Metformin is a broadly prescribed drug for type 2 diabetes that exerts antitumor activity, yet the mechanisms underlying this activity remain unclear. We show here that metformin treatment blocks the suppressive function of myeloid-derived suppressor cells ( SignificanceThe antitumor activity of an anti-diabetes drug is attributable to reduced immunosuppressive activity of myeloid-derived tumor suppressor cells.

Urchin-shaped NiCo 2 Se 4 (u-NCSe) nanostructures as efficient sulfur hosts are synthesized to overcome the limitations of lithium-sulfur batteries (LSBs). u-NCSe provides a beneficial hollow structure to relieve volumetric expansion, a superior electrical conductivity to improve electron transfer, a high polarity to promote absorption of lithium polysulfides (LiPS), and outstanding electrocatalytic activity to accelerate LiPS conversion kinetics. Owing to these excellent qualities as cathode for LSBs, S@u-NCSe delivers outstanding initial capacities up to 1403 mAh g −1 at 0.1 C and retains 626 mAh g −1 at 5 C with exceptional rate performance. More significantly, a very low capacity decay rate of only 0.016% per cycle is obtained after 2000 cycles at 3 C. Even at high sulfur loading (3.2 mg cm −2 ), a reversible capacity of 557 mAh g −1 is delivered after 600 cycles at 1 C. Density functional theory calculations further confirm the strong interaction between NCSe and LiPS, and cytotoxicity measurements prove the biocompatibility of NCSe. This work not only demonstrates that transition metal selenides can be promising candidates as sulfur host materials, but also provides a strategy for the rational design and the development of LSBs with long-life and high-rate electrochemical performance.

Original measurement data are available upon reasonable request.

Amorphous metal–organic frameworks (aMOFs) are an emerging family of attractive materials with great application potential, however aMOFs are usually prepared under harsh conditions and aMOFs with complex compositions and structures are rarely reported. In this work, an aMOF‐dominated nanocomposite (aMOF‐NC) with both structural and compositional complexity has been synthesized using a facile approach. A ligand‐competition amorphization mechanism is proposed based on experimental and density functional theory calculation results. The aMOF‐NC possesses a core–shell nanorod@nanosheet architecture, including a Fe‐rich Fe‐Co‐aMOF core and a Co‐rich Fe‐Co‐aMOF shell in the core–shell structured nanorod, and amorphous Co(OH)2 nanosheets as the outer layer. Benefiting from the structural and compositional heterogeneity, the aMOF‐NC demonstrates an excellent oxygen evolution reaction activity with a low overpotential of 249 mV at 10.0 mA cm−2 and Tafel slope of 39.5 mV dec−1.