Amorphous Molybdenum Sulfide on Three-Dimensional Hierarchical Hollow Microspheres Comprising Bamboo-like N-Doped Carbon Nanotubes as a Highly Active Hydrogen Evolution Reaction Catalyst

Abstract

Novel amorphous-MoSx-coated three-dimensional (3D) hierarchical hollow microspheres comprising one-dimensional bamboo-like N-doped carbon nanotubes (BNCNT/MoSx-HM) are developed as a highly active electrocatalyst for the hydrogen evolution reaction (HER). The 3D hierarchical microspheres are easily prepared via the growth of bamboo-like N-doped CNTs (BNCNTs) on both the inner and outer surfaces of Co3O4-MgO/carbon hollow microspheres, which are prepared by spray pyrolysis, followed by uniform MoSx coating of the surface. Metallic Co nanocrystals play a key role in the growth of BNCNTs, acting as catalysts for their nucleation. Owing to the electrostatic attraction between the N-doped sites in BNCNTs and the thiomolybdate precursor anions, few-layered amorphous MoSx catalysts are well deposited on BNCNT surfaces, even at low temperature. The 3D hierarchical hollow structure facilitates electrolyte access, and the synergistic effect between the MoSx catalyst material with ample active sites and the conductive N-doped CNTs increases electrochemical activity for the HER. Accordingly, electrochemical assessment of BNCNT/MoSx-HM reveals a overpotential of 159 mV at a current density of 10 mA cm(-2), a low Tafel slope of 41.1 mV dec(-1), and excellent stability in acidic conditions.