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.

In Situ Co-Crystallization for Fabrication of g-C3N4/Bi5O7I Heterojunction for Enhanced Visible-Light Photocatalysis

Abstract: We developed for the first time an in situ co-crystallization route for fabrication of a heterojunctional photocatalyst g-C3N4/Bi5O7I by adopting melamine and BiOI as coprecursors. This synthetic method enables intimate interfacial interaction with chemical bonding between g-C3N4 and Bi5O7I, which is beneficial for charge transfer at the interface. The photocatalysis properties of g-C3N4/Bi5O7I composites were studied by photodegradation of Rhodamine B (RhB) and phenol and generation of transient photocurrent with illumination of visible-light (λ > 420 nm), The results revealed that the g-C3N4/Bi5O7I composite shows enhanced photocatalytic reactivity compared to the pristine g-C3N4 and Bi5O7I samples. Investigations on the behaviors of charge carriers via electrochemical impedance spectra (EIS) and photoluminescence (PL) spectra suggests that the g-C3N4/Bi5O7I heterojunctional structure constructed of the in situ co-thermolysis approach is responsible for the efficient separation and transfer of photogene...

Electrodeposition of Hierarchical ZnO Nanorod-Nanosheet Structures and Their Applications in Dye-Sensitized Solar Cells

Abstract: We present a two-step electrochemical deposition process to synthesize hierarchical zinc oxide (ZnO) nanorod-nanosheet structures on indium tin oxide (ITO) substrate, which involves electrodeposition of ZnO nanosheet arrays on the conductive glass substrate, followed by electrochemical growth of secondary ZnO nanorods on the backbone of the primary ZnO nanosheets. The formation mechanism of the hierarchical nanostructure is discussed. It is demonstrated that annealing treatment of the primary nanosheets synthesized by the first-step deposition process plays a key role in synthesizing the hierarchical nanostructure. Photovoltaic properties of dye-sensitized solar cells (DSSCs) based on hierarchical ZnO nanostructures are investigated. The hierarchical ZnO nanorod-nanosheet DSSC exhibits improved device performance compared to the DSSC constructed using photoelectrode of bare ZnO nanosheet arrays. The improvement can be attributed to the enhanced dye loading, which is caused by the enlargement of internal surface area within the nanostructure photoelectrode. Furthermore, we perform a parametric study to determine the optimum geometric dimensions of the hierarchical ZnO nanorod-nanosheet photoelectrode through adjusting the preparation conditions of the first- and second-step deposition process. By utilizing a hierarchical nanostructure photoelectrode with film thickness of about 7 μm, the DSSC with an open-circuit voltage of 0.74 V and an overall power conversion efficiency of 3.12% is successfully obtained.

Phase Stability of Low-Density, Multiprincipal Component Alloys Containing Aluminum, Magnesium, and Lithium

Abstract: A series of low-density, multiprincipal component alloys containing high concentrations of Al, Mg, Li, Zn, Cu and/or Sn was designed using a strategy based on high-entropy alloys (HEAs). The alloys were prepared by induction melting under high-purity argon atmosphere, and the resulting microstructures were characterized in the as-cast condition. The resulting microstructures are multiphase and complex and contain significant volume fractions of disordered solutions and intermetallic compounds. By analyzing the atomic size difference, enthalpy of mixing, entropy of mixing, electronegativity difference, and valence electron concentration among the constituent elements, modified phase formation rules are developed for low-density multiprincipal component alloys that are more restrictive than previously established limits based on more frequently studied HEAs comprising mostly transition metals. It is concluded that disordered solid solution phases are generally less stable than competing ordered compounds when formulated from low-density elements including Al, Mg, and Li.

Ultrasound-modulated bubble propulsion of chemically powered microengines.

Abstract: The use of an ultrasound (US) field for rapid and reversible control of the movement of bubble-propelled chemically powered PEDOT/Ni/Pt microengines is demonstrated. Such operation reflects the US-induced disruption of normal bubble evolution and ejection, essential for efficient propulsion of catalytic microtubular engines. It offers precise speed control, with sharp increases and decreases of the speed at low and high US powers, respectively. A wide range of speeds can thus be generated by tuning the US power. Extremely fast changes in the motor speed (<0.1 s) and reproducible “On/Off” activations are observed, indicating distinct advantages compared to motion control methods based on other external stimuli. Such effective control of the propulsion of chemically powered microengines, including remarkable “braking” ability, holds considerable promise for diverse applications.