Interfacial hetero‐phase construction in nickel/molybdenum selenide hybrids to promote the water splitting performance AITranslate

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DOI：https://doi.org/10.1016/j.apmt.2021.101175

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Highlights • A hybrid consisting of NiSe crystalline and MoSex amorphous structure was designed and synthesized. The various heterogeneous interfaces in this structure contributed to promote the electrochemical catalytic reaction. In particular, the stability is greatly improved, while the activity is not significantly decreased. The obtained electrochemical performances are superior to the most previous reports from transition metal catalysts. • To reveal the underlying mechanism, the density functional theory calculation was employed to investigate the Gibbs free energy, electronic states and intermediates desorption. The results show that crystalline/amorphous hetero-phase structure can reduce the Gibbs free energy difference and increase the occupation densities of electronic states. • The high catalytic activity for hydrogen and oxygen evolution reaction (HER and OER) was achieved in this work. In this work, a novel hetero-phase interface structure (NiMoSe/NF-2), consisting of crystalline (NiSe) and amorphous (MoSex), was constructed by annealing Ni0.85Se/MoSex hybrid (NiMoSe/NF-1), synthesized through hydrothermal and selenylation steps. For hydrogen evolution and oxygen evolution reaction, the NiMoSe/NF-2 exhibited an overpotential of 91 mV (10 mA cm−2) and 307 mV (100 mA cm−2) with the Tafel slope of 48.1 mV dec−1 and 30.9 mV dec−1, respectively, superior to NiMoSe/NF-1. Meanwhile, much higher stability with 10 and 14 h tests was also respectively achieved for HER and OER. Using the NiMoSe/NF-2 as anode and cathode, the electrolyzer showed a long-time stability up to 14 h with the current density of 100 mA cm−2 at the potential of 1.91 V for overall water splitting. The density functional theory calculation validates that the crystalline/amorphous hetero-phase structure remarkably reduces the Gibbs free energy difference for both HER/OER and the increased occupation densities of electronic states near Fermi level accelerated charge transfer rate during electrocatalytic process. The hydrogen and oxygen intermediates desorption are facilitated by the downshift of Ni d-band center. The proposed crystalline/amorphous hetero-phase structure is prospective for designing bifunctional catalysts for water splitting. Graphical abstract An in-situ grown 3D bimetal ternary selenides (NiMoSe/NF-2) nanowire array was successfully fabricated through a high-temperature phase transition strategy for the first time. The crystalline NiSe in NiMoSe/NF-2 transformed from Ni0.85Se phase and the amorphous MoSex construct an interfacial balance, resulting in a bifunctional electrocatalyst for overall water splitting with strengthened stability without activity degradation. Download : Download high-res image (154KB) Download : Download full-size image