The role of oxygen in magnetron-sputtered Ta3N5 thin films for the photoelectrolysis of water

SURFACE & COATINGS TECHNOLOGY

卷:324

Article; Proceedings Paper

Rudolph, M.^1,2  Stanescu, D.³  Alvarez, J.⁴  Foy, E.⁵  Kleider, J. -P.⁴  Magnan, H.³  Minea, T.¹  Herlin-Boime, N.²  Bouchet-Fabre, B.²  Hugon, M. -C.¹ 

[1] Univ Paris Saclay, Univ Paris Sud, LPGP, CNRS, F-91405 Orsay, France

[2] Univ Paris Saclay, NIMBE, CEA, CNRS, F-91191 Gif Sur Yvette, France

[3] Univ Paris Saclay, CEA, SPEC, CNRS, F-91191 Gif Sur Yvette, France

[4] UPMC Univ Paris 06, Sorbonne Univ, Univ Paris Sud, GeePs,CNRS,UMR8507,Cent Supelec, F-91192 Gif Sur Yvette, France

[5] Univ Paris Saday, CEA Saday, LAPA IRAMAT, N1MBE,CEA,CNRS, F-91191 Gif Sur Yvette, France

关键词: Ta3N5;    Tantalum oxynitride;    Magnetron sputtering;    Photoelectrolysis;   

DOI  :  10.1016/j.surfcoat.2016.09.007

来源: Elsevier

【 摘 要 】

Ta3N5 has ideal properties for the efficient water splitting under sunlight illumination, but its formation is only triggered by the incorporation of oxygen in its lattice. As a result, material properties may deviate from those of an ideal Ta3N5 crystal, which can promote or impede the water splitting. This paper is to quantify variations in key properties relevant for the photoelectrolysis as a function of oxygen incorporation and to determine an optimum oxygen concentration. Thin films were prepared by direct current magnetron sputtering in an Ar/N-2/O-2 gas mixture at two different N-2 and varying O-2 concentrations. The films were characterized by grazing-incidence x-ray diffraction (GI-XRD), total transmission and reflectance spectroscopy (TTRS) from which the band gap is deduced, photocurrent measurements on which the calculation of the efficiency-mobility-lifetime (eta mu tau) product is based and photoelectrolysis experiments. Finally, the stability of films was determined by x-ray photoelectron spectroscopy (XPS) measured before and after the photoelectrolysis. We show that material properties degrade with oxygen incorporation during the film growth. At the thighest oxygen concentrations investigated, the material becomes amorphous and shows strong surface oxidation and a possible reaction with the electrolyte during the photoelectrolysis. Samples deposited at an oxygen concentration below 1%, exhibit the Ta3N5 phase, a band gap below 2.0 eV, a high mobility-lifetime product, photoelectrolytic activity and a good relative stability against surface oxidation during the photoelectrolysis. (C) 2016 Elsevier B.V. All rights reserved.

【 授权许可】

Free