Sites for High Efficient Photocatalytic Hydrogen Evolution on a Limited-Layered MoS2 Cocatalyst Confined on Graphene Sheets-The Role of Graphene
20 Nov 2012-Journal of Physical Chemistry C (American Chemical Society)-Vol. 116, Iss: 48, pp 25415-25424
TL;DR: In this paper, a high active cocatalyst, limited-layered MoS2 confined on RGO sheets as an alternative of Pt, for hydrogen evolution in dye-sensitized photocatalytic systems was reported.
Abstract: The development of an advanced cocatalyst is critical for improving the efficiency of the photocatalytic hydrogen evolution reaction. Noble metals such as platinum (Pt) have been identified to be the most active cocatalyst for this reaction; however, due to their low-abundance, high cost, their usage in the scale-up setup is impeditive. Here, we report a high active cocatalyst, limited-layered MoS2 confined on RGO sheets as an alternative of Pt, for hydrogen evolution in dye-sensitized photocatalytic systems. Growing a MoS2 cocatalyst on RGO sheets provides more available catalytically edge sites and thus exhibits much higher activity than large aggregated pristine MoS2 particles under visible light irradiation (≥420 nm). The apparent quantum efficiency (AQE) of 24% at 460 nm over an Eosin Y-sensitized MoS2/RGO photocatalyst has been achieved. In addition, the electrical coupling and synergistic effect between MoS2 and RGO sheets greatly facilitate the efficient electron transfer from photoexcited dye to ...
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TL;DR: This review for the first time summarizes all the developed earth-abundant cocatalysts for photocatalytic H2- and O2-production half reactions as well as overall water splitting.
Abstract: Photocatalytic water splitting represents a promising strategy for clean, low-cost, and environmental-friendly production of H2 by utilizing solar energy. There are three crucial steps for the photocatalytic water splitting reaction: solar light harvesting, charge separation and transportation, and the catalytic H2 and O2 evolution reactions. While significant achievement has been made in optimizing the first two steps in the photocatalytic process, much less efforts have been put into improving the efficiency of the third step, which demands the utilization of cocatalysts. To date, cocatalysts based on rare and expensive noble metals are still required for achieving reasonable activity in most semiconductor-based photocatalytic systems, which seriously restricts their large-scale application. Therefore, seeking cheap, earth-abundant and high-performance cocatalysts is indispensable to achieve cost-effective and highly efficient photocatalytic water splitting. This review for the first time summarizes all the developed earth-abundant cocatalysts for photocatalytic H2- and O2-production half reactions as well as overall water splitting. The roles and functional mechanism of the cocatalysts are discussed in detail. Finally, this review is concluded with a summary, and remarks on some challenges and perspectives in this emerging area of research.
1,990 citations
TL;DR: Two-dimensional (2D) transition-metal dichalcogenide (TMD) nanosheets have emerged as a fascinating new class of materials for catalysis, attractive for understanding the fundamental principles of electro- and photocatalysis, as well as for developing highly efficient, renewable, and affordable catalysts for large-scale production of hydrogen.
Abstract: Two-dimensional (2D) transition-metal dichalcogenide (TMD) nanosheets have emerged as a fascinating new class of materials for catalysis. These nanosheets are active for several important catalysis reactions including hydrogen evolution from water. The rich chemistry of TMDs combined with numerous strategies that allow tuning of their electronic properties make these materials very attractive for understanding the fundamental principles of electro- and photocatalysis, as well as for developing highly efficient, renewable, and affordable catalysts for large-scale production of hydrogen. Recent developments are highlighted and important challenges in using TMDs as catalysts are also discussed.
734 citations
TL;DR: A comprehensive overview of the recent research progress on graphene-based materials for hydrogen evolution from light-driven water splitting and the comparison between graphene and other carbon materials in solar water splitting is made.
Abstract: Hydrogen production from solar water splitting has been considered as an ultimate solution to the energy and environmental issues. Over the past few years, graphene has made great contribution to improving the light-driven hydrogen generation performance. This article provides a comprehensive overview of the recent research progress on graphene-based materials for hydrogen evolution from light-driven water splitting. It begins with a brief introduction of the current status and basic principles of hydrogen generation from solar water splitting, and tailoring properties of graphene for application in this area. Then, the roles of graphene in hydrogen generation reaction, including an electron acceptor and transporter, a cocatalyst, a photocatalyst, and a photosensitizer, are elaborated respectively. After that, the comparison between graphene and other carbon materials in solar water splitting is made. Last, this review is concluded with remarks on some challenges and perspectives in this emerging field.
680 citations
TL;DR: Recent advances in the application of graphene-based photocatalysts for solar-fuel production, including CO2 reduction to hydrocarbon fuel and water splitting to H2 are summarized.
Abstract: The production of solar fuel through photocatalytic water splitting and CO2 reduction using photocatalysts has attracted considerable attention owing to the global energy shortage and growing environmental problems. During the past few years, many studies have demonstrated that graphene can markedly enhance the efficiency of photocatalysts for solar-fuel generation because of its unique 2D conjugated structure and electronic properties. Herein we summarize the recent advances in the application of graphene-based photocatalysts for solar-fuel production, including CO2 reduction to hydrocarbon fuel and water splitting to H2. A brief overview of the fundamental principles for splitting of water and reduction of CO2 is given. The different roles of graphene in these graphene-based photocatalysts for improving photocatalytic performance are discussed. Finally, the perspectives on the challenges and opportunities for future research in this promising area are also presented.
659 citations
TL;DR: The photoelectrochemical measurement shows that the p-MoS2/n-rGO junction greatly enhances the charge generation and suppresses the charge recombination, which is responsible for enhancement of solar hydrogen generation.
Abstract: Molybdenum disulfide (MoS2) is a promising candidate for solar hydrogen generation but it alone has negligible photocatalytic activity. In this work, 5–20 nm sized p-type MoS2 nanoplatelets are deposited on the n-type nitrogen-doped reduced graphene oxide (n-rGO) nanosheets to form multiple nanoscale p–n junctions in each rGO nanosheet. The p-MoS2/n-rGO heterostructure shows significant photocatalytic activity toward the hydrogen evolution reaction (HER) in the wavelength range from the ultraviolet light through the near-infrared light. The photoelectrochemical measurement shows that the p-MoS2/n-rGO junction greatly enhances the charge generation and suppresses the charge recombination, which is responsible for enhancement of solar hydrogen generation. The p-MoS2/n-rGO is an earth-abundant and environmentally benign photocatalyst for solar hydrogen generation.
579 citations
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