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Both nitrogen-doped carbon (NC) and metal-nitrogen-carbon (MNC) materials have been extensively investigated in lithium-sulfur batteries to alleviate the "shuttle effect". MNC are generally synthesized using NC as the parent material, wherein nitrogen atoms in NC serve as the "bridge" to coordinate with metal atoms. So far, an important scientific issue has not been settled: does the introduction of metal sites into NC certainly enhance the Li-S battery performance? In this work, NC and MNC materials derived from the same precursor, a nitrogen-rich porous polymer, are systematically compared as cathode hosts for Li-S battery through theoretical calculations and experimental investigation. Li-S cell with NC as the cathode sulfur host exhibits better cycle performance at low current densities (0.1 and 0.2C), whereas MNC materials predominate at higher current densities (such as 1C and 2C). Based on theoretical calculation and experimental results, it is concluded that the introduction of metal sites into NC through nitrogen bonding promoted the catalytic capability for faster sulfur redox reaction kinetics, whereas the adsorption energy toward polysulfides decreased. This work provides important guidance for more targeted design of advanced materials for lithium-sulfur battery application in the future.
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Transition metal oxides (TMOs) are recognized as high-efficiency electrocatalyst systems for restraining the shuttle effect in lithium-sulfur (Li-S) batteries, owing to their robust adsorption capabilities for polysulfides. However, the sluggish catalytic conversion of Li2S redox and severe passivation effect of TMOs exacerbate polysulfide shuttling and reduce the cyclability of Li-S batteries, which significantly hinders the development of TMOs electrocatalysts. Here, through the anion-cation doping approach, dual incorporation of phosphorus and molybdenum into MnO2 (P,Mo-MnO2) was engineered, demonstrating effective mitigation of the passivation effect and allowing for the simultaneous immobilization of polysulfides and rapid redox kinetics of Li2S. Both experimental and theoretical investigations reveal the pivotal role of dopants in fine-tuning the d-band center and optimizing the electronic structure of MnO2. Furthermore, this well-designed configuration processes catalytic selectivity. Specifically, P-doping expedites rapid Li2S nucleation kinetics by minimizing reaction-free energy, while Mo-doping facilitates robust Li2S dissolution kinetics by mitigating decomposition barriers. This dual-doping approach equips P,Mo-MnO2 with robust bi-directional catalytic activity, effectively overcoming passivation effect and suppressing the notorious shuttle effect. Consequently, Li-S batteries incorporating P,Mo-MnO2-based separators demonstrate favorable performance than pristine TMOs. This design offers rational viewpoint for the development of catalytic materials with superior bi-directional sulfur electrocatalytic in Li-S batteries.
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BiVO4-based photoanode is one of the most promising photoanodes for photoelectrocatalytic water splitting. However, the serious problem of interface charge recombination limits its further development. Here, a Mo:BiVO4/NiOx/CPF-TCzB/NiCoBi photoanode is constructed with double hole transport layer and an energy level gradient to achieve an effective photo-generated holes extraction and accumulation at the surface electrocatalyst. The conjugated polycarbazole framework CPF-TCzB is used as hole transport layer to eliminate the charge recombination center between Mo:BiVO4 and NiCoBi electrocatalyst and realize the extraction and storage of photo-generated hole; NiOx nanoparticles are further inserted between Mo:BiVO4 and CPF-TCzB to form a gradient energy level, eliminating the energy level barrier and optimizing band alignment. As a result, Mo:BiVO4/NiOx/CPF-TCzB/NiCoBi achieves a much higher photocurrent densities of 3.14 mA cm-2 than that of Mo:BiVO4 (0.42 mA cm-2) at 0.6 V versus RHE. This work provides an specific way to adjust the band structure of BiVO4-based photoanodes and realize efficient hole extraction and storage for PEC water splitting.
