Heterogeneous FeNi2S4/Ni3S4 nanoparticles embedded CNT networks for efficient and stable water oxidation

Development of efficient and reliable transition metal-based oxygen evolution reaction (OER) catalysts has profound implications to achieve carbon-neutral economy in the future. Herein, a novel hybrid OER catalyst of heterogeneous FeNi2S4/Ni3S4 nanoparticles embedded CNT networks (FeNi2S4/Ni3S4@CNT) was prepared by a facile one-step hydrothermal reaction. The ultrafine heterogeneous nanoparticles of FeNi2S4 and Ni3S4 embedded CNT can expose abundant active sites and enhance the electrochemically active area; the electronic structure modulated by the bi-metallization of FeNi2S4 via partial substitution of Ni with Fe; the robust contact between conductive FeNi2S4 and Ni3S4 nanoparticles with abundant active sites on the surface and the CNT network with high conductivity can effectively promote the electron transfer; the 3D network with rich nanopores is beneficial to electrolyte penetration and gas release. These above merits and synergistic effects of FeNi2S4 and Ni3S4 endow the catalyst superior OER performances with an ultralow overpotential of 247 mV for the current density of 10 mA cm−2, a low Tafel slope of 53.7 mV dec−1 and remarkable durability over 20 h, surpassing those of commercial OER catalyst RuO2. This work provides a synergistic OER boosting strategy via bi-metallization, heterogeneous nanoparticle distribution and conductive skeleton to develop non-precious-based electrocatalyst by a facile one-pot synthesis method.