance in Alkaline and Acidic Media

Herein, a novel 6∼9 nm nitrogen‐doped Mo 2 C nanoparticles (Mo 2 C P) homogeneously decorated on 3D porous nitrogen‐doped Mo 2 C microflowers (Mo 2 C F) were prepared in situ to form 0D/3D Mo 2 C P/Mo 2 C F. This special structure combines the advantages of Mo 2 C P and porous Mo 2 C F to provide a high density of reaction sites and facilitate the diffusion of electrolyte and hydrogen. Mo 2 C P/Mo 2 C F exhibits excellent HER performance in both alkaline and acidic solutions. It only requires an overpotential of 96 and 118 mV to achieve a current density of 10 mA cm −2 ( η 10 ) in 1.0 M KOH and 0.5 M H 2 SO 4 , respectively. Moreover, it works better than commercial Pt/C at high current densities in 1.0 M KOH. The Tafel slopes are less than 50 mV/dec in both media, suggesting an obviously fast HER kinetics. Additionally, this study presents a universally applicable method to prepare M x C P/Mo 2 C F (M=Fe, Co, V) for different applications.