摘要
光催化技术通过直接利用太阳光来驱动一系列化学反应,被认为是合成精细化学品的有效手段.光催化反应条件简单温和,避免了传统热催化有机反应所需要的苛刻条件,且有效减少副反应的发生,提高催化反应选择性.传统的半导体光催化剂在光吸收能力和活化有机反应底物等方面均存在一些劣势.近年来,基于贵金属纳米颗粒局域表面等离激元共振效应的新型光催化剂被认为是一种理想的可见光光催化材料,并已受到了广泛关注.通常单一组分的贵金属等离激元纳米颗粒在光催化有机反应中依然表现出一定的局限性.近年来,科研人员发展了一些双金属组分等离激元光催化剂体系,将等离激元组分(如Au)作为光能收集器,与具有催化活性的金属组分(如Pd)耦合形成合金或异质结构,可以实现较好的光催化性能.然而,对双金属组分等离激元光催化的催化微观机制理解仍然存在很大挑战,尤其是光照激发之后如何在等离激元组分和催化活性组分之间实现能量转移,催化剂表面物理化学性质的改变如何促进化学反应的发生等问题值得进一步深入研究.本文以负载型金钯(AuPd)合金纳米颗粒光催化剂为研究对象,利用光照条件下原位X射线光电子能谱研究催化剂表面电荷态,发现在可见光照射下,AuPd合金纳米颗粒上原位形成了缺电子态的Pd位点(Pd^(δ+)),这在双金属组分AuPd合金纳米颗粒光催化中起着决定性作用.AuPd合金纳米颗粒光催化剂对可见光驱动的Heck交叉偶联反应表现出较好的转化率和选择性.光照条件下催化剂表面原位形成的Pd^(δ+)为Heck反应提供了理想的反应平台,在温和条件(40℃)下的催化效率与传统热催化条件(>100℃)下的催化反应相当.催化反应动力学研究结果表明,光催化过程可显著降低反应活化能.反应物分子吸附行为研究结果表明,碘苯分子是在AuPd合金纳米颗�
Plasmonic metal nanoparticles have emerged as important candidates for photocatalysis.Numerous studies have shown that coupling of a plasmonic component(such as Au)as the light energy harvester with a catalytically active metal component(such as Pd)to form hybrid or alloy structures could achieve enhanced catalytic performance.However,the microscopic mechanism relative to the multicomponent plasmonic photocatalysis is still elusive.Here,we find that the electron-deficient Pd sites(Pd^(δ+))on AuPd alloy nanoparticle were formed under visible light irradiation,which play a decisive role in the AuPd alloy nanoparticle photocatalysis.The in-situ formed Pd^(δ+)under irradiation offers ideal platform for the catalytic reaction which is comparable to that under thermal heating conditions(>100℃).The AuPd alloy nanoparticles show excellent conversion and selectivity for visible-light-driven Heck cross-coupling reaction under ambient conditions.The combination of experimental and density functional theory results suggest that the photocatalytic Heck reaction proceeds via a new radical-based single-electron transfer pathway on the AuPd alloy,and the in-situ formed Pd^(δ+)sites ideally provided efficient catalytic sites for the activation of reactant with much lower activation energy barrier under irradiation.The present work sheds light on the new mechanistic understandings of bimetallic plasmonic photocatalysis.
作者
王海凤
王凡
李小鹏
肖琪
罗维
许景三
Haifeng Wang;Fan Wang;Xiaopeng Li;Qi Xiao;Wei Luo;Jingsan Xu(State Key Laboratory for Modification of Chemical Fibers and Polymer Materials,College of Materials Science and Engineering,Donghua University,Shanghai 201620,China;Leibniz‐Institut für Katalyse e.V.an der Universität Rostock,Rostock 18059,Germany;School of Chemistry and Physics&Centre for Materials Science,Queensland University of Technology,Brisbane,QLD 4001,Australia)
基金
上海市科委浦江人才计划(21PJ1400400)
东华大学科研启动资金
中央高校基本科研业务费专项资金、东华大学研究生创新基金(CUSF-DH-D-2022006).
关键词
等离激元光催化
金钯合金
缺电子钯
表面电荷态
光催化Heck反应
Plasmonic photocatalysis
AuPd alloy
Electron-deficient Pd
Surface charge state
Photocatalytic Heck reaction
