Construction of composite films using carbon nanodots for blocking ultraviolet light from the Sun.

Carbon nanodots (CNDs) which demonstrate concentration-dependent emission and have a photoluminescence quantum yield of 45% were designed. Transparent CND-containing composite films (CND-films), obtained by combining the CNDs with polyvinyl alcohol in different proportions, were shown to block the UV component of sunlight. Whereas the pure PVA film could not block UV light, the ability of CND-films to block UV light could be adjusted by altering the proportion of CNDs in the film. The larger the proportion of CNDs, the greater the extent of UV blocking. CND-film containing 32 wt% CNDs completely blocked UV light (≤400 nm) from sunlight, without affecting the transmission of visible light (>800 nm). The ability of the CND-films to block the UV component of sunlight was investigated using a commercially available UV-induced color change card, which confirmed that the capacity of the CND-films to block UV light could be adjusted by altering the proportion of CNDs in the film. This study shows that CNDs with concentration-dependent long wavelength emission characteristics can be used as optical barrier units for the preparation of materials to block high-energy short wavelength light.

An Open-Framework Structured Material: [Ni(en)2]3[Fe(CN)6]2 as a Cathode Material for Aqueous Sodium- and Potassium-Ion Batteries.

Open-framework structured materials such as Prussian blue analogues and sodium superionic conductor (NASICON) materials have been regarded as promising electrode candidates for aqueous batteries. These materials exhibit outstanding long cycle stability and high rate capacity retention, due to their high ion diffusive rate in the crystal and the stable structure maintenance in the electrochemical reaction process. Herein, an open-framework structured material [Ni(en)2]3[Fe(CN)6]2 (NienHCF) is prepared and first used as a cathode material for aqueous sodium- and potassium-ion batteries. The resultant material exhibits a high output potential and outstanding cycle performance (93.4% after 500 cycles at 1 A g-1) in K-ion batteries. Meanwhile, the electrochemical reaction mechanism is investigated. After coupling with the activated carbon anode, the K-ion full cell has 91.5% capacity retention at 5 A g-1 and retains 77.2% after 1000 cycles at 0.5 A g-1, exhibiting the potential as an electrode material for rechargeable aqueous K-ion and Na-ion batteries.