催化学报 ›› 2023, Vol. 47: 254-264.DOI: 10.1016/S1872-2067(23)64393-1

• 论文 • 上一篇    下一篇

Co纳米颗粒修饰的相结CdS光氧化还原合成氢化安息香和产氢

张美玉a,c,1, 李孔明a,1, 胡春联a, 马康伟a, 孙万军a, 黄现强c,*(), 丁勇a,b,*()   

  1. a兰州大学功能有机分子化学国家重点实验室, 甘肃省先进催化重点实验室, 化学化工学院, 甘肃兰州730000
    b中国科学院兰州化学物理研究所, 羰基合成与选择氧化国家重点实验室, 甘肃兰州730000
    c聊城大学化学化工学院, 山东省化学储能与新型电池技术重点实验室, 山东聊城252059
  • 收稿日期:2022-11-24 接受日期:2023-01-04 出版日期:2023-04-18 发布日期:2023-03-20
  • 通讯作者: *电子信箱: hxq@lcu.edu.cn (黄现强),dingyong1@lzu.edu.cn (丁勇).
  • 作者简介:1共同第一作者.
  • 基金资助:
    国家自然科学基金(22075119);甘肃省自然科学基金(21JR7RA440)

Co nanoparticles modified phase junction CdS for photoredox synthesis of hydrobenzoin and hydrogen evolution

Meiyu Zhanga,c,1, Kongming Lia,1, Chunlian Hua, Kangwei Maa, Wanjun Suna, Xianqiang Huangc,*(), Yong Dinga,b,*()   

  1. aState Key Laboratory of Applied Organic Chemistry, Key Laboratory of Advanced Catalysis of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, Gansu, China
    bState Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, Gansu, China
    cShandong Provincial Key Laboratory of Chemical Energy Storage and Novel Cell Technology, School of Chemistry & Chemical Engineering, Liaocheng University, Liaocheng 252059, Shandong, China
  • Received:2022-11-24 Accepted:2023-01-04 Online:2023-04-18 Published:2023-03-20
  • Contact: *E-mail: hxq@lcu.edu.cn (X. Huang),dingyong1@lzu.edu.cn (Y. Ding).
  • About author:1Contributed equally to this work.
  • Supported by:
    National Natural Science Foundation of China(22075119);Natural Science Foundation of Gansu Province(21JR7RA440)

摘要:

为了应对日益加剧的环境和能源危机, 利用太阳能生产化学燃料迫在眉睫. 太阳能光催化水分解产氢因其可利用阳光生产绿色H2燃料被认为是一种廉价且环境友好的技术. 但是, 要实现理想的产H2通常依赖于牺牲试剂的消耗, 这会增加成本并会产生无利用价值的氧化产物. 实际上, 生物质(醇、胺和糖)可以替代牺牲试剂, 在产生H2的同时获得有经济价值的化学品. 其中, 苯甲醇的C-C偶联氧化产物包括安息香、脱氧安息香、氢化安息香等, 这些氧化产物是合成具有生物活性聚合物引发剂的重要结构基序. 然而, 目前光催化氧化苯甲醇的主要产物是苯甲醛, 很少得到高选择性的C-C偶联产物. 因此, 设计一种能够同时实现光催化产氢和C-C偶联产物的合成的新型光催化剂是光催化领域面临的重要挑战.

本文制备了Co纳米颗粒负载的共暴露(001)/(101)晶面的相结CdS, 并应用于光催化氧化苯甲醇合成氢化安息香和产氢. 可见光下照射9 h后, HC-CdS2/Co的光催化产氢速率达到11 mmol·g-1, 分别是C-CdS/Co和HC-CdS2产氢速率的4.7倍和34倍. 在HC-CdS2上负载Co后, 氢化安息香的选择性由12%提高到97%. 高分辨透射电子显微镜结果证实了相结和晶面结的存在. DFT计算得到H-CdS(101)和H-CdS(001)的能级位置和相应的功函数, 可以确定在H-CdS(101)和H-CdS(001)之间形成了晶面结. 当H-CdS(101)和H-CdS(001)形成晶面结时, 热平衡条件下的载流子扩散在H-CdS(101)和H-CdS(001)界面处形成耗尽层, 最终在界面处形成内置电场和能带弯曲, 有助于加速载流子的分离.

进一步探究了Co纳米颗粒在光催化氧化苯甲醇体系中所起的作用. 利用紫外光电子能谱研究了HC-CdS2与Co之间的界面电荷转移, 结果表明, HC-CdS2与Co之间形成了典型的肖特基结, 从而有效促进载流子的分离, 有利于驱动目标催化剂表面的光氧化还原催化反应. 同时, Co纳米颗粒被认为是质子还原的活性位点. 利用时间分辨光致发光光谱研究了Co纳米颗粒对HC-CdS2光激发电子-空穴对寿命的影响. 光激发载流子延迟的寿命证明Co助催化剂作为电子接收器, 为电子传递提供了有效的中继站, 从而抑制了载流子的复合. 通过对电子顺磁共振(EPR)谱图进行分析, 在乙腈-苯甲醇混合溶液中发现DMPO-⦁C7H8O自旋加合物的六重特征峰, 证实了⦁C7H8O自由基的形成. 综上, HC-CdS2/Co增强的光催化合成氢化安息香和产氢性能源于HC-CdS2/Co中相结、晶面结和肖特基结诱导的内置电场, 极大地促进了光生载流子的分离.

关键词: 晶面结, 内建电场, 产H2, 氢化安息香, 肖特基结

Abstract:

Coupling photocatalytic H2 production with organic synthesis attracts immense attention in the field of energy research through collecting the sustainable green energy and high value-added products. Although tremendous progress has been made towards devoting to the oxidation of benzyl alcohol, only very limited study can meet high selectivity of the C-C coupled products during the process of H2 evolution. Herein, the phase junction CdS (HC-CdS2) consisting of hexagonal CdS (H-CdS) with co-exposed facets of (001) and (101) and cubic CdS (C-CdS) was fabricated by fine tuning the proportion of cadmium and sulfur sources for photocatalytic H2 production and selective benzyl alcohol oxidation. The HC-CdS2 is able to maintain a robust H2 evolution rate of 11 mmol g-1 by loading cobalt as cocatalyst, which is 4.7 and 34 times higher than those for C-CdS/Co and HC-CdS2, respectively. Especially, the selectivity of hydrobenzoin elevated from 12% to 97% after loading Co on HC-CdS2 after light irradiation for 9 h. EPR and in situ DRIFTS tests indicated that the hydrogen atom from the C-H bond of benzyl alcohol was abstracted to form ·C7H8O free radical. Subsequently, the ·C7H8O free radical coupling yield hydrobenzoin as the final C-C coupling product by ameliorating charge separation resulted from the internal electric fields of facet junction and phase junction CdS and Schottky junction between CdS and Co. The strategy can be further extended to various aromatic alcohols and provide a reference for highly selective synthesis of high-added value chemicals coupled with H2 evolution.

Key words: Facet junction, Internal electric field, H2 evolution, Hydrobenzoin, Schottky junction