催化学报 ›› 2024, Vol. 63: 176-189.DOI: 10.1016/S1872-2067(24)60077-X

• 论文 • 上一篇    下一篇

In2.77S4/K+掺杂g-C3N4自组装S型异质结光催化H2O和O2合成H2O2

张棋祺a, 苗慧b, 王俊c,*(), 孙涛a,*(), 刘恩周a,*()   

  1. a西北大学化工学院, 西安特种能源材料重点实验室, 陕西西安 710127
    b西北大学物理学院, 陕西西安 710127
    c武汉大学电气与自动化学院, 湖北武汉 430072
  • 收稿日期:2024-04-30 接受日期:2024-06-13 出版日期:2024-08-18 发布日期:2024-08-19
  • 通讯作者: *电子信箱: liuenzhou@nwu.edu.cn (刘恩周),chemstst@nwu.edu.cn (孙涛),junwangwhu@whu.edu.cn (王俊).
  • 基金资助:
    国家自然科学基金(22378326);国家自然科学基金(22078261);国家自然科学基金(11974276);陕西省自然科学基础研究计划项目(2023-JC-YB-115);陕西省重点科技创新团队项目(2022TD-33);陕西省秦创原项目(QCYRCXM-2022-213)

Self-assembled S-scheme In2.77S4/K+-doped g-C3N4 photocatalyst with selective O2 reduction pathway for efficient H2O2 production using water and air

Qiqi Zhanga, Hui Miaob, Jun Wangc,*(), Tao Suna,*(), Enzhou Liua,*()   

  1. aSchool of Chemical Engineering/Xi’an Key Laboratory of Special Energy Materials, Northwest University, Xi’an 710127, Shaanxi, China
    bSchool of Physics, Northwest University, Xi’an 710127, Shaanxi, China
    cSchool of Electrical Engineering and Automation, Wuhan University, Wuhan 430072, Hubei, China
  • Received:2024-04-30 Accepted:2024-06-13 Online:2024-08-18 Published:2024-08-19
  • Contact: *E-mail: liuenzhou@nwu.edu.cn (E. Liu), chemstst@nwu.edu.cn (T. Sun), junwangwhu@whu.edu.cn (J. Wang).
  • Supported by:
    National Natural Science Foundation of China(22378326);National Natural Science Foundation of China(22078261);National Natural Science Foundation of China(11974276);Natural Science Basic Research Program of Shaanxi Province(2023-JC-YB-115);Shaanxi Key Science and Technology Innovation Team Project(2022TD-33);Qin Chuangyuan project of Shaanxi Province(QCYRCXM-2022-213)

摘要:

过氧化氢(H2O2)是具有广泛用途的绿色化学品, 也是理想的能源载体. 开发绿色高效的H2O2合成工艺是当前的研究热点, 采用光催化技术将H2O和O2转化为H2O2是一种理想的H2O2制备策略. 目前, 设计开发具有高效光能利用率、电荷分离和利用效率的催化剂是实现该技术应用的关键. 石墨相氮化碳(g-C3N4)因其能够产生1,4-内过氧化物和超氧自由基而具有优异的双电子氧还原选择性; 课题组前期研究发现(Chem. Eng. J., 2024, 482, 148844.), 氰基修饰的K+插层结晶性g-C3N4纳米片(KCN)具有优异的体相电荷转移效率. 然而, 由于KCN氧化能力不足, 表面电子空穴复合快, 难以实现水的高效氧化, H2O2产率较低. 通过构建S型异质结不仅能提高KCN电荷分离效率, 而且能增强其氧化能力, 有利于实现水氧化反应和氧还原反应的高效协同. In2.77S4价带空穴具有良好的氧化能力, 其能带与KCN匹配可形成S型异质结, 满足H2O和O2合成H2O2的热力学条件.

本文采用原位溶剂热法及煅烧法制备样品. 首先将KCN纳米片引入In2.77S4的生长体系中, 成功诱导了KCN与In2.77S4自组装, 最终形成了3D分级In2.77S4/KCN纳米花, 二者之间形成了紧密的2D/2D异质界面. 密度泛函理论计算、光电化学测试、电子顺磁共振和自由基捕获实验结果表明, In2.77S4和KCN之间形成了S型电荷迁移路径, 在能带弯曲、内建电场和库仑引力作用下, KCN价带空穴和In2.77S4导带电子在界面处快速复合, 使具有强氧化还原能力的In2.77S4价带空穴和KCN导带电子得到保留, 提高了载流子分离效率及水氧化反应热力学驱动力. 研究结果表明, 该异质结表面具有疏水性, 形成了气液固三相接触界面, 同时其独特的三维分级纳米结构加快了空气中O2向催化剂活性中心的扩散和吸附. 氧还原反应能垒计算表明, 异质结表面的O2质子化和H2O2脱附步骤能垒显著降低, 有效增强了表面反应动力学. 进一步分析发现, O2先与电子反应生成超氧自由基, 再与两个质子和电子反应生成H2O2, 而H2O与空穴发生氧化反应产生O2和质子, 有效促进了上述两步单电子还原过程. 在可见光照射下, 最优样品的H2O2生成速率可达1.36 mmol g-1 h-1, 分别是KCN和In2.77S4的9.2倍和4.1倍, 且具有较好的循环稳定性.

综上所述, 本文从反应热力学和动力学角度出发, 设计合成了具有紧密连接界面的3D分级结构疏水型S型异质结, 有效提升了H2O和O2合成H2O2的效率, 为开发无牺牲剂参与的绿色H2O2合成体系提供了理论及实验依据.

关键词: 光催化, 过氧化氢合成, 钾掺杂氮化碳, 硫化铟, S型异质结

Abstract:

The development of an efficient artificial H2O2 photosynthesis system is a challenging work using H2O and O2 as starting materials. Herein, 3D In2.77S4 nanoflower precursor was in-situ deposited on K+-doped g-C3N4 (KCN) nanosheets using a solvothermal method, then In2.77S4/KCN (IS/KCN) heterojunction with an intimate interface was obtained after a calcination process. The investigation shows that the photocatalytic H2O2 production rate of 50IS/KCN can reach up to 1.36 mmol g-1 h-1 without any sacrificial reagents under visible light irradiation, which is 9.2 times and 4.1 times higher than that of KCN and In2.77S4, respectively. The enhanced activity of the above composite can be mainly attributed to the S-scheme charge transfer route between KCN and In2.77S4 according to density functional theory calculations, electron paramagnetic resonance and free radical capture tests, leading to an expanded light response range and rapid charge separation at their interface, as well as preserving the active electrons and holes for H2O2 production. Besides, the unique 3D nanostructure and surface hydrophobicity of IS/KCN facilitate the diffusion and transportation of O2 around the active centers, the energy barriers of O2 protonation and H2O2 desorption steps are effectively reduced over the composite. In addition, this system also exhibits excellent light harvesting ability and stability. This work provides a potential strategy to explore a sustainable H2O2 photosynthesis pathway through the design of heterojunctions with intimate interfaces and desired reaction thermodynamics and kinetics.

Key words: Photocatalysis, H2O2 production, K+-doped g-C3N4, In2.77S4, S-scheme heterojunction