Built-In Stable Lithiophilic Sites in 3D Current Collectors for Dendrite Free Li Metal Electrode.

Stable lithiophilic sites in 3D current collectors are the key to guiding the uniform Li deposition and thus suppressing the Li dendrite growth, but such sites created by the conventional surface decoration method are easy to be consumed along with cycling. In this work, carbon fiber (CF)-based 3D porous networks with built-in lithiophilic sites that are stable upon cycling are demonstrated. Such heterostructured architecture is constructed by the introduction of zeolitic imidazolate framework-8-based nanoparticles during the formation of the 3D fibrous carbonaceous network and the following annealing. The introduced Zn species are found to be re-distributed along the entire individual CF in the 3D network, and function as lithiophilic sites that favor the homogenous lithium nucleation and growth. The 3D network also presents a multi-scale porous structure that improves the space utilization of the host. The corresponding symmetric cells adopting such 3D anode demonstrate excellent cycling performance, especially at a high rate (300 cycles at 10 mA cm-2 with a capacity of 5 mA h cm-2 ). A full cell with LiFePO4 cathode shows a capacity retention of 98% after cycling at 1C for 300 cycles. This method provides an effective design strategy for 3D hosting electrodes in dendrite-free alkali metal anode applications.

Disclosing the Origin of Irreversible Sodiation-Desodiation of a Cu4SnP10 Nanowire Anode by Ex Situ Transmission Electron Microscopy.

Cu4SnP10, a promising phosphide material for sodium-ion battery anode applications, suffers from poor cycling stability, and its mechanism remains unclear. This is largely due to the amorphous nature of the active materials upon cycling and its possible structural change at a small length scale (e.g., nanometers), making it difficult to access the phase/structural evolution of the electrode. In the present work, we show that the phase/structural change of the Cu4SnP10 nanowire electrode can be systematically investigated using a comprehensive set of ex situ transmission electron microscopy-based techniques, which are ideal for decay mechanism analysis of electrode materials of amorphous nature and with nanoscale structural evolution. The compositional elements of Cu4SnP10 nanowires are found to be spatially redistributed at a nanometer scale upon the initial sodiation, and this is partially reversible in the following desodiation process. Damage accumulates until a critical size of phase separation/segregation is reached, when the active material loss takes place, leading to fast deterioration of the entire Cu4SnP10 nanowire structure and thus its electrochemical performance. The phase segregation driven-active material loss is found to dominate the cycle-dependent capacity decay of the Cu4SnP10 nanowire electrode.

Charging a Negatively Curved Nanographene and Its Covalent Network.

This study explores a bottom-up approach toward negatively curved carbon allotropes from octabenzo[8]circulene, a negatively curved nanographene. Stepwise chemical reduction reactions of octabenzo[8]circulene with alkali metals lead to a unique highly reduced hydrocarbon pentaanion, which is revealed by X-ray crystallography suggesting a local view for the reduction and alkali metal intercalation processes of negatively curved carbon allotropes. Polymerization of the tetrabromo derivative of octabenzo[8]circulene by the nickel-mediated Yamamoto coupling reaction results in a new type of porous carbon-rich material, which consists of a covalent network of negatively curved nanographenes. It has a specific surface area of 732 m2 g-1 and functions as anode material for lithium ion batteries exhibiting a maximum capacity of 830 mAh·g-1 at a current density of 100 mA·g-1. These results indicate that this covalent network presents the key structural and functional features of negatively curved carbon allotropes.

Identification of novel uracil derivatives incorporating benzoic acid moieties as highly potent Dipeptidyl Peptidase-IV inhibitors.

Dipeptidyl Peptidase-IV (DPP-4) is a validated therapeutic target for type 2 diabetes. Aiming to interact with both residues Try629 and Lys554 in S2' site, a series of novel uracil derivatives 1a-l and 2a-i incorporating benzoic acid moieties at the N3 position were designed and evaluated for their DPP-4 inhibitory activity. Structure-activity relationships (SAR) study led to the identification of the optimal compound 2b as a potent and selective DPP-4 inhibitor (IC50 = 1.7 nM). Docking study revealed the additional salt bridge formed between the carboxylic acid and primary amine of Lys554 has a key role in the enhancement of the activity. Furthermore, compound 2b exhibited no cytotoxicity in human hepatocyte LO2 cells up to 50 µM. Subsequent in vivo evaluations revealed that the ester of 2b robustly improves the glucose tolerance in normal mice. The overall results have shown that compound 2b has the potential to a safe and efficacious treatment for T2DM.

