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Toward High Efficient CO2 Electroreduction on Morphology-controlled CuXO Nanocatalysts at Low Electrode Overpotential in Aqueous Solution
Last modified: 2014-10-11
Abstract
Electrochemical reduction of CO2 to form useful chemicals or fuels is a potentially efficient method of CO2 utilization and recycling [1], particular to liquid fuels (for example HCOOH or HCOO-),whcih could offer a carbon neutral solution for a variety of energy applications. For large-scale conversion of CO2 to fuels, water is the obvious, inexpensive, and environment-friendly solvent of choice compared to non-aqueous solvents with or without added water. Cu metal electrode has been actively investigated for CO2 electroreduction in both aqueous and non-aqueous solutions[2],because of its low cost and chemical robustness. A key technological challenge is the slow electrode kinetics (large overpotential almost 1 V) and poor product selectivity (a fairly broad mix of major and minor products including H2, C2H4, CH4), leading to wastage of energy and the insufficient utilization of resources[1]. In addition, the deactivation of Cu electrodes in CO2 reduction was found to be fast, especially in aqueous solutions[3]. Most recently, nanostructured surfaces of Cu metal could give more positive onset potential and higher current efficiency for CO2 reduction in aqueous solution [4,5]. The special morphology due to the nanostructure surface could provide abundant coordinated sites, thus providing more active sites for CO2 electroreduction and in controlling the product selectivity[6]. On the other hand, tin oxide related catalyst is reported to exhibit greatly enhanced CO2 reduction activity relative to a typical Sn electrode in aqueous electrolyte, and the metastable metal oxides persist on electrode surfaces during cathodic reactions[4], suggesting that metal oxides are promising candidates for CO2 reduction[5]. On the basis of these observations, we here report the remarkable observation that several morphology controlled CuXO nanocatalysts are highly efficient in electroreduction CO2, where the 3D-hierarchical CuxO nanosphers comprised of secondary structured nanosheets (50 nm) exhibit excellent Faradaic efficiency (59%) of produced formate even with water as the solvent.
References
[1] J. L. Qiao, Y. Y. Liu, Y.Y, F. Hong, J. J. Zhang, “A review of catalysts for the electroreduction of carbon dioxide to produce low-carbon fuels”, Chem. Soc. Rev., Vol. 43, pp. 631-675, 2014. [2] D. T. Whipple, P. J. Kenis, Prospects of CO2 utilization via direct heterogeneous electrochemical reduction, J. Phys. Chem. Lett. 2010, 1, 3451.[3] Y. Hori , Modern Aspects of Electrochemistry, Springer, New York, 2008, pp89.[4] Y. Chen, M. W. Kanan, CO2Reduction at Low Overpotential on Cu Electrodes Resulting from the Reduction of Thick Cu 2O Films J. Am. Chem.Soc. Vol. 134, pp 1986-1989, 2012.[5] Oh, Yeonji, H.Vrubel, S. Guidoux, X. Hu, Electrochemical reduction of CO2 in organic solvents catalyzed by MoO2, Chem. Commun., Vol. 50, pp. 3878-3881, 2014.[6] J. L. Qiao, P. Jiang, J. S. Liu, J. J. Zhang, Formation of Cu nanostructured electrode surfaces by an annealing–electroreduction procedure to achieve high-efficiency CO2 electroreduction, Electrochem. Commun. Vol. 38, pp. 8-11, 2014.
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