Synthesis and properties of nanoporous Ag2S/CuS catalyst for hydrogen evolution reaction

Nanoporous CuS and Ag 2 S/CuS composite are synthesized by chemical dealloying method. The Ag 2 S content of the composite catalysts is controlled by Ag atom in the original amorphous alloys. The composite catalysts reveal an good activity for hydrogen evolution reaction (HER) with a small potential of ∼0.2   V when current density is 10   mA   cm −2 and a high current density of 163.4   mA   cm −2 at 400   mV overpotential, which is associated with the enriched active sites on CuS and the improved electrical conductivity by Ag 2 S. The Tafel slope of Ag 2 S/CuS (75   mV   dec −1 ) indicates that the combination of VH (Volmer-Heyrovsky) and VT (Volmer-Tafel) mechanisms might be involved to produce molecular hydrogen over Ag 2 S/CuS catalysts and the rate-determining step is likely some other than purely Heyrovsky or Tafel step. In addition, the composites exhibit good durability in acidic electrolytes and this method would open up a new type of highly efficient electrocatalyst.