In Situ Monitoring of H 2 -Induced Nonstoichiometry in Cu 2 O

• Published in: The journal of physical chemistry letters 2022-06, Vol.13 (24), p.5597-5604
• Main Authors: Wang, Jianyu, Li, Chaoran, Zhu, Yaguang, Boscoboinik, Jorge Anibal, Zhou, Guangwen
• Format: Article
• Language: English
• ISSN: 1948-7185; 1948-7185
• DOI: 10.1021/acs.jpclett.2c00988

Using ambient-pressure X-ray photoelectron spectroscopy and Auger electron spectroscopy to monitor the reduction of Cu O in H , we identify the formation of an intermediate, oxygen-deficient Cu O phase and its progressive inward growth into the deeper region of the oxide. Complemented by atomistic modeling, we show that the oxygen-deficient Cu O formation occurs via molecular H adsorption at the Cu O surface, which results in the loss of lattice oxygen from the formation of H O molecules that desorb spontaneously from the oxide surface. The resulting oxygen-deficient Cu O is a stable intermediate that persists before the Cu O is fully reduced to metallic Cu. The oxygen vacancy-induced charge of the coordinating Cu atoms results in a satellite feature in Cu LMM, which can be used as a fingerprint to identify nonstoichiometry in oxides and local charge transfer induced by the nonstoichiometry.