Synergetic Effect of Conjugated Ni(OH)2/IrO2 Cocatalyst on Titanium-Doped Hematite Photoanode for Solar Water Splitting

• Published in: Journal of physical chemistry. C 2015-08
• Main Authors: Wang, Zhiliang, Liu, Guiji, Ding, Chunmei, Chen, Zheng, Zhang, Fuxiang, Shi, Jingying, Li, Can
• Format: Article
• Language: eng ; jpn
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/acs.jpcc.5b04892

Hematite is a promising photoanode material for renewable solar fuel production via photoelectrochemical (PEC) water splitting. However, the fast electron–hole recombination and sluggish surface reaction retard it from getting satisfied performance. Herein, hematite nanorod arrays doped with titanium (Ti–Fe2O3) on the surface were prepared by a solution-based process. Because of one-dimension anisotropy and improved charge transfer property, the photocurrent density is doubled compared to pure Fe2O3 at 1.50 V vs RHE under simulated sunlight (AM 1.5 G) irradiation. Loading conjugated Ni­(OH)2/IrO2 cocatalyst further leads to about 200 mV negative shift of the onset potential and dramatic increase of the applied bias photon-to-current efficiency (ABPE). We find that Ni­(OH)2 can efficiently capture the photogenerated holes from hematite as a hole-storage layer (HSL) to improve the charge transfer process across the interface of hematite and IrO2 electrocatalyst. Furthermore, the stored photogenerated holes in Ni­(OH)2 can be utilized by IrO2 for water oxidation more facilely. This synergetic effect along with the efficient surface doping are proposed to be responsible for the enhanced performance.