Utilizing Cationic Vacancies and Spontaneous Polarization on Cathode to Enhance Zinc-Ion Storage and Inhibit Dendrite Growth in Zinc-Ion Batteries.

High energy density and intrinsic safety are the central pursuits in developing rechargeable Zinc-ion batteries (ZIBs). The capacity and stability of nickel cobalt oxide (NCO) cathode are unsatisfactory because of its semiconductor character. Herein, we propose a built-in electric field (BEF) approach by synergizing cationic vacancies and ferroelectric spontaneous polarization on cathode side to facilitate electron adsorption and suppress zinc dendrite growth on the anode side. Concretely, NCO with cationic vacancies was constructed to expand lattice spacing for enhanced zinc-ion storage. Heterojunction with BEF leads to the Heterojunction//Zn cell exhibiting a capacity of 170.3 mAh g-1 at 400 mA g-1 and delivering a competitive capacity retention of 83.3 % over 3000 cycles at 2 A g-1 . We conclude the role of spontaneous polarization in suppressing zinc dendrite growth dynamics, which is conducive to developing high-capacity and high-safety batteries via tailoring defective materials with ferroelectric polarization on the cathode.

Morphology and Structure Engineering in Nanofiber Reactor: Tubular Hierarchical Integrated Networks Composed of Dual Phase Octahedral CoMn2 O4 /Carbon Nanofibers for Water Oxidation.

1D hollow nanostructures combine the advantages of enhanced surface-to-volume ratio, short transport lengths, and efficient 1D electron transport, which can provide more design ideas for the preparation of highly active oxygen evolution (OER) electrocatalysts. A unique architecture of dual-phase octahedral CoMn2 O4 /carbon hollow nanofibers has been prepared via a two-step heat-treatment process including preoxidation treatment and Ostwald ripening process. The hollow and porous structures provide interior void spaces, large exposed surfaces, and high contact areas between the nanofibers and electrolyte and the morphology can be engineered by adjusting the heating conditions. Due to the intimate electrical and chemical coupling between the oxide nanocrystals and integrated carbon, the dual-phase octahedral CoMn2 O4 /carbon hollow nanofibers exhibit excellent OER activity with overpotentials of 337 mV at current density of 10 mA cm-2 and Tafel slope of 82 mV dec-1 . This approach will lead to the new perception of design issue for the nanoarchitecture with fine morphology, structures, and excellent electrocatalytic activity.

Eight In. Wafer-Scale Epitaxial Monolayer MoS2.

Large-scale, high-quality, and uniform monolayer molybdenum disulfide (MoS2) films are crucial for their applications in next-generation electronics and optoelectronics. Epitaxy is a mainstream technique for achieving high-quality MoS2 films and is demonstrated at a wafer scale up to 4-in. In this study, the epitaxial growth of 8-in. wafer-scale highly oriented monolayer MoS2 on sapphire is reported as with excellent spatial homogeneity, using a specially designed vertical chemical vapor deposition (VCVD) system. Field effect transistors (FETs) based on the as-grown 8-in. wafer-scale monolayer MoS2 film are fabricated and exhibit high performances, with an average mobility and an on/off ratio of 53.5 cm2 V-1 s-1 and 107, respectively. In addition, batch fabrication of logic devices and 11-stage ring oscillators are also demonstrated, showcasing excellent electrical functions. This work may pave the way of MoS2 in practical industry-scale applications.

Effects of Morning Blue-Green 500 nm Light Therapy on Cognition and Biomarkers in Middle-Aged and Older Adults with Subjective Cognitive Decline and Mild Cognitive Impairment: Study Protocol for a Randomized Controlled Trial.

BACKGROUND: Given that there is no specific drug to treat Alzheimer's disease, non-pharmacologic interventions in people with subjective cognitive decline (SCD) and amnestic mild cognitive impairment (aMCI) are one of the most important treatment strategies. OBJECTIVE: To clarify the efficacy of blue-green (500 nm) light therapy on sleep, mood, and physiological parameters in patients with SCD and aMCI is an interesting avenue to explore. METHODS: This is a monocentric, randomized, and controlled trial that will last for 4 weeks. We will recruit 150 individuals aged 45 years or older from memory clinics and divide them into 5 groups: SCD treatment (n = 30), SCD control (n = 30), aMCI treatment (n = 30), aMCI control (n = 30), and a group of healthy adult subjects (n = 30) as a normal control (NC). RESULTS: The primary outcome is the change in subjective and objective cognitive performance between baseline and postintervention visits (4 weeks after baseline). Secondary outcomes include changes in performance assessing from baseline, postintervention to follow-up (3 months after the intervention), as well as sleep, mood, and physiological parameters (including blood, urine, electrophysiology, and neuroimaging biomarkers). CONCLUSION: This study aims to provide evidence of the impact of light therapy on subjective and objective cognitive performance in middle-aged and older adults with SCD or aMCI. In addition, we will identify possible neurophysiological mechanisms of action underlying light therapy. Overall, this trial will contribute to the establishment of light therapy in the prevention of Alzheimer's disease.

In situ interfacial engineering of nickel tungsten carbide Janus structures for highly efficient overall water splitting.

