A leather-based electrolyte for all-in-one configured flexible supercapacitors.

In this paper, a top-down method is used to partially hydrolyze leather to achieve a leather-based gel electrolyte, and successfully develop a leather-based all-in-one configured flexible supercapacitor. The hierarchical structure of collagen fibers effectively solves the interface problem of flexible supercapacitors, and at the same time endows the gel electrolyte with degradability and reproducibility.

Repurposed Leather with Sensing Capabilities for Multifunctional Electronic Skin.

Electronic skin (e-skin), an important part toward the realization of artificial intelligence, has been developing through comprehending, mimicking, and eventually outperforming skin in some aspects. Most of the e-skin substrates are flexible polymers, such as polydimethylsiloxane (PDMS). Although PDMS was found to be biocompatible, it is not suitable for long-time wearing due to its air impermeability. This study reports a simple and designable leather based e-skin by merging the natural sophisticated structure and wearing comfort of leather with the multifunctional properties of nanomaterials. The leather based e-skin could make leather, "the dead skin," repurposed for its sensing capabilities. This e-skin can be applied in flexible pressure sensors, displays, user-interactive devices, etc. It provides a new class of materials for the development of multifunctional e-skin to mimic or even outshine the functions of real skin.

Wearable Leather-Based Electronics for Respiration Monitoring.

This article presents a leather-based respiration sensor based on the ionic conductivity change of leather, caused by humidity variation during breathing. Leather was applied as a flexible substrate due to its biocompatibility, hydroscopicity, porosity, and ionic conductivity. Printing method was employed to fabricate the sensor, which could convert human respiration to electrical signals. By combining the leather with silver nanowires (AgNWs), data about human respiration rate, respiration depth, and respiration pattern can be acquired easily through a noninvasive way. Such sensor could work tens of hours consecutively due to the unique properties of leather.

Fabrication of Flexible Transparent Electrode with Enhanced Conductivity from Hierarchical Metal Grids.

Flexible transparent conductive electrodes (FTCEs) are essential components for numerous optoelectronic devices. In this work, we have fabricated the hierarchical metal grids (HMG) FTCEs by a facile and low-cost, near-field photolithography strategy. Compared to normal metal grids (MG), the HMG structure can provide distinctly increased conductivity of the electrode yet without obvious reduction of the optical transmittance. This HMG sample possesses excellent optoelectronic performance and high mechanical flexibility, making it a promising component for practical applications.

Hybridization of Metal Nanoparticles with Metal-Organic Frameworks Using Protein as Amphiphilic Stabilizer.

Here, a facile strategy is reported to efficiently hybridize metal nanoparticles (MNPs) with typical metal-organic frameworks (MOFs) of ZIF-8 (zeolitic imidazolate framework-8), which employs bovine serum albumin (BSA, a serum albumin protein derived from cows) as the amphiphilic stabilizer to increase the affinity of MNP toward MOFs. For instance, the as-synthesized PdNPs/ZIF-8 composites with diameter from 100 to 200 nm always maintain well-defined crystalline structure, and the PdNPs with small size of ∼2 nm are well-dispersed in the crystal of MOFs without serious aggregations due to the BSA stabilizer. In Suzuki cross-coupling reactions of aryl halide, the PdNPs/ZIF-8 as catalysts have exhibited high activity and satisfied reusability owing to the use of BSA stabilizer as well as the fixing of MOFs matrixes. In addition, the strategy also can be extended to synthesize other kinds of MNPs/MOFs hybrid composites with tunable particle size, which brings more opportunity for functional MOFs hybrid materials.

Metal-Organic Framework Wears a Protective Cover for Improved Stability.

Metal-organic frameworks (MOFs) with an ordered channel and porosity show great promise for a myriad of purposes. Unfortunately, the coordination bond of metal ions and organic ligands easily weakens in unfavorable environments, which poses a key problem in expanding the application of MOFs. Herein, we report a general and efficient strategy to enhance the stability and preserve the porosity of MOFs by coating them with reduced graphene oxide (rGO). The prepared hybrid material consisted of MOFs and rGO, as the core and the protective shell, respectively. It is worth noting that the obtained MOFs@rGO composite material maintained a well-defined crystal structure and showed good catalytic activity as well as enhanced stability. Notably, this novel and general method of coating MOFs with a thin protective rGO shell will broaden the application fields of MOFs and open up a new avenue for the research of MOFs.

Centimeter-scale subwavelength photolithography using metal-coated elastomeric photomasks with modulated light intensity at the oblique sidewalls.

