Imperial College London
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DrAndreasKafizas

Faculty of Natural Sciences, Department of Chemistry

Senior Lecturer
 
 
 
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Contact

 

+44 (0)20 7594 6752a.kafizas Website

 
 
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Location

 

301GMolecular Sciences Research HubWhite City Campus

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Summary

 

Publications

Citation

BibTex format

@article{Kafizas:2019:10.1016/j.cattod.2017.11.014,
author = {Kafizas, A and Xing, X and Selim, S and Mesa, CA and Ma, Y and Burgess, C and McLachlan, MA and Durrant, JR},
doi = {10.1016/j.cattod.2017.11.014},
journal = {Catalysis Today},
pages = {59--66},
title = {Ultra-thin Al<inf>2</inf>O<inf>3</inf>coatings on BiVO<inf>4</inf>photoanodes: Impact on performance and charge carrier dynamics},
url = {http://dx.doi.org/10.1016/j.cattod.2017.11.014},
volume = {321-322},
year = {2019}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - Bismuth vanadate (BiVO 4 ) has emerged as one of the most promising photoanode materials for oxidising water due to its visible light activity and low cost. Recent studies have shown that the performance of BiVO 4 photoanodes can be remarkably improved when coated with ultra-thin passivation layers. In this article we investigate the use of ultra-thin Al 2 O 3 layers grown using atomic layer deposition (ALD). At an optimum thickness (~0.33nm, 3 ALD cycles), the Al 2 O 3 layer favourably shifted the onset potential by ~200mV and increased photocatalytic currents for the water oxidation reaction. When held at 1.23V RHE , we observe a remarkable increase in the theoretical solar photocurrent; from ~0.47mAcm -2 in uncoated BiVO 4 to ~3.0mAcm -2 in Al 2 O 3 -coated BiVO 4 . Using transient photocurrent (TPC) and transient absorption spectroscopy (TAS) the charge carrier dynamics in Al 2 O 3 -coated BiVO 4 photoanodes were examined for the first time. TPC showed that photogenerated electrons in the BiVO 4 layer were extracted within ~1ms. TAS showed that the remaining holes oxidised water from ~100ms to 1s. Ultra-thin Al 2 O 3 coatings did not improve the reaction kinetics towards water oxidation, but rather, suppressed bi-molecular recombination on the μs-ms timescale in BiVO 4 , and increased the yield of long-lived holes on the ms-s timescale required to oxidise water. This is attributed to an inhibition of surface recombination on BiVO 4 by Al 2 O 3 , which inhibited the early timescale recombination of charge carriers formed within the space charge layer.
AU  - Kafizas,A
AU  - Xing,X
AU  - Selim,S
AU  - Mesa,CA
AU  - Ma,Y
AU  - Burgess,C
AU  - McLachlan,MA
AU  - Durrant,JR
DO  - 10.1016/j.cattod.2017.11.014
EP  - 66
PY  - 2019///
SN  - 0920-5861
SP  - 59
TI  - Ultra-thin Al<inf>2</inf>O<inf>3</inf>coatings on BiVO<inf>4</inf>photoanodes: Impact on performance and charge carrier dynamics
T2  - Catalysis Today
UR  - http://dx.doi.org/10.1016/j.cattod.2017.11.014
UR  - http://hdl.handle.net/10044/1/54993
VL  - 321-322
ER  -
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