Synthesis of Co9S8@CNT hydrogen production composites by one-step pyrolysis of monomolecule precursor

Abstract

Co9S8 is a highly promising electrochemically active material for energy devices; its rational design and manufacture for further enhancing the electrochemical activity and durability are still challenging. Herein, Co9S8@CNT compounds are synthesized by one-step pyrolysis, which self-assembled the monomolecular precursor and carbon nanotubes (CNTs). The CNTs effectively improve the electrical conductivity of the materials and availability of the catalytically active sites, which means that the electrochemical ability of Co9S8@CNT is better than that of individual Co9S8 and CNTs. The onset potential of Co9S8@CNT is 132 mV, which has greatly decreased. At the mass current density of 10 mA mg−1, the overpotential is 337 mV, and the Tafel slope is 49.8 mV dec−1. The addition of CNTs makes up for the deficiency of low electrical conductivity of the CoSx. Furthermore, the three-dimensional (3D) structure of the composite improves its electrocatalytically active surface area, and the electrocatalytic ability has been improved efficiently, owing to the increased number of catalytic sites on the surface.