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Tuning the Deoxygenation of Bulk-Dissolved Oxygen in Copper C

Li, Chaoran, Zhang, Peihong, Wang, Jianyu, Boscoboinik, Jorge Anibal, Zhou, Guangwen
Journal of physical chemistry 2018 v.122 no.15 pp. 8254-8261
X-ray photoelectron spectroscopy, copper, hydrogen, oxygen, physical chemistry, temperature
Using synchrotron-based ambient-pressure X-ray photoelectron spectroscopy, we report the tuning of the deoxygenation process of bulk dissolved oxygen in copper via a combination of H₂ gas flow and elevated temperature. We show that a critical temperature of ∼580 °C exists for driving segregation of bulk dissolved oxygen to form chemisorbed oxygen on the Cu surface, which subsequently reacts with hydrogen to form OH species and then H₂O molecules that desorb from the surface. This deoxygenation process is tunable by a progressive stepwise increase of temperature that results in surface segregation of oxygen from deeper regions of bulk Cu. Using atomistic simulations, we show that the bulk-dissolved oxygen occupies octahedral sites of the Cu lattice and the deoxygenation process involves oxygen migration between octahedral and tetrahedral sites with a diffusion barrier of ∼0.5 eV.