Tuning Interface Bridging Between MoSe2 and Three-Dimensional Carbon Framework by Incorporation of MoC Intermediate to Boost Lithium Storage Capability

© 2020, The Author(s). Highlights: MoSe2/MoC/C multiphase boundaries boost ionic transfer kinetics.MoSe2 (5–10 nm) with rich edge sites is uniformly coated in N-doped framework.The obtained MoSe2 nanodots achieved ultralong cycle performance in LIBs and high capacity retention in full cell. Abstract: Interface engineering has been widely explored to improve the electrochemical performances of composite electrodes, which governs the interface charge transfer, electron transportation, and structural stability. Herein, MoC is incorporated into MoSe2/C composite as an intermediate phase to alter the bridging between MoSe2- and nitrogen-doped three-dimensional (3D) carbon framework as MoSe2/MoC/N–C connection, which greatly improve the structural stability, electronic conductivity, and interfacial charge transfer. Moreover, the incorporation of MoC into the composites inhibits the overgrowth of MoSe2 nanosheets on the 3D carbon framework, producing much smaller MoSe2 nanodots. The obtained MoSe2 nanodots with fewer layers, rich edge sites, and heteroatom doping ensure the good kinetics to promote pseudo-capacitance contributions. Employing as anode material for lithium-ion batteries, it shows ultralong cycle life (with 90% capacity retention after 5000 cycles at 2 A g−1) and excellent rate capability. Moreover, the constructed LiFePO4//MoSe2/MoC/N–C full cell exhibits over 86% capacity retention at 2 A g−1 after 300 cycles. The results demonstrate the effectiveness of the interface engineering by incorporation of MoC as interface bridging intermediate to boost the lithium storage capability, which can be extended as a potential general strategy for the interface engineering of composite materials.[Figure not available: see fulltext.

Truxene-Centered Electron Acceptors for Non-Fullerene Solar Cells: Alkyl Chain and Branched Arm Engineering

A series of symmetrical truxene-centered and 3-ethylrhodanine end-capped electron acceptors with high absorption coefficient, namely Tr(Hex)6-3RD, Tr(Dec)6-3RD, and Tr(Hex)6-6RD, were prepared and constructed for non-fullerene solar cells. To satisfy solution-processability, multiple energy levels, and suitable morphology, these three acceptors were comparatively studied through alkyl chain (hexyl/decyl) and branched-arm engineering (three/six branched arms). The six-bladed propeller acceptor of Tr(Hex)6-6RD recorded the power conversion efficiency (PCE) of 1.1% blending with PTB7-Th without additional additives and post-processing. This work highly broadens the potential applications of star-shaped truxene building blocks in the fields of organic electronics

Unraveling the main chain effects of fused thiophene conjugated polymers in electrochromism

The influence of increasing fused thiophene rings for the corresponding conjugated polymers [polythiophene (PT), poly(thieno[3,2-b]thiophene) (PTT) and poly(dithieno[3,2-b:2’,3’-d]thiophene) (PDTT)] on their photophysical and electrochemical properties, morphology and electrochromic performance are investigated in detail in this study. PDTT is the easiest of the three polymers to prepare and has the lowest onset oxidation potential of 1.17 V because of its increased donor ability, lower than those of PTT (1.41 V) and PT (1.82 V). PDTT also exhibits the best electrochemical and thermal stability because of its extended conjugated skeleton. The PT, PTT and PDTT polymers present poor, good and moderate electrochromic properties, respectively, with increasing fused thiophene rings. PTT displays the highest ΔT of 35% in 700 nm, the fastest response time of 1.0 s and the maximum colouration efficiency (CE) of 94 cm2 C-1, which is attributed to its enhanced morphology, since the PTT film is conducive to the promotion of ions to dope and dedope. Flexible electrochromic devices are fabricated and PTT exhibits the highest ΔT (60% in 480 nm and 16% in 660 nm), as well as excellent stability with less than a 5% ΔT reduction after successive cycling of 1000 s. All these findings indicate that the precise regulation of the fused thiophene is crucial in achieving high performance in electrochromism, which provides insight for the design of electrochromic conjugated polymers and flexible electrochromic devices

Characteristics of Sedimentary Organic Matter in Tidal Estuaries: A Case Study from the Minjiang River Estuary

