Defect engineering of P doped Fe7S8 porous nanoparticles for high-performance asymmetric supercapacitor and oxygen evolution electrocatalyst.

This manuscript reports the porous P-Fe 7 S 8 nanospheres synthesized by phosphorus doping into Fe 3 S 4 nanospheres obtained from one-step vulcanization strategy. The structure performs well in supercapacitor, and the Ni x Fe 1-x S samples synthesized by the same vulcanization strategy show excellent electrocatalysis performance in oxygen evolution reaction. [Display omitted] Transition metal sulfides are promising battery-type materials for electrochemical energy storage and a great electrocatalyst for oxygen evolution reaction (OER). However, the poor conductivity and sluggish reaction kinetic as well as the deficiency of electrochemically active sites hinder the practical application of Fe x S y. Herein, we design Fe 7 S 8 porous nanoparticles with surface phosphate ions and enriched sulfur-vacancies (P-Fe 7 S 8), which is reported as a new high-specific-capacity material for asymmetric supercapacitor. Benefiting from the merits of substantially improved electrical conductivity and increased active sites, the optimized P-Fe 7 S 8 negative electrode delivers ultra-high specific capacitance of 804.7F/g at 0.4 mA. Moreover, the assembled NiS//P-Fe 7 S 8 ASC presents an impressive specific capacitance of 335.9F/g at 1.2 A/g, a high energy density of 134.8 Wh/kg at a power density of 1042.1 W/kg, and great flexibility under different bending angles. Furthermore, the one-step vulcanization process is provided with universal applicability for the synthesis of Ni x Fe 1-x S bimetallic sulfide. With the synergy effect produced by the bimetal, the Ni 0.5 Fe 0.5 S hollow porous nanoparticles exhibit the remarkable activity of oxygen evolution reaction with a low overpotential of 174 mV at 10 mA cm−2 and Tafel slope of 41 mV dec−1. This simple method provides new insight into the synthesis of novel multifunctional metal sulfide nanomaterials. [ABSTRACT FROM AUTHOR]