A bifunctional electrocatalyst based on interfacial engineering of CeO2 and NiSe2 for boosting electrocatalytic water splitting†

Herein, a novel self-supported bifunctional electrocatalyst with a three-dimensional core–shell structure of NiSe₂ nanoparticles encapsulated by CeO₂ films is reported. It has the following advantages: (i) the high conductivity of nickel foam substrate self-supported NiSe₂ efficient for favorable electron transfer, (ii) interconversion of Ce⁴⁺ and Ce³⁺ for efficiently optimizing the energetics of OER intermediates based on density functional theory simulations, and (iii) interfacial engineering between NiSe₂ nanoparticles and CeO₂ for efficacious oxygen ion exchange and electronic transmission. CeO₂–NiSe₂ demonstrates excellent overpotentials of 125 mV and 72 mV for the OER and the HER at 10 mA cm⁻², respectively, and superior long cycling stability. Moreover, a low voltage of 1.56 V is demonstrated when CeO₂–NiSe₂ is utilized as self-supported electrodes for the total water splitting reaction. This discovery is expected to provide a new approach for the synthesis of efficient bifunctional electrocatalysts and regeneration of clean energy.