Latest ArticlesHigh-temperature proton exchange membranes (HT-PEMs) possess excellent thermal and outstanding electrochemical stability, providing an avenue to realize high-temperature proton exchange membranes fuel cells (HT-PEMFCs) with both superior power density and long-term durability. Unfortunately, polybenzimidazole (PBI), a typical material for conventional HT-PEMs, fails to compromise the high nonaqueous proton conductivity and high mechanical properties, thus hindering their practical applications. Achieving efficient nonaqueous proton conduction is crucial for HT-PEMFC, and many insightful research works have been done in this area. However, there still lacks a report that integrates the host-guest interactions of phosphoric acid doping and the structural stability of polymers to systematically illustrate modification strategies. Here, we summarize recent advancements in enhancing the nonaqueous proton conduction of HT-PEMs. Various polymer structure modification strategies, including main chain and side group modification, cross-linking, blocking, and branching, are reviewed. Composite approaches of polymer, including compounding with organic porous polymers, filling the inorganic components and modifying with ionic liquids, etc., are also covered in this work. These strategies endow the HT-PEMs with more free volume, nanophase-separated structure, and multi-stage proton transfer channels, which can facilitate the proton transportation and improve their performance. Finally, current challenges and future directions for further enhancements are also outlined.
Although considerable research efforts have been devoted to the design and development of non-noble electrocatalysts for oxygen evolution reaction (OER), substantial enhancement of OER performance with commercial-scale water electrolysis remains a big challenge. This could result from the difficulties in detecting the intrinsic properties and overlooking the assembly process for electrochemical OER process. Here, we employ a microjet collision method to investigate the intrinsic OER activities of individual NiZnFeOx entities with and without a moderate magnetic field. Our results demonstrate that single NiZnFeOx nanoparticles (NPs) show the excellent OER performance with a lowest onset potential (~1.35 V vs. RHE) and a greatest magnetic enhancement (~118%) among bulk materials, single agglomerations and NPs. Furthermore, we explore the utility of theoretical investigation by density functional theory (DFT) calculations for studying OER process on NiZnFeOx surfaces without and with spin alignment, indicating monodispersed NiZnFeOx NPs with totally spin alignment facilitates the OER process under the external magnetic field. It is found that the well-dispersion of NiZnFeOx NPs would increase the electrical conductivity and the surface spin state, resulting in promoting their OER activities. This work provides a test for uncovering the essential roles of NPs assembly to a significant promotion of their magnet-assisted OER.
Selective molecular recognition in water is routine for bioreceptors, but remains challenging for synthetic hosts. This is principally because noncovalent interactions are usually less efficient in aqueous environments. By mimicking the cavity feature of bioreceptors, Prof. Wei Jiang proposed and clarified the concept of "endo-functionalized cavity". Through situating polar binding sites into a deep hydrophobic cavity, we designed and synthesized several macrocyclic hosts, among which amide naphthotubes are the most representative. The hosts can selectively recognize various polar molecules including organic micropollutants, drug molecules, and chiral molecules in water by employing the hydrophobic effect and shielded hydrogen bonding. In addition, these biomimetic hosts have been applied in spectroscopic analysis, adsorptive separation and self-assembly. In this review, we provide an overview of recent advances on amide naphthotubes with special emphasis on the efforts of Jiang's group. We are convinced that these biomimetic macrocycles will make further contributions to supramolecular chemistry and beyond.
An efficient NH and C(sp3)-H functionalization of aryl ketones with benzylamines/amino acids was developed under mild conditions by virtue of anodic oxidation. A variety of functionalized 2,5-diaryloxazoles were obtained with good to excellent yields. Moreover, some important natural products can be prepared by this method. The reaction features a broad substrate scope, scalability, metal-free and chemical oxidant-free.
Particle engineering has opened the floodgates to material science in both fundamental and application field. However, covalent interactions have not yet been adequately designed in the particle engineering for functional colloidal photonic crystals (CPCs). Herein, we achieved covalent coupling between carboxyl-rich poly(styrene-acrylic acid) (P(St-AA)) monodispersed colloidal particles and amine-rich carbon dots (CDs) based on an feasible and universal particle engineering strategy. The designed CDs-grafted P(St-AA) monodispersed colloidal particles initiate a hydrogen bond-driven assembly mode and ensure the construction of large-scale crack-free CPCs. Moreover, the CDs equipped with selective broad-band absorption capacity could improve the saturation of structural colors for high-visibility CPCs. Furthermore, an injectable photonic hydrogel (IPH) is developed to design CPC supraball hydrogel via integrating the CDs-grafted P(St-AA) CPC supraballs with supramolecular hydrogel. Combining superior flexibility, sufficient self-healing capacity of supramolecular hydrogel with visual optical information of our CPC supraballs, a cyclically reversible coding and decoding system was developed. Meanwhile, we firstly demonstrated the novel strategy of 3D supraballs-based passive cooling. The designed 3D CPC supraball hydrogel presents nearly full observation angle reflections behavior and excellent water evaporation capacity and achieves 3.6 ℃ temperature drops, showing the application advantages in 3D thermal management. This work not only provides a new insight for manipulating optical properties of CPCs, but also demonstrates an easy-to-perform platform, as well as indicates the direction for the promising application of CPCs.