Regulating chemical bonds to balance the adsorption and disassociation of water molecules on catalyst surfaces is crucial for overall water splitting in alkaline solution. Here we report a facile strategy for designing Ni2W4C-W3C Janus structures with abundant Ni-W metallic bonds on surfaces through interfacial engineering. Inserting Ni atoms into the W3C crystals in reaction progress generates a new Ni2W4C phase, making the inert W atoms in W3C be active sites in Ni2W4C for overall water splitting. The Ni2W4C-W3C/carbon nanofibers (Ni2W4C-W3C/CNFs) require overpotentials of 63 mV to reach 10 mA cm-2 for hydrogen evolution reaction (HER) and 270 mV to reach 30 mA cm-2 for oxygen evolution reaction (OER) in alkaline electrolyte, respectively. When utilized as both cathode and anode in alkaline solution for overall water splitting, cell voltages of 1.55 and 1.87 V are needed to reach 10 and 100 mA cm-2, respectively. Density functional theory (DFT) results indicate that the strong interactions between Ni and W increase the local electronic states of W atoms. The Ni2W4C provides active sites for cleaving H-OH bonds, and the W3C facilitates the combination of Hads intermediates into H2 molecules. The in situ electrochemical-Raman results demonstrate that the strong absorption ability for hydroxyl and water molecules and further demonstrate that W atoms are the real active sites.

Photocatalysis-Assisted Co3O4/g-C3N4 p-n Junction All-Solid-State Supercapacitors: A Bridge between Energy Storage and Photocatalysis.

Supercapacitors with the advantages of high power density and fast discharging rate have full applications in energy storage. However, the low energy density restricts their development. Conventional methods for improving energy density are mainly confined to doping atoms and hybridizing with other active materials. Herein, a Co3O4/g-C3N4 p-n junction with excellent capacity is developed and its application in an all-solid-state flexible device is demonstrated, whose capacity and energy density are considerably enhanced by simulated solar light irradiation. Under photoirradiation, the capacity is increased by 70.6% at the maximum current density of 26.6 mA cm-2 and a power density of 16.0 kW kg-1. The energy density is enhanced from 7.5 to 12.9 Wh kg-1 with photoirradiation. The maximum energy density reaches 16.4 Wh kg-1 at a power density of 6.4 kW kg-1. It is uncovered that the lattice distortion of Co3O4, reduces defects of g-C3N4, and the facilitated photo-generated charge separation by the Co3O4/g-C3N4 p-n junction all make contributions to the promoted electrochemical storage performance. This work may provide a new strategy to enhance the energy density of supercapacitors and expand the application range of photocatalytic materials.

Understanding the Role of Nanoscale Heterointerfaces in Core/Shell Structures for Water Splitting: Covalent Bonding Interaction Boosts the Activity of Binary Transition-Metal Sulfides.

The appropriate catalyst model with a precisely designed interface is highly desirable for revealing the real active site at the atomic level. Herein, we report a proof-of-concept strategy for creating an exposed and embedding interface model by constructing a unique Co9S8 core with a full WS2 shell (Co9S8/FWS2) and a half WS2 shell (Co9S8/HWS2) to uncover the synergistic effect of heterointerfaces on the catalytic performances. Tailoring the heteroepitaxial growth of WS2 shell, Co9S8/HWS2 with exposed Co-S-W interfaces leads to the exceptional electron density changes on edged-S atoms with large amounts of lone-pair electrons. Meanwhile, the unique Co9S8/HWS2 could accelerate the kinetic adsorption of hydrogen- and oxygen-containing intermediates. Such Co9S8/HWS2 electrocatalysts show extremely low overpotentials of 78 and 290 mV at a current density of 10 mA cm-2 for hydrogen evolution reaction (HER) and oxygen evolution reaction, respectively. Using Co9S8/HWS2 as both the cathode and anode, an alkali electrolyzer delivers a current density of 10 mA cm-2 at a quite low cell voltage of 1.60 V. The results of both operando Raman spectroscopy and electron spin resonance indicate the presence of S-S terminal and S-S bridging with unsaturated S atoms during the HER process. The present work reveals the synergistic effects of nanoscale interfaces on overall electrocatalytic water splitting.

Low-Electronegativity Vanadium Substitution in Cobalt Carbide Induced Enhanced Electron Transfer for Efficient Overall Water Splitting.

Developing highly efficient electrocatalysts while revealing the active site and reaction mechanism is essential for electrocatalytic water splitting. To overcome the number and location limitations of defects in the electrocatalyst induced by conventional transition-metal atom (e.g. Fe, Co, and Ni) surface doping, we report a facile strategy of substitution with lower electronegative vanadium in the cobalt carbide, leading to larger amounts of defects in the whole lattice. The self-supported and quantitatively substituted VxCo3-xC (0 ≤ x ≤ 0.80) was one-step synthesized in the electrospun carbon nanofibers (CNFs) through the solid-state reaction. Particularly, the V0.28Co2.72C/CNFs exhibit superior hydrogen evolution reaction and oxygen evolution reaction activity and deliver a current density of 10 mA cm-2 at 1.47 V as the alkaline electrolyzer, which is lower than the values for the Pt/C-Ir/C couple (1.60 V). The operando Raman spectra and density functional theory calculations show that the enhanced electron transfer from V to the orbit of the Co atom makes Co a local negative charge center and leads to a significant increase in efficiency for overall water splitting.