Leaf-inspired hierarchical porous CdS/Au/N-TiO₂ heterostructures for visible light photocatalytic hydrogen evolution

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• 作者：Han Zhou ; Liang Ding ; Tongxiang Fan ; Jian Ding ; Di Zhang ; Qixin Guo
• 关键词：Photocatalytic hydrogen evolution ; Leaf photosynthesis ; Hierarchical porous ; Heterostructures
• 刊名：Applied Catalysis B: Environmental
• 出版年：5 April, 2014
• 年：2014
• 卷：147
• 期：Complete
• 页码：221-228
• 全文大小：3370 K

文摘

Photosynthesis has been for many years a fascinating source of inspiration for the development of model systems able to achieve efficient solar-to-chemical transduction. In the hot field of artificial photosynthesis, considerable progress has been made toward converting solar energy into the carbon-free fuel 鈥渉ydrogen鈥?through photocatalytic water splitting. Here, we report a promising photocatalytic system with both desirable morphology and suitable band-gap configuration for efficient visible light water splitting. Such photocatalyst is realized by the inspiration from leaf's morphology and photosynthesis basic mechanism - Z scheme reaction. The unique architectures - hierarchical macro/mesoporous morphology of natural leaves are retained in the man-made systems to enhance overall light harvesting and to offer more absorption and reaction sites for the catalytic reactions. The photocatalytic modules - CdS(shell)/Au(core)/N-TiO₂ heterostructures are served as a prototype here to demonstrate this concept, in which N-TiO₂ and CdS serve as PS II and PS I, respectively, while Au acts as the electron transfer mediator, contributing to the enhancement of electron hole separation and interfacial charge transfer. The CdS(shell)/Au(core)/N-TiO₂ heterostructures are obtained via a two-step photodeposition method. The particle sizes of Au cores, the contents and thicknesses of CdS shells are controlled by varying the synthetic parameters (e.g. irradiation time) to obtain an optimized activity. The H₂ evolution rates of optimized CdS/Au/N-TiO₂ heterostructures are about 2.6 times of N-TiO₂ under UV/visible light, and about 270 times of Au/N-TiO₂ under visible light irradiation. The systems have high visible light harvesting, high hydrogen evolution rate and long electron-hole lifetimes compared with non-incorporated systems. The design of this system is based on both biological morphology and mechanism paradigms, which would provide a proof of concept for the bio-inspired design of artificial photosynthetic system for enhanced photocatalytic performance.