Porous core-shell N-doped Mo2C@C nanospheres derived from inorganic-organic hybrid precursors for highly efficient hydrogen evolution

Using inorganic-organic MoO42-/aniline-pyrrole (MoO42--Polymer) hybrids nanospheres as precursors, we synthesize the porous core-shell N-doped Mo2C@C nanospheres with the three advantages including porous nanostructures, conductive substrate and N-doping, which may maximize the activity of electrocatalysts for hydrogen evolution reaction (HER). The as-prepared Mo2C@NC has the porous core-shell nanospherical structure with ultrafine Mo2C nanoparticles as core and ultrathin N-doped carbon (NC) nanolayers as shell. The aniline-pyrrole in MoO42--Polymer prevents fast growth and severe aggregation of Mo2C and form porous structure composed of ultrafine Mo2C, which implies the more exposed active sites. On the other hand, the carbonization of MoO42--Polymer produces the ultrathin N-doped carbon shell on the surface of Mo2C@NC nanospheres, which can optimize electronic structures and greatly improve charge transfer rate. Through varying MoO(4)(2-)content and carbonization temperature, the optimized Mo2C@NC sample exhibits enhanced HER performance and long-time stability both in acidic and alkaline solution. It requires an onset potential of only 110 mV and 60 mV, striking kinetic metrics (Tafel slope: 83 mV dec(-1) and 70 mV dec(-1)) in 0.5 M H2SO4 and in 1 M KOH, respectively. Therefore, designing unique inorganic-organic hybrid nanostructures may open up a new way for excellent electrocatalysts for HER. (C) 2018 Elsevier Inc. All rights reserved.