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BACKGROUND: Clinically, various diseases cause myocardial ischemia (MI), which further induces severe cardiac injury and leads to high mortality in patients. Ginsenoside Re, one of the major ginsenosides in ginseng, can regulate the level of oxidative stress in the injured myocardium. Thus, it may attenuate MI injury, but the related mechanism has not been comprehensively studied. PURPOSE: This study aimed to investigate the anti-MI effect and comprehensively mechanisms of Ginsenoside Re. STUDY DESIGN/METHODS: Oxygen-glucose deprivation (OGD), oxidative-induced cardiomyocyte injury, and isoproterenol-induced MI mice were used to explore their protective effect of Ginsenoside Re. An integrated approach of network pharmacology, molecular docking, and tandem mass tag proteomics was applied to determine the corresponding common potential targets of Ginsenoside Re against MI, such as target proteins and related pathways. The major anti-MI target proteins and related pathways were validated by immunofluorescence (IF) assay and Western blotting (WB). RESULTS: Ginsenoside Re (1.32-168.93 µM) had low toxicity to normal cardiomyocytes, and increased the survival of oxidative stress-injured (OGD-induced injury or H2O2-induced injury) cardiomyocytes in this concentration range. It regulated the reactive oxygen species (ROS) level in OGD-injured cardiomyocytes; stabilized the nuclear morphology, mitochondrial membrane potential (MMP), and mitochondrial function; and reduced apoptosis. Meanwhile, Ginsenoside Re (5-20 mg/kg) alleviated cardiac injury in MI mice and maintained cardiac function. Through network pharmacology and proteomics, the relevant mechanisms revealed several key pathways of Ginsenoside Re anti-MI, including inhibition of MAPK pathway protein phosphorylation, downregulation of phosphorylated PDPK1, AKT, and STAT3, and upregulation of TGF-ß3, ferroptosis pathway (upregulation of GPX4 and downregulation of phosphorylation level of MDM2) and AMPK pathway (regulating the synthesis of cholesterol in the myocardium by downregulation of HMGCR). The key proteins of these target pathways were validated by IF and/or WB. CONCLUSION: Ginsenoside Re may target MAPK, AKT, ferroptosis pathways and AMPK pathway to prevent and/or treat MI injury and protect cardiomyocytes from oxidative damage.
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Ginsenosídeos , Isquemia Miocárdica , Miócitos Cardíacos , Farmacologia em Rede , Estresse Oxidativo , Proteômica , Espécies Reativas de Oxigênio , Ginsenosídeos/farmacologia , Animais , Camundongos , Miócitos Cardíacos/efeitos dos fármacos , Isquemia Miocárdica/tratamento farmacológico , Estresse Oxidativo/efeitos dos fármacos , Masculino , Espécies Reativas de Oxigênio/metabolismo , Simulação de Acoplamento Molecular , Camundongos Endogâmicos C57BL , Transdução de Sinais/efeitos dos fármacos , Panax/química , Apoptose/efeitos dos fármacosRESUMO
Among various anode materials, SiOx is regarded as the next generation of promising anode due to its advantages of high theoretical capacity with 2680 mA h g-1, low lithium voltage platform, and rich natural resources. However, the pure SiOx-based materials have slow lithium storage kinetics attributed to their low electron/ion conductive properties and the large volume change during lithiation/delithiation, restricting their practical application. Optimizing the SiOx material structures and the fabricating methods to mitigate these fatal defects and adapt to the market demand for energy density is critical. Hence, SiOx material with TiO1-xNx phase modification has been prepared by simple, low-cost, and scalable ball milling and then combined with nitridation. Consequently, based on the TiO1-xNx modified layer, which boosts high ionic/electronic conductivity, chemical stability, and excellent mechanical properties, the SiOx@TON-10 electrode shows highly stable lithium-ion storage performance for lithium-ion half/full batteries due to a stable solid-electrolyte interface layer, fast Li+ transport channel, and alleviative volumetric expansion, further verifying its practical feasibility and universal applicability.
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BACKGROUND: Vascular smooth muscle cells (VSMCs) are commonly used as seed cells in tissue-engineered vascular constructions. However, their variable phenotypes and difficult to control functions pose challenges. This study aimed to overcome these obstacles using a three-dimensional culture system. METHODS: Calf VSMCs were administered tumor necrosis factor-alpha (TNF-α) before culturing in two- and three-dimensional well plates and polyglycolic acid (PGA) scaffolds, respectively. The phenotypic markers of VSMCs were detected by immunofluorescence staining and western blotting, and the proliferation and migration abilities of VSMCs were detected by CCK-8, EDU, cell counting, scratch, and Transwell assays. RESULTS: TNF-α rapidly decreased the contractile phenotypic markers and elevated the synthetic phenotypic markers of VSMCs, as well as markedly increasing the proliferation and migration ability of VSMCs under two- and three-dimensional culture conditions. CONCLUSIONS: TNF-α can rapidly induce a phenotypic shift in VSMCs and change their viability on PGA scaffolds.
