Lattice-controllable in-situ synthesis of Co-Ni-mixed sulfide/polypyrrole nanostructures on carbon paper for hydrogen evolution reaction in alkaline media.

Developing high-performance and low-cost electrocatalysts for the hydrogen evolution reaction (HER) favorably promotes large-scale hydrogen production from water. Here, we design a nanocomposite of Co 9 S 8 -Ni 9 S 8 nanodiscs (CNS) in-situ grown from polypyrrole hollow nanospheres (PHS) on carbon paper (CP) via unipolar pulse electrodeposition (UPED) technique as HER catalyst in alkaline media. The lattice structure along with the interlacing nanodiscs-like morphology of the Co 9 S 8 -Ni 9 S 8 mischcrystal is controllable by UPED method. The optimal CNS/PHS/CP electrode obtained with pulse potential of − 0.80 V exhibits favorable catalytic activity with low overpotential (186 mV at 10 mA cm−2), superior stability performance (for 100 h with no current density decay), and high electrochemically active surface area up to 1925 cm2, which should be attributed to the interlacing Co 9 S 8 -Ni 9 S 8 mischcrystal with rich active sites, the ingenious combination with conductive polymer, and the integrated electron-proton conductive network. This work will provide a new sight to design low-cost bimetallic sulfide-based electrocatalysts for high-performance HER in water splitting. [Display omitted] • In-situ growth of Ni 9 S 8 -Co 9 S 8 is controllable by unipolar pulse electrodeposition. • Precise regulation of mischcrystal lattice works on the morphology optimization. • Escape from binder contributes to high conductivity and HER catalytic activity. • Integrated frame, large ECSA and rich active sites lift HER dynamics and stability. • The CNS-0.80 catalyst exhibits low overpotential and superior long-term stability. [ABSTRACT FROM AUTHOR]