Water splitting and the band edge positions of TiO2

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61388955%3A_____%2F16%3A00458866" target="_blank" >RIV/61388955:_____/16:00458866 - isvavai.cz</a>

Výsledek na webu

<a href="http://dx.doi.org/10.1016/j.electacta.2016.03.122" target="_blank" >http://dx.doi.org/10.1016/j.electacta.2016.03.122</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.electacta.2016.03.122" target="_blank" >10.1016/j.electacta.2016.03.122</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Water splitting and the band edge positions of TiO2

Popis výsledku v původním jazyce

The possibility of splitting water by UV-light on a TiO2 electrode has created great interest in the material, however, it has been later questioned whether rutile can do the job at all without external bias. Anatase was suggested instead, but its efficiency is still a subject of debate. The problem is related to the position of the band edges, that is, of the Fermi-level (EF), with respect to the redox potentials of water. Here we present hybrid-functional calculations to align the band structures with the vacuum level, assuming the rutile (110) and anatase (101) surface being exposed to water. Our results show that both are capable of water splitting if no adsorbates other than molecular water are present. On a fully hydroxylated surface (i.e., H+ and OH- adsorption on undercoordinated surface oxygen and titanium atoms, respectively), EF is only ∼0.5 eV above the H+/H2 potential in case of anatase, and - depending on the level of reduction - roughly at, or below it for rutile. We also show, that the band edges (and EF) shift up if OH+ groups dominate the surface, increasing the driving force for water splitting. This is in line with the experience on titania reduced in hydrogen. Our results are further confirmed by calculating EF without the presence of water, and comparing it to work function measurements by photoelectron spectroscopy.

Název v anglickém jazyce

Water splitting and the band edge positions of TiO2

Popis výsledku anglicky

The possibility of splitting water by UV-light on a TiO2 electrode has created great interest in the material, however, it has been later questioned whether rutile can do the job at all without external bias. Anatase was suggested instead, but its efficiency is still a subject of debate. The problem is related to the position of the band edges, that is, of the Fermi-level (EF), with respect to the redox potentials of water. Here we present hybrid-functional calculations to align the band structures with the vacuum level, assuming the rutile (110) and anatase (101) surface being exposed to water. Our results show that both are capable of water splitting if no adsorbates other than molecular water are present. On a fully hydroxylated surface (i.e., H+ and OH- adsorption on undercoordinated surface oxygen and titanium atoms, respectively), EF is only ∼0.5 eV above the H+/H2 potential in case of anatase, and - depending on the level of reduction - roughly at, or below it for rutile. We also show, that the band edges (and EF) shift up if OH+ groups dominate the surface, increasing the driving force for water splitting. This is in line with the experience on titania reduced in hydrogen. Our results are further confirmed by calculating EF without the presence of water, and comparing it to work function measurements by photoelectron spectroscopy.

Druh

J_x - Nezařazeno - Článek v odborném periodiku (Jimp, Jsc a Jost)

CEP obor

CG - Elektrochemie

OECD FORD obor

—

Projekt

<a href="/cs/project/GA13-07724S" target="_blank" >GA13-07724S: Materiálové inženýrství pro inovativní Graetzelovy solární články</a><br>

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2016

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Electrochimica acta

ISSN

0013-4686

e-ISSN

—

Svazek periodika

199

Číslo periodika v rámci svazku

MAY 2016

Stát vydavatele periodika

GB - Spojené království Velké Británie a Severního Irska

Počet stran výsledku

8

Strana od-do

27-34

Kód UT WoS článku

000375127200004

EID výsledku v databázi Scopus

2-s2.0-84962271879