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 FeNi 3 −Fe 3 O 4 heterogeneous nanoparticles (NPs) homogenously anchored on a matrix of metal-organic framework (MOF) nanosheets and carbon nanotubes (FeNi 3 −Fe 3 O 4 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/cm 2 ; it has a very low overpotential of 108 mV for HER and also shows an ultralow overpotential of 360 mV to reach 10 mA/cm 2 for overall water splitting by outperforming the precious-metal-based electrocatalysts (Pt/C and RuO 2 ; 393 mV at η 10 ). Moreover, it exhibits excellent longterm stability. This work presents a rational nanoarchitecture design and facile fabrication strategy to obtain nonprecious metalbased electrocatalysts with high efficiency and excellent long-lasting abilities.

Because of the sluggish oxygen evolution kinetics, it is extremely important but still challenging to develop low-cost, efficient, and stable electrocatalysts for oxygen evolution reaction (OER) to enhance the efficiency of water electrolysis. Herein, for the first time, we present a novel heterostructure catalyst, constructed by ultrafine NiS/Fe3O4 heterostructural nanoparticles decorated on a carbon nanotube (CNT) matrix (NiS/Fe3O4 HNPs@CNT), which is synthesized by a facile hydrothermal reaction and subsequent sulfurization process. The NiS/Fe3O4 HNPs@CNT hybrid delivers superior OER activity in alkaline medium: it delivers a current density of 10 mA cm–2 at an ultralow overpotential of 243 mV with a small Tafel slope of 44.2 mV dec–1, which outperforms the benchmark RuO2 electrocatalyst; moreover, it exhibits terrific long-term stability over 36 h without any noticeable performance decay. The exceptional OER performance can be attributed to the unique nanoarchitecture, high conductivity of the CNT matrix, and particularly, the interaction between the Ni and Fe species in NiS/Fe3O4 heterostructural nanoparticles. This work introduces a sensible nanoarchitecture design with a facile and novel fabrication strategy to attain nonprecious metal-based composite catalysts with high OER performance and outstanding long-term stability.

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It is challengeable to obtain a scalable method to synthesize nonprecious electrocatalysts with high efficiency and stability for overall water splitting, to replace the costly and scarce noble metal based electrocatalysts (e.g., Pt-and Ru-based materials). Herein, bimetallic (Fe, Co)P nanoparticles decorated in carbon nanotube network (FCP-CN) are synthesized through a facile and scalable spray drying and subsequent phosphorization process. The FCP-CN hybrid delivers excellent performance in hydrogen evolution reaction both in acidic and alkaline media, oxygen evolution reaction, and overall water splitting: it possesses an Pt-like hydrogen evolution reaction activity with an ultralow onset overpotential of 18 mV in acid; remarkably, it shows an ultrasmall Tafel slope of 38 mV dec −1 in oxygen evolution reaction; being employed as both cathode and anode, this catalyst demonstrates promising performance of overall water splitting with high long-term stability. The performance is superior among recently reported transition-metal-based catalysts for overall water splitting. This work provides a scalable and low-cost synthesis strategy to synthesize nonprecious and multifunctional transition-metal-based catalysts with unique nanoarchitecture and outstanding catalytic performance for water splitting.