Hydrogen Production over Titania‐Based Photocatalysts

Leung, Dennis Y.C.; Fu, Xianliang; Cui-fang, Wang; Ni, Meng; Wang, Xuxu; Fu, Xianzhi

doi:10.1002/cssc.201000014

Cited by 438 publications

(288 citation statements)

References 277 publications

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“…The trapping ability is largely determined by the work functions of the noble metals, which are greater than those of many semiconductors. Taking TiO 2 for an example, 6 a Schottky barrier can be formed at the metal/TiO 2 interface. Schottky barrier is a kind of junction which can facilitate charge separation ( Figure 1B).…”

Section: Cocatalysts For Water Reduction Half Reactionmentioning

confidence: 99%

“…Inspired by the above primary work, we further examined hydrogenase mimic [(μ-SPh-4-NH 2 ) 2 Fe 2 (CO) 6 ] (denoted as [Fe 2 S 2 ]) as the cocatalyst for H 2 evolution using semiconductor (ZnS) as the photoharvester and ascorbic acid (H 2 A) as the electron donor ( Figure 2B). 12 Remarkably, photocatalytic H 2 production with more than 2600 turnover numbers (based on [Fe 2 S 2 ]) and an initial TOF of 100 h À1 were achieved.…”

Section: Cocatalysts For Water Reduction Half Reactionmentioning

confidence: 99%

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Roles of Cocatalysts in Photocatalysis and Photoelectrocatalysis

et al. 2013

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S ince the 1970s, splitting water using solar energy has been a focus of great attention as a possible means for converting solar energy to chemical energy in the form of clean and renewable hydrogen fuel. Approaches to solar water splitting include photocatalytic water splitting with homogeneous or heterogeneous photocatalysts, photoelectrochemical or photoelectrocatalytic (PEC) water splitting with a PEC cell, and electrolysis of water with photovoltaic cells coupled to electrocatalysts. Though many materials are capable of photocatalytically producing hydrogen and/or oxygen, the overall energy conversion efficiency is still low and far from practical application. This is mainly due to the fact that the three crucial steps for the water splitting reaction: solar light harvesting, charge separation and transportation, and the catalytic reduction and oxidation reactions, are not efficient enough or simultaneously. Water splitting is a thermodynamically uphill reaction, requiring transfer of multiple electrons, making it one of the most challenging reactions in chemistry.This Account describes the important roles of cocatalysts in photocatalytic and PEC water splitting reactions. For semiconductor-based photocatalytic and PEC systems, we show that loading proper cocatalysts, especially dual cocatalysts for reduction and oxidation, on semiconductors (as light harvesters) can significantly enhance the activities of photocatalytic and PEC water splitting reactions. Loading oxidation and/or reduction cocatalysts on semiconductors can facilitate oxidation and reduction reactions by providing the active sites/reaction sites while suppressing the charge recombination and reverse reactions. In a PEC water splitting system, the water oxidation and reduction reactions occur at opposite electrodes, so cocatalysts loaded on the electrode materials mainly act as active sites/reaction sites spatially separated as natural photosynthesis does. In both cases, the nature of the loaded cocatalysts and their interaction with the semiconductor through the interface/junction are important. The cocatalyst can provide trapping sites for the photogenerated charges and promote the charge separation, thus enhancing the quantum efficiency; the cocatalysts could improve the photostability of the catalysts by timely consuming of the photogenerated charges, particularly the holes; most importantly, the cocatalysts catalyze the reactions by lowering the activation energy. Our research shows that loading suitable dual cocatalysts on semiconductors can significantly increase the photocatalytic activities of hydrogen and oxygen evolution reactions, and even make the overall water splitting reaction possible. All of these findings suggest that dual cocatalysts are necessary for developing highly efficient photocatalysts for water splitting reactions.

