Templating Sol鈥揋el Hematite Films with Sacrificial Copper Oxide: Enhancing Photoanode Performance with Nanostructure and Oxygen Vacancies

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• 作者：Yang Li ; N茅stor Guijarro ; Xiaoli Zhang ; Mathieu S. Pr茅vot ; Xavier A. Jeanbourquin ; Kevin Sivula ; Hong Chen ; Yongdan Li
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2015
• 出版时间：August 12, 2015
• 年：2015
• 卷：7
• 期：31
• 页码：16999-17007
• 全文大小：509K
• ISSN：1944-8252

文摘

Nanostructuring hematite films is a critical step for enhancing photoelectrochemical performance by circumventing the intrinsic limitations on minority carrier transport. Herein, we present a novel sol鈥揼el approach that affords nanostructured hematite films by including CuO as sacrificial templating agent. First, by annealing in air at 450 掳C a film comprising an intimate mixture of CuO and Fe₂O₃ nanoparticles is obtained. The subsequent treatment with NaCl and annealing at 700 掳C under Argon reveals a nanostructured highly crystalline hematite film devoid of copper. Photoelectrochemical investigations reveal that the incorporation of CuO as templating agent and the inert conditions employed during the annealing play a crucial role in the performance of the hematite electrodes. Mott鈥揝chottky analysis shows a higher donor concentration when annealing in inert conditions, and even higher when combined with the NaCl treatment. These findings agree well with the presence of an oxygen-deficient shell on the material鈥檚 surface evidenced by FT-IR and XPS measurements. Likewise, the incorporation of the CuO enhances the photocurrent obtained at 1.23 V from 0.55 to 0.8 mA路cm^鈥? because of an improved nanostructure. Optimized films demonstrate an incident photon-to-current efficiency (IPCE) of 52% at 380 nm when applying 1.23 V versus RHE, and a faradaic efficiency for water splitting close to unity.