Photoelectrochemical Splitting of Water at Nanocrystalline n-Fe2O3 Thin-Film Electrodes

• Published in: The journal of physical chemistry. B Vol. 103; no. 34; pp. 7184 - 7189
• Main Authors: Khan, Shahed U. M, Akikusa, Jun
• Format: Journal Article
• Language: English
• Published: American Chemical Society 26.08.1999
• ISSN: 1520-6106; 1520-5207
• DOI: 10.1021/jp990066k

Semiconducting nanocrystalline thin films of n-Fe2O3 were synthesized by a spray−pyrolytic method. These films were used for the photoelectrochemical splitting of water to hydrogen and oxygen gases. The rates of photoelectrochemical splitting of water at these thin-film electrodes were found to depend on the spray time, substrate temperature, solvent composition in the spray solution, and the concentration of the spray solution. The maximum photocurrent density of 3.7 mA cm-2 at 0.7 V/saturated calomel electrode (SCE) was obtained at the n-Fe2O3 film synthesized using the optimum condition of substrate temperature of 350 °C, the spray time of 60 s, and the spray solution of 0.11 M FeCl3 in 100% ethanol. The band gap energy of this film was found 2.05 eV. The flatband potential of −0.74 V/SCE and the apparent donor density of 2.2 × 1020 cm-3 were found from the Mott−Schottky plots at the AC frequency of 1000 Hz. The n-Fe2O3 films synthesized using the optimum conditions gave rise to a total conversion efficiency of 4.92% and a practical photoconversion efficiency of 1.84% at an applied potential of 0.2 V/SCE at pH 14.