Accumulation and elimination of iron oxide nanomaterials in zebrafish(Danio rerio) upon chronic aqueous exposure

A 52-day continuous semi-static waterborne exposure（test media renewed daily） regimen was employed to investigate the accumulation and elimination profiles of two iron oxide nanomaterials（nano-Fe2O3 and nano-Fe3O4） in zebrafish（Danio rerio）. Adult zebrafish were exposed to nanomaterial suspensions with initial concentrations of 4.0 and 10.0 mg/L for28 days and then were moved to clean water for 24 days to perform the elimination experiment. Fe content was measured in fish body and feces to provide data on accumulation and elimination of the two iron oxide nanomaterials in zebrafish. The experiment revealed that：（1） high accumulation of nano-Fe2O3 and nano-Fe3O4 were found in zebrafish, with maximum Fe contents, respectively, of 1.32 and 1.25 mg/g for 4.0 mg/L treatment groups and 1.15 and 0.90 mg/g for 10.0 mg/L treatment groups;（2） accumulated nanoparticles in zebrafish can be eliminated efficiently（the decrease of body burden of Fe conforms to a first-order decay equation） when fish were moved to nanoparticle-free water,and the elimination rates ranged from 86% to 100% by 24 days post-exposure; and（3）according to analysis of Fe content in fish excrement in the elimination phase, iron oxide nanomaterials may be adsorbed via the gastrointestinal tract, and stored for more than12 days.

Two-dimensional metal oxide nanosheets for rechargeable batteries

Two-dimensional（2D） metal oxide nanosheets have attracted much attention as potential electrode materials for rechargeable batteries in recent years. This is primarily due to their natural abundance, environmental compatibility, and low cost as well as good electrochemical properties. Despite the fact that most metal oxides possess low conductivity, the introduction of some conductive heterogeneous components, such as nano-carbon, carbon nanotubes（CNTs）, and graphene, to form metal oxide-based hybrids,can effectively overcome this drawback. In this mini review, we will summarize the recent advances of three typical 2D metal oxide nanomaterials, namely, binary metal oxides, ternary metal oxides, and hybrid metal oxides, which are used for the electrochemical applications of next-generation rechargeable batteries, mainly for lithium-ion batteries（LIBs） and sodium-ion batteries（SIBs）. Hence, this review intends to functionalize as a good reference for the further research on 2D nanomaterials and the further development of energy-storage devices.

Facile synthesis of hierarchical flower-like Ag/Cu2O and Au/Cu2O nanostructures and enhanced catalytic performance in electrochemical reduction of CO2

Novel,hierarchical,flower-like Ag/Cu2O and Au/Cu2O nanostructures were successfully fabricated and applied as efficient electrocatalysts for the electrochemical reduction of CO2.Cu2O nanospheres with a uniform size of^180 nm were initially synthesized.Thereafter,Cu2O was used as a sacrificial template to prepare a series of Ag/Cu2O composites through galvanic replacement.By varying the Ag/Cu atomic ratio,Ago.12/Cu2O,having a hierarchical,flower-like nanostructure with intersecting Ag nanoflakes encompassing an inner Cu2O sphere,was prepared.The as-prepared Ag/Cu2O samples presented higher Faradaic efficiencies(FE)for CO and relatively suppressed H2 evolution than the parent Cu2O nanospheres due to the combination of Ag with Cu2O in the former.Notably,the highest CO evolution rate was achieved with Ago.12/Cu2O due to the larger electroactive surface area furnished by the hierarchical structure.The same hier-archical flower-like structure was also obtained for the Auo./Cu2O composite,where the FEco(10%)was even higher than that of Ago.12/Cu2O.Importantly,the results reveal that Ago.12/Cu2O and Auo./Cu2O both exhibit remarkably improved stability relative to Cu2O.This study presents a facile method of developing hierarchical metal-oxide composites as fficient and stable electrocatalysts for the electrochemical reduction of CO2.

Sub-100 nm hollow SnO_2@C nanoparticles as anode material for lithium ion batteries and significantly enhanced cycle performances

Rational designing and controlling of nanostructures is a key factor in realizing appropriate properties required for the high-performance energy fields. In the present study, hollow Sn O2@C nanoparticles（NPs） with a mean size of 50 nm have been synthesized in large-scale via a facile hydrothermal approach.The morphology and composition of as-obtained products were studied by various characterized techniques. As an anode material for lithium ion batteries（LIBs）, the as-prepared hollow Sn O2@C NPs exhibit significant improvement in cycle performances. The discharge capacity of lithium battery is as high as 370 m Ah g 1, and the current density is 3910 m A g 1（5 C） after 573 cycles. Furthermore, the capacity recovers up to 1100 m Ah g 1at the rate performances in which the current density is recovered to 156.4 m A g 1（0.2 C）. Undoubtedly, sub-100 nm Sn O2@C NPs provide significant improvement to the electrochemical performance of LIBs as superior-anode nanomaterials, and this carbon coating strategy can pave the way for developing high-performance LIBs.