Latest ArticlesNitrogen-doping of carbon support (N-C) for platinum (Pt) nanoparticles to form Pt/N-C catalyst represents an effective strategy to promote the electrocatalysis of cathodic oxygen reduction reaction (ORR) in proton exchange membrane fuel cells. For fundamental understanding, clearly identifying the metal-support effect on enhancement mechanisms of ORR electrocatalysis is definitely needed. In this work, the impact of Pt-support interaction via interfacial Pt-N coordination on electrocatalytic ORR activity and stability in Pt/N-C catalyst is deeply studied through structural/compositional characterizations, electrochemical measurements and theoretical DFT-calculations/AIMD-simulations. The resulting Pt/N-C catalyst exhibits a superior electrocatalytic performance compared to the commercial Pt/C catalyst in both half-cell and H2-O2 fuel cell. Experimental and theoretical results reveal that the interfacial Pt-N coordination enables electron transfer from N-C support to Pt nanoparticles, which can weaken the adsorption strength of oxygen intermediates on Pt surface to improve ORR activity and induce the strong Pt-support interaction to enhance electrochemical stability.
Customized design of well-defined cathode structures with abundant adsorption sites and rapid diffusion dynamics, holds great promise in filling capacity gap of carbonaceous cathodes towards high-performance Zn-ion hybrid supercapacitors (ZHC). Herein, we fabricate a series of dynamics-oriented hierarchical porous carbons derived from the unique organic-inorganic interpenetrating polymer networks. The interpenetrating polymer networks are obtained through physically knitting polyferric chloride (PFC) network into the highly crosslinked resorcinol-formaldehyde (RF) network. Instead of covalent bonding, physical interpenetrating force in such RF-PFC networks efficiently relieves the RF skeleton shrinkage upon pyrolysis. Meanwhile, the in-situ PFC network sacrifices as a structure-directing agent to suppress the macrophase separation, and correspondingly 3D hierarchical porous structure with plentiful ion-diffusion channels (pore volume of 1.35 cm3/g) is generated in the representative HPC4 via nanospace occupation and swelling effect. Further removal of Fe fillers leaves behind a large accessible specific surface area of 1550 m2/g for enhanced Zn-ion adsorption. When used as the cathode for ZHC, HPC4 demonstrates a remarkable electrochemical performance with a specific capacity of 215.1 mAh/g at 0.5 A/g and a high Zn2+ ion diffusion coefficient of 11.1 × 10−18 cm2/s. The ZHC device yields 117.0 Wh/kg energy output at a power density of 272.1 W/kg, coupled with good cycle lifespan (100,000 cycles@10 A/g). This work inspires innovative insights to accelerate Zn diffusion dynamics by structure elaboration towards high-capacity cathode materials.
Phosphorus-based anode is a promising anode for sodium-ion batteries (SIBs) due to its high specific capacity, however, suffers from poor electronic conductivity and unfavorable electrochemical reversibility. Incorporating metals such as copper (Cu) into phosphorus has been demonstrated to not only improve the electronic conductivity but also accommodate the volume change during cycling, yet the underline sodiation mechanism is not clear. Herein, take a copper phosphide and reduced graphene oxide (CuP2/C) composite as an example, which delivers a high reversible capacity of > 900 mAh/g. Interestingly, it is revealed that the native oxidation PO components of the CuP2/C composite show higher electrochemical reversibility than the bulk CuP2, based on a quantitative analysis of high-resolution solid-state 31P NMR, ex-situ XPS and synchrotron X-ray diffraction characterization techniques. The sodiation products Na3PO4 and Na4P2O7 derived from PO could react with Na-P alloys and regenerate to PO during charge process, which probably accounts for the high reversible capacity of the CuP2/C anode. The findings also illustrate that the phosphorus transforms into nanocrystalline Na3P and NaP alloys, which laterally shows crystallization-amorphization evolution process during cycling.
Heterodimerization in RTKs is of vital importance in the RTK signaling and cell functions. Heterodimerization between RTKs can result in diversity of downstream signals, increasing the ability of cells to respond to external experiments. Traditional RTKs heterodimerization always occur in the same families and is lack of agonists to activate the heterodimeric RTKs signaling pathway. Herein, we developed the DNA agonist based on bivalent aptamers for the heterodimerized RTKs of different families, AF/AM-1, which could simultaneously activate FGFR1 and c-Met signaling. It is the first agonist that realizing the heterodimerization and activation of FGFR1 and c-Met, two different RTK families. The activation of FGFR1/c-Met heterodimer result in the down-stream signals transduction, such as the phosphorylation of Akt and Erk, inducing the cell migration and proliferation. The DNA agonist for RTK heterodimer of different families would have potential applications in the fields of biomedicine.
Pure near-infrared (NIR) phosphorescent materials with emission peak larger than 700 nm are of great significance for the development of optoelectronics and biomedicine. We have designed and synthesized two new B-embedded pure near-infrared (NIR)-emitting iridium complexes (Ir(Bpiq)2acac and Ir(Bpiq)2dpm) with peaks greater than 720 nm. More importantly, they exhibit very narrow phosphorescent emission with full width at half maximum (FWHM) of only about 50 nm (0.12 eV), resulting in a high NIR content (> 90%) in their spectrum. In view of better optical property and solubility, the complex Ir(Bpiq)2dpm was used as the emitting layer of a solution-processed OLED device, and achieved good maximum external quantum efficiency (EQE) (2.8%) peaking at 728 nm. This research provides an important strategy for the design of narrowband NIR-emitting phosphorescent iridium complexes and their optoelectronic applications.
