Covalent netting restrains dissolution enabling stable high-loading and high-rate iron difluoride cathodes.

Metal fluoride conversion cathodes are promising for the production of cheap, sustainable, and high-energy lithium-ion batteries. Yet, such systems are plagued by active material dissolution that causes capacity fade and hinders commercialization. Here, a covalent netting strategy is proposed to overcome this hurdle. In a proof-of-concept design, polydopamine derived carbon-mediated covalent binding inhibited the dissolution, while the pyrolyzed bacterial cellulose netting structure furnished fast electronic and ionic transport pathways. We demonstrate high-capacity, high-rate and long-lasting stability attained at practical loading levels. Our investigations suggest that the covalent netting-enabled formation of a robust and efficient blocking layer, highly competent in suppressing the leaching, is key for a stable performance. The successful stabilization of metal difluorides in the absence of electrolyte engineering opens an avenue for their practical deployment in future higher-level but lower-cost batteries, and provides a solution to similar challenges encountered by other dissolving energy electrode materials.

Halbach array assisted assembly of orderly aligned nickel nanowire networks as transparent conductive films.

The aspect ratio and arrangement of nanowires play an important role in achieving excellent optoelectronic performance for metal nanowire-based transparent conductive films (TCFs). However, limited to the technology and material properties, studies are always focused on only one of the issues. Here, a novel strategy for manipulating the relative aspect ratio and arrangement of nickel nanowires (NiNWs) at nanoscale by Halbach array assisted assembly technology is introduced. Head-to-tail nickel nanowire chains as large as hundreds of micrometers are formed as a result of the dipole-dipole interactions of wire-wire. The arrangement of nickel nanowires can be preciously controlled by layer-by-layer deposition. Notably, the alignment create a significant improvement on the optoelectronic performance of nickel nanowire TCFs. The optimized orderly aligned NiNWs TCFs demonstrate super optoelectronic performance (90 Ω sq-1, 86%) than disordered NiNW TCFs (200 Ω sq-1, 80%). Moreover, NiNW-based TCFs exhibit outstanding long-term oxidation stability at 80 °C over 30 d as well as high-temperature oxidization stability even up to 300 °C, that is the most stable metal nanowire-based TCFs in air as far as we know. The low-cost, good optoelectronic performance and excellent oxidation resistance of aligned NiNWs will make them as attractive alternatives to silver nanowires for TCFs application.

Covalently stabilized Pd clusters in microporous polyphenylene: an efficient catalyst for Suzuki reactions under aerobic conditions.

A novel catalyst composed of a microporous polyphenylene network and covalently stabilized Pd clusters (Pd/MPP) for highly efficient Suzuki-Miyaura coupling is synthesized with an in-situ one-pot chemical approach, through the catalytic trimerization of 1,3,5-triethynylbenzene. The unique Pd/MPP cluster exhibits very high catalytic activity for a broad scope of Suzuki-Miyaura reactions with short reaction time, good yield, and high turnover number and turnover frequency values, even in aqueous media under aerobic conditions. The strong covalent interaction between Pd and MPP network prevents the agglomeration or leaching of Pd clusters and enables the catalyst to remain highly active, even after a number of cycles.

Direct access to metal or metal oxide nanocrystals integrated with one-dimensional nanoporous carbons for electrochemical energy storage.

Metal and metal oxide nanocrystals have sparked great interest due to their excellent catalytic, magnetic, and electronic properties. Particularly, the integration of metallic nanocrystals and one-dimensional (1D) electronically conducting carbons to form metal-carbon hybrids can lead to enhanced physical and chemical properties or even the creation of new properties with respect to single component materials. However, direct access to thermally stable and structurally ordered 1D metal-carbon hybrids remains a primary challenge. We report an in situ fabrication of Co(3)O(4) or Pt nanocrystals incorporated into 1D nanoporous carbons (NPCs) via an organometallic precursor-controlled thermolysis approach. The AB(2)-type (one diene and two dienophile) 3,4-bis(4-dodecynylphenyl)-substituted cyclopentadienone and its relevant cobalt or platinum complex are first impregnated into the nanochannels of AAO (anodic alumina oxide) membranes. The intermolecular Diels-Alder reaction of these precursor molecules affords the formation of cobalt or platinum functionalized polyphenylene skeletons. Subsequent thermolysis transforms the polyphenylene backbones into 1D nanoporous carbonaceous frameworks, while the metallic moieties are reduced into Co or Pt nanocrystals, respectively. After removal of the AAO template, 1D NPCs/Co(3)O(4) or NPCs/Pt are obtained, for which structural characterizations reveal that high-quality Co(3)O(4) or Pt nanocrystals are distributed homogeneously within carbon frameworks. These unique 1D metal-carbon hybrids exhibit a promising potential in electrochemical energy storage. NPCs/Co(3)O(4) is evaluated as an electrode material in a supercapacitor, for which Co(3)O(4) nanocrystals contribute an exceptionally high gravimetric capacitance value of 1066 F g(-1). NPCs/Pt is applied as an electrocatalyst showing excellent catalytic efficiency toward methanol oxidation in comparison to commercial E-TEK (Pt/C) catalyst.

Functionalization of self-assembled hexa-peri-hexabenzocoronene fibers with peptides for bioprobing.

A novel water-soluble hexa-peri-hexabenzocoronene (HBC) derivative with peripheral functional groups, which facilitates a two-step assembly process in water that includes fiber formation via pi stacking and subsequent peptide probing via electrostatic interactions, is reported. In the first step, the HBC derivative self-assembles into water-soluble red-fluorescent fibers that serve as templates for further functionalization with biomolecules. In the second assembly step, the peripheral functional groups bind green-fluorescent fluorescein-conjugated peptides, leading to the formation of well-defined fibers that were visualized as dual-color fibers in double-fluorescence imaging.