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Optimized magnetron-sputtered CuFeO2 thin films for PEC water spitting application
* 1, 2 , 2 , 3 , 2
1  Department of Chemistry, College of Natural and Computational Sciences, Mekelle University, P.O. Box 231, Mekelle city, Ethiopia
2  Faculty of Science, Pavol Jozef Šafárik University, Park Angelinum 9, 04001 Košice city, Slovakia
3  Institute of Aurel Stodola, University of Žilina, Komenskeho 843, 03101, Liptovský Mikuláš, Slovakia
Academic Editor: Donald Tryk

Abstract:

CuFeO2 (CFO) has been recently identified as a promising photocathode material for photoelectrochemical (PEC) water splitting. However, this p-type semiconductor suffers from poor photo-induced electron–hole separation and charge collection. In this study, CFO thin films were successfully sputtered via a magnetron sputtering technique, and their PEC experiments were carried out under front-side chopped illumination in 1M NaOH electrolyte against a Ag/AgCl reference electrode. In argon, the thin films produced low photocurrent, while in oxygen, it enhanced the photocurrent and rose to 0.55 mAcm-2 at 0.4 V vs. RHE (VRHE). The synthesis parameters dictated the water splitting efficiency; when the power of the Fe target increased from 160 W to 200 W, the photo-current density enhanced and reached the highest value of 0.55 at 0.4 V vs. RHE (VRHE) due to its lower charge transfer resistance according to EIS data. Similarly, the Cu power was optimized in which the highest J-V was produced with a power of 40 W rather than 60 and 80 W. The other constituent of CFO that affects the PEC activity is oxygen; an oxygen flow rate of 2 sccm (with O2:Ar = 1:9) was optimal; increasing this further reduced the J-V. AFM spectroscopy revealed that the roughness of the thin films increased as a function of Fe and Cu sputtering power, whereas SEM-EDAX inferred a homogeneous distribution of the elemental constituents.

Keywords: CuFeO2; Water splitting; Thin films; Magnetron sputtering; Photoelectrochemical

 
 
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