Octahedral Cu₂O-modified TiO₂ nanotube arrays for efficient photocatalytic reduction of CO₂

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• 作者：Yanfang Li^a ; ^&dagger ; ; Wenpei Zhang^a ; ^&dagger ; ; Xing Shen^a ; Pengfei Peng^a ; Liangbin Xiong^b ; ^{xiong_lb@yahoo.com" class="auth_mail" title="E-mail the corresponding author} ; Ying Yu^a ; ^{yuying01@mail.ccnu.edu.cn" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Titania nanotube arrays ; Octahedral cuprous oxide nanoparticles ; Photocatalytic carbon dioxide reduction ; Hydrocarbon product ; Photoactivity
• 刊名：Chinese Journal of Catalysis
• 出版年：2015
• 出版时间：December 2015
• 年：2015
• 卷：36
• 期：12
• 页码：2229-2236
• 全文大小：2157 K

文摘

A photocatalyst composed of TiO₂ nanotube arrays (TNTs) and octahedral Cu₂O nanoparticles was fabricated, and its performance in the photocatalytic reduction of CO₂ under visible and simulated solar irradiation was studied. The average nanotube diameter and length was 100 nm and ∼5 μm, respectively. The different amount of octahedral Cu₂O modified TNTs were obtained by varying electrochemical deposition time. TNTs modified with an optimized amount of Cu₂O nanoparticles exhibited high efficiency in the photocatalysis, and the predominant hydrocarbon product was methane. The methane yield increased with increasing Cu₂O content of the catalyst up to a certain deposition time, and decreased with further increase in Cu₂O deposition time. Insufficient deposition time (5 min) resulted in a small amount of Cu₂O nanoparticles on the TNTs, leading to the disadvantage of harvesting light. However, excess deposition time (45 min) gave rise to entire TNT surface being most covered with Cu₂O nanoparticles with large sizes, inconvenient for the transport of photo-generated carriers. The highest methane yield under simulated solar and visible light irradiation was observed for the catalysts prepared at a Cu₂O deposition time of 15 and 30 min respectively. The morphology, crystallization, photoresponse and electrochemical properties of the catalyst were characterized to understand the mechanism of its high photocatalytic activity. The TNT structure provided abundant active sites for the adsorption of reactants, and promoted the transport of photogenerated carriers that improved charge separation. Modifying the TNTs with octahedral Cu₂O nanoparticles promoted light absorption, and prevented the hydrocarbon product from oxidation. These factors provided the Cu₂O-modified TNT photocatalyst with high efficiency in the reduction of CO₂, without requiring co-catalysts or sacrificial agents.