Carbon Nanomaterials With Hollow Structures: A Mini-Review

Carbon nanomaterials with high electrical conductivity, good chemical, and mechanical stability have attracted increasing attentions and shown wide applications in recent years. In particularly, hollow carbon nanomaterials, which possess ultrahigh specific surface area, large surface-to-volume ratios, and controllable pore size distribution, will benefit to provide abundant active sites, and mass loading vacancy, accelerate electron/ion transfer as well as contribute to the specific density of energy storage systems. In this mini-review, we summarize the recent progresses of hollow carbon nanomaterials by focusing on the synthesis approaches and corresponding nanostructures, including template-free and hard-template carbon hollow structures, metal organic framework-based hollow carbon structures, bowl-like and cage-like structures, as well as hollow fibers. The design and synthesis strategies of these hollow carbon nanomaterials have been systematically discussed. Finally, the emerging challenges and future prospective for developing advanced hollow carbon structures were outlined.

(Ni,Co)Se@Ni(OH)2 heterojunction nanosheets as an efficient electrocatalyst for the hydrogen evolution reaction

A heterogeneous structure composed of a selenide and Ni(OH)2 can accelerate electron transfer and enrich active sites.

Advances in the use of Graphene Nanocomposites for the Electrochemical Determination of Glucose: A Review

Background: The glucose detection is of great significance in biomedicine. In clinical medicine, diabetes seriously endangers human health. By accurately measuring the blood glucose content of diabetic patients, diabetes can be effectively monitored and treated. At present, there are many methods for measuring glucose content, such as chromatography, spectroscopy, and electrochemical methods. Among them, electrochemical glucose sensors are widely used because of their high reliability, low cost and easy operation. Methods: Combining graphene with other nanomaterials (including graphene, metal oxides, semiconductor nanoparticles, polymers, dye molecules, ionic liquids and biomolecules) is an effective way to expand or enhance the sensing performance. Results: The composite of graphene and nanomaterials is an effective way to enhance the functionality of the electrochemical sensor. Graphene can accelerate electron transfer and realize direct electrochemistry and biological sensing. At the same time, graphene derivatives with rich composition and structure provide the possibility to further regulate their electrochemical performance.These graphene composite-based biosensors have shown excellent sensitivity and selectivity for glucose detection. Conclusion: Electrochemical glucose sensor based on graphene composite has received extensive attention. Although these materials have made significant progress in improving the sensitivity, lowering the detection limit and broadening the linear range, there are still facing challenges that require further study.

Promoting mechanism of electronic shuttle for bioavailability of Fe(III) oxide and its environmental significance

The biological reduction process of Fe(III) not only strongly affects the circulation of C, N, O, P and other elements in the environment, but also plays an important role in the transformation and degradation of organic and inorganic pollutants. Most Fe(III) oxides existing in nature have low bioavailability due to their poor solubility or strongly crystalline form with stable chemical properties. Addition of a substance having redox activity can form an electron shuttle cycle between Fe(III) oxide and the microorganism, which can not only enhance the bioavailability of Fe(III) and accelerate electron transfer, but also improve the removal efficiency of contaminants. This paper compares and analyzes several common redox active substances, for their promoting effect and limiting factors of Fe(III) bioavailability. Moreover, the mechanism by which the electron shuttle promotes the bioavailability of Fe(III) oxide is discussed. This review demonstrates that the electron shuttle promotes the Fe(III) bioreaction process for the degradation and removal of heavy metals, polycyclic aromatic hydrocarbons, azo dyes and other pollutants, which is of great environmental significance.

Ni3Se4@MoSe2 Composites for Hydrogen Evolution Reaction

Transition metal dichalcogenides (TMDs) have been considered as one of the most promising electrocatalysts for the hydrogen evolution reaction (HER). Many studies have demonstrated the feasibility of significant HER performance improvement of TMDs by constructing composite materials with Ni-based compounds. In this work, we prepared Ni3Se4@MoSe2 composites as electrocatalysts for the HER by growing in situ MoSe2 on the surface of Ni3Se4 nanosheets. Electrochemical measurements revealed that Ni3Se4@MoSe2 nanohybrids are highly active and durable during the HER process, which exhibits a low onset overpotential (145 mV) and Tafel slope (65 mV/dec), resulting in enhanced HER performance compared to pristine MoSe2 nanosheets. The enhanced HER catalytic activity is ascribed to the high surface area of Ni3Se4 nanosheets, which can both efficiently prevent the agglomeration issue of MoSe2 nanosheets and create more catalytic edge sites, hence accelerate electron transfer between MoSe2 and the working electrode in the HER. This approach provides an effective pathway for catalytic enhancement of MoSe2 electrocatalysts and can be applied for other TMD electrocatalysts.

HELL: High-Energy Electrons by Laser Light, a User-Oriented Experimental Platform at ELI Beamlines

Laser wake field acceleration (LWFA) is an efficient method to accelerate electron beams to high energy. This is a benefit in research infrastructures where a multidisciplinary environment can benefit from the different secondary sources enabled, having the opportunity to extend the range of applications that is accessible and to develop new ideas for fundamental studies. The ELI Beamline project is oriented to deliver such beams to the scientific community both for applied and fundamental research. The driver laser is a Ti:Sa diode-pumped system , running at a maximum performance of 10 Hz, 30 J, and 30 fs. The possibilities to setup experiments using different focal lengths parabolas, as well as the possibility to counter-propagate a second laser beam intrinsically synchronized, are considered in the electron acceleration program. Here, we review the laser-driven electron acceleration experimental platform under implementation at ELI Beamlines, the HELL (High-energy Electrons by Laser Light) experimental platform .