Development of ternary iron vanadium oxide semiconductors for applications in photoelectrochemical water oxidation

• Published in: RSC advances 2016-01, Vol.6 (6), p.4992-4999
• Main Authors: Mandal, Harahari, Shyamal, Sanjib, Hajra, Paramita, Bera, Aparajita, Sariket, Debasis, Kundu, Sukumar, Bhattacharya, Chinmoy
• Format: Article
• Language: English
• Subjects: Conversion; Energy gaps (solid state); Illumination; Indium tin oxide; Oxidation; Photons; Semiconductors; Spectra
• ISSN: 2046-2069; 2046-2069
• DOI: 10.1039/c5ra22586h

Herein, we report the synthesis of Fe-V-oxides via the drop casting of metal precursor solutions in different proportions onto an indium tin oxide (ITO) coated glass followed by annealing in air at 500 °C for 3 h. UV-vis spectroscopy of the Fe-V-oxides indicates absorption due to 'direct' and 'indirect' band gaps, although Fe-oxide shows a direct band gap nature. Scanning electron microscopy-energy dispersive X-ray (SEM-EDX) and X-ray diffraction (XRD) studies reveal different surface morphologies with variable crystalline phases for the Fe 2 O 3 , FeVO 4 , FeV 2 O 4 and Fe 2 VO 4 semiconductors. The photoelectrochemical (PEC) water oxidation reaction over the different materials reveals that the FeV 2 O 4 semiconductor exhibits the maximum photocurrent of 0.18 mA cm −2 at an applied bias of +1.0 V ( vs. Ag/AgCl) under the illumination of 100 mW cm −2 compared to the other Fe 2 O 3 , FeVO 4 and Fe 2 VO 4 semiconductors. Electrochemical impedance spectroscopic (Mott-Schottky) analysis confirms n-type semiconductivity for all the materials with highest donor density, in the order of 2.7 × 10 20 cm −3 , for the FeV 2 O 4 thin film, and PL spectra are useful for measuring the separation efficiency of the photo-generated charge carriers. Chronoamperometric studies under constant illumination of the best semiconductor (FeV 2 O 4 ) indicate the significant stability of the material, and photoelectrochemical action spectra demonstrate 22% incident photon to current conversion efficiency (IPCE) and 60% absorbed photon to current conversion efficiency (APCE). Herein, we report the synthesis and photoelectrochemical characterizations of n-type Fe-V-oxide semiconductors thin film via drop cast method in different proportions onto indium tin oxide coated glass followed by annealing in air at 500 °C for 3 h.