Acta Chimica Sinica ›› 2022, Vol. 80 ›› Issue (6): 772-780.DOI: 10.6023/A22010030 Previous Articles     Next Articles



王丹a, 封波a, 张晓昕b, 刘亚楠a, 裴燕a, 乔明华a,*(), 宗保宁b,*()   

  1. a 复旦大学化学系 上海市分子催化和功能材料重点实验室 上海 200438
    b 中国石化石油化工科学研究院 催化材料与反应工程国家重点实验室 北京 100083
  • 投稿日期:2022-01-16 发布日期:2022-07-07
  • 通讯作者: 乔明华, 宗保宁
  • 基金资助:
    国家重点研发专项项目(2016YFB0301602); 石油化工催化材料与反应工程国家重点实验室(中国石油化工股份有限公司石油化工科学研究院)开放基金; 国家自然科学基金(21872035); 上海市科委科技基金(19DZ2270100)

Nitrogen-doped Carbon Pyrolyzed from ZIF-8 for Electrocatalytic Oxygen Reduction to Hydrogen Peroxide

Dan Wanga, Bo Fenga, Xiaoxin Zhangb, Yanan Liua, Yan Peia, Minghua Qiaoa(), Baoning Zongb()   

  1. a Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Department of Chemistry, Fudan University, Shanghai 200438, China
    b State Key Laboratory of Catalytic Materials and Reaction Engineering, Research Institute of Petroleum Processing, SINOPEC, Beijing 100083, China
  • Received:2022-01-16 Published:2022-07-07
  • Contact: Minghua Qiao, Baoning Zong
  • Supported by:
    National Key Research and Development Project of China(2016YFB0301602); State Key Laboratory of Catalytic Materials and Reaction Engineering (RIPP, SINOPEC); National Natural Science Foundation of China(21872035); Science and Technology Commission of Shanghai Municipality(19DZ2270100)

Electrochemical production of H2O2 from O2 via the two-electron reduction reaction (2e-ORR) is a green and safe process that is being heavily investigated. Zeolitic imidazolate frameworks (ZIF) as a subclass of metal-organic frameworks (MOFs) have attracted enormous scientific interests due to their high porosity, excellent mechanical stability, tunable surface properties, and exceptional chemical and thermal stabilities. Herein, a series of pyrolyzed ZIF catalysts (p-ZIF) were synthesized by treating 2-methylimidazole zinc salt (ZIF-8) at high temperatures (900, 950 and 1000 ℃). During pyrolysis, zinc was vaporized, leaving the metal-free nitrogen-doped porous graphitic carbon materials. The effects of the pyrolysis temperature on the structure and catalytic performance of the p-ZIF catalysts in 2e-ORR were systematically studied. In 2e-ORR in an acidic electrolyte, the p-ZIF catalysts displayed low overpotential, low Tafel slope, and negligible activity loss after 3000 cycles of accelerated durability testing (ADT). In particular, the p-ZIF-950 catalyst possessed the highest H2O2 partial current of 0.185 mA at 0 V vs. RHE, followed by the p-ZIF-900 (0.146 mA) and p-ZIF-1000 (0.135 mA) catalysts. The H2O2 selectivity over the p-ZIF-950 catalyst was also constantly higher than those over the other two p-ZIF catalysts across the potential range investigated and maximized at 89.2%. Highly efficient and durable H2O2 production was demonstrated on the p-ZIF-950 catalyst by the linear accumulation of H2O2 to 522 mmol•gcat-1 within 6 h, translating to an H2O2 production rate of 87 mmol•gcat-1•h-1. The morphology, composition, carbon defect, texture, and surface chemical state were characterized by techniques such as transmission electron microscopy (TEM), elemental analysis, Raman spectroscopy, N2 physisorption, and X-ray photoelectron spectroscopy (XPS). The p-ZIF catalysts not only nicely carried over the regular rhombic dodecahedral morphology of ZIF-8, but also possessed abundant amount of nitrogen, high specific surface area, and hierarchical pore structure. According to the characterization results, the specific surface area and carbon defect are unlikely the key factors that determine the catalytic performance, while the evolutions of the average pore size and surface content of graphitic N mimicked those of the H2O2 partial current and selectivity on the p-ZIF catalysts. In light of the literature works, the large pore size is proposed to facilitate the in-diffusion of O2 and out-diffusion of H2O2, while the graphitic N is able to enhance the activation of O2 and desorption of H2O2, both of which are beneficial to the kinetics of the 2e-ORR reaction.

Key words: hydrogen peroxide, ZIF-8, pyrolysis, electrocatalysis, oxygen reduction reaction