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 NiSX 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 NiSX can be tuned through unipolar pulse electrodeposition. The PPy with high conductivity is conducive to prevent the NiSX from collapse and improve the stability of the HER. As a result, the optimized Ni3S2/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 Ni3S2 facilitates to increase the number of active sites. The precise lattice regulation contributes to achieve high HER performance.