Fluorescence lateral flow immunoassay (LFA) has emerged as a powerful tool for rapid screening of various biomarkers owing to its simplicity, sensitivity and flexibility. It is noteworthy that fluorescent probe mainly determines the analytical performance of LFA. Due to the emission and excitation wavelengths are located in the visible region, most fluorophores are inevitably subject to light scattering and background autofluorescence. Herein, we reported a novel LFA sensor based on the second near-infrared (NIR-Ⅱ) fluorescent probe with excellent anti-interference capability. The designed NIR-Ⅱ probe was the Nd3+ and Yb3+ doped rare earth nanoparticles (RENPs) by employing Nd3+ as energy donor and Yb3+ as energy acceptor, which of the donor-acceptor energy transfer (ET) efficiency reached up to 80.7%. Meanwhile, relying on the convenient and effective encapsulation strategy of poly(lactic-co-glycolic acid) (PLGA) microspheres to RENPs, the surface functionalized NIR-Ⅱ probe (RE@PLGA) was obtained for subsequent bioconjugation. Benefiting from the optical advantages of NIR-Ⅱ probe, this proposed NIR-Ⅱ LFA displayed a good linear relationship ranging from 7 ng/mL to 200 ng/mL for the detection of α-fetoprotein (AFP), an important biomarker of hepatocellular carcinoma (HCC). The limit of detection (LOD) was determined as low as 3.0 ng/mL, which was of 8.3 times lower than clinical cutoff value. It is promising that LFA sensor based on this efficient RENPs probe provides new opportunities for high sensitive detection of various biomarkers in biological samples.
Designing highly active electrocatalysts for the hydrogen evolution reaction (HER) and oxygen evolution and reduction reactions (OER and ORR) is pivotal to renewable energy technology. Herein, based on density functional theory (DFT) calculations, we systematically investigate the catalytic activity of iron-nitrogen-carbon based covalent organic frameworks (COF) monolayers with axially coordinated ligands (denotes as FeN4-X@COF, X refers to axial ligand, X = -SCN, -I, -H, -SH, -NO2, -Br, -ClO, -Cl, -HCO3, -NO, -ClO2, -OH, -CN and -F). The calculated results demonstrate that all the catalysts possess good thermodynamic and electrochemical stabilities. The different ligands axially ligated to the Fe active center could induce changes in the charge of the Fe center, which further regulates the interaction strength between intermediates and catalysts that governs the catalytic activity. Importantly, FeN4-SH@COF and FeN4OH@COF are efficient bifunctional catalysts for HER and OER, FeN4OH@COF and FeN4-I@COF are promising bifunctional catalysts for OER and ORR. These findings not only reveal promising bifunctional HER/OER and OER/ORR catalysts but also provide theoretical guidance for designing optimum iron-nitrogen-carbon based catalysts.
As the global population ages, osteoporotic bone fractures leading to bone defects are increasingly becoming a significant challenge in the field of public health. Treating this disease faces many challenges, especially in the context of an imbalance between osteoblast and osteoclast activities. Therefore, the development of new biomaterials has become the key. This article reviews various design strategies and their advantages and disadvantages for biomaterials aimed at osteoporotic bone defects. Overall, current research progress indicates that innovative design, functionalization, and targeting of materials can significantly enhance bone regeneration under osteoporotic conditions. By comprehensively considering biocompatibility, mechanical properties, and bioactivity, these biomaterials can be further optimized, offering a range of choices and strategies for the repair of osteoporotic bone defects.
As more and more studies have shown that lipid molecules play an important role in the whole biology, in-depth analysis of lipid structure has become particularly important in lipidomics. Mass spectrometry (MS), as the preferred tool for lipid analysis, has greatly promoted the development of this field. However, the existing MS methods still face many difficulties in the in-depth or even comprehensive analysis of lipid structure. In this review, we discuss recent advances in MS methods based on double bond-specific chemistries for the resolving of C=C location and geometry isomers of lipids. This progress has greatly advanced the lipidomics analysis to a deeper structural level and facilitated the development of structural lipid biology.
α-MnO2 is a potential positive electrode material for aqueous zinc-ion batteries, but its electrochemical performance of zinc storage requires further improvement. In this paper, potassium ion-doped manganese dioxide nanoscrolls (KMnO2) with oxygen vacancy were synthesized by a one-step hydrothermal method. It was observed that the electrochemical specific capacity was 250.9 mAh/g at a current density of 0.2 C, which was better than the existing commercial α-MnO2. At a high current of 1 C, these batteries demonstrate improved cycle stability. Synchrotron radiation and other experiments as well as DFT theoretical calculations provided additional evidence that K doping was efficient in regulating the metal bond type and the mean charge regulation of covalent bonds with oxygen atoms in MnO2. When MnO and MnK bonds are present, KMnO2 showed outstanding adsorption of Zn2+ and further enhanced the Zn2+ embedding process. Simultaneously, oxygen defects caused by doping boosted the development of the nanoscroll structure, leading to an increase in active sites available for electrochemical reactions and subsequently enhancing the electrical conductivity of α-MnO2. This study exhibits the potential of optimizing materials based on manganese with the introduction of a potassium doping strategy, resulting in improved performance for aquatic zinc-ion batteries, and presents novel perspectives for related research.
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