The high polarity of water molecules inevitably causes the decomposition of perovskites. We retard the degradation by introducing an ultrathin ALD–Al ₂ O ₃ layer, which has almost no negative effect on performance.

Pump it up: Carbon nanotube yarns can be used as electrochemical actuators because infiltration with ions causes a contraction in length and an expansion in diameter. Either positive or negative ions can cause this effect. Chu et al. constructed an all-solid-state muscle that eliminated the need for an electrolyte bath, which may expand the potential for its use in applications. By infiltrating the yarns with charged polymers, the fibers start partially swollen, so the length can increase through the loss of ions. It is thus possible to increase the overall stroke of the muscle. Further, these composite materials show a surprising increase in stroke with scan rate. Science , this issue p. 494

We synthesized nitrogen-doped graphene quantum dots (N-GQDs) under a high temperature range of 800–1200 °C and high pressure of 4.0 GPa through a solid-to-solid process.

We demonstrated that graphene oxide (GO) can be oxidized and cut into graphene quantum dots (GQDs) by hydroxyl radicals (˙OH), which is obtained by the catalytic decomposition of hydrogen peroxide (H₂O₂) with a tungsten oxide nanowire (W₁₈O₄₉) catalyst. The clean oxidizing agent (H₂O₂) and the solid catalyst lead to a simple GQD preparing method without any by-products. The obtained GQD aqueous solution can be directly applied to fluorescence imaging in vitro without any further purification. The effect of the W₁₈O₄₉ catalyst on the ˙OH formation is discussed, and the size of GQDs can be controlled via changing the concentration of hydroxyl radicals.