Electrochemical reduction of CO2 is a promising route for sustainable production of fuels. A grand challenge is developing low-cost and efficient electrocatalysts that can enable rapid conversion with high product selectivity. Here we design a series of nickel phthalocyanine molecules supported on carbon nanotubes as molecularly dispersed electrocatalysts (MDEs), achieving CO2 reduction performances that are superior to aggregated molecular catalysts in terms of stability, activity and selectivity. The optimized MDE with methoxy group functionalization solves the stability issue of the original nickel phthalocyanine catalyst and catalyses the conversion of CO2 to CO with >99.5% selectivity at high current densities of up to −300 mA cm−2 in a gas diffusion electrode device with stable operation at −150 mA cm−2 for 40 h. The well-defined active sites of MDEs also facilitate the in-depth mechanistic understandings from in situ/operando X-ray absorption spectroscopy and theoretical calculations on structural factors that affect electrocatalytic performance.
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Y.L. acknowledges financial support from Shenzhen fundamental research funding (grant no. JCYJ20160608140827794) and Guangdong-Hong Kong-Macao Joint Laboratory for Photonic-Thermal-Electrical Energy Materials and Devices (grant no. 2019B121205001). H.W. acknowledges funding support from the US National Science Foundation (grant no. CHE-1651717). Z.F. thanks the start-up support from Oregon State University. Y.-G.W. acknowledges financial supports from Guangdong Provincial Key Laboratory of Catalysis (grant no. 2020B121201002). J.L. is supported by National Natural Science Foundation of China (grant nos. 21590792, 91426302 and 21433005). The computational resource is supported from the Center for Computational Science and Engineering (SUSTech) and Tsinghua National Laboratory for Information Science and Technology. TEM, MS and ICP data were obtained using equipment maintained by SUSTech Core Research Facilities. We acknowledge the technical support from R. Rosenberg at 4-ID, Advanced Photon Source (APS) of Argonne National Laboratory (ANL). XAS measurements were performed at 9-BM and DND-CAT 5-BM. The use of APS of ANL is supported by Department of Energy under contract no. DE-AC02-06CH11357. DND-CAT is supported through E. I. duPont de Nemours and Company, Northwestern University and The Dow Chemical Company.
The authors declare no competing interests.
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Zhang, X., Wang, Y., Gu, M. et al. Molecular engineering of dispersed nickel phthalocyanines on carbon nanotubes for selective CO2 reduction. Nat Energy 5, 684–692 (2020). https://doi.org/10.1038/s41560-020-0667-9