In-situ controllable electrodeposition of NiSx nanostructures coupled with polypyrrole for enhanced hydrogen evolution reaction.

The development of effective and inexpensive electrocatalysts for hydrogen evolution reaction (HER) plays a key role in future energy system. Herein, we report a series of NiS x composited with polypyrrole (PPy) hollow nanospheres on carbon papers (CPs) to promote the HER performance. The crystal phase and lattice configuration of the in-situ grown NiS x can be tuned through unipolar pulse electrodeposition. The PPy with high conductivity is conducive to prevent the NiS x from collapse and improve the stability of the HER. As a result, the optimized Ni 3 S 2 /PPy/CP electrode manifests a low overpotential of 149 mV (vs. RHE) at 10 mA cm−2, an exceptional long-term stability over 100 h, and a large electrochemically active surface area of 1173.75 cm2. Furthermore, it is found that the exposure of (110), (122) and (300) planes of Ni 3 S 2 facilitates to increase the number of active sites. The precise lattice regulation contributes to achieve high HER performance. [Display omitted] • A series of NiS x /PPy/CP composite electrocatalysts were prepared for HER. • The crystalline phase of NiS x can be tuned by controlling the lattice structure. • The (110), (122) and (300) lattice planes of Ni 3 S 2 provide rich active sites for HER. • The optimal Ni 3 S 2 /PPy/CP showed a low overpotential of 149 mV at 10 mA cm−2. • PPy is able to protect active substance from loss and improve long-term stability. [ABSTRACT FROM AUTHOR]