Fabrication of BaTaO2N Thin Films by Interfacial Reactions of BaCO3/Ta3N5 Layers on a Ta Substrate and Resulting High Photoanode Efficiencies During Water Splitting. Issue 4 (31st January 2020)

• Record Type: Journal Article
• Authors: Nishimae, Shinji; Mishima, Yuji; Nishiyama, Hiroshi; Sasaki, Yutaka; Nakabayashi, Mamiko; Inoue, Yasunobu; Katayama, Masao; Domen, Kazunari
• Is Part Of: Solar RRL. Volume 4:Issue 4(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-01-31
• Subjects: barium tantalum oxynitrides -- interfacial layer reactions -- photoanodes -- thin films -- water splitting; Solar energy -- Periodicals; Photovoltaic power generation -- Periodicals; Solar energy -- Research -- Periodicals; Photovoltaic power generation -- Research -- Periodicals; Periodicals; 333.7923
• DOI: 10.1002/solr.201900542
• Languages: English
• ISSNs: 2367-198X

Abstract

Abstract : Thin films of barium tantalum oxynitride (BaTaO2 N) with thicknesses of 150–680 nm are grown on TaN/Ta substrates via the interfacial reaction of BaCO3 /Ta3 N5 layers in a N2 atmosphere. A TaN thin film is first deposited on a Ta substrate by the Ar/N2 ion sputtering of a Ta target, and then covered with a TaO x layer by Ar/O2 sputtering. The TaO x layer is subsequently nitrided in an NH3 flow to a Ta3 N5 layer. Finally, Ba metal is deposited on the Ta3 N5 /TaN/Ta substrate under vacuum, oxidized, and carbonized to produce BaCO3 . The interfacial reaction between the BaCO3 and Ta3 N5 layers is conducted in a N2 atmosphere at high temperatures. X‐ray diffraction patterns confirm BaTaO2 N and Ta2 N phases on the Ta substrates, while cross‐sectional scanning electron microscopy images show a three‐layer BaTaO2 N/Ta2 N/Ta structure. Cobalt oxide (CoO x )‐deposited BaTaO2 N/Ta2 N/Ta photoanodes for water oxidation provide a high photocurrent of 4.6 mA cm −2 at 1.23 V (vs RHE) and an incident photon‐to‐current conversion efficiency of 9% at 600 nm under simulated AM1.5G irradiation. The efficiency of this photoanode is remarkably improved compared with previously reported photoanode thin films. Interestingly, a BaTaO2 N/Ta2 N/Ta electrode with similar photoanode performance is also obtained via the interfacial reaction between TaN and BaCO3 layers. Abstract : Thin films of barium tantalum oxynitride (BaTaO2 N) are grown on TaN/Ta substrates via the interfacial reaction of BaCO3 /Ta3 N5 layers in a N2 atmosphere. The efficiency of cobalt oxide (CoO x )‐deposited BaTaO2 N/Ta2 N/Ta photoanodes is remarkably improved compared with previously reported photoanode thin films. A BaTaO2 N/Ta2 N/Ta electrode with similar photoanode performance is also obtained via the interfacial reaction between TaN and BaCO3 layers.