Prussian-blue-derived FeS2 spheres with abundant pore canals for efficient hydrogen evolution reaction

•A simple method is demonstrated to fabricate novel FeS2 spheres with abundant pore canals from Prussian-blue.•The obtained porous FeS2 spheres deliver excellent HER activity in both acidic and alkaline media.•The porous FeS2 spheres show the long-term electrochemical stability in both acidic and alkaline media. A simple method is demonstrated to fabricate novel FeS2 spheres with abundant pore canals from Prussian-blue. Impressively, the porous FeS2 spheres exhibit excellent hydrogen evolution performance in both acidic and alkaline media, deverling an overpotential of 136 mV and 158 mV to attain a current density of 10 mA cm−2 in 0.5 M H2SO4 and 1.0 M KOH, respectively.