Three-dimensional (3D) hierarchical coral-like Mn-doped Ni2P–Ni5P4/NF catalyst for efficient oxygen evolution

Developing earth-abundant and high-efficient catalysts for the oxygen evolution reaction (OER) to enhance the efficiency of water splitting is highly desirable. Metal-doping and construction of heterogeneous structure are two start-of-the-art strategies to increase the OER activity of transition metal materials. In this work, we exhibit the design and construction of a unique coral-like 3D hierarchical Mn-doped Ni 2 P–Ni 5 P 4 /NF (Mn–Ni–P/NF) OER catalyst. The Mn-doped Ni 2 P–Ni 5 P 4 /NF hybrid catalyst is synthesized on Ni foam by hydrothermal and followed in situ phosphidation, which exhibits superior OER catalytic performance with an overpotential of 230 mV (vs. RHE) at a current density of 10 mA/cm 2 and 70 mV lower than Ni 2 P–Ni 5 P 4 /NF (300 mV). Furthermore, it also exhibits good long-term stability for 20 h. This work provides a good thought named metal-doping transition metal phosphide complexes to improve the catalytic activity for OER. Such a superior OER performance is main attributed to the unique morphology, the doping of metal Mn regulating the metal phosphide Ni 2 P–Ni 5 P 4 nanosheet structure to be a 3D rough high-active-sites nanorod structure with the in situ formed oxidized Ni species on the surface and effective composite nanostructures. Coral-like Mn–Ni–P/NF nanorod array heterostructure shows excellent OER catalyst performance of 230 mV at 10 mA/cm 2 in 1 M KOH. • Mn-doping Ni 2 P–Ni 5 P 4 /NF electrocatalyst ("two in one") with a unique coral-like hierarchical structure has been prepared. • At a current density of 10 mA/cm 2 , only a low overpotential of 230 mV is required, which is 70 mV less than the overpotential of Ni 2 P–Ni 5 P 4 /NF. The data is superior to most non-noble-metal catalysts in literature. • The catalyst exhibits good long-term electrochemical stability during oxygen evolution process. • All the above results certainly benefits from a unique morphology, metal Mn-doping and the synergistic effects of Ni 2 P–Ni 5 P 4 , the in situ formed oxidized Ni species on the surface and effective composite nanostructures. • This work not only offers an attractive and cost-effective catalyst for alkaline oxygen evolution, but also provides important strategy for designing and synthesizing Ni-based catalysts with enhanced OER activity.