A three-phase and multi-interface NiMnP/Ni2P/MnP4/NF bifunctional electrocatalyst with rose-shaped morphology improving the performance of overall water splitting

A three-dimensional rose-like micro-nano structured NiMnP/Ni 2 P/MnP 4 multiphase heterogeneous architecture was fabricated on nickel foam via hydrothermal and phosphorization processes. The 3D micro-nano structure conferred the catalyst with excellent hydrophilicity, facilitating electrolyte penetration on its surface and thereby enhancing charge and reaction medium transport. The multiphase heterogeneous structure provided abundant heterogeneous interfaces, thereby offering more active sites. Additionally, the interface electron reconstruction resulted in lower interfacial charge transport resistance (2.12 Ω), enabling faster catalytic reaction kinetics. As a bifunctional electrocatalyst, the NiMnP/Ni 2 P/MnP 4 /NF composite achieved a current density of 10 mA cm −2 with 57 mV and 74 mV for HER overpotential in acidic and basic electrolytes, respectively, close to the Pt/C catalyst (31 mV in acidic and 57 mV in basic). Its OER overpotential was only 232 mV@ 10 mA cm −2 , even lower than the noble metal OER catalyst of RuO 2 (260 mV@ 10 mA/cm 2 ). Moreover, in overall water splitting tests, the NiMnP/Ni 2 P/MnP 4 /NF∥NiMnP/Ni 2 P/MnP 4 /NF cell required only 1.54 V to reach 10 mA cm −2 , comparable to that of all-pure-precious-metal cell (1.52 V in Pt/C∥RuO 2 ).