Hetero-metallic active sites coupled with strongly reductive polyoxometalate for selective photocatalytic CO2-to-CH4 conversion in water

Shuai-Lei Xie; Jiang Liu; Long-Zhang Dong; Shun-Li Li; Ya-Qian Lan; Zhong-Min Su

doi:10.1039/C8SC03471K

Hetero-metallic active sites coupled with strongly reductive polyoxometalate for selective photocatalytic CO₂-to-CH₄ conversion in water†

Shuai-Lei Xie,^a Jiang Liu,*^b Long-Zhang Dong,

^b Shun-Li Li,^b Ya-Qian Lan*^b and Zhong-Min Su

*^ac

Author affiliations

* Corresponding authors

^a Institute of Functional Material Chemistry, Department of Chemistry, National & Local United Engineering Lab for Power Battery, Northeast Normal University, Changchun 130024, P. R. China
E-mail: zmsu@nenu.edu.cn

^b School of Chemistry and Materials Science, Jiangsu Key Laboratory of Biofunctional Materials, Nanjing Normal University, Nanjing 210023, P. R. China
E-mail: liuj@njnu.edu.cn, yqlan@njnu.edu.cn

^c School of Chemistry and Environmental Engineering, The Collaborative Innovation Center of Optical Materials and Chemistry, CUST, Changchun University of Science and Technology, Changchun 130028, P. R. China

Abstract

The photocatalytic reduction of CO₂ to value-added methane (CH₄) has been a promising strategy for sustainable energy development, but it is challenging to trigger this reaction because of its necessary eight-electron transfer process. In this work, an efficient photocatalytic CO₂-to-CH₄ reduction reaction was achieved for the first time in aqueous solution by using two crystalline heterogeneous catalysts, H{[Na₂K₄Mn₄(PO₄) (H₂O)₄]⊂{[Mo₆O₁₂(OH)₃(HPO₄)₃(PO₄)]₄[Mn₆(H₂O)₄]}·16H₂O (NENU-605) and H{[Na₆CoMn₃(PO₄)(H₂O)₄]⊂{[Mo₆O₁₂(OH)₃(HPO₄)₃(PO₄)]₄[Co_1.5Mn_4.5]}·21H₂O (NENU-606). Both compounds have similar host inorganic polyoxometalate (POM) structures constructed with strong reductive {P₄Mo₆^V} units, homo/hetero transition metal ions (Mn^II/Co^IIMn^II) and alkali metal ions (K⁺ and/or Na⁺). It is noted that the {P₄Mo₆^V} cluster including the six Mo^V atoms served as a multi-electron donor in the case of a photocatalytic reaction, while the transition metal ions functioned as catalytically active sites for adsorbing and activating CO₂ molecules. Additionally, the presence of alkali metal ions was believed to assist in the capture of more CO₂ for the photocatalytic reaction. The synergistic combination of the above-mentioned components in NENU-605 and NENU-606 effectively facilitates the accomplishment of the required eight-electron transfer process for CH₄ evolution. Furthermore, NENU-606 containing hetero-metallic active sites finally exhibited higher CH₄ generation selectivity (85.5%) than NENU-605 (76.6%).

This article is part of the themed collections: Most popular 2019-2020 inorganic, main group and crystal engineering chemistry articles, Most popular 2018-2019 main group, inorganic and organometallic chemistry articles and How can chemistry adapt to a low carbon future

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DOI: https://doi.org/10.1039/C8SC03471K
Article type: Edge Article
Submitted: 05 Aug 2018
Accepted: 01 Oct 2018
First published: 02 Oct 2018
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry

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Chem. Sci., 2019,10, 185-190

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Hetero-metallic active sites coupled with strongly reductive polyoxometalate for selective photocatalytic CO₂-to-CH₄ conversion in water

S. Xie, J. Liu, L. Dong, S. Li, Y. Lan and Z. Su, Chem. Sci., 2019, 10, 185 DOI: 10.1039/C8SC03471K

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