Wuhan University of Technology

About: Wuhan University of Technology is a education organization based out in Wuhan, China. It is known for research contribution in the topics: Microstructure & Catalysis. The organization has 40384 authors who have published 36724 publications receiving 575695 citations. The organization is also known as: WUT.

Improved visible-light photocatalytic activity of porous carbon self-doped ZnO nanosheet-assembled flowers

Abstract: Hierarchical flower-like C-doped ZnO superstructures (ZnO flowers) assembled from porous nanosheets are obtained by pyrolysis of morphology-analogous Zn5(CO3)2(OH)6 precursors. The prepared ZnO flowers are characterized by X-ray diffraction, thermogravimetic and differential scanning calorimeter analysis, scanning electron microscopy, transmission electron microscopy, N2 sorption measurements, UV-vis diffuse reflectance spectra and X-ray photoelectron spectroscopy. The production of OH radicals on the ZnO surface under visible-light irradiation is detected by a photoluminescence technique using terephthalic acid as a probe molecule. The visible-light photocatalytic activity is evaluated by photocatalytic decomposition of the dye RhB in aqueous solution. The hierarchical organization of nanosheets, the multimode voids between and within porous nanosheets, together with annealing-induced in situ carbon self-doping within the ZnO lattice, account for the enhanced light-absorption capacity, extended light-response range and thus better photocatalytic activity of the ZnO flowers. Furthermore, first-principle density functional theory (DFT) calculation further confirms the C-doping induced red shift in the absorption edges of C-doped ZnO flowers.

High-Energy-Density Dielectric Polymer Nanocomposites with Trilayered Architecture

Abstract: The development of advanced dielectric materials with high electric energy densities is of crucial importance in modern electronics and electric power systems. Here, a new class of multilayer-structured polymer nanocomposites with high energy and power densities is presented. The outer layers of the trilayered structure are composed of boron nitride nanosheets dispersed in poly(vinylidene fluoride) (PVDF) matrix to provide high breakdown strength, while PVDF with barium strontium titanate nanowires forms the central layer to offer high dielectric constant of the resulting composites. The influence of the filler contents on the electrical polarization, breakdown strength, and energy density is examined. Simulations are carried out to model the electrical tree formation in the layered nanocomposites and to verify the experimental breakdown results. The trilayered polymer nanocomposite with an optimized filler content displays a discharged energy density of 20.5 J cm−3 at Weibull breakdown strength of 588 MV m−1, which is among the highest discharged energy densities reported so far. Moreover, the nanocomposite exhibits a superior power density of 0.91 MW cm−3, more than nine times that of the commercially available biaxially oriented polypropylene. The findings of this research provide a new design paradigm for high-performance dielectric polymer nanocomposites.

Regulating Fe-spin state by atomically dispersed Mn-N in Fe-N-C catalysts with high oxygen reduction activity.

Abstract: As low-cost electrocatalysts for oxygen reduction reaction applied to fuel cells and metal-air batteries, atomic-dispersed transition metal-nitrogen-carbon materials are emerging, but the genuine mechanism thereof is still arguable. Herein, by rational design and synthesis of dual-metal atomically dispersed Fe,Mn/N-C catalyst as model object, we unravel that the O2 reduction preferentially takes place on FeIII in the FeN4 /C system with intermediate spin state which possesses one eg electron (t2g4eg1) readily penetrating the antibonding π-orbital of oxygen. Both magnetic measurements and theoretical calculation reveal that the adjacent atomically dispersed Mn-N moieties can effectively activate the FeIII sites by both spin-state transition and electronic modulation, rendering the excellent ORR performances of Fe,Mn/N-C in both alkaline and acidic media (halfwave positionals are 0.928 V in 0.1 M KOH, and 0.804 V in 0.1 M HClO4), and good durability, which outperforms and has almost the same activity of commercial Pt/C, respectively. In addition, it presents a superior power density of 160.8 mW cm−2 and long-term durability in reversible zinc–air batteries. The work brings new insight into the oxygen reduction reaction process on the metal-nitrogen-carbon active sites, undoubtedly leading the exploration towards high effective low-cost non-precious catalysts. The working mechanism of several low-cost electrocatalyst materials is still arguable. Here the authors show a model Fe,Mn/N-C catalyst where the oxygen reduction preferentially takes place on Fe(III) sites with the intermediate spin state (t2g4 eg1) caused by the adjacent Mn-N moieties.