催化学报 ›› 2021, Vol. 42 ›› Issue (5): 781-794.DOI: 10.1016/S1872-2067(20)63690-7

• 论文 • 上一篇    下一篇

MgO和Au纳米颗粒共修饰g-C3N4光催化剂增强CO2-H2O光催化反应过程

李乃旭a,c, 黄美优a, 周建成a,c,*(), 刘茂昌b,d,#(), 敬登伟b,$()   

  1. a东南大学化学与化工学院, 江苏南京211189
    b西安交通大学动力工程多相流国家重点实验室, 国际可再生能源研究中心, 陕西西安710049
    c中国林业科学研究院林产化学工业研究所, 江苏省生物质能源与材料重点实验室, 江苏南京210042
    d西安交通大学苏州研究院, 江苏苏州215123
  • 收稿日期:2020-05-09 接受日期:2020-05-09 出版日期:2021-05-18 发布日期:2021-01-29
  • 通讯作者: 周建成,刘茂昌,敬登伟
  • 基金资助:
    国家重点研究发展计划(2018YFB1502000);英国皇家学会牛顿高级学者基金(NA191163);国家自然科学基金(21576050);国家自然科学基金(51602052);国家自然科学基金(51672210);江苏省自然科学基金(BK20150604);中央高校基本科研业务费专项资金资助(3207045403);中央高校基本科研业务费专项资金资助(3207045409);中央高校基本科研业务费专项资金资助(3207046414);江苏省生物质与材料重点实验室基金(JSBEM202001);江苏省高校优势学科建设工程资助项目(PAPD);东南大学仲英青年学者

MgO and Au nanoparticle Co-modified g-C3N4 photocatalysts for enhanced photoreduction of CO2 with H2O

Naixu Lia,c, Meiyou Huanga, Jiancheng Zhoua,c,*(), Maochang Liub,d,#(), Dengwei Jingb,$()   

  1. aSchool of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, Jiangsu, China
    bInternational Research Center for Renewable Energy, State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an 710049, Shaanxi, China
    cJiangsu Key Laboratory for Biomass Energy and Material, Institute of Chemical Industry of Forest Products, Chinese Academy of Forestry, Nanjing 210042, Jiangsu, China
    dSuzhou Academy of Xi’an Jiaotong University, Suzhou 215123, Jiangsu, China
  • Received:2020-05-09 Accepted:2020-05-09 Online:2021-05-18 Published:2021-01-29
  • Contact: Jiancheng Zhou,Maochang Liu,Dengwei Jing
  • About author:$ Tel: +86-29-82668721; E-mail: dwjing@mail.xjtu.edu.cn
    # Tel: +86-29-82668296-18; E-mail: maochangliu@mail.xjtu.edu.cn;
    * Tel: +86-25-52090618; E-mail: jczhou@seu.edu.cn;
  • Supported by:
    National Key Research and Development Program of China(2018YFB1502000);Newton Advanced Fellowship of the Royal Society(NA191163);National Natural Science Foundation of China(21576050);National Natural Science Foundation of China(51602052);National Natural Science Foundation of China(51672210);Jiangsu Provincial Natural Science Foundation of China(BK20150604);Fundamental Research Funds for the Central Universities of China(3207045403);Fundamental Research Funds for the Central Universities of China(3207045409);Fundamental Research Funds for the Central Universities of China(3207046414);Foundation of Jiangsu Key Laboratory for Biomass Energy and Material(JSBEM202001);Priority Academic Program Development (PAPD) of Jiangsu Higher Education Institutions;Zhongying Young Scholar of Southeast University

摘要:

