{"title":"Ni-loaded Co-NC catalysts for promoting electrocatalytic nitrate reduction to ammonia","authors":"Fang Zhao, Yidi Liu, Chengjie Li, Zhen Yuan, Qianqian Hua, Liguo Gao, Xuefeng Ren, Peixia Yang, Anmin Liu","doi":"10.1039/d4cy00942h","DOIUrl":null,"url":null,"abstract":"The Haber–Bosch process, the traditional method of ammonia synthesis, uses hydrogen derived from steam reforming of hydrocarbons; and involves harsh operating conditions of high temperatures (300–600 °C) and pressures (200–400 atm), expending a vast amount of energy each year. Recently, there has been a lot of interest in the electrochemical nitrogen reduction process (NRR) to NH<small><sub>3</sub></small>, which is inspired by natural microbial nitrogen fixation. However, the stable N<img alt=\"[triple bond, length as m-dash]\" border=\"0\" src=\"https://www.rsc.org/images/entities/char_e002.gif\">N violent hydrogen evolution reaction hindered the development of the NRR. In comparison, the electrocatalytic nitrate reduction reaction (NO<small><sub>3</sub></small>RR) has significant advantages. The much lower dissociation energy of N<img alt=\"[double bond, length as m-dash]\" border=\"0\" src=\"https://www.rsc.org/images/entities/char_e001.gif\">O (204 kJ mol<small><sup>−1</sup></small>) is required; nitrate is widespread in surface water. Herein, an electrocatalyst loaded with Ni onto CoZn@ZIF by a simple impregnation method is reported, which possesses a nitrogen-doped graphitic carbon structure after pyrolytic carbonization. Detailed experiments showed that the NiCo-NC catalyst significantly accelerated the NO<small><sub>3</sub></small>RR compared to Co-NC. NiCo-NC exhibited remarkable NO<small><sub>3</sub></small>RR activity. At −0.6 V and −1.1 V, ammonia yields of 5.01 mg cm<small><sup>−2</sup></small> h<small><sup>−1</sup></small> and 10.12 mg cm<small><sup>−2</sup></small> h<small><sup>−1</sup></small> were obtained, with FEs reaching 92.75% and 96.65%, respectively. The catalyst showed excellent electrochemical stability in 24-hour electrolysis experiments and five-cycle stability tests. Meanwhile, <small><sup>15</sup></small>N isotope labeling experiments further verified the source of N in NH<small><sub>4</sub></small><small><sup>+</sup></small> from NO<small><sub>3</sub></small><small><sup>−</sup></small>.</img></img>","PeriodicalId":66,"journal":{"name":"Catalysis Science & Technology","volume":null,"pages":null},"PeriodicalIF":4.4000,"publicationDate":"2024-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Catalysis Science & Technology","FirstCategoryId":"92","ListUrlMain":"https://doi.org/10.1039/d4cy00942h","RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"CHEMISTRY, PHYSICAL","Score":null,"Total":0}
引用次数: 0
Abstract
The Haber–Bosch process, the traditional method of ammonia synthesis, uses hydrogen derived from steam reforming of hydrocarbons; and involves harsh operating conditions of high temperatures (300–600 °C) and pressures (200–400 atm), expending a vast amount of energy each year. Recently, there has been a lot of interest in the electrochemical nitrogen reduction process (NRR) to NH3, which is inspired by natural microbial nitrogen fixation. However, the stable NN violent hydrogen evolution reaction hindered the development of the NRR. In comparison, the electrocatalytic nitrate reduction reaction (NO3RR) has significant advantages. The much lower dissociation energy of NO (204 kJ mol−1) is required; nitrate is widespread in surface water. Herein, an electrocatalyst loaded with Ni onto CoZn@ZIF by a simple impregnation method is reported, which possesses a nitrogen-doped graphitic carbon structure after pyrolytic carbonization. Detailed experiments showed that the NiCo-NC catalyst significantly accelerated the NO3RR compared to Co-NC. NiCo-NC exhibited remarkable NO3RR activity. At −0.6 V and −1.1 V, ammonia yields of 5.01 mg cm−2 h−1 and 10.12 mg cm−2 h−1 were obtained, with FEs reaching 92.75% and 96.65%, respectively. The catalyst showed excellent electrochemical stability in 24-hour electrolysis experiments and five-cycle stability tests. Meanwhile, 15N isotope labeling experiments further verified the source of N in NH4+ from NO3−.
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