Issue 20, 2019

Origin of the overall water splitting activity of Ta3N5 revealed by ultrafast transient absorption spectroscopy

Abstract

Tantalum nitride (Ta3N5) is one of the few visible light absorbing photocatalysts capable of overall water splitting (OWS), by which the evolution of both H2 and O2 is possible. Despite favourable energetics, realizing the OWS or efficient H2 evolution in Ta3N5 prepared by the nitridation of tantalum oxide (Ta2O5) or Ta foil remains a challenge even after 15 years of intensive research. Recently our group demonstrated OWS in Ta3N5 when prepared by the short time nitridation of potassium tantalate (KTaO3). To obtain a mechanistic insight on the role of Ta precursor and nitridation time in realizing OWS, ultrafast dynamics of electrons (3435 nm probe) and holes (545 nm probe) is investigated using transient absorption spectroscopy. Electrons decay majorly by trapping in Ta3N5 prepared by the nitridation of Ta2O5, which do not show OWS. However, OWS activity in Ta3N5 prepared by 0.25 hour nitridation of KTaO3 is particularly favoured by the virtually absent electron and hole trapping. On further increasing the nitridation time of KTaO3 from 0.25 to 10 hour, trapping of both electron and hole is enhanced which concurrently results in a reduction of the OWS activity. Insights from correlating the synthesis conditions—structural defects—carrier dynamics—photocatalytic activity is of importance in designing novel photocatalysts to enhance solar fuel production.

Graphical abstract: Origin of the overall water splitting activity of Ta3N5 revealed by ultrafast transient absorption spectroscopy

Supplementary files

Article information

Article type
Edge Article
Submitted
15 1 2019
Accepted
25 4 2019
First published
25 4 2019
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2019,10, 5353-5362

Origin of the overall water splitting activity of Ta3N5 revealed by ultrafast transient absorption spectroscopy

D. H. K. Murthy, H. Matsuzaki, Z. Wang, Y. Suzuki, T. Hisatomi, K. Seki, Y. Inoue, K. Domen and A. Furube, Chem. Sci., 2019, 10, 5353 DOI: 10.1039/C9SC00217K

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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