物理化学学报 >> 2018, Vol. 34 >> Issue (8): 938-944.doi: 10.3866/PKU.WHXB201801263

所属专题： 绿色化学

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1-辛基-3-甲基咪唑功能化石墨片负载氧化亚铜催化二氧化碳电还原制乙烯

宁汇1,2,王文行1,毛勤虎1,郑诗瑞1,杨中学1,赵青山1,吴明铂1,*()   

  1. 1 中国石油大学(华东)化学工程学院，重质油国家重点实验室，山东 青岛 266580
    2 中国科学院炭材料重点实验室(中国科学院山西煤炭化学研究所)，太原 030001
  • 收稿日期:2018-01-03 发布日期:2018-04-03
  • 通讯作者: 吴明铂 E-mail:wumb@upc.edu.cn
  • 基金资助:
    中科院炭材料重点实验室开放基金(KLCMKFJJ1706);国家自然科学基金(51372277);国家自然科学基金(51572296);国家自然科学基金(U1662113)

Catalytic Electroreduction of CO2 to C2H4 Using Cu2O Supported on 1-Octyl-3-methylimidazole Functionalized Graphite Sheets

Hui NING1,2,Wenhang WANG1,Qinhu MAO1,Shirui ZHENG1,Zhongxue YANG1,Qingshan ZHAO1,Mingbo WU1,*()   

  1. 1 State Key Laboratory of Heavy Oil Processing, College of Chemical Engineering, China University of Petroleum, Qingdao 266580, Shandong Province, P. R. China
    2 CAS Key Laboratory of Carbon Materials, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, P. R. China
  • Received:2018-01-03 Published:2018-04-03
  • Contact: Mingbo WU E-mail:wumb@upc.edu.cn
  • Supported by:
    The project was supported by the CAS Key Laboratory of Carbon Materials, China(KLCMKFJJ1706);the National Natural Science Foundation of China(51372277);the National Natural Science Foundation of China(51572296);the National Natural Science Foundation of China(U1662113)

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摘要：

电催化还原二氧化碳制备乙烯是备受关注的热点问题，高效催化剂的制备是决定乙烯产率的关键因素。本文在1-辛基-3-甲基咪唑氯的水溶液(OmimCl : H2O = 1 : 5，体积比)中通过电剥离石墨棒制备了1-辛基-3-甲基咪唑功能化石墨片(ILGS)，在水溶液中负载氧化亚铜后得到氧化亚铜/1-辛基-3-甲基咪唑功能化石墨片复合材料(Cu2O/ILGS)，通过透射电镜、X射线光电子能谱、拉曼光谱和X射线衍射对其组成和结构进行了系统研究，发现ILGS由多层石墨烯组成，表面富含缺陷。这些缺陷被1-辛基-3-甲基咪唑通过共价键修饰，形成类似鸟巢状的微结构，平均直径5 nm的Cu2O纳米颗粒在石墨片表面均匀分散。在0.1 mol∙L−1碳酸氢钾水溶液中，研究了Cu2O/ILGS在不同电压下催化CO2电还原的性能。结果表明，Cu2O是主要活性中心并在CO2还原过程中被逐渐还原成铜，导致产物的法拉第效率随着反应时间而变，在−1.3 V (vs RHE)电压下，乙烯的法拉第效率最高达到14.8%，其性能归因于Cu2O/ILGS复合材料中的鸟巢状微结构对Cu2O纳米颗粒的稳定作用。

关键词: 氧化亚铜, 石墨片, 二氧化碳还原, 乙烯, 离子液体

Abstract:

The electrocatalytic reduction of CO2 to C2H4 is a topic of great interest. It is known that the preparation of efficient catalysts for this transformation is the key factor that determines the yield of C2H4. In this study, we prepared 1-octyl-3-methylimidazole functionalized graphite sheets (ILGS) in a facile manner by the electro-exfoliation of pure graphite rod in an aqueous solution of 1-octyl-3-methylimidazolium chloride (OmimCl : H2O = 1 : 5, V/V) at 10 V. They were then dispersed in an aqueous solution of copper chloride and sodium citrate. Subsequent reduction with sodium borohydride led to the formation of a composite comprised of cuprous oxide supported on Omim-functionalized graphite sheets (Cu2O/ILGS). This composite was found to be an efficient catalyst for the electroreduction of carbon dioxide to ethylene. The as-made materials were characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and X-ray diffraction (XRD). The TEM images showed that the ILGS were composed of multiple layers of graphene. The XRD pattern and Raman spectrum indicated that the surface of the ILGS possessed several defects. In the electro-exfoliation process, the defects in the ILGS were modified in situ by covalent bonding with Omim groups, which was also confirmed by XPS. The Cu2O nanoparticles with an average diameter of 5 nm were uniformly distributed on the surface of the ILGS because the Omim groups grafted to the graphite sheets acted as anchors and prevented their aggregation by the steric effect. The electrocatalytic activities of Cu2O/ILGS for CO2 reduction were measured at different voltages in 0.1 mol L–1 KHCO3 aqueous solution under ambient temperature and pressure. These experiments showed that the catalytic performance of the Cu2O/ILGS composite was determined by cuprous oxide, while the ILGS displayed nearly no catalytic activity in the electroreduction of carbon dioxide. The faradaic efficiency of hydrogen and carbon dioxide reduction products changed with the reaction time because of the reduction of Cu2O to Cu under the electroreduction conditions. The faradaic efficiency of ethylene was ~14.8% at –1.3 V (versus reversible hydrogen electrode). The performance of Cu2O/ILGS in the catalytic electroreduction of carbon dioxide was attributed to the stabilization of the Cu2O nanoparticles by the nest-like microstructures in the Cu2O/ILGS composite.

Key words: Cu2O, Graphite sheets, CO2 reduction, Ethylene, Ionic liquids