Synergistic modulation in a triphasic NiP-NiP@NiS system manifests remarkable overall water splitting.

The potential for water splitting electrocatalysts with high efficiency paves the way for a sustainable future in hydrogen energy. However, this task is challenging due to the sluggish kinetics of the oxygen evolution reaction (OER), which has a significant impact on the hydrogen evolution reaction (HER). Herein multi-heterointerface of NiP-NiP@NiS was fabricated by a two-step synthesis procedure that consist the development of NiP-NiP nanosheets over nickel foam followed by the electrodeposition of NiS. The HR-TEM analysis shows that the NiP-NiP@NiS nanosheets array provide numerous well-exposed diverse heterointerfaces. The electrochemical investigations conducted on the NiP-NiP@NiS nanosheets for complete water splitting indicate that they possess an overpotential of 73 mV and 230 mV in HER and OER respectively, enabling them to generate a current density of 10 and 50 mA cm. The nanosheets also demonstrate Tafel slope values of 95 mV dec and 83 mV dec for HER and OER, respectively. The HER stability of the catalyst was conducted for 45 h using chronoamperometric technique under a current density of 20 mA cm, while the stability test for OER was carried out at current densities of 100 and 200 mA cm for 100 h each. Furthermore, in the overall water splitting, the catalyst exhibits a cell voltage of 1.47 V@10 mA cm and displayed a stability operation for 100 h at a current density of 150 mA cm.