Developing narrow-bandgap organic semiconductors is important to facilitate the advancement of organic photovoltaics (OPVs). Herein, two near-infrared non-fused ring acceptors (NIR NFRAs), PTBFTT-F and PTBFTT-Cl have been developed with A-πA-πD-D-πD-πA-A non-fused structures. It is revealed that the introduction of electron deficient π-bridge (πA) and multiple intramolecular noncovalent interactions effectively retained the structural planarity and intramolecular charge transfer of NFRAs, extending strong NIR photon absorption up to 950 nm. Further, the chlorinated acceptor, with the enlarged π-surface compared to the fluorinated counterpart, promoted not only molecular stacking in solid, but also the desirable photochemical stability in ambient, which are helpful to thereby improve the exciton and charge dynamics for the corresponding OPVs. Overall, this work provides valuable insights into the design of NIR organic semiconductors.
The photovoltaic properties of double-cable conjugated polymers are significantly influenced by the length of the alkyl linkers that connect donor backbones and acceptor side units. In this study, a series of 2-(3-oxo-2,3-dihydroinden-1-ylidene)malononitrile (IC)-based double-cable polymers with alkyl linkers ranging from C8H16 to C16H32 (Px, x = 8, 10, 12, 14, 16) were synthesized for single-component organic solar cells (SCOSCs). Among these, the linker length x = 12 (P12) is found to optimize the power conversion efficiencies (PCEs) in SCOSCs. Specifically, PCEs increase from P8 to P12 and then decline from P12 to P16. Detailed investigations of optical absorption, charge transport, and morphology provide insights into the underlying factors contributing to these PCE variations. The findings indicate that the exceptional photovoltaic properties observed in P12 can be attributed to three key factors: A delicate balance between enhanced charge separation facilitated by the increased spacer length and reduced crystallinity resulting from longer spacers, higher charge mobilities, and well-balanced hole/electron transport characteristics. This study highlights the critical role of linker length in determining the photovoltaic properties of double-cable conjugated polymer-based SCOSCs and offers valuable guidance for the design of novel double-cable conjugated polymers.
Organic semiconductor single crystals (OSSCs) have shown their promising potential in high-performance organic field-effect transistors (OFETs). The interfacial dielectric layers are critical in these OFETs as they not only govern the key semiconductor/dielectric interface quality but also determine the growth of OSSCs by their wetting properties. However, reported interfacial dielectric layers either need rigorous preparation processes, rely on certain surface chemistry reactions, or exhibit poor solvent resistance, which limits their applications in low-cost, large-area, monolithic fabrication of OSSC-based OFETs. In this work, polyethylene (PE) thin films and lamellar single crystals are utilized as the interfacial dielectric layers, providing solvent resistive but wettable surfaces that facilitate the crystallization of 6,13-bis(tri-isopropylsilylethynyl)pentacene (TIPS-PEN) and 6,13-bis(triisopropylsilylethynyl)-5,7,12,14-tetraazapentacene (TIPS-TAP). As evidenced by the presence of ambipolar behavior in TIPS-PEN single crystals and the high electron mobility (2.3 ± 0.34 cm2 V-1 s-1) in TIPS-TAP single crystals, a general improvement on electron transport with PE interfacial dielectric layers is revealed, which likely associates with the chemically inertness of the saturated C-H bonds. With the advantages in both processing and device operation, the PE interfacial dielectric layer potentially offers a monolithic way for the enhancement of electron transport in solution-processed OSSC-based OFETs.
A practical method for the construction of difluoromethylene-containing 1,4-thiazine moieties using readily available diethyl bromodifluoromethanephosphonate (BrCF2PO(OEt)2) as difluorocarbene precusor has been developed. This transformation features the efficient capture of difluorocarbene by pyridinium 1,4-zwitterionic thiolates. A series of structurally novel and functionalized difluoromethylene-containing 1,4-thiazine derivatives were thus synthesized in good yields.
RNA modifications have been involved in numerous biological processes, and aberrations of these modifications are tightly associated with various diseases including cancer. Herein, we developed graphene-based solid-phase extraction and robust ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) combined with stable isotope-dilution for simultaneous enrichment and accurate determination of 17 modified nucleosides in human urine. We found graphene could effectively adsorb various modified nucleosides in human urine samples. With this method, we identified and quantified these modified nucleosides in urine samples collected from lung cancer patients and healthy controls. We revealed that the levels of 12 modified nucleosides were all diminished in urine from lung cancer patients, compared with healthy controls. It is worth noting that we demonstrated, for the first time, the presence of 5,2′-O-dimethyluridine (m5Um) in human urine. Together, we established a robust analytical method for simultaneous determinations of 17 modified nucleosides in human urine, and our results revealed a close correlation between the concentrations of urinary modified nucleosides and the occurrence of lung cancer, implying the potential applications of these modified nucleosides as noninvasive biomarkers for the early detection of lung cancer. Moreover, this study will stimulate future investigations on the regulatory roles of RNA modifications in the initiation and progression of lung cancer.
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