Binary molten salt in situ synthesis of sandwich-structure hybrids of hollow β-Mo2C nanotubes and N-doped carbon nanosheets for hydrogen evolution reaction

Focused exploration of earth-abundant and cost-efficient non-noble metal electrocatalysts with superior hydrogen evolution reaction (HER) performance is very important for large-scale and efficient electrolysis of water. Herein, a sandwich composite structure (designed as MS-Mo 2 C@NCNS) of β- Mo 2 C hollow nanotubes (HNT) and N-doped carbon nanosheets (NCNS) is designed and prepared using a binary NaCl–KCl molten salt (MS) strategy for HER. The temperature-dominant Kirkendall formation mechanism is tentatively proposed for such a three-dimensional hierarchical framework. Due to its attractive structure and componential synergism, MS-Mo 2 C@NCNS exposes more effective active sites, confers robust structural stability, and shows significant electrocatalytic activity/stability in HER, with a current density of 10 mA cm −2 and an overpotential of only 98 mV in 1 M KOH. Density functional theory calculations point to the synergistic effect of Mo 2 C HNT and NCNS, leading to enhanced electronic transport and suitable adsorption free energies of H* (Δ G H* ) on the surface of electroactive Mo 2 C. More significantly, the MS-assisted synthetic methodology here provides an enormous perspective for the commercial development of highly active non-noble metal electrocatalysts toward efficient hydrogen evolution.