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Movimento Celular , Proliferação de Células , Sobrevivência Celular , Músculo Liso Vascular , Miócitos de Músculo Liso , Fenótipo , Alicerces Teciduais , Fator de Necrose Tumoral alfa , Fator de Necrose Tumoral alfa/metabolismo , Fator de Necrose Tumoral alfa/farmacologia , Músculo Liso Vascular/citologia , Músculo Liso Vascular/metabolismo , Animais , Proliferação de Células/efeitos dos fármacos , Movimento Celular/efeitos dos fármacos , Miócitos de Músculo Liso/citologia , Miócitos de Músculo Liso/metabolismo , Miócitos de Músculo Liso/efeitos dos fármacos , Alicerces Teciduais/química , Bovinos , Células Cultivadas , Engenharia Tecidual/métodos , Técnicas de Cultura de Células em Três Dimensões/métodosRESUMO
BACKGROUND: The contractile phenotype of vascular smooth muscle cells (VSMCs) results in good diastolic and contractile capacities, and its altered function is the main pathophysiological basis for diseases such as hypertension. VSMCs exist as a synthetic phenotype in vitro, making it challenging to maintain a contractile phenotype for research. It is widely recognized that the common medium in vitro is significantly less crowded than in the in vivo environment. Additionally, VSMCs have a heightened sense for detecting changes in medium crowding. However, it is unclear whether macromolecular crowding (MMC) helps maintain the VSMCs contractile phenotype. PURPOSE: This study aimed to explore the phenotypic, behavioral and gene expression changes of VSMCs after increasing the crowding degree by adding carrageenan (CR). METHODS: The degree of medium crowding was examined by a dynamic light scattering assay; VSMCs survival and activity were examined by calcein/PI cell activity and toxicity and CCK-8 assays; VSMCs phenotypes and migration were examined by WB and wound healing assays; and gene expression was examined by transcriptomic analysis and RT-qPCR. RESULTS: Notably, 225 µg/mL CR significantly increased the crowding degree of the medium and did not affect cell survival. Simultaneously, CR significantly promoted the contraction phenotypic marker expression in VSMCs, shortened cell length, decreased cell proliferation, and inhibited cell migration. CR significantly altered gene expression in VSMCs. Specifically, 856 genes were upregulated and 1207 genes were downregulated. These alterations primarily affect the cellular ion channel transport, microtubule movement, respiratory metabolism, amino acid transport, and extracellular matrix synthesis. The upregulated genes were primarily involved in the cytoskeleton and contraction processes of VSMCs, whereas the downregulated genes were mainly involved in extracellular matrix synthesis. CONCLUSIONS: The in vitro study showed that VSMCs can maintain the contractile phenotype by sensing changes in the crowding of the culture environment, which can be maintained by adding CR.
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Carragenina , Músculo Liso Vascular , Miócitos de Músculo Liso , Fenótipo , Músculo Liso Vascular/metabolismo , Músculo Liso Vascular/efeitos dos fármacos , Miócitos de Músculo Liso/metabolismo , Miócitos de Músculo Liso/efeitos dos fármacos , Carragenina/farmacologia , Movimento Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Contração Muscular/efeitos dos fármacos , Animais , Humanos , Sobrevivência Celular/efeitos dos fármacosRESUMO
Catalytic conversion of polysulfides emerges as a promising approach to improve the kinetics and mitigate polysulfide shuttling in lithium-sulfur (Li-S) batteries, especially under conditions of high sulfur loading and lean electrolyte. Herein, we present a separator architecture that incorporates double-terminal binding (DTB) sites within a nitrogen-doped carbon framework, consisting of polar Co0.85Se and Co clusters (Co/Co0.85Se@NC), to enhance the durability of Li-S batteries. The uniformly dispersed clusters of polar Co0.85Se and Co offer abundant active sites for lithium polysulfides (LiPSs), enabling efficient LiPS conversion while also serving as anchors through a combination of chemical interactions. Density functional theory calculations, along with in situ Raman and X-ray diffraction characterizations, reveal that the DTB effect strengthens the binding energy to polysulfides and lowers the energy barriers of polysulfide redox reactions. Li-S batteries utilizing the Co/Co0.85Se@NC-modified separator demonstrate exceptional cycling stability (0.042% per cycle over 1000 cycles at 2 C) and rate capability (849 mAh g-1 at 3 C), as well as deliver an impressive areal capacity of 10.0 mAh cm-2 even in challenging conditions with a high sulfur loading (10.7 mg cm-2) and lean electrolyte environments (5.8 µL mg-1). The DTB site strategy offers valuable insights into the development of high-performance Li-S batteries.
