Nat Commun 11, 2432 (2020)

Black indium oxide a photothermal CO₂ hydrogenation catalyst

Lu Wang^1,2, Yuchan Dong², Tingjiang Yan³, Zhixin Hu⁴, Abdinoor A. Jelle², Débora Motta Meira^5,6, Paul N. Duchesne², Joel Yi Yang Loh⁷, Chenyue Qiu⁸, Emily E. Storey⁷, Yangfan Xu², Wei Sun⁹, Mireille Ghoussoub², Nazir P. Kherani^7,8, Amr S. Helmy⁷ & Geoffrey A. Ozin²

1 School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, 518172 Shenzhen, Guangdong, China.

2 Solar Fuels Group, Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, ON M5S 3H6, Canada.

3 College of Chemistry and Chemical Engineering, Qufu Normal University, 273165 Qufu, Shandong, China.

4 Center for Joint Quantum Studies and Department of Physics, Institute of Science, Tianjin University, Tianjin, China.

5 CLS@APS, Advanced Photon Source, Argonne National Laboratory, Lemont, IL 60439, USA.

6 Canadian Light Source Inc., 44 Innovation Boulevard, Saskatoon, SK S7N 2V3, Canada.

7 Department of Electrical and Computer Engineering, University of Toronto, Toronto, Canada.

8 Department of Materials Science and Engineering, University of Toronto, 184 College Street, Toronto, ON M5S 3E4, Canada.

9 State Key Laboratory of Silicon Materials and School of Materials Science and Engineering, Zhejiang University, 310027 Hangzhou, Zhejiang, China.

Email: Lu Wang (lwangresearch@gmail.com)  Zhixin Hu (zhixin.hu@tju.edu.cn)  Geoffrey A. Ozin (g.ozin@utoronto.ca)

Abstract

Nanostructured forms of stoichiometric In₂O₃ are proving to be efficacious catalysts for the gas-phase hydrogenation of CO₂. These conversions can be facilitated using either heat or light; however, until now, the limited optical absorption intensity evidenced by the pale-yellow color of In₂O₃ has prevented the use of both together. To take advantage of the heat and light content of solar energy, it would be advantageous to make indium oxide black. Herein, we present a synthetic route to tune the color of In₂O₃ to pitch black by controlling its degree of non-stoichiometry. Black indium oxide comprises amorphous non-stoichiometric domains of In₂O_3-x on a core of crystalline stoichiometric In₂O₃, and has 100% selectivity towards the hydrogenation of CO₂ to CO with a turnover frequency of 2.44 s⁻¹ .