Harbin Engineering University

About: Harbin Engineering University is a education organization based out in Harbin, Heilongjiang, China. It is known for research contribution in the topics: Control theory & Microstructure. The organization has 31149 authors who have published 27940 publications receiving 276787 citations. The organization is also known as: HEU.

Recent Advances in the Electro-Oxidation of Urea for Direct Urea Fuel Cell and Urea Electrolysis

Abstract: This paper provides an overview of recent advances in urea electro-oxidation. Urea sources are abundant from human urine, urea-containing wastewater, and industrial urea, thus becoming an attractive option as anodic fuel for the application in direct urea fuel cells (DUFCs). Besides, as a hydrogen-rich chemical fuel, urea can also be electrolyzed to produce hydrogen for energy storage in the near future. The exact mechanisms of urea decomposition are pretty different in alkaline or neutral mediums and are separately discussed in detail. More importantly, the development of anodic electro-catalysts is of great significance for improving the electrochemical performance of both DUFCs and urea electrolysis cells, which is systematically summarized in our review. Challenges and prospects on the future development of urea electro-oxidation are particularly proposed.

Stacking fault and unoccupied densities of state dependence of electromagnetic wave absorption in SiC nanowires

Abstract: Understanding the relationship between the defects and properties could give the guidance to tailor the materials by virtue of regulating defects. In the present research, β-SiC nanowires (NWs) with different states of stacking faults have been fabricated by varying the heating temperature. The stacking fault states are characterized by transmission electron microscope and powder X-ray diffractometer. The electronic structures are investigated by X-ray absorption near-edge structures (XANES) at C K-edge and Si K-edge. Microstructural analysis revealed that the content of stacking faults in SiC NWs decreased significantly with an increase of heating temperature. The unoccupied density of states (DOS) in the C K-edge XANES spectra positively correlated with stacking fault contents in SiC NWs. The stacking fault planes were inclined at an angle of 35° to the growth direction at a heating temperature of 1400 °C, which were converted to perpendicular to the growth direction as the temperature increased to 1600 °C. The inclined stacking fault planes in the domain induced strongest dielectric resonance. The SiC NWs synthesized at 1400 °C with the highest carbon unoccupied DOS possess the most stacking fault content and numerous dipoles, which result in extensive polarization and energy dissipation under an altering electromagnetic field. As a result, a lowest reflection loss (RL) value of −30 dB and an effective absorption band (RL < −10 dB) covering a frequency range of 3.7 GHz were achieved.