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The construction of functional interlayers for separator modification in Li-S batteries has been proven to be a feasible and effective strategy to alleviate the shuttle effect. However, several challenging issues in interlayer design and fabrication, including the tedious material preparation process and high weight loading of the interlayer on the pristine separator, jeopardize the battery energy density. In this work, a nitrogen-abundant nanoporous carbon/graphene (NC/G) composite was synthesized by a facile method and fabricated into a lightweight membrane, which was investigated as a multifunctional interlayer in a Li-S battery. The abundant nitrogen sites and nanoporous structure of NC/G can effectively anchor and trap polysulfides; graphene (G) can create an excellent conductive network in NC/G. These attributes of NC/G are able to efficiently boost the sulfur redox reaction kinetics and significantly suppress the shuttle effect, leading to superb battery performance. More importantly, the low density of NC/G was conducive to reducing the load on the separator, thus reducing the decline in battery energy density, which is promising for practical applications. Even at an ultra-low loading of NC/G on the pristine separator (0.08 mg cm-2), the battery showed a competitive electrochemical performance compared with many reported materials. We believe this work provides a strategic guidance for the future fabrication of promising functional interlayers for practical Li-S battery applications.
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Successful in vitro culture of small-diameter tissue-engineered vascular grafts (TEVGs) requires rapid deposition of biomacromolecules secreted by vascular smooth muscle cells in a polyglycolic acid mesh scaffold's three-dimensional (3D) porous environment. However, common media have lower crowding conditions than in vivo tissue fluids. In addition, during the early stages of construction, most of the biomolecules secreted by the cells into the medium are lost, which negatively affects the TEVG culture process. In this study, we propose the use of macromolecular crowding (MMC) to enhance medium crowding to improve the deposition and self-assembly efficiency of major biomolecules in the early stages of TEVG culture. The addition of carrageenan significantly increased the degree of MMC in the culture medium without affecting cell viability, proliferation, and metabolic activity. Protein analysis demonstrated that the deposition of collagen types I and III and fibronectin increased significantly in the cell layers of two-dimensional and 3D smooth muscle cell cultures after the addition of a MMC agent. Collagen type I in the culture medium decreased significantly compared with that in the medium without a MMC agent. Scanning electron microscopy demonstrated that MMC agents considerably enhanced the formation of matrix protein structures during the early stages of 3D culture. Hence, MMC modifies the crowding degree of the culture medium, resulting in the rapid formation of numerous matrix proteins and fiber structures. Impact Statement Small-diameter tissue-engineered vascular grafts (TEVGs) are one of the most promising means of treating cardiovascular diseases; however, the in vitro construction of TEVGs has some limitations, such as slow deposition of extracellular matrix (ECM), long culture period, and poor mechanical properties. We hypothesized that macromolecular crowding can increase the crowding of the culture medium to construct a more bionic microenvironment, which enhances ECM deposition in the medium to the cell layer and reduces collagen loss, accelerating and enhancing TEVG culture and construction in vitro.
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Prótese Vascular , Miócitos de Músculo Liso , Engenharia Tecidual , Engenharia Tecidual/métodos , Animais , Miócitos de Músculo Liso/metabolismo , Miócitos de Músculo Liso/citologia , Proteínas da Matriz Extracelular/metabolismo , Substâncias Macromoleculares/metabolismo , Alicerces Teciduais/química , Músculo Liso Vascular/citologia , Músculo Liso Vascular/metabolismo , Proliferação de Células/efeitos dos fármacos , HumanosRESUMO
As a crucial component responsible for the oxygen reduction reaction (ORR), cobalt-rich perovskite-type cathode materials have been extensively investigated in protonic ceramic fuel cell (PCFC). However, their widespread application at a commercial scale is considerably hindered by the high cost and inadequate stability. In response to these weaknesses, the study presents a novel cobalt-free perovskite oxide, Ba0.95La0.05(Fe0.8Zn0.2)0.95O3-δ (BLFZ0.95), with the triple-conducting (H+|O2-|e-) property as an active and robust air electrode for PCFC. The B-site deficiency state contributes significantly to the optimization of crystal and electronic structure, as well as the increase in oxygen vacancy concentration, thus in turn favoring the catalytic capacity. As a result, the as-obtained BLFZ0.95 electrode demonstrates exceptional electrochemical performance at 700 °C, representing extremely low area-specific resistance of 0.04 Ω cm2 in humid air (3 vol.% H2O), extraordinarily high peak power density of 1114 mW cm-2, and improved resistance against CO2 poisoning. Furthermore, the outstanding long-term durability is achieved without visible deterioration in both symmetrical and single cell modes. This study presents a simple but crucial case for rational design of cobalt-free perovskite cathode materials with appreciable performance via B-site deficiency regulation.
