Facile and scalable synthesis of heterostructural NiSe2/FeSe2 nanoparticles as efficient and stable binder-free electrocatalyst for oxygen evolution reaction

Oxygen evolution reaction (OER) is a rate-limiting step in electrocatalytic water splitting due to its sluggish reaction kinetics. Therefore, it is still challengeable to develop an inexpensive and efficient OER catalyst via a facile and scalable synthesis method. To address such issues, herein, we present a facile and scalable approach to prepare ultrathin NiSe2/FeSe2 heterostructural nanoparticles in-situ grown on NiFe foam (NFS/NFF), which can be employed as a self-supported non-noble metal-based catalyst for OER. The NFS/NFF catalyst delivers outstanding OER performance with a small Tafel slope of 57.07 mV dec−1 and a low overpotential of 274 mV at 40 mA cm−2 and displays terrific long-term stability, surpassing the performance of commercial RuO2 and single component NiSe2/NF catalyst. The results of XPS manifest that there is a strong heterointerface interaction between NiSe2 and FeSe2. In addition, combined with density functional theory (DFT) calculations, we further confirmed that the synergistic interface effect between NiSe2 and FeSe2 reduces the value of the Gibbs free energy of oxygen-containing intermediates as determining step (RDS) from 3.15 eV (NiSe2) to 2.41 eV (NiSe2/FeSe2 heterostructures), leading to excellent OER performance. This work provides a novel strategy to rationally design and fabricate selenide-based heterostructural nanoparticles via a facile method, which can extend to prepare other non-precious OER catalysts with high efficiency and long-term stability.