Striving Toward Noble-Metal-Free Photocatalytic Water Splitting: The Hydrogenated-Graphene鈥揟iO2 Prototype

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• 作者：Thuy-Duong Nguyen-Phan ; Si Luo ; Zongyuan Liu ; Andrew D. Gamalski ; Jing Tao ; Wenqian Xu ; Eric A. Stach ; Dmitry E. Polyansky ; Sanjaya D. Senanayake ; Etsuko Fujita ; Jos茅 A. Rodriguez
• 刊名：Chemistry of Materials
• 出版年：2015
• 出版时间：September 22, 2015
• 年：2015
• 卷：27
• 期：18
• 页码：6282-6296
• 全文大小：725K
• ISSN：1520-5002

文摘

Graphane, graphone, and hydrogenated graphene (HG) have been extensively studied in recent years due to their interesting properties and potential use in commercial and industrial applications. The present study reports investigation of hydrogenated graphene/TiO_2鈥?i>x (HGT) nanocomposites as photocatalysts for H₂ and O₂ production from water without the assistance of a noble metal cocatalyst. By combination of several techniques, the morphologies, bulk/atomic structure, and electronic properties of all the powders were exhaustively interrogated. Hydrogenation treatment efficiently reduces TiO₂ nanoparticles, while the graphene oxide sheets undergo the topotactic transformation from a graphene-like structure to a mixture of graphitic and turbostratic carbon (amorphous/disordered) upon altering the calcination atmosphere from a mildly reducing to a H₂-abundant environment. Remarkably, the hydrogenated graphene鈥揟iO_2鈥?i>x composite that results upon H₂-rich reduction exhibits the highest photocatalytic H₂ evolution performance equivalent to low loading of Pt (鈭?.12 wt %), whereas the addition of HG suppresses the O₂ production. We propose that such an enhancement can be attributed to a combination of factors including the introduction of oxygen vacancies and Ti³⁺ states, retarding the recombination of charge carriers, and thus, facilitating the charge transfer from TiO_2鈥?i>x to the carbonaceous sheet.