Owing to the unique electronic properties, rare‐earth modulations in noble‐metal electrocatalysts emerge as a critical strategy for a broad range of renewable energy solutions such as water‐splitting ...and metal–air batteries. Beyond the typical doping strategy that suffers from synthesis difficulties and concentration limitations, the innovative introduction of rare‐earth is highly desired. Herein, a novel synthesis strategy is presented by introducing CeO2 support for the nickel–iron–chromium hydroxide (NFC) to boost the oxygen evolution reaction (OER) performance, which achieves an ultralow overpotential at 10 mA cm−2 of 230.8 mV, the Tafel slope of 32.7 mV dec−1, as well as the excellent durability in alkaline solution. Density functional theory calculations prove the established d–f electronic ladders, by the interaction between NFC and CeO2, evidently boosts the high‐speed electron transfer. Meanwhile, the stable valence state in CeO2 preserves the high electronic reactivity for OER. This work demonstrates a promising approach in fabricating a nonprecious OER electrocatalyst with the facilitation of rare‐earth oxides to reach both excellent activity and high stability.
A novel and highly efficient hybrid electrocatalyst is synthesized by NiFeCr hydroxide deposited on a porous peapod‐like Cu@CeO2 nanotube array. The introduction of CeO2 supplies abundant d–f orbital ladders to construct a highly efficient electron transfer expressway, leading to superior alkaline oxygen evolution reaction performance.
Structural engineering and compositional controlling are extensively applied in rationally designing and fabricating advanced freestanding electrocatalysts. The key relationship between the spatial ...distribution of components and enhanced electrocatalysis performance still needs further elaborate elucidation. Here, CeO2 substrate supported CoS1.97 (CeO2‐CoS1.97) and CoS1.97 with CeO2 surface decorated (CoS1.97‐CeO2) materials are constructed to comprehensively investigate the origin of spatial architectures for the oxygen evolution reaction (OER). CeO2‐CoS1.97 exhibits a low overpotential of 264 mV at 10 mA cm−2 due to the stable heterostructure and faster mass transfer. Meanwhile, CoS1.97‐CeO2 has a smaller Tafel slope of 49 mV dec−1 through enhanced adsorption of OH−, fast electron transfer, and in situ formation of Co(IV)O2 species under the OER condition. Furthermore, operando spectroscopic characterizations combined with theoretical calculations demonstrate that spatial architectures play a distinguished role in modulating the electronic structure and promoting the reconstruction from sulfide to oxyhydroxide toward higher chemical valence. The findings highlight spatial architectures and surface reconstruction in designing advanced electrocatalytic materials.
Two novel CeO2/CoS1.97 heterostructure electrocatalysts (CeO2‐CoS1.97 and CoS1.97‐CeO2) are constructed to investigate the relationships between spatial architectures and oxygen evolution reaction (OER) performances, where different configuration endows hybrids with distinct intermediate adsorption, modulated electronic structures, and promoted electrochemical reconstruction, thus improving the OER kinetics and performances. This work sheds light on the importance of rational design and synthesis of advanced hybrid electrocatalysts with functional spatial architectures.
Atomic‐thick interfacial dominated bifunctional catalyst NiO/CoO transition interfacial nanowires (TINWs) with abundant defect sites display high electroactivity and durability in the oxygen ...evolution reaction (OER) and the oxygen reduction reaction (ORR). Density functional theory (DFT) calculations show that the excellent OER/ORR performance arises from the electron‐rich interfacial region coupled with defect sites, thus enabling a fast‐redox rate with lower activation barrier for fast electron transfer. When assembled as an air‐electrode, NiO/CoO TINWs delivered the high specific capacity of 842.58 mAh gZn−1, the large energy density of 996.44 Wh kgZn−1 with long‐time stability of more than 33 h (25 °C), and superior performance at low (−10 °C) and high temperature (80 °C).
An oxygen removing and re‐doping process applied to NiCo2O4 nanowires (NW) gives so‐called NiO/CoO transition interfacial nanowires (TINWs) with an abundance of interfacial defects. The atomic‐thick interface makes NiO/CoO TINWs highly efficient and stable bifunctional oxygen evolution/oxygen reduction reaction (OER/ORR) catalysts, and gives a wide working temperature range (−10 to 80 °C) for portable Zn–air batteries.
Rare earth (RE) materials, which are excited in the ultraviolet and emit in the visible light spectrum, are widely used as phosphors for lamps and displays. In the 1960’s, researchers reported an ...abnormal emission phenomenon where photons emitted from a RE element carried more energy than those absorbed, owing to the sequential energy transfer between two RE ionsYb3+-sensitized Er3+ or Tm3+in the solid state. After further study, researchers named this abnormal emission phenomenon upconversion (UC) emission. More recent approaches take advantage of solution-based synthesis, which allows creation of homogenous RE nanoparticles (NPs) with controlled size and structure that are capable of UC emission. Such nanoparticles are useful for many applications, especially in biology. For these applications, researchers seek small NPs with high upconversion emission intensity. These UCNPs have the potential to have multicolor and tunable emissions via various activators. A vast potential for future development remains by developing molecular antennas and energy transfer within RE ions. We expect UCNPs with optimized spectra behavior to meet the increasing demand of potential applications in bioimaging, biological detection, and light conversion. This Account focuses on efforts to control the size and modulate the spectra of UCNPs. We first review efforts in size control. One method is careful control of the synthesis conditions to manipulate particle nucleation and growth, but more recently researchers have learned that the doping conditions can affect the size of UCNPs. In addition, constructing homogeneous core/shell structures can control nanoparticle size by adjusting the shell thickness. After reviewing size control, we consider how diverse applications impose different requirements on excitation and/or emission photons and review recent developments on tuning of UC spectral profiles, especially the extension of excitation/emission wavelengths and the adjustment and purification of emission colors. We describe strategies that employ various dopants and others that build rationally designed nanostructures and nanocomposites to meet these goals. As the understanding of the energy transfer in the UC process has improved, core/shell structures have been proved useful for simultaneous tuning of excitation and emission wavelengths. Finally, we present a number of typical examples to highlight the upconverted emission in various applications, including imaging, detection, and sensing. We believe that with deeper understanding of emission phenomena and the ability to tune spectral profiles, UCNPs could play an important role in light conversion studies and applications.
