A single atom Ir doped heterophase of a NiMoP-NiMoPxOy ultrathin layer assembled on CNTs-graphene for high-performance water splitting

Abstract

The rational construction of efficient and robust with a high-performance electrocatalyst have been required in industrial green H₂ production. In this study, single atom Iridium (Ir) introduced into both phases of an amorphous NiMoP_xO_y and crystalline NiMoP phase generates enriched active sites with high intrinsic activity, and the catalyst material coating on the carbon nanotube interconnected graphene sheet on copper foam (Ir-NiMoP-NiMoP_xO_y/CNTs-Gr/Cu) serves as an electron transport pathway and improves the surface area and protective layer. The engineered material exhibits excellent electrochemical water splitting characteristics, similar to those of Ir-NiMoP-MoNiP_xO_y/CNTs-Gr/Cu, showing a small overpotential of 138 mV for the hydrogen evolution reaction (HER) and 220 mV at 20 mA cm⁻² for the oxygen evolution reaction (OER). The overall water splitting of Ir-NiMoP-NiMoP_xO_y/CNTs-Gr/Cu in 1.0 M KOH was extremely stable after 150 hours of operation at 50 mA cm⁻². Density functional theory calculations show that the real active sites are Ir and Mo in the hybrid amorphous/crystalline phase of Ir-NiMoP-MoNiP_xO_y, providing a new pathway for designing an effective catalyst for future applications in the hydrogen production field.