Transition metal manganese induces structural reorganization of Mn_xMo_1-xSe₂ for efficient overall water splitting

Heterostructure construction and morphology modulation strategies are effective ways to improve catalyst activity. Herein, we have prepared a series of Mn_xMo_1-xSe₂ (x = 0-1) composite material by doping with manganese (Mn) and reconstructed its morphology. The hydrogen evolution reaction and oxygen evolution reaction (HER/OER) activities of both Mn_xMo_1-xSe₂ were significantly enhanced after Mn doping. Among them, Mn_0.4Mo_0.6Se₂ showing the best HER and OER activities in 0.5 M H₂SO₄. Notably, the cell voltage of the Mn_0.4Mo_0.6Se₂ || Mn_0.4Mo_0.6Se₂ acid electrolyzer at 10 mA cm^-2 was only 1.52 V. The doping of Mn reduces the electron density of Mo so that it has enough empty d orbitals to accommodate the electrons, which are transferred from MoSe₂ to MnSe₂, leading to a charge redistribution that optimizes the adsorption energies of water and intermediates. The flower-like structure composed of interwoven nanosheets facilitates electrolyte penetration and gas diffusion. The increased thickness and relatively rough edges of the nanosheets and the reduced diameter of the nanoflower gives them better mechanical strength, which improves their catalytic activity and stability. Effective theoretical support is provided for the preparation of efficient and stable transition metal selenide catalysts in overall water splitting.