[en] Highlights: • Nitrogen-doped carbon supported few-layer MoSe₂ (FL-MoSe₂/NC) is prepared. • It exhibits low onset potential and small overpotential. • It exhibits a greatly reduced Tafel slope and a higher exchange current density. • MoSe₂ with few-layers and short fringe lengths exposes more edge and defect sites. • There exists a strong coupling between MoSe₂ and NC. Development of advanced electrocatalysts to drive efficient hydrogen evolution reaction through water splitting is vital in many energy related technologies. Herein the development of nitrogen-doped carbon supported fewer-layer MoSe₂ (FL-MoSe₂/NC) through calcining the hydrothermal product of the Se and Mo precursors in the presence of ammonium citrate is reported. This FL-MoSe₂/NC is highly efficient for the hydrogen evolution reaction (HER) and exhibits a remarkably low onset potential of 15.2 mV, an extremely small overpotential of 74.6 mV (vs. RHE) at 10 mA cm⁻², a greatly reduced Tafel slope of 45.2 mV dec⁻¹, and a higher exchange current density of 0.266 mA cm⁻². The performance of the FL-MoSe₂/NC is much higher than that of most Mo-based HER electrocatalysts reported to date and even comparable to that of other most active non-precious metal based catalysts, suggesting the great potential of using the FL-MoSe₂/NC as an efficient catalyst for the HER. The NC is believed to play an important role in the high performance of the FL-MoSe₂/NC. It does not only promote a strong interaction between MoSe₂ and the NC, but facilitates the formation of MoSe₂ with few layers and shorter lattice fringe lengths, which expose more active sites accessible to the HER.

[en] Highlights: • Hierarchical micro-nanostructure of transition metal oxide was designed. • MOF-derived nanoporous Co₃O₄ was obtained. • Electrospinning technique was used to construct the nanoporous structure. • The Co₃O₄ as supercapacitor electrodes shows high specific capacitance. -- Abstract: The design and synthesis of hierarchical micro-nano structures of transition metal oxides have played an essential role in the supercapacitor field. In this work, in situ three-dimensional construction of nanoporous cobalt oxide (Co₃O₄) has been derived from the metal-organic framework (MOF) distributed evenly in electrospun polyacrylonitrile nanofibers. Due to large specific surface area and network architectures, the as-synthesized Co₃O₄ electrode notably presents a high specific capacitance of 970 F/g at a current density of 1 A/g. Besides, the as-obtained electrode exhibits a high energy density of 54.6 Wh/kg at a power density of 360.6 W/kg and maintains a capacitance retention of 77.5% after 5000 cycles at 6 A/g. Therefore, this method paves a way to produce the nanoporous MOF-derived Co₃O₄ network architecture as advanced electrodes materials, which shows an application potential for the energy storage industry.