Imperial College London
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DrYifanDong

Faculty of Natural Sciences, Department of Chemistry

 
 
 
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Contact

 

yifan.dong12 Website

 
 
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Location

 

G22Molecular Sciences Research HubWhite City Campus

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Summary

 

Publications

Citation

BibTex format

@article{Yang:2019:10.1021/jacs.9b04556,
author = {Yang, W and Godin, R and Kasap, H and Moss, B and Dong, Y and Hillman, SAJ and Steier, L and Reisner, E and Durrant, JR},
doi = {10.1021/jacs.9b04556},
journal = {Journal of the American Chemical Society},
pages = {11219--11229},
title = {Electron accumulation induces efficiency bottleneck for hydrogen production in carbon nitride photocatalysts},
url = {http://dx.doi.org/10.1021/jacs.9b04556},
volume = {141},
year = {2019}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - This study addresses the light intensity dependence of charge accumulation in a photocatalyst suspension, and its impact on both charge recombination kinetics and steady-state H2 evolution efficiency. Cyanamide surface functionalized melon-type carbon nitride (NCNCNx) has been selected as an example of emerging carbon nitrides photocatalysts because of its excellent charge storage ability. Transient spectroscopic studies (from ps to s) show that the bimolecular recombination of photogenerated electrons and holes in NCNCNx can be well described by a random walk model. Remarkably, the addition of hole scavengers such as 4-methylbenzyl alcohol can lead to ∼400-fold faster recombination kinetics (lifetime shortening to ∼10 ps). We show that this acceleration is not the direct result of ultrafast hole extraction by the scavenger, but is rather caused by long-lived electron accumulation in NCNCNx after hole extraction. The dispersive pseudo-first order recombination kinetics become controlled by the density of accumulated electrons. H2 production and steady-state spectroscopic measurements indicate that the accelerated recombination caused by electron accumulation limits the H2 generation efficiency. The addition of a reversible electron acceptor and mediator, methyl viologen (MV2+), accelerates the extraction of electrons from the NCNCNx and increases the H2 production efficiency under one sun irradiation by more than 30%. These results demonstrate quantitatively that while long-lived electrons are essential to drive photoinduced H2 generation in many photocatalysts, excessive electron accumulation may result in accelerated recombination losses and lower performance, and thus highlight the importance of efficient electron and hole extraction in enabling efficient water splitting photocatalysts.
AU  - Yang,W
AU  - Godin,R
AU  - Kasap,H
AU  - Moss,B
AU  - Dong,Y
AU  - Hillman,SAJ
AU  - Steier,L
AU  - Reisner,E
AU  - Durrant,JR
DO  - 10.1021/jacs.9b04556
EP  - 11229
PY  - 2019///
SN  - 1520-5126
SP  - 11219
TI  - Electron accumulation induces efficiency bottleneck for hydrogen production in carbon nitride photocatalysts
T2  - Journal of the American Chemical Society
UR  - http://dx.doi.org/10.1021/jacs.9b04556
UR  - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000476684700036&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
UR  - https://pubs.acs.org/doi/10.1021/jacs.9b04556
UR  - http://hdl.handle.net/10044/1/72848
VL  - 141
ER  -
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