Efficient and Selective Interplay Revealed: CO 2 Reduction to CO over ZrO 2 by Light with Further Reduction to Methane over Ni 0 by Heat Converted from Light

• Published in: Angewandte Chemie International Edition Vol. 60; no. 16; pp. 9045 - 9054
• Main Authors: Zhang, Hongwei, Itoi, Takaomi, Konishi, Takehisa, Izumi, Yasuo
• Format: Journal Article
• Language: English
• Published: Germany 12.04.2021
• Subjects: concerted mechanism; metallic nickel; mass chromatography; 13CO2; correlated Debye model; zirconium oxide
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202016346

The reaction mechanism of CO photoreduction into methane was elucidated by time-course monitoring of the mass chromatogram, in situ FTIR spectroscopy, and in situ extended X-ray absorption fine structure (EXAFS). Under CO , H , and UV/Vis light, CH was formed at a rate of 0.98 mmol h  g using Ni (10 wt %)-ZrO that was effective at 96 kPa. Under UV/Vis light irradiation, the CO exchange reaction and FTIR identified physisorbed/chemisorbed bicarbonate and the reduction because of charge separation in/on ZrO , followed by the transfer of formate and CO onto the Ni surface. EXAFS confirmed exclusive presence of Ni sites. Then, FTIR spectroscopy detected methyl species on Ni , which was reversibly heated to 394 K owing to the heat converted from light. With D O and H , the H/D ratio in the formed methane agreed with reactant H/D ratio. This study paves the way for using first row transition metals for solar fuel generation using only UV/Vis light.