This article introduces an environmentally friendly and more economical method for preparing red selenium nanoparticles (Se-NPs) with high stability, good biocompatibility, and narrow size using yeast as a bio-reducing agent with high antioxidant, immune regulation, and low toxicity than inorganic and organic Se. The yeast-derived Se-NPs were characterized by scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The results revealed spherical-shaped particles of Se-NPs with an average diameter of 71.14 ± 18.17 nm, an amorphous structure, and surface enhancement with an organic shell layer, that provide precise geometry and stability in the formation of bio-inert gray or black Se-NPs instead of red Se-NPs. Furthermore, the addition of 0.3−0.8 mg/kg Se-NPs in the feed significantly improved the health of mice. As Se-NPs stimulated the oxidative state of mice, it significantly increased the level of GSH-Px, SOD, and AOC, and decreased the level of MDA. The yeast-derived Se-NPs alleviated the immunosuppression induced by cyclophosphamide, whereas protected the liver, spleen, and kidney of mice, stimulated the humoral immune potential of the mice, and significantly increased the levels of I g M, IgA, and I g G. These results indicated that the yeast-derived Se-NPs, as a trace element feed additive, increased the defense of the animal against oxidative stress and infectious diseases and therefore Se-NPs can be used as a potential antibiotic substitute for animal husbandry.

The atomic-level metal-modulated MOFs as an advanced trifunctional electrocatalyst for oxygen evolution reaction, hydrogen evolution reaction and oxygen reduction reaction.

Creating ordered two-dimensional (2D) metal–organic framework (MOF) nanomaterials is conducive to understanding the structure–property relationship for rationally designing high-efficiency electrocatalysts. However, the controllable synthesis of ultrathin MOF nanosheets with predesigned structures and anticipative properties is still a great challenge. Here, we reported an electrolyte-assisted electrochemical approach to in situ exfoliate the intrinsic 2D MOF crystals with the Ni4Ln cluster as a secondary building unit (SBU) into ultrathin metal–organic nanosheets. Notably, the electric current density of the oxygen evolution reaction rapidly increases from 9.4 to 31.0 mA cm–2 at 1.8 V and the Tafel slope reduces from 150 to 87 mV dec–1, originating from electrochemically delaminating the thick 2D MOF precursors into ultrathin (∼4 nm) nanosheets to expose more catalytic active sites. Furthermore, the electrocatalytic oxygen evolution reaction (OER) activity of these 2D heterometallic MOF nanosheets can be effectively manipulated through precisely altering the lanthanide component of the Ni4Ln SBU in the layered MOFs. Density functional theory calculations reveal that the lanthanide ion of the SBU affects the adsorption and desorption capacity of active nickel centers to OER-relevant species, leading to the difference of the catalytic activity.

Contributions: (I) Conception and design: Q Hu; (II) Administrative support: D Xiong; (III) Provision of study materials or patients: L Li; (IV)

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