Background and Purpose
Oxidative stress and neuronal apoptosis play key roles in traumatic brain injury. We investigated the protective effects of astaxanthin against traumatic brain injury and its ...underlying mechanisms of action.
Experimental Approach
A weight‐drop model of traumatic brain injury in vivo and hydrogen peroxide exposure in vitro model were established. Brain oedema, behaviour tests, western blot, biochemical analysis, lesion volume, histopathological study and cell viability were performed.
Key Results
Astaxanthin significantly reduced oxidative insults on Days 1, 3 and 7 after traumatic brain injury. Neuronal apoptosis was also ameliorated on Day 3. Additionally, astaxanthin improved neurological functions up to 3 weeks after traumatic brain injury. Astaxanthin treatment dramatically enhanced the expression of peroxiredoxin 2 (Prx2), nuclear factor‐erythroid 2‐related factor 2 (NRF2/Nrf2) and sirtuin 1 (SIRT1), while it down‐regulated the phosphorylation of apoptosis signal‐regulating kinase 1 (ASK1) and p38. Inhibition of Prx2 by siRNA injection reversed the beneficial effects of astaxanthin against traumatic brain injury. Additionally, Nrf2 knockout prevented the neuroprotective effects of astaxanthin in traumatic brain injury. In contrast, overexpression of Prx2 in Nrf2 knockout mice attenuated the secondary brain injury after traumatic brain injury. Moreover, inhibiting SIRT1 by EX527 dramatically inhibited the neuroprotective effects of astaxanthin and suppressed SIRT1/Nrf2/Prx2/ASK1/p38 pathway both in vivo and in vitro.
Conclusion and Implications
Astaxanthin improved the neurological functions and protected the brain from injury after traumatic brain injury, primarily by reducing oxidative stress and neuronal death via SIRT1/Nrf2/Prx2/ASK1/p38 signalling pathway and might be a new candidate to ameliorate traumatic brain injury.
Anti‐counterfeiting techniques have become a global topic since they is correlated to the information and data safety, in which multimodal luminescence is one of the most desirable candidates for ...practical applications. However, it is a long‐standing challenge to actualize robust multimodal luminescence with high thermal stability and humid resistance. Conventionally, the multimodal luminescence is usually achieved by the combination of upconversion and downshifting luminescence, which only responds to the electromagnetic waves in a limited range. Herein, the Yb3+/Er3+/Bi3+ co‐doped Cs2Ag0.6Na0.4InCl6 perovskite material is reported as an efficient multimodal luminescence material. Beyond the excitation of ultraviolet light and near‐infrared laser (980 nm), this work extends multimodal luminescence to the excitation of X‐ray. Besides the flexible excitation sources, this material also shows the exceptional luminescence performance, in which the X‐ray detection limit reaches the level of nGy s−1, indicating a great potential for further application as a colorless pigment in the anti‐counterfeiting field. More importantly, the obtained double perovskite features high stability against both humidity and temperature up to 400 °C. This integrated multifunctional luminescent material provides a new directional solution for the development of multifunctional optical materials and devices.
A Yb3+/Er3+/Bi3+ co‐doped Cs2Ag0.6Na0.4InCl6 double‐perovskite material shows multi‐modal luminescence under excitation by X‐rays, ultraviolet light, and near‐infrared laser light (980 nm), which also features high stability against humidity and high temperature (up to 400 °C). This luminescent material further extends the functionality and potential for future commercial applications in anti‐counterfeiting and X‐ray detection.
Potassium-ion batteries (KIBs) are considered important substitutes for lithium-ion batteries (LIBs) owing to the abundance of K resources. Herein, a novel three-dimensional macroporous ...antimony@carbon composite (Sb@C-3DP) is fabricated by a simple KCl template method with a single bi-functional precursor potassium antimony tartrate. The Sb@C-3DP electrode delivers an excellent rate capability (286 mA h g −1 at 1 A g −1 ) and remarkable reversible capacity (516 mA h g −1 at a low current density of 0.05 A g −1 ). Moreover, an outstanding long-term cycling stability (97% capacity retention after 260 cycles) is also achieved, which is benefited from the unique microstructure that can accommodate the huge volumetric change of Sb during depotassiation and potassiation processes. A full cell constructed by coupling Sb@C-3DP with a Prussian blue cathode exhibits a high energy density (197.6 W h kg −1 ) and power density (2067.9 W kg −1 ).
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