A Redox‐Mediator‐Free Solar‐Driven Z‐Scheme Water‐Splitting System Consisting of Modified Ta3N5 as an Oxygen‐Evolution Photocatalyst. Issue 23 (12th April 2013)

• Record Type: Journal Article
• Authors: Ma, Su Su Khine; Maeda, Kazuhiko; Hisatomi, Takashi; Tabata, Masashi; Kudo, Akihiko; Domen, Kazunari
• Is Part Of: Chemistry. Volume 19:Issue 23(2013)
• Page Start: 7480
• Page End: 7486
• Publication Date: 2013-04-12
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201300579
• Languages: English
• ISSNs: 0947-6539

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>Tantalum nitride (Ta<sub>3</sub>N<sub>5</sub>) modified with various O<sub>2</sub>‐evolution cocatalysts was employed as a photocatalyst for water oxidation under visible light (<italic>λ</italic>>420 nm) in an attempt to construct a redox‐mediator‐free Z‐scheme water‐splitting system. Ta<sub>3</sub>N<sub>5</sub> was prepared by nitriding Ta<sub>2</sub>O<sub>5</sub> powder under a flow of NH<sub>3</sub> at 1023–1223 K. The activity of Ta<sub>3</sub>N<sub>5</sub> for water oxidation from an aqueous AgNO<sub>3</sub> solution as an electron acceptor without cocatalyst was dependent on the generation of a well‐crystallized Ta<sub>3</sub>N<sub>5</sub> phase with a low density of anionic defects. Modification of Ta<sub>3</sub>N<sub>5</sub> with nanoparticulate metal oxides as cocatalysts for O<sub>2</sub> evolution improved water‐oxidation activity. Of the cocatalysts examined, cobalt oxide (CoO<sub><italic>x</italic></sub>) was found to be the most effective, improving the water‐oxidation efficiency of Ta<sub>3</sub>N<sub>5</sub> by six to seven times. Further modification of CoO<sub><italic>x</italic></sub>/Ta<sub>3</sub>N<sub>5</sub> with metallic Ir as an electron sink allowed one to achieve Z‐scheme water splitting under simulated sunlight through interparticle electron transfer without the need for a shuttle redox mediator in combination with Ru‐loaded SrTiO<sub>3</sub> doped with Rh as a H<sub>2</sub>‐evolution photocatalyst.</p> </abstract>