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158 results on '"Li, J.F."'

39. Water Structure at the Multilayers of Palladium deposited at nanostructured Au electrodes

Author

Zhang, Y.J., Su, Z.F., Li, J.F., and Lipkowski, J.

Subjects
water structure, palladium multilayers, ATR-SEIRA
Abstract

In situ ATR-SEIRAS experiments were carried out to describe water structure at the surface of multilayers of Pd modified nanopatterned gold film electrodes in contact with aqueous 0.1 M HClO4 solution. The results show that the surface water becomes more ordered when the thickness of the Pd film increases. The “ice-like water” band becomes stronger and for the electrode with 5 ML Pd@Au, the ratio of “ice-like water” to “liquid-like water” becomes larger than that in bulk water. Concomitantly, the population of “monomers” or small water clusters diminishes. All surface water bands increase when hydrogen adsorption takes place. The bending band corresponding to “monomers” or “multimers” water is observed chiefly at the potentials of hydrogen adsorption. Natural Sciences and Engineering Research Council of Canada (NSERC)the National Natural Science Foundation of China (NSFC), the "111" Project (B17027), and the National Key Research and Development Program of China.

Published
2021

44. What Vibrational Spectroscopy Tells about Water Structure at the Electrified Palladium-Water Interface

Author

Zhang, Y.J., Su, Z.F., Li, J.F., and Lipkowski, J.

Subjects
Water structure, ATR-SEIRAS, Palladium
Abstract

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of Physical Chemistry C, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acs.jpcc.0c03453. The knowledge of the structure and properties of water adsorbed on metal surfaces is relevant for understanding electrocatalytic reactions. A monolayer of Pd deposited at a gold electrode surface is known to have enhanced electrocatalytic properties. To shed new light on these properties, the present study describes investigations of water structure at monolayer Pd film deposited at a nanostructured gold electrode consisting of ∼50 nm large nanoparticles supported at a Si hemisphere. Attenuated total reflection surface enhanced infrared reflection absorption spectroscopy (ATR-SEIRAS) was applied to measure vibrational spectra of water molecules at the electrode surface. The surface enhancement of the electric field of the photon allowed one to determine spectra of water molecules interacting with the Pd film. The results show that surface water is a mosaic of “ice-like”, “liquid-like”, and monomer or small clusters of water molecules. In addition, hydronium ions are present at the Pd surface in an acidic solution. The relative contribution of these structures depends on the pH and electrode potential. The surface water is more ordered at potentials corresponding to the adsorption of hydrogen atoms. Natural Sciences and Engineering Research Council of Canada (NSERC), National Natural Science Foundation of China (NSFC), "111" Project, National Key Research and Development Program of China

Published
2020

45. Microstructure and strengthening mechanisms of 90W–7Ni–3Fe alloys prepared using laser melting deposition

Author

Wang, Y.P., Ma, S.Y., Yang, X.S., Zhou, Y.Z., Liu, X., Li, J.F., Zhang, J.J., Li, C., Wang, X.Y., Le, G. M., Zhang, Y., Wang, Y.P., Ma, S.Y., Yang, X.S., Zhou, Y.Z., Liu, X., Li, J.F., Zhang, J.J., Li, C., Wang, X.Y., Le, G. M., and Zhang, Y.

Abstract

The microstructure and mechanical properties of a 90W–7Ni–3Fe heavy alloy manufactured using laser melting deposition (LMD) have been investigated with a goal of understanding the LMD process and the relevant strengthening mechanisms. A reference sample prepared using liquid phase sintering (LPS) with similar composition has been used for comparison to isolate effects of the processing rate. The results show that the nearly fully-dense LMD sample consists of two periodically alternating sublayers containing different volume fractions of W particles. Compared to the reference LPS sample, the LMD sample has a higher W content in the binder matrix, a more refined microstructure, a higher dislocation density and a lower contiguity between W particles. Furthermore, the LMD sample has a yield strength of 822 ± 30 MPa, which is about 200 MPa higher than that of the reference LPS sample. This strength difference is quantitatively analyzed based on the microstructural observations. It is shown that the increased fraction of W-matrix interfaces, a higher interface bonding strength and more pronounced constraint effects, resulting from the higher processing temperature and fast cooling of LMD, provide extra strengthening. The present study provides an important basis for optimizing the LMD process for manufacture of high W content tungsten heavy alloys with improved mechanical properties.

Published
2020

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