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Grafted biopolymer binders are demonstrated to improve the processability and cycling stability of the silicon (Si) nanoparticle anodes. However, there is little systematical exploration regarding the relationship between grafting density and performance of grafted binder for Si anodes, especially when Si particles exceed the critical breaking size. Herein, a series of guar gum grafted polyacrylamide (GP) binders with different grafting densities are designed and prepared to determine the optimal grafting density for maximizing the electrochemical performance of Si submicroparticle (SiSMP) anodes. Among various GP binders, GP5 with recommended grafting density demonstrates the strongest adhesion strength, best mechanical properties, and highest intrinsic ionic conductivity. These characteristics enable the SiSMP electrodes to sustain the electrode integrity and accelerate lithium-ion transport kinetics during cycling, resulting in high capacity and stable cyclability. The superior role of GP5 binder in enabling robust structure and stable interface of SiSMP electrodes is revealed through the PeakForce atomic force microscopy and in situ differential electrochemical mass spectrometry. Furthermore, the stable cyclabilities of high-loading SiSMP@GP5 electrode with ultralow GP5 content (1 wt%) at high areal capacity as well as the good cyclability of Ah-level LiNi0.8Co0.1Mn0.1O2/SiSMP@GP5 pouch cell strongly confirms the practical viability of the GP5 binder.
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Background: The preclinical diagnosis of tumors is of great significance to cancer treatment. Near-infrared fluorescence imaging technology is promising for the in-situ detection of tumors with high sensitivity. Methods: Here, a fluorescent probe was synthesized on the basis of Au nanoclusters with near-infrared light emission and applied to fluorescent cancer cell labeling. Near-infrared methionine-N-Hydroxy succinimide Au nanoclusters (Met-NHs-AuNCs) were prepared successfully by one-pot synthesis using Au nanoclusters, methionine, and N-Hydroxy succinimide as frameworks, reductants, and stabilizers, respectively. The specific fluorescence imaging of tumor cells or tissues by fluorescent probe was studied on the basis of SYBYL Surflex-DOCK simulation model of LAT1 active site of overexpressed receptor on cancer cell surface. The results showed that Met-NHs-AuNCs interacted with the surface of LAT1, and C_Score scored the conformation of the probe and LAT1 as five. Results: Characterization and in vitro experiments were conducted to explore the Met-NHs-AuNCs targeted uptake of cancer cells. The prepared near-infrared fluorescent probe (Met-NHs-AuNCs) can specifically recognize the overexpression of L-type amino acid transporter 1 (LAT1) in cancer cells so that it can show red fluorescence in cancer cells. Meanwhile, normal cells (H9c2) have no fluorescence. Conclusion: The fluorescent probe demonstrates the power of targeting and imaging cancer cells.
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Nanopartículas Metálicas , Neoplasias , Humanos , Corantes Fluorescentes , Neoplasias/metabolismo , Imagem Óptica/métodos , Metionina/química , Racemetionina , Succinimidas , Ouro/químicaRESUMO
A water-soluble glycopeptide (named GL-PWQ3) with a molecular weight (Mw) of 2.40 × 104 g/mol was isolated from Ganoderma lucidum fruiting body by hot water extraction, membrane ultrafiltration, and gel column chromatography, which mainly consisted of glucose and galactose. Based on the methylation, FT-IR, 1D, and 2D NMR analysis, the polysaccharide portion of GL-PWQ3 was identified as a glucogalactan, which was comprised of unsubstituted (1,6-α-Galp, 1,6-ß-Glcp, 1,4-ß-Glcp) and monosubstituted (1,2,6-α-Galp and 1,3,6-ß-Glcp) in the backbone and possible branches that at the O-3 position of 1,3-Glcp and T-Glcp, and the O-2 position of T-Fucp, T-Manp or T-Glcp. The chain conformational study by SEC-MALLS-RI and AFM revealed that GL-PWQ3 was identified as a highly branched polysaccharide with a polydispersity index of 1.25, and might have compact sphere structures caused by stacked multiple chains. Moreover, the GL-PWQ3 shows strong anti-oxidative activity in NRK-52E cells. This study provides a theoretical basis for further elucidating the structure-functionality relationships of GL-PWQ3 and its potential application as a natural antioxidant in pharmacotherapy as well as functional food additives.