As one of the main interfaces of the Earth system, estuaries show the strongest land–sea interaction in the carbon cycle, which links terrestrial ecosystems to the marginal sea. Furthermore, estuaries are considered as one of the most active intermediate reservoirs for both terrestrial and marine matter due to complex hydrodynamic processes regulated by the river runoff, wave and tide. Processing of organic matter (OM) in tidal estuaries modifies its transfer and transformation from the river to the sea, so studies of on the source and distributions of estuarine OM can help us understand the behavior of production, exchange, transport and burial of diverse OM within this transition zone before entering the marginal sea. In this paper, we took the Minjiang River Estuary (MRE) as a typical system in which there is strong influence of the tide. The source, composition and spatial distribution of OM in surface sediments of MRE were deciphered based on multiple organic geochemical properties for source-specific biomarkers (n-alkanes, n-alkanols, sterols) and bulk OM. Results show that sedimentary organic components were negatively correlated with sediment grain size, which indicates fine particles such as silt and clay are the major carriers of the OM signals in tidal estuaries. Source-specific biomarker proxies indicate that in terms of source diversity the sedimentary OM in the MRE shows mixed signals of terrestrial and marine sources, and the proportion of terrestrial OM decreases with the increase in distance from the land. The fractional contributions of OM from the riverine (i.e., terrestrial), marine and deltaic sources were quantitatively estimated using a Monte Carlo (MC) three-end-member mixing model based on C/N and δ13C values, and the average contributions of the three sources are 40 ± 10%, 48 ± 10% and 12 ± 4%, respectively, with little contribution from deltaic sources. The dispersion of sedimentary OM from different sources in the MRE is primarily controlled by the depositional environment determined by dynamic conditions and tidal processes play a significant role in the redistribution of sedimentary OM dispersion patterns. Compared with other large estuaries in southeast China, the OM accumulation contribution in the tide dominated small and medium-sized estuaries such as the MRE which is largely dependent on riverine and marine deliveries. The MRE has a high potential for both terrestrial and marine organic carbon (OC) burial, with an accumulation rate of 3.39 ± 1.83 mg cm−2 yr−1 for terrestrial OC, and an accumulation rate of 3.18 ± 0.68 mg cm−2 yr−1 for marine OC in muddy sediment, making it an important contributor to the sedimentary carbon sink of the marginal sea

Ultra-High-Energy Density in Layered Sodium-Ion Battery Cathodes through Balancing Lattice-Oxygen Activity and Reversibility

Lattice-oxygen redox in layered metal oxide cathodes offers a promising way to exploit high-energy density sodium-ion batteries. However, oxidation and reduction of lattice-oxygen are always asymmetric, showing poor reversibility upon charging and discharging due to the activated oxygen loss and subsequent structural rearrangement. Here, a layered Na0.7[Li0.2Mn0.7Co0.1]O2 (NLMCO) is developed by balancing lattice-oxygen activity and reversibility, which can deliver a record energy density of 729.7 Wh kg−1, further exceeding the state-of-the-art Na0.75[Li0.25Mn0.75]O2 (NLMO, 638.4 Wh kg−1). In light of electron paramagnetic resonance spectroscopy, in situ differential electrochemical mass spectroscopy, and electrochemical testing results, the highly activated lattice-oxygen is effectively stabilized in NLMCO without oxygen molecule release while obvious oxygen release is detected in the highly activated NLMO. Benefiting from the enhanced transition metal-oxygen covalency and reduced band energy gap, the NLMCO electrode demonstrates simultaneously high lattice-oxygen activity and reversibility, thus resulting in excellent rate and cycling performance, as well as ultra-high energy density. The findings highlight the critical association of energy density and lattice-oxygen redox reversibility, which will inspire more interest in anionic redox-based high-energy batteries

Achieving a Deeply Desodiated Stabilized Cathode Material by the High Entropy Strategy for Sodium-ion Batteries

Manganese-based layered oxides are currently of significant interest as cathode materials for sodium-ion batteries due to their low toxicity and high specific capacity. However, the practical applications are impeded by sluggish intrinsic Na+ migration and poor structure stability as a result of Jahn–Teller distortion and complicated phase transition. In this study, a high-entropy strategy is proposed to enhance the high-voltage capacity and cycling stability. The designed P2-Na0.67Mn0.6Cu0.08Ni0.09Fe0.18Ti0.05O2 achieves a deeply desodiation and delivers charging capacity of 158.1 mAh g−1 corresponding to 0.61 Na with a high initial Coulombic efficiency of 98.2 %. The charge compensation is attributed to the cationic and anionic redox reactions conjunctively. Moreover, the crystal structure is effectively stabilized, leading to a slight variation of lattice parameters. This research carries implications for the expedited development of low-cost, high-energy-density cathode materials for sodium-ion batteries

Alzheimer's disease pathophysiology in the retina

The retina is an emerging CNS target for potential noninvasive diagnosis and tracking of Alzheimer's disease (AD). Studies have identified the pathological hallmarks of AD, including amyloid β-protein (Aβ) deposits and abnormal tau protein isoforms, in the retinas of AD patients and animal models. Moreover, structural and functional vascular abnormalities such as reduced blood flow, vascular Aβ deposition, and blood-retinal barrier damage, along with inflammation and neurodegeneration, have been described in retinas of patients with mild cognitive impairment and AD dementia. Histological, biochemical, and clinical studies have demonstrated that the nature and severity of AD pathologies in the retina and brain correspond. Proteomics analysis revealed a similar pattern of dysregulated proteins and biological pathways in the retina and brain of AD patients, with enhanced inflammatory and neurodegenerative processes, impaired oxidative-phosphorylation, and mitochondrial dysfunction. Notably, investigational imaging technologies can now detect AD-specific amyloid deposits, as well as vasculopathy and neurodegeneration in the retina of living AD patients, suggesting alterations at different disease stages and links to brain pathology. Current and exploratory ophthalmic imaging modalities, such as optical coherence tomography (OCT), OCT-angiography, confocal scanning laser ophthalmoscopy, and hyperspectral imaging, may offer promise in the clinical assessment of AD. However, further research is needed to deepen our understanding of AD's impact on the retina and its progression. To advance this field, future studies require replication in larger and diverse cohorts with confirmed AD biomarkers and standardized retinal imaging techniques. This will validate potential retinal biomarkers for AD, aiding in early screening and monitoring.</p