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捕获激子的慢俄歇复合实现了高效的多电子转移
作者:小柯机器人 发布时间:2021/11/24 15:35:21

美国埃默里大学Tianquan Lian团队报道了在CdS–Pt纳米棒异质结构中,捕获激子的慢俄歇复合实现了高效的多电子转移。相关研究成果发表在2021年11月19日出版的《美国化学会杂志》。

太阳能-燃料转换反应通常需要多个质子耦合电子转移(PCET)过程,该过程由多个光子吸收产生的高能电子和/或空穴提供动力。光吸收体的多重电子转移与催化中心的多重PCET反应的有效耦合,是太阳能高效选择性转化为化学燃料的关键挑战之一。

该文中,研究人员研究了带有Pt尖端的量子受限CdS纳米棒中的多电子转移动力学,其中CdS棒作为光吸收器,Pt尖端作为催化中心。通过激发通量相关的瞬态吸收光谱测量,研究表明CdS棒中的多激子俄歇复合速率遵循载流子碰撞模型,knA=n2(n–1)/4k2A,双激子寿命(1/k2A)为2.0±0.2 ns。在CdS–Pt纳米棒中,从CdS导带边缘到Pt的电子转移动力学对激发通量的依赖性可以忽略不计,半衰期为5.6±0.6 ps。

由于与俄歇复合竞争,通过多电子转移到Pt的多激子解离效率从双激子态的100%降低到22激子态的~41%。n电荷分离态复合(Pt中有n个电子,CdS中有n个空穴)的半衰期从单电荷分离态的10μs降低到9个电荷分离态的42 ns。

该发现表明了在强光照下驱动多电子光催化反应和通过多电子转移控制产物选择性的可能性。

附:英文原文

Title: Slow Auger Recombination of Trapped Excitons Enables Efficient Multiple Electron Transfer in CdS–Pt Nanorod Heterostructures

Author: Yawei Liu, David A. Cullen, Tianquan Lian

Issue&Volume: November 19, 2021

Abstract: Solar-to-fuel conversion reaction often requires multiple proton-coupled electron transfer (PCET) processes powered by the energetic electrons and/or holes generated by the absorption of multiple photons. The effective coupling of multiple electron transfer from the light absorber with the multiple PCET reactions at the catalytic center is one of the key challenges in efficient and selective conversion of solar energy to chemical fuels. In this paper, we examine the dynamics of multiple electron transfer in quantum confined CdS nanorods with a Pt tip, in which the CdS rod functions as the light absorber and the Pt tip the catalytic center. By excitation-fluence-dependent transient absorption spectroscopic measurements, we show that the multiexciton Auger recombination rate in CdS rods follows a carrier-collision model, knA = n2(n – 1)/4k2A, with a biexciton lifetime (1/k2A) of 2.0 ± 0.2 ns. In CdS–Pt nanorods, electron transfer kinetics from the CdS conduction band edge to the Pt show negligible dependence on the excitation fluence, occurring with a half-life time of 5.6 ± 0.6 ps. The efficiency of multiple exciton dissociation by multiple electron transfer to Pt decreases from 100% in biexciton states to ~41% at 22 exciton state due to the competition with Auger recombination. The half-lifetime of the n-charge separated state recombination (with n electrons in the Pt and n holes in the CdS) decreases from 10 μs in the single charge separated state to 42 ns in nine charge separated states. Our findings suggest the possibility of driving multielectron photocatalytic reactions under intense illumination and controlling product selectivity through multielectron transfer.

DOI: 10.1021/jacs.1c09125

Source: https://pubs.acs.org/doi/10.1021/jacs.1c09125

 

期刊信息

JACS:《美国化学会志》,创刊于1879年。隶属于美国化学会,最新IF:14.612
官方网址:https://pubs.acs.org/journal/jacsat
投稿链接:https://acsparagonplus.acs.org/psweb/loginForm?code=1000