Amorphous and crystalline interface engineering of FeSeOx/Mo-NiSe2 nanoarrays for synergistically boosting electrocatalytic water oxidation

Exploring integrated regulation strategies to boosting electrocatalytic performance is essential to design more efficient and inexpensive OER catalysts. Herein, amorphous and crystalline (a-c) interface engineering and heteroatom doping are integrated to construct a novel electrocatalyst containing amorphous FeSeOx and crys-talline Mo-doped NiSe2 (denoted as FeSeOx/Mo-NiSe2) via pseudocrystalline replication method and selenization treatment. The resultant FeSeOx/Mo-NiSe2 electrocatalyst with 3D hierarchical nanoarchitectures of nanorod arrays covered by interlocking nanoblocks exposes more active sites and accelerated reaction kinetics. Furthermore, a-c interface engineering and heteroatom doping can synergistically enhance the intrinsic activity and charge transfer capability of NiSe2 by decreasing the electron diffusion distance and flexibly modulating the electronic structure, which contributes to boost the oxygen evolution reaction (OER) performance. Consequently, the obtained FeSeOx/Mo-NiSe2 achieves a low overpotential of 205 mV at 10 mA cm-2, which outperforms many other transitions metal selenides electrocatalysts. Density functional theory (DFT) calculations demonstrate that the formation of an internal electric field between FeSeOx and Mo-NiSe2 accelerates charge transport and op-timizes the adsorption/desorption of oxygen-containing intermediates, thereby accelerating the reaction kinetics and improving the OER performance. This work serves as a point of reference for designing innovative metal selenides based electrocatalysts combining a-c interface engineering and heteroatom doping.