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Section: Cocatalysts For Water Reduction Half Reactionmentioning

confidence: 99%

Section: Cocatalysts For Water Reduction Half Reactionmentioning

confidence: 99%

Roles of Cocatalysts in Photocatalysis and Photoelectrocatalysis

et al. 2013

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“…42 However, clean hydrogen production still remains a big challenge. 43,44 One possible way to produce clean hydrogen is via photocatalytic splitting of water on oxide surfaces using sunlight. 45 However, the low efficiency of such processes has hindered developments in this direction.…”

Section: Photocatalysis Of Methanol On Tio 2 (110)mentioning

confidence: 99%

“…Despite the difficulties, photocatalyzed splitting of water on TiO 2 surface has been extensively investigated, and many strategies have been proposed to increase the hydrogen production, e.g., loading TiO 2 with a noble metal or other semiconductor, doping, sensitizing and adding sacrificial species. 44 It has been reported that methanol is an effective sacrificial agent for hydrogen production. 46,47 Clearly, the photochemistry of methanol on TiO 2 plays a significant role in this process.…”

Section: Photocatalysis Of Methanol On Tio 2 (110)mentioning

confidence: 99%

Surface photochemistry probed by two-photon photoemission spectroscopy

Zhou

Ren

et al. 2012

Energy Environ. Sci.

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Two-photon photoemission (2PPE) has been widely used in the study of electronic structure and dynamics of unoccupied electronic states on different types of surfaces and interfaces. Since 2PPE probes electronically excited states, it should be sensitive to surface excited electronic structure changes that accompany surface chemical reactions. Therefore, this method could potentially be used to study the kinetics and dynamics of surface chemical reactions as well as surface photocatalysis. In this article, we briefly review recent progress made in the study of surface photochemistry and photocatalysis using the time-dependent 2PPE (TD-2PPE) method. A few examples are given to demonstrate the application of this method in probing surface photochemistry and photocatalysis, particularly photocatalysis of methanol on TiO 2 surfaces. Since many problems associated with surface photochemistry and surface photocatalysis are related to energy and environmental issues, the 2PPE technique could have important applications in the study of the fundamental problems in energy and environmental sciences.

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“…TiO 2 (titania) is one of the most extensively studied semiconductor photocatalysts due to its potential to help overcome the worldwide energy shortage while also counteracting issues of climate change and environmental contamination [1][2][3]. Since the first report of its use for hydrogen generation via the photocatalytic decomposition of water by Fujishima and Honda [4], TiO 2 has attracted significant interest as a photocatalyst due to its favorable band edge positions, which are well-matched with the redox potentials of water, CO 2 , and a variety of organic compounds.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Catalytic Applications of Non-Metal Doped Mesoporous Titania

et al. 2017

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Mesoporous titania (mp-TiO 2 ) has drawn tremendous attention for a diverse set of applications due to its high surface area, interfacial structure, and tunable combination of pore size, pore orientation, wall thickness, and pore connectivity. Its pore structure facilitates rapid diffusion of reactants and charge carriers to the photocatalytically active interface of TiO 2 . However, because the large band gap of TiO 2 limits its ability to utilize visible light, non-metal doping has been extensively studied to tune the energy levels of TiO 2 . While first-principles calculations support the efficacy of this approach, it is challenging to efficiently introduce active non-metal dopants into the lattice of TiO 2 . This review surveys recent advances in the preparation of mp-TiO 2 and their doping with non-metal atoms. Different doping strategies and dopant sources are discussed. Further, co-doping with combinations of non-metal dopants are discussed as strategies to reduce the band gap, improve photogenerated charge separation, and enhance visible light absorption. The improvements resulting from each doping strategy are discussed in light of potential changes in mesoporous architecture, dopant composition and chemical state, extent of band gap reduction, and improvement in photocatalytic activities. Finally, potential applications of non-metal-doped mp-TiO 2 are explored in water splitting, CO 2 reduction, and environmental remediation with visible light.

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Hydrogen Production over Titania‐Based Photocatalysts

Cited by 438 publications

References 277 publications

Roles of Cocatalysts in Photocatalysis and Photoelectrocatalysis

Roles of Cocatalysts in Photocatalysis and Photoelectrocatalysis

Surface photochemistry probed by two-photon photoemission spectroscopy

Synthesis and Catalytic Applications of Non-Metal Doped Mesoporous Titania

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