Issue 1, 2019

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

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[Co1.5Mn4.5]}·21H2O (NENU-606). Both compounds have similar host inorganic polyoxometalate (POM) structures constructed with strong reductive {P4Mo6V} units, homo/hetero transition metal ions (MnII/CoIIMnII) and alkali metal ions (K+ and/or Na+). It is noted that the {P4Mo6V} cluster including the six MoV 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%).

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

Supplementary files

Article information

Article type
Edge Article
Submitted
05 avq 2018
Accepted
01 okt 2018
First published
02 okt 2018
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY-NC license

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

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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