Gradient doping of phosphorus in Fe2O3 nanoarray photoanodes for enhanced charge separation

• Published in: Chemical science (Cambridge) Vol. 8; no. 1; pp. 91 - 100
• Main Authors: Luo, Zhibin, Li, Chengcheng, Liu, Shanshan, Wang, Tuo, Gong, Jinlong
• Format: Journal Article
• Language: English
• Published: 01-01-2017
• Subjects: Electric charge; Electrodes; Hematite; Oxidation; Phosphorus; Photocurrent; Photoelectric effect; Separation
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/c6sc03707k

Hematite ( alpha -Fe2O3) is a promising candidate for solar-to-hydrogen energy conversion. However, the low carrier mobility and extremely high charge recombination rate limit the practical application of hematite in solar water splitting. This paper describes the fabrication of a Fe2O3 photoanode with gradient incorporation of phosphorus (P) employing a facile dipping and annealing method to improve the charge separation for enhanced photoelectrochemical water oxidation. This gradient P incorporation increases the width of band bending over a large region in Fe2O3, which is crucial for promoting the charge separation efficiency in the bulk. Although both gradient and homogeneous P-incorporated Fe2O3 samples exhibit similar electrical conductivity, the Fe2O3 electrode with a gradient P concentration presents an additional charge separation effect. A photocurrent of similar to 1.48 mA cm-2 is obtained at 1.23 V vs. reversible hydrogen electrode (vs. RHE) under air mass 1.5G illumination. Additionally, the H2O oxidation kinetics of Fe2O3 with gradient P incorporation was further improved upon loading cobalt phosphate as cocatalyst, reaching a photocurrent of similar to 2.0 mA cm-2 at 1.23 V vs. RHE.