FeS₂@C Core–Shell Nanochains as Efficient Electrocatalysts for Hydrogen Evolution Reaction

The development of noble metal free hydrogen evolution electrocatalysts which make water splitting more feasible and energy efficient is an urgent issue. Iron sulfides have recently emerged as promising candidates of the state-of-art noble metal free electrocatalysts and attracted enormous research interests for their superior catalytic efficiency and high crustal abundance. But research studies on iron sulfides were often plagued by their structure instability and low electronic conductivity. Herein, we report on a uniform carbon coated FeS2 (FeS2@C) nanochain material prepared by a magnetic-field-guided interface coassembly approach. In particular, the Fe3O4 nanospheres as precursors are assembled into chains during polymer coating process in dynamic magnetic field environment, followed by the successive carbonization and sulfidation to generate FeS2@C. The carbon layer not only protects FeS2 from decaying during electrocatalysis but also enhances the catalytic activity owing to the interfacial interaction between metal nanoparticles and nanocarbon. As a result, FeS2@C can act as highly active and stable electrocatalysts toward hydrogen evolution reaction (HER). It delivers a current density of 10 mA/cm2 at overpotential of 195 mV to catalyze HER and remains almost unchanged for 150 h.