物理化学学报 >> 2021, Vol. 37 >> Issue (8): 2010073.doi: 10.3866/PKU.WHXB202010073

所属专题: 二维光催化材料

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二维/二维FeNi-LDH/g-C3N4复合光催化剂用于促进CO2光还原反应

李瀚, 李芳, 余家国, 曹少文()   

  • 收稿日期:2020-10-29 录用日期:2020-12-02 发布日期:2020-12-21
  • 通讯作者: 曹少文 E-mail:swcao@whut.edu.cn
  • 基金资助:
    国家自然科学基金(51922081);国家自然科学基金(21773179);国家自然科学基金(51961135303);国家自然科学基金(51932007);国家自然科学基金(U1705251);国家重点研发计划(2018YFB1502001);湖北省自然科学基金(2017CFA031);中央高校基本科研业务费(WUT: 2019-III-196);中央高校基本科研业务费(2020-YB-010)

2D/2D FeNi-LDH/g-C3N4 Hybrid Photocatalyst for Enhanced CO2 Photoreduction

Han Li, Fang Li, Jiaguo Yu, Shaowen Cao()   

  • Received:2020-10-29 Accepted:2020-12-02 Published:2020-12-21
  • Contact: Shaowen Cao E-mail:swcao@whut.edu.cn
  • About author:Shaowen Cao, Email: swcao@whut.edu.cn
  • Supported by:
    the National Natural Science Foundation of China(51922081);the National Natural Science Foundation of China(21773179);the National Natural Science Foundation of China(51961135303);the National Natural Science Foundation of China(51932007);the National Natural Science Foundation of China(U1705251);the National Key Research and Development Program of China(2018YFB1502001);the Natural Science Foundation of Hubei Province of China(2017CFA031);the Fundamental Research Funds for the Central Universities, China(WUT: 2019-III-196);the Fundamental Research Funds for the Central Universities, China(2020-YB-010)

摘要:

本研究工作使用尿素作为前驱体,通过两步煅烧法得到具有较高比表面积(97 m2·g-1)的g-C3N4纳米片。然后,通过简单的水热法将FeNi层状双氢氧化物(FeNi-LDH)助催化剂负载到g-C3N4纳米片上,从而获得基于g-C3N4的二维/二维复合光催化剂。实验表明,在二维/二维FeNi-LDH/g-C3N4复合材料上,光催化还原二氧化碳生成甲醇的产率要远高于在纯g-C3N4上获得甲醇的产率。一系列表征结果证明,FeNi-LDH/g-C3N4复合光催化剂的光吸收得到了增强,同时FeNi-LDH/g-C3N4复合光催化剂对二氧化碳的吸附能力也得到了提高。更重要的是,FeNi-LDH的引入有效地抑制了光生电子和空穴的复合,进一步提高了g-C3N4的光催化二氧化碳还原活性。此外,通过改变用于光催化性能测试的FeNi-LDH的负载量,发现FeNi-LDH的最佳负载量为4% (质量分数),对应的甲醇生产率为1.64 μmol·h-1·g-1,是纯的g-C3N4的6倍。这项研究提供了一种有效的策略,即通过负载层状铁镍双金属氢氧化物作为助催化剂来提高g-C3N4的光催化二氧化碳还原活性。

关键词: 光催化, 二维/二维异质结, 层状双氢氧化物, 太阳能转化, 电荷转移

Abstract:

Photocatalytic reduction of carbon dioxide into chemical fuels is a promising route to generate renewable energy and curtail the greenhouse effect. Therefore, various photocatalysts have been intensively studied for this purpose. Among them, g-C3N4, a 2D metal-free semiconductor, has been a promising photocatalyst because of its unique properties, such as high chemical stability, suitable electronic structure, and facile preparation. However, pristine g-C3N4 suffers from low solar energy conversion efficiency, owing to its small specific surface area and extensive charge recombination. Therefore, designing g-C3N4 (CN) nanosheets with a large specific surface area is an effective strategy for enhancing the CO2 reduction performance. Unfortunately, the performance of CN nanosheets remains moderate due to the aforementioned charge recombination. To counter this issue, loading a cocatalyst (especially a two-dimensional (2D) one) can enable effective electron migration and suppress electron-hole recombination during photo-irradiation. Herein, CN nanosheets with a large specific surface area (97 m2·g-1) were synthesized by a two-step calcination method, using urea as the precursor. Following this, a 2D/2D FeNi-LDH/g-C3N4 hybrid photocatalyst was obtained by loading a FeNi layered double hydroxide (FeNi-LDH) cocatalyst onto CN nanosheets by a simple hydrothermal method. It was found that the production rate of methanol from photocatalytic CO2 reduction over the FeNi-LDH/g-C3N4 composite is significantly higher than that of pristine CN. Following a series of characterization and analysis, it was demonstrated that the FeNi-LDH/g-C3N4 composite photocatalyst exhibited enhanced photo-absorption, which was ascribed to the excellent light absorption ability of FeNi-LDH. The CO2 adsorption capacity of the FeNi-LDH/g-C3N4 hybrid photocatalyst improved, owing to the large specific surface area and alkaline nature of FeNi-LDH. More importantly, the introduction of FeNi-LDH on the CN nanosheet surface led to the formation of a 2D/2D heterojunction with a large contact area at the interface, which could promote the interfacial separation of charge carriers and effectively inhibit the recombination of the photogenerated electrons and holes. This subsequently resulted in the enhancement of the CO2 photo-reduction activity. In addition, by altering the loading amount of FeNi-LDH for photocatalytic performance evaluation, it was found that the optimal loading amount was 4% (w, mass fraction), with a methanol production rate of 1.64 μmol·h-1·g-1 (approximately 6 times that of pure CN). This study provides an effective strategy to improve the photocatalytic CO2 reduction activity of g-C3N4 by employing 2D layered double hydroxide as the cocatalyst. It also proposes a protocol for the successful design of 2D/2D photocatalysts for solar energy conversion.

Key words: Photocatalysis, 2D materials, Layered double hydroxide, Solar energy conversion, Charge transfer

MSC2000: 

  • O643