By coating polydimethylsiloxane (PDMS) relief structures with a layer of opaque metal such as gold, the incident light is strictly allowed to pass through the nanoscopic apertures at the sidewalls of PDMS reliefs to expose underlying photoresist at nanoscale regions, thus producing subwavelength nanopatterns covering centimeter-scale areas. It was found that the sidewalls were a little oblique, which was the key to form the nanoscale apertures. Two-sided and one-sided subwavelength apertures can be constructed by employing vertical and oblique metal evaporation directions, respectively. Consequently, two-line and one-line subwavelength nanopatterns with programmable feature shapes, sizes, and periodicities could be produced using the obtained photomasks. The smallest aperture size and line width of 80 nm were achieved. In contrast to the generation of raised positive photoresist nanopatterns in phase shifting photolithography, the recessed positive photoresist nanopatterns produced in this study provide a convenient route to transfer the resist nanopatterns to metal nanopatterns. This nanolithography methodology possesses the distinctive advantages of simplicity, low cost, high throughput, and nanoscale feature size and shape controllability, making it a potent nanofabrication technique to enable functional nanostructures for various potential applications.

Synthesis of stable heterogeneous catalysts by supporting carbon-stabilized palladium nanoparticles on MOFs.

Cycling instability of catalysts is a persisting challenge in heterogeneous catalysis. In this work, we reported an effective in situ strategy for preparing ZIF-8 supported carbon-stabilized Pd nanoparticles (C@Pd/ZIF-8). The original ZIF-8 structure was well-preserved after the formation of Pd nanoparticles and amorphous carbon. Here, the Pd nanoparticles were encapsulated in the carbon matrix with a good dispersion. The as-prepared catalysts showed a better activity and cycling stability for the hydrogenation of C[double bond, length as m-dash]C containing substrates. C@Pd/ZIF-8 catalysts are reusable without significant loss of activity after 5 cycles, exhibiting higher cycling stability than those prepared from directly supported Pd nanoparticles on ZIF-8 (Pd/ZIF-8).

Rewritable multilevel memory performance of a tetraazatetracene donor-acceptor derivative with good endurance.

A new tetraazatetracene derivative, 2,3-[4,4'-bis(N,N-diphenylamino)benzyl]-5,12-bis[(triisopropylsilyl)ethynyl]-1,4,6,11-tetraazatetracene (TPAs-BTTT), displays rewritable multilevel memory behavior, which is probably induced by multielectron intramolecular charge transfer (CT).

Parallel near-field photolithography with metal-coated elastomeric masks.

Developing a cost-effective nanolithography strategy that enables the production of subwavelength features with various shapes over large areas is a long-standing goal in the nanotechnology community. Herein, an inexpensive nanolithographic technique that combines the wafer-scale production capability of photolithography with the subwavelength feature size controllability of near-field photolithography was developed to fabricate centimeter-scale up to wafer-scale sub-100-nm variously shaped nanopatterns on surfaces. The wafer-scale elastomeric trench-based photomasks with subwavelength apertures created at the apexes were compatible with mask aligners, allowing for the production of wafer-scale subwavelength nanopatterns with adjustable feature sizes, shapes, and periodicities. The smallest feature sizes of 50 and 80 nm were achieved on positive tone and negative tone photoresist surfaces, respectively, which could be ascribed to a near-field optical effect. The fabricated centimeter-scale nanopatterns were functionalized to study cell-matrix adhesion and migration. Compared to currently developed nanolithographic methods that approach similar functionalities, this facile nanolithographic strategy combines the merits of low cost, subwavelength feature size, high throughput, and varied feature shapes, making it an affordable approach to be used in academic research for researchers at most institutions.

In situ synthesis of large-area single sub-10 nm nanoparticle arrays by polymer pen lithography.

In order to take advantage of the unique properties of nanoparticles in integrated devices, it is desirable to position monodispersed nanoparticles on substrates with controlled placement. Herein, we utilize small molecules such as ethylene glycol (EG) or glycerol to facilitate the delivery of nanoparticle precursors to the substrates in the polymer pen lithography (PPL) process. Subsequently, large-area ordered single nanoparticle arrays, including sub-10 nm Ag nanoparticle, 30 nm Au nanoparticle and 80 nm Fe2O3 nanoparticle arrays have been synthesized in situ with controllable sizes and pitches.

A fishnet electrochemical Hg2+ sensing strategy based on gold nanoparticle-bioconjugate and thymine-Hg(2+)-thymine coordination chemistry.

A novel electrochemical biosensing strategy based on a three-dimensional fishnet of DNA-linked nanoparticle supramolecular structure triggered by the analyst for detection of Hg(2+) has been designed. The detection limit is 7.38 pM and the sensor's selectivity and facility have been significantly improved.