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Reishi , Reishi/química , Espectroscopia de Infravermelho com Transformada de Fourier , Polissacarídeos/química , Glucose/análise , Peso Molecular , ÁguaRESUMO
The interfacial compatibility between cathodes and sulfide solid-electrolytes (SEs) is a critical limiting factor of electrochemical performance in all-solid-state lithium-ion batteries (ASSLBs). This work presents a gas-solid interface reduction reaction (GSIRR), aiming to mitigate the reactivity of surface oxygen by inducing a surface reconstruction layer (SRL) . The application of a SRL, CoO/Li2 CO3 , onto LiCoO2 (LCO) cathode results in impressive outcomes, including high capacity (149.7 mAh g-1 ), remarkable cyclability (retention of 84.63% over 400 cycles at 0.2 C), outstanding rate capability (86.1 mAh g-1 at 2 C), and exceptional stability in high-loading cathode (28.97 and 23.45 mg cm-2 ) within ASSLBs. Furthermore, the SRL CoO/Li2 CO3 enhances the interfacial stability between LCO and Li10 GeP2 S12 as well as Li3 PS4 SEs. Significantly, the experiments suggest that the GSIRR mechanism can be broadly applied, not only to LCO cathodes but also to LiNi0.8 Co0.1 Mn0.1 O2 cathodes and other reducing gases such as H2 S and CO, indicating its practical universality. This study highlights the significant influence of the surface chemistry of the oxide cathode on interfacial compatibility, and introduces a surface reconstruction strategy based on the GSIRR process as a promising avenue for designing enhanced ASSLBs.
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BACKGROUND: The adhesion and survival state of cells on scaffold material is a major problem in tissue-engineered blood vessel (TEBV) culture. Platelet-rich plasma (PRP) contains a large amount of biologically active factors and fibrin, which is expected to play an important role in TEBV culture. PURPOSE: To combine PRP with cells and scaffold material to promote cell adhesion and biological activity on the scaffold material. METHODS: The adhesion status and migration of SMCs under the optimal concentration suitable for SMC growth and the optimal concentration of PRP were examined by scanning electron microscopy, HE staining, CCK-8 assays, qPCR, WB, and other experimental methods and compared with those under the conventional culture (20% FBS); finally, the effect of PRP on the deposition of ECM in vascular tissue engineering culture was verified by three-dimensional culture. RESULTS: PRP at 20% is a suitable concentration for SMCs. Compared with the control group, the 20% PRP group had better migration, and the number of SMC adhesions was significantly higher than that of the control group. In addition, collagen deposition in the experimental group was significantly higher than that in the control group. CONCLUSION: PRP (20%) can promote SMC adhesion, migration, and collagen deposition on the scaffold material.
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Músculo Liso Vascular , Plasma Rico em Plaquetas , Humanos , Músculo Liso Vascular/metabolismo , Colágeno , Adesão Celular , Stents , Células CultivadasRESUMO
Chiral molecules show differences in their chemical and optical properties due to the different spatial arrangements of the atoms in the two enantiomers. A common way to optically differentiate them is to detect the disparity in the absorption of light by the two enantiomers, i.e. absorption circular dichroism (CD). However, the CD of typical molecules is very small, limiting the sensitivity of chiroptical analysis based on CD. Cavity ring-down spectroscopy (CRDS) is a well-known ultrasensitive absorption spectroscopic method for low-absorbing gas-phase samples because the multiple reflections of light in the cavity greatly increase the absorption path. By inserting a prism into the cavity, the optical mode undergoes total internal reflection (TIR) at the prism surface and the evanescent wave (EW) enables the absorption detection of condensed-phase samples within a very thin layer near the prism surface, called EW-CRDS. Here, we propose an ultrasensitive chiral absorption spectroscopy platform using dielectric metasurface-assisted EW-CRDS. We theoretically show that, upon linearly polarized and oblique incidence, the metasurface exhibits minimum scattering and absorption loss, introduces negligible polarization change, and locally converts the linearly polarized light into near fields with finite optical chirality, enabling CD detection with EW-CRDS that typically works with linearly polarized light. We evaluate the ring-down time in the presence of chiral molecules and determine the sensitivity of the cavity as a function of total absorption from the molecules. The findings open the avenue for the ultrasensitive thin film detection of chiral molecules using CRDS techniques.
