Long Ren

3D hierarchical porous graphene aerogel with tunable meso-pores on graphene nanosheets for high-performance energy storage.

New and novel 3D hierarchical porous graphene aerogels (HPGA) with uniform and tunable meso-pores (e.g., 21 and 53u2009nm) on graphene nanosheets (GNS) were prepared by a hydrothermal self-assembly process and an in-situ carbothermal reaction. The size and distribution of the meso-pores on the individual GNS were uniform and could be tuned by controlling the sizes of the Co3O4 NPs used in the hydrothermal reaction. This unique architecture of HPGA prevents the stacking of GNS and promises more electrochemically active sites that enhance the electrochemical storage level significantly. HPGA, as a lithium-ion battery anode, exhibited superior electrochemical performance, including a high reversible specific capacity of 1100u2009mAh/g at a current density of 0.1u2009A/g, outstanding cycling stability and excellent rate performance. Even at a large current density of 20u2009A/g, the reversible capacity was retained at 300u2009mAh/g, which is larger than that of most porous carbon-based anodes reported, suggesting it to be a promising candidate for energy storage. The proposed 3D HPGA is expected to provide an important platform that can promote the development of 3D topological porous systems in a range of energy storage and generation fields.

3D binder-free MoSe2 nanosheets/carbon cloth electrodes for efficient and stable hydrogen evolution prepared by simple electrophoresis deposition strategy

We successfully developed a simple electrophoretic deposition (EPD) method to decorate the MoSe2 nanosheets on the carbon fiber surface of carbon cloth (MoSe2/CC). With this process, MoSe2 nanosheets can be uniformly and tightly deposited on this flexible conductor to form a 3D binder-free electrode for hydrogen evolution reaction (HER). The film thickness can also be controlled by the EPD time. Directly used as binder-free electrodes for hydrogen evolution reaction, the as-prepared 3D MoSe2/CC samples exhibit excellent catalytic activity in an acidic electrolyte (21u2009mA/cm2 at an over-potential of 250u2009mV). Variation of MoSe2 nanosheets film thickness in the electrodes could affect the catalytic activity, and it was found that the MoSe2/CC sample prepared with 60u2009min EPD time shows the highest HER activity amongst these different thickness samples. Moreover, stability tests though long-term potential cycles (no degradation after 1000 continuous potential cycles) and extended electrolysis confirm the exceptional durability of the catalyst. This development offers us an attractive and active 3D electrode for electrochemical water splitting.

A ferroelectric photocatalyst Ag10Si4O13 with visible-light photooxidation properties

Ferroelectric p-block semiconductors are regarded as a new family of visible-light photocatalysts because of their dispersive and anisotropic band structures, as well as their intrinsic internal electric field. Silver silicates belong to this family and have band structures and an internal electric field that can be engineered by modulating the stoichiometry of Ag and SiO4. Here, we have developed a new ferroelectric p-block photocatalyst, Ag10Si4O13, by materials design and band engineering, which exhibits excellent photocatalytic activity towards the degradation of organic compounds, which is driven by visible light. Owing to the unique d10 and sp/p configurations in its electronic structure, Ag10Si4O13 possesses an indirect band gap of 1.72 eV with a highly dispersive conductive band and a flat valence band. This electronic structure promotes the generation, separation, and mobility of photo-induced charge carriers under visible-light illumination, which has been verified experimentally and theoretically. The compatible energy level of the conduction band determines its strong photo-oxidative capability. Moreover, the charge transfer process takes advantage of the existence of an internal electric field in Ag10Si4O13, which is attributed to the distorted SiO4 chain structure.

Band-gap engineering of BiOCl with oxygen vacancies for efficient photooxidation properties under visible-light irradiation

It remains a great challenge to understand the role of oxygen vacancies in determining the photooxidation properties of semiconductors under visible-light irradiation. Herein, BiOCl with oxygen vacancies is proposed as an excellent model to study the relationship between oxygen vacancies and photooxidation properties. BiOCl nanosheets with abundant oxygen vacancies are synthesized via a facile solvothermal route. Theoretical and experimental results reveal that after the introduction of oxygen vacancies, a new electron donor level appears in the band gap of BiOCl, extending the absorption from the ultraviolet to the visible regime. As expected, BiOCl nanosheets with oxygen vacancies exhibit visible-light-driven photocatalytic activity towards oxygen evolution. In addition, BiOCl with abundant oxygen vacancies exhibits a higher visible-light photocurrent and more efficient photoinduced charge separation and transportation than BiOCl with a small number of oxygen vacancies. The introduction of oxygen vacancies on the surfaces of semiconductors provides a promising way to improve the visible-light photooxidation activity of photocatalysts.

New monatomic layer clusters for advanced catalysis materials

摘要“单原子层团簇”催化剂这一新概念, 不同于单原子催化剂和传统的纳米颗粒催化, 是由单原子建造新型的二维单原子层催化剂. 单原子层团簇催化剂的活性中心明确, 且原子间的相互作用会极大提高催化反应的选择性. 因此该催化剂材料不仅具有优异的催化性能, 还具有良好的选择性. 基于此, 作者同时分析和指出了未来的单原子层团簇催化剂的可能重点研究方向以及挑战.

Recent progress on liquid metals and their applications

Abstract Gallium-based liquid metals show excellent thermal and electrical conductivities with low viscosity and non-toxicity. Their melting points are either lower than or close to room temperature, which endows them with additional advantages in comparison to the solid metals; for example, they are flexible, stretchable and reformable at room temperature. Recently, great improvements have been achieved in developing multifunctional devices by using Ga-based liquid metals, including actuators, flexible circuits, bio-devices and self-healing superconductors. Here, we review recent research progress on Gallium-based liquid metals, especially on the applications aspects. These applications are mainly based on the unique properties of liquid metals, including low melting point, flexible and stretchable mechanical properties, excellent electrical and thermal conductivities and biocompatibility.

A Liquid‐Metal‐Based Magnetoactive Slurry for Stimuli‐Responsive Mechanically Adaptive Electrodes

Electrical communication between a biological system and outside equipment allows one to monitor and influence the state of the tissue and nervous networks. As the bridge, bioelectrodes should possess both electrical conductivity and adaptive mechanical properties matching the target soft biosystem, but this is still a big challenge. A family of liquid-metal-based magnetoactive slurries (LMMSs) formed by dispersing magnetic iron particles in a Ga-based liquid metal (LM) matrix is reported here. The mechanical properties, viscosity, and stiffness of such materials rapidly respond to the stimulus of an applied magnetic field. By varying the intensity of the magnetic field, regulation within a factor of 1000 of the Youngs modulus from ≈kPa to ≈MPa, and the ability to reach GPa with more dense iron particles inside the LMMS are demonstrated. With the advantage of high conductivity of the LM matrix, the functions of the LMMS are not only limited to the soft implanted electrodes or penetrating electrodes in biosystems: the electrical response based on the LMMS electrodes can also be precisely tuned by simply regulating the applied magnetic field.