光催化CO2还原制备太阳燃料被广泛关注并逐渐形成研究热点, 该过程利用可再生清洁能源太阳能, 在低温低压的温和条件下驱动CO2还原制备CO、CH4、CH3OH等燃料气体或者高附加值的碳氢化合物. 半导体光催化剂能够将清洁的太阳能有效地转化为化学能, 其中, g-C3N4由于其成本低、毒性低、稳定性高和带隙窄等优点, 被广泛应用于光催化领域. 然而, 纯g-C3N4具有光利用效率低和光生电子-空穴复合率高的缺点, 导致光催化活性相对较低. 因此, 需要对g-C3N4进行修饰改性来提高其光催化性能. 一方面, MgO具有强大的CO2吸附能力, 可用于修饰半导体以提高光催化还原CO2的反应活性. 另一方面, 助催化剂尤其是贵金属, 不仅能够捕获电子以提高光生电子-空穴对的分离效率, 而且还能提供反应的活性位点. 本文通过沉淀和煅烧法制备了不同复合量的MgO-g-C3N4催化剂, 同时负载贵金属Au作为助催化剂, 用于光催化CO2和H2O反应, 考察MgO含量和不同贵金属助催化剂对光催化活性的影响. 发现Au和3% MgO共改性的g-C3N4光催化剂上表现出最佳的光催化性能, 3 h后CO, CH4, CH3OH和CH3CHO的产量分别高达423.9、83.2、47.2和130.4 μmol/g.

本文分别研究了MgO和贵金属Au作为助催化剂对光催化行为的影响. XPS结果表明, Au/MgO-g-C3N4纳米片中形成了Mg-N键; UV-vis漫反射光谱表明Au/MgO-g-C3N4复合催化剂能够大大地增强紫外和可见光的吸收, 且Au纳米颗粒具有表示等离子体共振(SPR)效应; PL光谱、TRPL光谱和光电化学测试都显示了MgO和Au的加入可以有效地提高光生电荷载流子的分离效率, 这是由于Mg-N键的存在以及Au纳米颗粒对电子的捕获作用. CO2吸附曲线证明了MgO的存在能够增强对CO2的吸附; CO2-TPD测试则表明CO2的有效吸附主要发生在MgO和Au纳米颗粒的界面处, 而该界面正是光生电子和活化吸附后的CO2反应的活性位点. 值得注意的是, 在Au/3% MgO-g-C3N4三元催化剂上CO的产量是纯g-C3N4的29倍. 实验和表征结果均表明, MgO和Au的共修饰显著提高了纯g-C3N4的光催化活性, 这是由于三元光催化剂各组分之间的协同作用所致. 助催化剂MgO可以激活CO2(吸附在MgO和Au颗粒之间的界面), 并且MgO-g-C3N4纳米片中形成的Mg-N键在电荷转移中起着重要作用. 同时, Au颗粒修饰的MgO-g-C3N4可以通过SPR效应增加可见光的吸收, 并进一步降低H2O对CO2的光还原活化能; 且Au纳米颗粒能够捕获电子, 从而促进光生载流子的分离. 本研究通过MgO和Au纳米颗粒共修饰的方法改性传统的光催化剂, 具有光催化还原CO2的应用前景.

关键词: CO2光还原, MgO, Au, g-C3N4, 光催化, 协同效应, 助催化剂

Abstract:

The photoreduction of CO2 to achieve high-value-added hydrocarbons under simulated sunlight irradiation is advantageous, but challenging. In this study, a series of MgO and Au nanoparticle-co-modified g-C3N4 photocatalysts were synthesized and subsequently applied for the photocatalytic reduction of CO2 with H2O under simulated solar irradiation. The best photocatalytic performance was demonstrated by the Au and 3% MgO-co-modified g-C3N4 photocatalysts with CO, CH4, CH3OH, and CH3CHO yields of 423.9, 83.2, 47.2, and 130.4 μmol/g, respectively, in a 3-h reaction. We investigated the effects of MgO and Au as cocatalysts on photocatalytic behaviors, respectively. The characterizations and experimental results showed that the enhanced photocatalytic activity was due to the synergistic effect among the components of the ternary photocatalyst. The cocatalyst MgO can activate CO2 (adsorbed at the interface between the MgO and Au particles), and the Mg-N bonds formed in the MgO-CN nanosheets played an important role in the charge transfer. Meanwhile, the Au particles that were modified into MgO/g-C3N4 can increase the absorption of visible light via the surface plasmon resonance effect and further reduce the activation energies of the photoreduction of CO2 using H2O. This study provided an effective method for the modification of traditional primary photocatalysts with promising performance for photocatalytic CO2 reduction.

Key words: CO2 photoreduction, MgO, Au, g-C3N4, Photocatalysis, Synergistic effect, Cocatalyst