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In this work, the impact of metallic and dielectric conducting substrates, gold and indium tin oxide (ITO)-coated glass, on the whispering gallery modes (WGMs) of semiconductor π-conjugated polymer microspheres is investigated. Hyperspectral mapping was performed to obtain the excitation-position-dependent emission spectra of the microspheres. Substrate-dependent quenching of WGMs sensitive to mode polarization was observed and explained. On a glass substrate, both transverse-electric (TE) and transverse-magnetic (TM) WGMs are quenched due to frustrated total internal reflection. On a gold substrate, however, only the TM WGMs are allowed in symmetry to leak into surface plasmons. An atomically flat gold substrate with subwavelength slits was used to experimentally verify the leakage of WGMs into the surface plasmon polaritons (SPPs). This work provides insight into the damping mechanisms of WGMs in microspheres on metallic and dielectric substrates.
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Stable cycling of LiCoO2 (LCO) cathode at high voltage is extremely challenging due to the notable structural instability in deeply delithiated states. Here, using the sol-gel coating method, LCO materials (LMP-LCO) are obtained with bulk Mg-doping and surface LiMgPO4 /Li3 PO4 (LMP/LPO) coating. The experimental results suggest that the simultaneous modification in the bulk and at the surface is demonstrated to be highly effective in improving the high-voltage performance of LCO. LMP-LCO cathodes deliver 149.8 mAh g-1 @4.60 V and 146.1 mAh g-1 @4.65 V after 200 cycles at 1 C. For higher cut-off voltages, 4.70 and 4.80 V, LMP-LCO cathodes still achieve 144.9 mAh g-1 after 150 cycles and 136.8 mAh g-1 after 100 cycles at 1 C, respectively. Bulk Mg-dopants enhance the ionicity of CoO bond by tailoring the band centers of Co 3d and O 2p, promoting stable redox on O2- , and thus enhancing stable cycling at high cut-off voltages. Meanwhile, LMP/LPO surface coating suppresses detrimental surface side reactions while allowing facile Li-ion diffusion. The mechanism of high-voltage cycling stability is investigated by combining experimental characterizations and theoretical calculations. This study proposes a strategy of surface-to-bulk simultaneous modification to achieve superior structural stability at high voltages.
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Boosting oxygen evolution reaction by local surface plasmon resonance (LSPR) provides breakthrough opportunities for the promotion of solar energy conversion; the potential of LSPR, however, has rarely been tapped and investigated. Here, we report the precise regulation of commercial Au nanoparticles plasmonic nanomaterial and OER electrocatalysts, viz., the NiCoOx electrocatalytic layer with hole transport ability and photothermal effect is prepared on the surface of Au nanoparticles by photoelectrodeposition. The NiCoOx layer not only increases the transmission distance of holes generated by plasmonic Au nanoparticles, but also reduce the agglomeration of plasmonic Au nanoparticles during long-time OER reaction, which greatly improves the OER catalytic ability. The current density of NiCoOx /Au anode achieves 16.58â mA cm-2 at 2.0â V versus RHE, which is about 6.5â times of pristine NiCoOx anode (2.56â mA cm-2 ) and 47â times of pristine Au anode (0.35â mA cm-2 ). More importantly, with the LSPR and photothermal effect of plasmonic Au nanoparticles, the NiCoOx /Au anode provides additional current density of 7.01â mA cm-2 after illumination, and maintains no attenuation for more than 2000â s. Benefiting from the solution of agglomeration problem of plasmonic Au nanoparticles in the long-time OER process and the effective utilization of generated holes of plasmonic Au nanoparticles, this design can provide guidance for the application of plasmonic materials in the field of electrocatalysis.