Multi-crystalline N-doped Cu/CuxO/C foam catalyst derived from alkaline N-coordinated HKUST-1/CMC for enhanced 4-nitrophenol reduction

Xiaodan Sun; Peng He; Zhu Gao; Yuanxing Liao; Shaoxia Weng; Zhongxing Zhao; Hua Song; Zhenxia Zhao

doi:10.1016/j.jcis.2019.06.004

Multi-crystalline N-doped Cu/Cu_xO/C foam catalyst derived from alkaline N-coordinated HKUST-1/CMC for enhanced 4-nitrophenol reduction

J Colloid Interface Sci. 2019 Oct 1:553:1-13. doi: 10.1016/j.jcis.2019.06.004. Epub 2019 Jun 3.

Authors

Xiaodan Sun¹, Peng He², Zhu Gao¹, Yuanxing Liao¹, Shaoxia Weng¹, Zhongxing Zhao³, Hua Song⁴, Zhenxia Zhao⁵

Affiliations

¹ Department of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004, China.
² Department of Chemical and Petroleum Engineering, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada.
³ Guangxi Key Laboratory for Electrochemical Energy Materials, Guangxi University, Nanning 530004, China.
⁴ Department of Chemical and Petroleum Engineering, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada. Electronic address: sonh@ucalgary.ca.
⁵ Department of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004, China. Electronic address: zhaozhenxia@gxu.edu.cn.

PMID: 31176086
DOI: 10.1016/j.jcis.2019.06.004

Abstract

Multi-crystalline N-doped Cu/Cu_xO/C foam catalysts are successfully synthesized from N-coordinated HKUST-1/cellulose and applied in 4-nitrophenol (4-NP) reduction. Effects of N content and basicity on Cu morphology, crystal lattice and size, component dispersion and oxidation states in catalysts are systematically investigated. Moreover, transforming powder catalysts to foam morphology is proposed to further enhance catalytic performance and facilitate more feasible industrial applications. Results reveal that alkaline N-dopant simultaneously inhibits the growth of Cu crystals to only 3-5 nm and restrains Cu(II) reduction in HKUST-1 during calcination. This facilitates the formation of a special multi-crystalline Cu/Cu₂O/CuO structure. Furthermore, Cu₂O species on catalyst surface increase with increasing alkaline strength and N dopant content. Graphitic nano-structure catalyzed by Cu sites in HKUST-1 greatly enhances electron transfer in 4-NP reduction leading to 21 times faster kinetics and better recycle performance by melamine-doped Cu/Cu_xO/C foam catalyst than bare Cu/C catalyst directly from HKUST-1. Moreover, carbon foam derived from CMC can further amplify Cu dispersion and inhibit its agglomeration, thus promotes catalyst stability during cycling performance. Therefore, the proposed in-situ N doping and foam shaping strategy can efficiently enhance catalytic activity and reaction stability for 4-NP reduction, which can be envisaged of potential value for other similar industrial catalysis.

Keywords: 4-NP reduction; Alkaline N-Cu/Cu(x)O/C; Foam catalyst; In-situ N-coordinated MOF; Multi-crystalline.

Published by Elsevier Inc.