University of Science and Technology Beijing

About: University of Science and Technology Beijing is a education organization based out in Beijing, China. It is known for research contribution in the topics: Microstructure & Alloy. The organization has 41558 authors who have published 44473 publications receiving 623229 citations. The organization is also known as: Beijing Steel and Iron Institute.

Template-free precursor-surface-etching route to porous, thin g-C3N4 nanosheets for enhancing photocatalytic reduction and oxidation activity

Abstract: Metal-free graphitic carbon nitride (g-C3N4) has sparked considerable interest due to its efficient photocatalytic activity in many fields. Development of new tactics toward improving the photocatalytic performance of g-C3N4 remains active and challenging. In this study, we uncover an unprecedented template-free precursor (melamine) pre-treatment protocol to achieve porous g-C3N4 nanosheets for efficient photocatalytic reduction and oxidation reaction. The introduction of thiourea solution in the hydrothermal pre-treatment process etches the surface of melamine, thus yielding the porous, thin g-C3N4 nanosheets. The microstructure and porosity of g-C3N4 can be adjusted only by controlling the thiourea amount. The as-obtained porous g-C3N4 nanosheets are found to be endowed with not only increased specific surface area, but also enhanced photoabsorption in the visible light region. Systematic characterizations of the charge movement behavior (transient photocurrent, linear sweep voltammetry, electrochemical impedance spectra, photoluminescence and surface photovoltage spectroscopy) disclose that the separation of photogenerated charge carriers is remarkably boosted by fabricating such a porous nanosheet structure. Benefiting from these advantages, porous g-C3N4 nanosheets present profoundly enhanced visible-light photocatalytic performance for H2 evolution (3.3-fold increase) and NO removal from the gaseous phase (5.5 times increase) in contrast to the pristine bulk g-C3N4. Our current study may offer an alternative approach to designing high-performance g-C3N4 nanomaterials for energy and environmental applications.

New insights and perspectives into biological materials for flexible electronics

Abstract: Biological materials have robust hierarchical structures capable of specialized functions and the incorporation of natural biologically active components, which have been finely tuned through millions of years of evolution. These highly efficient architectural designs afford remarkable transport and mechanical properties, which render them attractive candidates for flexible electronic sensing technologies. This review provides a comprehensive overview of the fundamental aspects and applications of biological materials for flexible electronic devices and discusses various classes of biological materials by describing their unique structures and functions. We discuss the effect of the biological activity of biological materials on the improved properties in detail, because this effect overcomes the limited bioavailability and restricted morphology of materials generally encountered in traditional flexible electronic devices. We also summarize various approaches for the design and functionalization of natural materials and their applications in flexible electronic devices for use in biomedical, electron, energy, environmental and optical fields. Finally, we provide new insights and perspectives to further describe trends for future generations of biological materials, which are likely to be critical components (building blocks or elements) in future flexible electronics.

In situ co-pyrolysis fabrication of CeO2/g-C3N4 n–n type heterojunction for synchronously promoting photo-induced oxidation and reduction properties

Abstract: Development of efficient photocatalysts with both photoinduced oxidation and reduction properties is of great importance for environmental and energy applications. Herein, we report the fabrication of CeO2/g-C3N4 hybrid materials by a simple in situ co-pyrolysis method using Ce(IO3)3 and melamine as precursors. The CeO2/g-C3N4 composite catalysts possess outstanding photocatalytic activity for phenol degradation and NO removal under visible light irradiation. The degradation efficiency reaches up to 68.5 and 17.3 times higher than that of pure CeO2 and g-C3N4, respectively. Significantly, it simultaneously exhibits an enhanced hydrogen production rate, which is 1.5 times that of the pure g-C3N4. The highly enhanced photo-induced oxidation and reduction activity could be attributed to the construction of a CeO2/g-C3N4 n–n type heterojunction established by our in situ co-pyrolysis route, which enables intimate interaction across the phase interfaces; this facilitates separation and transfer of photoexcited charge carriers. This study could not only provide a facile and general approach to the fabrication of high-performance carbon-nitride-based photocatalytic materials, but also increase our understanding further on designing new hybrid composite photocatalysts for multi-functional applications.

ZnS-SnS@NC Heterostructure as Robust Lithiophilicity and Sulfiphilicity Mediator toward High-Rate and Long-Life Lithium-Sulfur Batteries.

Abstract: Lithium-sulfur (Li-S) batteries are severely hindered by the low sulfur utilization and short cycling life, especially at high rates. One of the effective solutions to address these problems is to improve the sulfiphilicity of lithium polysulfides (LiPSs) and the lithiophilicity of the lithium anode. However, it is a great challenge to simultaneously optimize both aspects. Herein, by incorporating the merits of strong absorbability and high conductivity of SnS with good catalytic capability of ZnS, a ZnS-SnS heterojunction coated with a polydopamine-derived N-doped carbon shell (denoted as ZnS-SnS@NC) with uniform cubic morphology was obtained and compared with the ZnS-SnS2@NC heterostructure and its single-component counterparts (SnS@NC and SnS2@NC). Theoretical calculations, ex situ XANES, and in situ Raman spectrum were utilized to elucidate rapid anchoring-diffusion-transformation of LiPSs, inhibition of the shuttling effect, and improvement of the sulfur electrochemistry of bimetal ZnS-SnS heterostructure at the molecular level. When applied as a modification layer coated on the separator, the ZnS-SnS@NC-based cell with optimized lithiophilicity and sulfiphilicity enables desirable sulfur electrochemistry, including high reversibility of 1149 mAh g-1 for 300 cycles at 0.2 C, high rate performance of 661 mAh g-1 at 10 C, and long cycle life with a low fading rate of 0.0126% each cycle after 2000 cycles at 4 C. Furthermore, a favorable areal capacity of 8.27 mAh cm-2 is maintained under high sulfur mass loading of 10.3 mg cm-2. This work furnishes a feasible scheme to the rational design of bimetal sulfides heterostructures and boosts the development of other electrochemical applications.

High efficiency Bi2Te3-based materials and devices for thermoelectric power generation between 100 and 300 °C

Abstract: By suppressing intrinsic excitation in p-type Bi2Te3-based materials, we report maximum and average zT values of up to 1.4 and 1.2 between 100 and 300 °C, respectively. Thermoelectric modules based on these high performance materials show energy conversion efficiencies of up to 6.0% under a temperature gradient of 217 K, and are greatly superior to current Bi2Te3-based modules.