Combining Mesoporosity and Ti-Doping in Hematite Films for Water Splitting

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• 作者：Caroline Toussaint ; Hoang Long Le Tran ; Pierre Colson ; Jennifer Dewalque ; B茅n茅dicte Vertruyen ; Bernard Gilbert ; Ngoc Duy Nguyen ; Rudi Cloots ; Catherine Henrist
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：January 29, 2015
• 年：2015
• 卷：119
• 期：4
• 页码：1642-1650
• 全文大小：527K
• ISSN：1932-7455

文摘

In this study, we report the synthesis of Ti-doped mesoporous hematite films by soft-templating for application as photoanodes in the photoelectrolysis of water (water splitting). Because the activation of the dopant requires a heat treatment at high temperature (鈮?00 掳C), it usually results in the collapse of the mesostructure. We have overcome this obstacle by using a temporary SiO₂ scaffold to hinder crystallite growth and thereby maintain the mesoporosity. The beneficial effect of the activated dopant has been confirmed by comparing the photocurrent of doped and undoped films treated at different temperatures. The role of the mesostructure was investigated by comparing dense, collapsed, and mesoporous films heated at different temperatures and characterized under front and back illumination. It turns out that the preservation of the mesotructure enables a better penetration of the electrolyte into the film and therefore reduces the distance that the photogenerated holes have to travel to reach the electrolyte. As a result, we found that mesoporous films with dopant activation at 850 掳C perform better than comparable dense and collapsed films.