Performance and mechanism of ammonia production by electrocatalytic nitrate reduction based on dodecahydro-closo-dodecaborate hybrid

Jiajia Wang; Xuefan Deng; Haixu Zhao; Xun Liu; Mai Zheng; Zan Jiang; Long Zhang; Haibo Zhang

doi:10.1016/j.jcis.2023.08.132

Performance and mechanism of ammonia production by electrocatalytic nitrate reduction based on dodecahydro-closo-dodecaborate hybrid

J Colloid Interface Sci. 2023 Dec 15;652(Pt A):945-951. doi: 10.1016/j.jcis.2023.08.132. Epub 2023 Aug 22.

Authors

Jiajia Wang¹, Xuefan Deng², Haixu Zhao², Xun Liu², Mai Zheng², Zan Jiang³, Long Zhang⁴, Haibo Zhang⁵

Affiliations

¹ School of Optoelectronic Materials and Technology, Jianghan University, Wuhan 430056, China; College of Chemistry and Molecular Sciences, Engineering Research Center of Organosilicon Compounds & Materials, Ministry of Education, Wuhan University, Wuhan 430072, China.
² College of Chemistry and Molecular Sciences, Engineering Research Center of Organosilicon Compounds & Materials, Ministry of Education, Wuhan University, Wuhan 430072, China.
³ College of Chemistry and Molecular Sciences, Engineering Research Center of Organosilicon Compounds & Materials, Ministry of Education, Wuhan University, Wuhan 430072, China. Electronic address: lzh131@jhun.edu.cn.
⁴ School of Optoelectronic Materials and Technology, Jianghan University, Wuhan 430056, China. Electronic address: timejz@whu.edu.cn.
⁵ College of Chemistry and Molecular Sciences, Engineering Research Center of Organosilicon Compounds & Materials, Ministry of Education, Wuhan University, Wuhan 430072, China. Electronic address: haibozhang1980@gmail.com.

PMID: 37634367
DOI: 10.1016/j.jcis.2023.08.132

Abstract

Ammonia is an essential food and fertilizer component and is a fundamental raw material for industry and agriculture. In contrast, nitrate is the main pollutant that causes eutrophication in water. Electrocatalysis is a clean and efficient method for simultaneous nitrate removal and ammonia production. However, because ammonia production from the electrocatalytic nitrate reduction reaction (NO₃RR) is a complex eight-electron process with slow kinetics, designing the cathode catalyst is critical for improving the ammonia yield. In this study, boron (B) doped metal oxides (TiZn₂O₄@B-x) obtained by coupling dodecahydro-closo-dodecaborate anions ([closo-B₁₂H₁₂]^2-) and ZnTi-layered double hydroxides (ZnTi-LDH) after calcination was used as the cathode for the NO₃RR. Specifically, TiZn₂O₄@B-700 exhibited excellent ammonia yield (21809.24 μg h^-1 mg_cat^-1) and Faraday efficiency (FE) of (93.15%) at -1.8 V versus saturated calomel electrode (SCE). Furthermore, TiZn₂O₄@B-700 exhibited superior cycling stability and resistance to ionic interference. Moreover, density functional theory (DFT) calculations indicated that incorporating B increased the electron transfer rate and reduced the free energy required for the rate-limiting step of ammonia production via the NO₃RR, thereby increasing the ammonia yield. This study provides a new concept for designing catalysts for green ammonia synthesis.

Keywords: Ammonia production; Cathode catalyst; Composite material; Electrocatalytic nitrate reduction reaction (NO(3)RR); Mechanism study.