FeNi3–Fe3O4 Heterogeneous Nanoparticles Anchored on 2D MOF Nanosheets/1D CNT Matrix as Highly Efficient Bifunctional Electrocatalysts for Water Splitting

It is still challengeable to develop a nonprecious bifunctional electrocatalyst for both hydrogen and oxygen evolution reactions (HER and OER), with higher efficiency and superior durability over the benchmark noble-metal-based electrocatalysts. To address such issues, for the first time, we design and synthesize FeNi3–Fe3O4 heterogeneous nanoparticles (NPs) homogenously anchored on a matrix of metal-organic framework (MOF) nanosheets and carbon nanotubes (FeNi3–Fe3O4 NPs/MOF-CNT) by a facile hydrothermal reaction and subsequent partial decomposition of a low-cost and earth-abundant Ni/Fe/C precursor. Due to its unique porous nanoarchitecture constructed by ultrafine nanoparticles anchored on two-dimensional (2D) nanosheets/one-dimensional (1D) CNT matrix, it can be employed as a bifunctional electrocatalyst with superior electrocatalytic activity for water splitting: it delivers a small Tafel slope of 37 mV/dec for OER and requires only a very low overpotential of 234 mV to obtain 10 mA/cm2; it has a very low overpotential of 108 mV for HER and also shows an ultralow overpotential of 360 mV to reach 10 mA/cm2 for overall water splitting by outperforming the precious-metal-based electrocatalysts (Pt/C and RuO2; 393 mV at η10). Moreover, it exhibits excellent long-term stability. This work presents a rational nanoarchitecture design and facile fabrication strategy to obtain nonprecious metal-based electrocatalysts with high efficiency and excellent long-lasting abilities.