TY - JOUR
T1 - The effects of ultrasound on nickel and copper powders
AU - Suslick, Kenneth S.
AU - Casadonte, Dominick J.
AU - Doktycz, Stephen J.
N1 - Funding Information:
Special thanks are due Dr. Frank Scheltens for assistance with the scanning electron micrographs, Dr. Irena Dulmer for training on both the Jeol 35C and Hitachi S-800 scanning electron microscopes, and Nancy Finnegan for the Auger electron spectra; both analyses were carried out in the Center for Microanalysis of Materials, University of Illinois, which is supported by the US Department of Energy under contract DE-AC 02-76ER 01198. We also thank Brian Borglum and Professor R.C. Buchanan for their aid in obtaining surface area measurements. The support of the National Science Foundation (CHE 8319929) is greatly appreciated. KSS gratefully acknowledges the receipt of an NIH Research Center Development Award and of a Sloan Foundation Research Fellowship.
PY - 1989
Y1 - 1989
N2 - The use of high-intensity ultrasound to enhance the reactivity of metal surfaces has become a routine synthetic technique. In spite of this, the origin of rate enhancements in both stoichiometric and catalytic reactions remains unexplored. To this end, we have examined the effects of ultrasound on metal powders in terms of their particle and surface morphology, their atomic composition, and their reactivity. Specifically, we have discovered that ultrasonic irradiation of Ni and Cu powders leads to dramatic changes in morphology: individual surfaces are smoothed and particles are consolidated into extended aggregates. Surface composition was probed by Auger electron spectroscopy depth profiles, which revealed that ultrasonic irradiation removed the surface oxide coating, but also produced (especially for Cu) a deposition of surface carbon. The effects on reactivity can be substantial: ultrasonic irradiation enhances the activity of Ni powder as a hydrogenation catalyst by > 105 and significantly increases the reactivity of Cu powder as a stoichiometric reagent. We beleive that these effects are due to interparticle collisons driven by the turbulent flow created by the ultrasonic field. It is likely that the origin of the enhanced chemical reactivity comes from the removal of the surface oxide passivating layer which these collisions induce.
AB - The use of high-intensity ultrasound to enhance the reactivity of metal surfaces has become a routine synthetic technique. In spite of this, the origin of rate enhancements in both stoichiometric and catalytic reactions remains unexplored. To this end, we have examined the effects of ultrasound on metal powders in terms of their particle and surface morphology, their atomic composition, and their reactivity. Specifically, we have discovered that ultrasonic irradiation of Ni and Cu powders leads to dramatic changes in morphology: individual surfaces are smoothed and particles are consolidated into extended aggregates. Surface composition was probed by Auger electron spectroscopy depth profiles, which revealed that ultrasonic irradiation removed the surface oxide coating, but also produced (especially for Cu) a deposition of surface carbon. The effects on reactivity can be substantial: ultrasonic irradiation enhances the activity of Ni powder as a hydrogenation catalyst by > 105 and significantly increases the reactivity of Cu powder as a stoichiometric reagent. We beleive that these effects are due to interparticle collisons driven by the turbulent flow created by the ultrasonic field. It is likely that the origin of the enhanced chemical reactivity comes from the removal of the surface oxide passivating layer which these collisions induce.
UR - http://www.scopus.com/inward/record.url?scp=0024613420&partnerID=8YFLogxK
U2 - 10.1016/0167-2738(89)90254-3
DO - 10.1016/0167-2738(89)90254-3
M3 - Article
AN - SCOPUS:0024613420
SN - 0167-2738
VL - 32-33
SP - 444
EP - 452
JO - Solid State Ionics
JF - Solid State Ionics
IS - PART 1
ER -