Sand-Fixation Model for Interface Engineering of Layered Titania and N/O-Doped Carbon Composites to Enhance Potassium/Sodium Storage.

Layered titania (L-TiO2 ) holds great potential for potassium-ion batteries (PIBs) and sodium-ion batteries (SIBs) due to their high specific capacity. Synthesizing L-TiO2 functional materials for high-capacity and long cyclability battery remains challenging due to the unstable and poor conductivity of bare L-TiO2 . In nature, plant growth can stabilize land by preventing sands from dispersing following desertification. Inspired by nature's "sand-fixation model," Al3+ "seeds" are in situ grown on layered Ti3 C2 Tx "land." Subsequently, NH2 -MIL-101(Al) "plants" with Al as metal nodes are grown on the Ti3 C2 Tx "land" by self-assembly. After annealing and etching processes (similar to desertification), NH2 -MIL-101(Al) is transformed into interconnected N/O-doped carbon (MOF-NOC), which not only acts as a plant-like function to prevent the pulverization of L-TiO2 transformed from Ti3 C2 Tx but also improves the conductivity and stability of MOF-NOC@L-TiO2 . Al species are selected as seeds to improve interfacial compatibility and form intimate interface heterojunction. Systematic ex situ analysis discloses that the ions storage mechanism can be endowed by mixed contribution of non-Faradaic and Faradaic capacitance. Consequently, the MOF-NOC@L-TiO2 electrodes exhibit high interfacial capacitive charge storage and outstanding cycling performance. The interface engineering strategy inspired by "sand-fixation model" provides a reference for designing stable layered composites.

Engineering Low-Cost Organic Cathode for Aqueous Rechargeable Battery and Demonstrating the Proton Intercalation Mechanism for Pyrazine Energy Storage Unit.

Seeking organic cathode materials with low cost and long cycle life that can be employed for large-scale energy storage remains a significant challenge. This work has synthesized an organic compound, triphenazino[2,3-b](1,4,5,8,9,12-hexaazatriphenylene) (TPHATP), with as high as 87.16% yield. This compound has a highly π-conjugated and rigid molecular structure, which is synthesized by capping hexaketocyclohexane with three molecules of 2,3-diaminophenazine derived from low-cost o-phenylenediamine, and is used as a cathode material for assembling aqueous rechargeable zinc ion batteries. Both experiments and DFT calculations demonstrate that the redox mechanism of TPHATP is predominantly governed by H+ storage. The Zn-intercalation product of nitride-type compound, is too unstable to form in water. Moreover, the TPHATP cathode exhibits a capacity of as high as 318.3 mAh g-1 at 0.1 A g-1 , and maintained a stable capacity of 111.9 mAh g-1 at a large current density of 10 A g-1 for 5000 cycles with only a decay of 0.000512% per cycle. This study provides new insights into understanding pyrazine as an active redox group and offers a potential affordable aqueous battery system for grid-scale energy storage.

Assessing pathways of heavy metal accumulation in aquaculture shrimp and their introductions into the pond environment based on a dynamic model and mass balance principle.

The impact of heavy metals (HMs) on the quality of aquaculture products has attracted worldwide attention. Since Litopenaeus vannamei is a popular aquaculture product among consumers worldwide, it is of great importance to guarantee its dietary safety. An in-situ monitoring program lasting for three months in a typical Litopenaeus vannamei farm found that Pb (100 %) and Cr (86 %) in the adult shrimp were higher than the safety guidelines. In the meantime, Cu (100 %), Cd (100 %) in the water and Cr (40 %) in the feed exceeded the corresponding thresholds. Therefore, quantification of different exposure pathways of shrimp and contamination origins in pond is valuable to improve the dietary safety of the shrimp. Based on Optimal Modeling for Ecotoxicological Applications (OMEGA), Cu was primarily from the ingestion of feed, accounting for 67 % of bioaccumulation, while Cd, Pb and Cr primarily entered shrimp through the adsorption from overlying water (53 % for Cd and 78 % for Pb) and porewater (66 % for Cr), respectively. The HMs in the pond water were further tracked based on a mass balance analysis. The main source of Cu in the aquaculture environment was feed, being responsible for 37 % of the total input. Pb, Cd and Cr were primarily from the inlet water with contributions of 84 %, 54 % and 52 %, respectively. In summary, the proportions of different exposure pathways and origins of HMs in pond-cultured shrimp and its living environment varied widely. To keep end-consumers eating healthily, species specific treatment is required. Feed should be regulated more for Cu. Aimed pretreatments for Pb and Cd in influent water are needed and an additional immobilization for Cr in sediment porewater should be investigated. After implementation of these treatments, the food quality improvement could be further quantified based on our prediction model.

N, O and S co-doped hierarchical porous carbon derived from a series of samara for lithium and sodium storage: Insights into surface capacitance and inner diffusion.

Efficiently selecting biomass precursors to prepare porous carbon with rich pore structure and heteroatom doping, and clearly distinguishing the storage behavior of Li+ and Na+ in porous carbon are still the key issues for the development and utilization of biomass-based carbon materials. In this work, four kinds of samara with a hollow structure are used as carbon sources to prepare an N, O and S co-doped hierarchical porous carbon. As the anode for Li/Na-ion batteries, the reversible specific capacity of N, O and S co-doped hierarchical porous carbon (HPC-UP-6) is 1072.3 mAh·g-1 (0.0744 A·g-1) and 333.2 mAh·g-1 (0.1 A·g-1), respectively. The ultra-high specific capacity reveals the rationality of preferentially selecting plant fruits with hollow structures as precursors. In addition, further comparative studies show that the contribution rate of surface-induced capacitance in sodium-ion batteries is more than 10% higher than that in lithium-ion batteries, indicating that Na+ tends to be stored on the surface of porous carbon. This principle of selecting biomass precursors and the new understanding of the storage mechanism of Li+/Na+ in biomass-based porous carbon can guide the design and preparation of new carbon materials with high capacity and high-rate performance.