Understanding the effects of 3D porous architectures on promoting lithium or sodium intercalation in iodine/C cathodes synthesized via a biochemistry-enabled strategy.

Rechargeable sodium-iodine and lithium-iodine batteries have been demonstrated to be promising and scalable energy-storage devices, but their development has been seriously limited by challenges such as their inferior stability and the poor kinetics of iodine. Anchoring iodine to 3D porous carbon is an effective strategy to overcome these defects; however, both the external architecture and internal microstructure of the 3D porous carbon host can greatly affect the ion intercalation of iodine/C electrodes. To realize the full potential of iodine electrodes, a biochemistry-enabled route was developed to enable the controllable design of different 3D porous architectures, from hollow microspheres to 3D foam, for use in iodine/C cathodes. Two types of spores with spherical cells, i.e. Cibotium Barometz (C. Barometz) and Oetes Sinesis (O. Sinesis), are employed as bio-precursors. By carefully controlling the degree of damage on the bio-precursors, different targeted carbon hosts were fabricated. Systematic studies were carried out to clarify the structural effects on modifying the ion-intercalation capabilities of the iodine/C cathodes in lithium-iodine and sodium-iodine batteries. Our results demonstrate the profound performance improvements of both 3D bio-foam and hollow sphere because their hierarchically porous structures can strongly immobilize iodine. Notably, the 3D bio-foam based iodine composites achieve faster ion kinetics and enhanced rate capability than their hollow sphere based counterparts. This was attributed to their higher micro/mesopore volume, larger surface area and improved packing density, which result in the highly efficient adsorption of iodine species. By virtue of the thinnest slices, the iodine/bio-foam derived from C. Barometz spores achieves the best high-rate long-term cycling capability, which retains 94% and 91% of their capacities in lithium-iodine and sodium-iodine batteries after 500 cycles, respectively. With the help of the biochemistry-assisted technique, our study provides a much-needed fundamental insight for the rational design of 3D porous iodine/C composites, which will promote a significant research direction for the practical application of lithium/sodium-iodine batteries.

A NaV3(PO4)3@C hierarchical nanofiber in high alignment: exploring a novel high-performance anode for aqueous rechargeable sodium batteries.

The development of aqueous rechargeable sodium batteries (ARSBs) demands high-performance electrode materials, especially anode materials with low operating potential and competent electrochemical properties. The lithium/sodium vanadium phosphate family with good structural stability and abundant vanadium chemistry versatility is a promising series for energy storage applications. Herein, a new member in the sodium vanadium phosphate family, i.e. NaV3(PO4)3, is introduced as a novel anode candidate for ARSBs. For the first time, its sodium intercalation mechanism in an aqueous electrolyte is explored, and moreover, the well-aligned NaV3(PO4)3@porous carbon nanofiber is constructed to fulfil its full potential. Based on the reversible phase transformation and 3D open framework, the NaV3(PO4)3 is demonstrated to be reliable in the aqueous electrolyte. Favored by the well-aligned, highly porous and hierarchical 1D nanoarchitecture, the freestanding aligned NaV3(PO4)3@porous carbon hybrid film achieves fast electron/ion transport capability and good mechanical flexibility, resulting in its superior high-rate properties and excellent cycling durability. Moreover, a full cell is fabricated using the aligned NaV3(PO4)3@C nanofiber as the anode and Na0.44MnO2 as the cathode. The cell is capable of high-rate long-term cycling, which retains 84% of the capacity after five hundred cycles at alternate 20 and 5C. Therefore, this work not only demonstrates a novel high-performance anode material for ARSBs, but also introduces a general applicable and highly efficient architecture of aligned 1D nanofibers for energy storage applications.

From a 3D hollow hexahedron to 2D hierarchical nanosheets: controllable synthesis of biochemistry-enabled Na7V3(P2O7)4/C composites for high-potential and long-life sodium ion batteries.

Tailoring materials into different structures offers unprecedented opportunities in the realization of their functional properties. Particularly, controllable design of diverse structured electrode materials is regarded as a crucial step towards fabricating high-performance batteries. Herein, a general biochemistry-directed strategy has been developed to fabricate functional materials with controllable architectures and superior performance. The natural structure of fern (i.e. Cibotium) spores realizes the formation of a three-dimensional hexahedral bio-precursor. Either its core or shell is targeted to be destroyed, resulting in different architectures, from a 3D hollow hexahedron to a 2D hierarchical nanosheet, of the final product. As a case study, sodium vanadium pyrophosphate (i.e. Na7V3(P2O7)4) is employed as the electrochemically active material in this study. The crucial role of controllable damage in the construction of diverse architectures is discussed. Moreover, the relationship between different outside architectures, internal microstructures and the sodium intercalation capabilities of the bio-composites is clarified. Among all the samples, the 2D nanosheet with hierarchical structures has the smallest particle size and the highest surface area, which are favourable for its fast sodium intercalation. As a result, it is capable of high-rate long-term cycling, which achieves a high cycling efficiency of 93% after 500 cycles at 20C. However, a 3D hollow hexahedron has a thick shell and inferior surface characteristics, which greatly limits its sodium transport kinetics and leads to inferior performance. Therefore, the present work not only highlights a general, green and energy-efficient biochemistry-enabled strategy to prepare high-performance electrode materials, but also provides clues to controllably design diverse architectures for functional materials.

Cloning and Functional Analysis of Pax6 from the Hydrothermal Vent Tubeworm Ridgeia piscesae.

The paired box 6 (Pax6) gene encodes a transcription factor essential for eye development in a wide range of animal lineages. Here we describe the cloning and characterization of Pax6 gene from the blind hydrothermal vent tubeworm Ridgeia piscesae (RpPax6). The deduced RpPax6 protein shares extensive sequence identity with Pax6 proteins from other species and contains both the paired domain and a complete homeodomain. Phylogenetic analysis indicates that it clusters with the corresponding sequence from the closely related species Platynereis dumerilii (P. dumerilii) of Annelida. Luciferase reporter assay indicate that RpPax6 protein suppresses the transcription of sine oculis (so) in D. melanogaster, interfering with the C-terminal of RpPax6. Taking advantage of Drosophila model, we show that RpPax6 expression is not able to rescue small eye phenotype of ey2 mutant, only to cause a more severe headless phenotype. In addition, RpPax6 expression induced apoptosis and inhibition of apoptosis can partially rescue RpPax6-induced headless phenotype. We provide evidence RpPax6 plays at least two roles: it blocks the expression of later-acting transcription factors in the eye development cascade, and it promotes cell apoptosis. Our results indicate alternation of the Pax6 function may be one of the possible causes that lead the eye absence in vestimentiferan tubeworms.