Transition‐metal oxides as faradaic charge‐storage intermediates sandwiched between conductor and electrolyte are key components to store/deliver high‐density energy in microsupercapacitors for many applications in miniaturized portable electronics and microelectromechanical systems. While the conductor facilitating their electron transports, they generally suffer from a switch of rate‐determining step to their sluggish redox reactions in pseudocapacitive energy storage, during which poor cation accessibility and diffusion leads to high internal resistances and lowers volumetric capacitance and rate performance. Here it is shown that the faradaic processes in a model system of MnO2 can be radically boosted by tuning crystallographic structures from cryptomelane (α‐MnO2) to birnessite (δ‐MnO2). As a result of greatly enhanced Na+ accessibility and diffusion, 3D layered crystalline δ‐MnO2 microelectrodes exhibit volumetric capacitance as high as ≈922 F cm−3 (≈1.5‐fold higher than α‐MnO2, ≈617 F cm−3) and excellent rate performance. This enlists δ‐MnO2 microsupercapacitor to deliver ultrahigh stack electrical powers (up to ≈295 W cm−3) while maintaining volumetric energy density much higher than that of thin‐film lithium battery.

Transition-metal oxides show genuine potential in replacing state-of-the-art carbonaceous anode materials in lithium-or sodium-ion batteries because of their much higher theoretical capacity. However, they usually undergo massive volume change, which leads to numerous problems in both material and electrode levels, such as material pulverization, instable solid-electrolyte interphase, and electrode failure. Here, it is demonstrated that lithium-ion breathable hybrid electrodes with 3D architecture tackle all these problems, using a typical conversion-type transition-metal oxide, Fe 3 O 4 , of which nanoparticles are anchored onto 3D current collectors of Ni nanotube arrays (NTAs) and encapsulated by δ-MnO 2 layers (Ni/Fe 3 O 4 @MnO 2 ). The δ-MnO 2 layers reversibly switch lithium insertion/extraction of internal Fe 3 O 4 nanoparticles and protect them against pulverizing and detaching from NTA current collectors, securing exceptional integrity retention and efficient ion/electron transport. The Ni/Fe 3 O 4 @ MnO 2 electrodes exhibit superior cyclability and high-capacity lithium storage (retaining ≈1450 mAh g −1 , ≈96% of initial value at 1 C rate after 1000 cycles).

Picric acid (PA) is a severe environmental and security risk due to its unstable, toxic, and explosive properties. It is also challenging to detect in trace amounts and in situ because of its highly acidic and anionic character. Here, we assess sensing of PA under nonlaboratory conditions using surface-enhanced Raman scattering (SERS) silver nanopillar substrates and hand-held Raman spectroscopy equipment. The advancing elasto-capillarity effects are explained by molecular dynamics simulations. We obtain a SERS PA detection limit on the order of 20 ppt, corresponding attomole amounts, which together with the simple analysis methodology demonstrates that the presented approach is highly competitive for ultrasensitive analysis in the field.

Nanoarchitectured electroactive materials can boost rates of Li insertion/extraction, showing genuine potential to increase power output of Li-ion batteries. However, electrodes assembled with low-dimensional nanostructured transition metal oxides by conventional approach suffer from dramatic reductions in energy capacities owing to sluggish ion and electron transport kinetics. Here we report that flexible bulk electrodes, made of three-dimensional bicontinuous nanoporous Cu/MnO2 hybrid and seamlessly integrated with Cu solid current collector, substantially optimizes Li storage behavior of the constituent MnO2. As a result of the unique integration of solid/nanoporous hybrid architecture that simultaneously enhances the electron transport of MnO2, facilitates fast ion diffusion and accommodates large volume changes on Li insertion/extraction of MnO2, the supported MnO2 exhibits a stable capacity of as high as ~1100 mA h g−1 for 1000 cycles, and ultrahigh charge/discharge rates. It makes the environmentally friendly and low-cost electrode as a promising anode for high-performance Li-ion battery applications.

Breviscapine is a flavonoid extracted from Erigeron breviscapus. Hand.-Mazz, and it has been reported that breviscapine can activate K+ channels and block Ca2+ channels. In this paper, we studied the cardioprotective effects of breviscapine on electrocardiogram (ECG) changes (ST-segment elevation), infarction size in dog heart subjected to myocardial infarction caused by left coronary artery ligation and lactate dehydrogenase (LDH) leakage, changes of intracellular free Ca2+ levels, apoptosis and necrosis in cultured neonatal rat cardiomyocytes subjected to hypoxia. Additionally, the effect of breviscapine on myocardial oxygen consumption was detected in dog myocardium in vitro. The results showed that breviscapine treatment (1 mg/kg, 2 mg/kg and 4 mg/kg) significantly reduced ST-segment elevation and infarction size in hearts subjected to myocardial infarction, that breviscapine treatment (14.29 microg/mL, 28.57 microg/mL and 57.14 microg/mL) significantly decreased oxygen consumption in myocardium, and that breviscapine treatment (5 microg/mL, 10 microg/mL and 20 microg/mL) significantly reduced LDH leakage, intracellular free Ca2+ levels, apoptosis and necrosis in cardiomyocytes subjected to hypoxia. In conclusion, the present study indicates that breviscapine is in favor of myocardial protection.

Aqueous rechargeable microbatteries are promising on-chip micropower sources for a wide variety of miniaturized electronics. However, their development is plagued by state-of-the-art electrode materials due to low capacity and poor rate capability. Here we show that layered potassium vanadium oxides, KxV2O5·nH2O, have an amorphous/crystalline dual-phase nanostructure to show genuine potential as high-performance anode materials of aqueous rechargeable potassium-ion microbatteries. The dual-phase nanostructured KxV2O5·nH2O keeps large interlayer spacing while removing secondary-bound interlayer water to create sufficient channels and accommodation sites for hydrated potassium cations. This unique nanostructure facilitates accessibility/transport of guest hydrated potassium cations to significantly improve practical capacity and rate performance of the constituent KxV2O5·nH2O. The potassium-ion microbatteries with KxV2O5·nH2O anode and KxMnO2·nH2O cathode constructed on interdigital-patterned nanoporous metal current microcollectors exhibit ultrahigh energy density of 103 mWh cm−3 at electrical power comparable to carbon-based microsupercapacitors.

Nanostructured transition‐metal oxides can store high‐density energy in fast surface redox reactions, but their poor conductivity causes remarkable reductions in the energy storage of most pseudocapacitors at high power delivery (fast charge/discharge rates). Here it is shown that electron‐correlated oxide hybrid electrodes made of nanocrystalline vanadium sesquioxide and manganese dioxide with 3D and bicontinuous nanoporous architecture (NP V2O3/MnO2) have enhanced conductivity because of metallization of electron‐correlated V2O3 skeleton via insulator‐to‐metal transition. The conductive V2O3 skeleton at ambient temperature enables fast electron and ion transports in the entire electrode and facilitates charge transfer at abundant V2O3/MnO2 interface. These merits significantly improve the pseudocapacitive behavior and rate capability of the constituent MnO2. Symmetric pseudocapacitors assembled with binder‐free NP V2O3/MnO2 electrodes deliver ultrahigh electrical powers (up to ≈422 W cm23) while maintaining the high volumetric energy of thin‐film lithium battery with excellent stability.

No abstract