The bifunctional regulation of interconnected Zn-incorporated ZrO2 nanoarrays in antibiosis and osteogenesis.

New generation biomaterials should be designed to bear long-term antibacterial activity, biocompatibility and even osteogenesis facilitation. In this study, the bifunctional regulation of antibiosis and osteogenesis is realized by the highly-ordered and interconnecting Zn-incorporated ZrO2 nanoarrays, which are prepared by a hydrothermal approach with the precursor hydrolyzed in situ and allow long-term controllable Zn release. The content of incorporated Zn can be easily controlled by pH of the HCl solution used for etching. All Zn-incorporated nanoarrays show good antibacterial properties against both Escherichia coli (E. coli, Gram-negative) and Staphylococcus aureus (S. aureus, Gram-positive), as indicated by high antibacterial rates and the apparent inhibition zone. Analysis of the biocompatibility confirms that the hybrid nanoarrays could cause varying degrees of promotion for the adhesion and spreading of MC3T3-E1 cells. Zn incorporated ZrO2 nanotubes balance antibiosis and osteogenesis delicately, as proved by the up-regulated MTT and ALP activities, as well as the increase of bone-related gene expression (the mRNA level of OCN, OPN and BMP-2). The novel bone implant materials with better antibacterial properties can promote the osteogenesis, and have promising applications in biomedical devices and antibacterial control systems.

Composite of macroporous carbon with honeycomb-like structure from mollusc shell and NiCo(2)O(4) nanowires for high-performance supercapacitor.

Novel biological carbon materials with highly ordered microstructure and large pore volume have caused great interest due to their multifunctional properties. Herein, we report the preparation of an interconnected porous carbon material by carbonizing the organic matrix of mollusc shell. The obtained three-dimensional carbon skeleton consists of hexangular and tightly arranged channels, which endow it with efficient electrolyte penetration and fast electron transfer, enable the mollusc shell based macroporous carbon material (MSBPC) to be an excellent conductive scaffold for supercapacitor electrodes. By growing NiCo2O4 nanowires on the obtained MSBPC, NiCo2O4/MSBPC composites were synthesized. When used on supercapacitor electrode, it exhibited anomalously high specific capacitance (∼1696 F/g), excellent rate performance (with the capacity retention of 58.6% at 15 A/g) and outstanding cycling stability (88% retention after 2000 cycles). Furthermore, an all-solid-state symmetric supercapacitor was also assembled based on this NiCo2O4/MSBPC electrode and showed good electrochemical performance with an energy density of 8.47 Wh/kg at 1 A/g, good stability over 10000 cycles. And we believe that more potential applications beyond energy storage can be developed based on this MSBPC.

Mesoporous CoO nanocubes @ continuous 3D porous carbon skeleton of rose-based electrode for high-performance supercapacitor.

Supercapacitors have attracted lots of attentions for energy storage because of their outstanding electrochemical properties, and various kinds of carbon materials have been used to improve the performance. In this work, we innovatively elevate a natural rose-based continuous 3D porous carbon skeleton. The as-prepared carbon skeleton is graphited to some extent and possesses hierarchical interconnected 3D porous structures, providing a high electrical conductive and electrolyte easy-infiltrated substrate for the fabrication of ideal monolithic composite electrodes. Then, we utilized it as scaffold to prepare mesoporous CoO nanocubes @ continuous 3D porous carbon skeleton of rose composite-based electrode for supercapacitor via hydrothermal approach. The obtained material exhibits a noticeable pseudocapacitive performance with a brilliant capacitance of 1672 F/g at 1 A/g and as high as 521 F/g at 40 A/g. It also should be noted that ∼82% of the capacitance was maintained after 3000 cycles at 5 A/g, and only 40% capacitance loss after 1500 cycles at a relatively high current density of 10 A/g.