Abstract - City University of Hong Kong · 2019. 9. 24. · Abstract Fig. 1 | Structure of...
Transcript of Abstract - City University of Hong Kong · 2019. 9. 24. · Abstract Fig. 1 | Structure of...
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Abstract
Fig. 1 | Structure of compounds used in this study. Cobalt complexes [Co2(biqpy)]4+ (1) and [Co(qpy)]2+ (2), molecular sensitizers ([Ru(phen)3]2+, Pheno) and
sacrificial reductant 1,3-dimethyl-2-phenylbenzimidazoline (BIH). Crystal structure of [Co2(biqpy)Cl(MeOH)(H2O)]3+.
Fig. 2 | Photocatalytic CO2 reduction products with [Co2(biqpy)]Cl4 as catalyst.
Fig. 3 | CV plots and infrared spectroelectrochemistry spectra. a, CVs of [Co2(biqpy)]Cl4 in MeCN; b, Infrared
spectroelectrochemistry experiment on [Co2(biqpy)]4+in the presence of 0.5 M TEA in MeCN under CO2; Inset, calculated
structure of the CO2-reduced complex adduct.
Fig. 4 | Proposed
mechanism
It is highly desirable to discover molecular catalysts with controlled selectivity for visible-light-driven CO2 reduction to fuels. In the design of catalysts employing earth-abundant metals, progress has been made for CO production, but formate generation has been observed more rarely. Here, we report a binuclear Co complex bearing a bi-quaterpyridine ligand that can selectively reduce CO2 to HCOO− or CO under visible light irradiation. Selective formate production (maximum of 97%) was obtained with a turnover number of up to 821 in basic acetonitrile solution. Conversely, in the presence of a weak acid, CO2 reduction affords CO with high selectivity (maximum of 99%) and a maximum turnover number of 829. The catalytic process is controlled by the two Co atoms acting synergistically, and the selectivity can be steered towards the desired product by simply changing the acid co-substrate.
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rban
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Energy (cm-1)
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E = -0.35 V / -0.85 Vb)
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+ 20% (v%) TEA under CO2
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Potential / V vs SCE
Cu
rren
t/ m
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a)