Synergistic modulation in a triphasic Ni₅P₄-Ni₂P@Ni₃S₂ 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 Ni₅P₄-Ni₂P@Ni₃S₂ was fabricated by a two-step synthesis procedure that consist the development of Ni₅P₄-Ni₂P nanosheets over nickel foam followed by the electrodeposition of Ni₃S₂. The HR-TEM analysis shows that the Ni₅P₄-Ni₂P@Ni₃S₂ nanosheets array provide numerous well-exposed diverse heterointerfaces. The electrochemical investigations conducted on the Ni₅P₄-Ni₂P@Ni₃S₂ 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^-2. The nanosheets also demonstrate Tafel slope values of 95 mV dec^-1 and 83 mV dec^-1 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^-1, while the stability test for OER was carried out at current densities of 100 and 200 mA cm^-1 for 100 h each. Furthermore, in the overall water splitting, the catalyst exhibits a cell voltage of 1.47 V@10 mA cm^-2 and displayed a stability operation for 100 h at a current density of 150 mA cm^-1.