Aqueous synthesis of Z-scheme photocatalyst powders and thin-film photoanodes from earth abundant elements. Issue 2 (April 2018)

• Record Type: Journal Article
• Authors: Šutka, A.; Vanags, M.; Joost, U.; Šmits, K.; Ruža, J.; Ločs, J.; Kleperis, J.; Juhna, T.
• Is Part Of: Journal of environmental chemical engineering. Volume 6:Issue 2(2018)
• Page Start: 2606
• Page End: 2615
• Publication Date: 2018-04
• Subjects: Z-scheme -- Photocatalyst -- Hematite -- Photoanode -- Photoelectrochemical properties; Chemical engineering -- Environmental aspects -- Periodicals; Environmental engineering -- Periodicals; Chemical engineering -- Environmental aspects; Environmental engineering; Periodicals; 660.0286
• DOI: 10.1016/j.jece.2018.04.003
• Languages: English
• ISSNs: 2213-2929

Abstract

Graphical abstract: Highlights: Aqueous synthesis method to obtain Z-scheme photocatalysts is demonstrated. Amorphous nanoparticle sediment as a platform for building Z-scheme is demonstrated. Z-scheme is based on earth abundant elements: n-type Fe2 O3 and p-type Ca2 Fe2 O5 . The p - n heterojunction provides Z-scheme charge transfer. Developed aqueous method is used also to obtain heterojunction photoanodes. Abstract: Solid-state narrow band gap semiconductor heterostructures with a Z-scheme charge-transfer mechanism are the most promising photocatalytic systems for water splitting and environmental remediation under visible light. Herein, we construct all-solid Z-scheme photocatalytic systems from earth abundant elements (Ca and Fe) using an aqueous synthesis procedure. A novel Z-scheme two-component Fe2 O3 /Ca2 Fe2 O5 heterostructure is obtained in a straightforward manner by soaking various iron-containing nanoparticles (amorphous and crystalline) with Ca(NO3 )2 and performing short (20 min) thermal treatments at 820 °C. The obtained powder materials show high photocatalytic performances for methylene blue dye degradation under visible light (45 mW/cm 2 ), exhibiting a rate constant up to 0.015 min −1 . The heterostructure exhibits a five-fold higher activity compared to that of pristine hematite. The experiments show that amorphous iron-containing substrate nanoparticles trigger the Fe2 O3 /Ca2 Fe2 O5 heterostructure formation. We extended our study to produce Fe2 O3 /Ca2 Fe2 O5 nanoheterostructure photoanodes via the electrochemical deposition of amorphous iron-containing sediment were used. The visible-light (15 mW/cm 2 ) photocurrent increases from 183 μA/cm 2 to 306 μA/cm 2 after coupling hematite and Ca2 Fe2 O5 . Notably, the powders and photoanodes exhibit distinct charge-transfer mechanisms evidenced by the different stabilities of the heterostructures under different working conditions.