Welcome To Website IAS

Hot news
Achievement

Independence Award

- First Rank - Second Rank - Third Rank

Labour Award

- First Rank - Second Rank -Third Rank

National Award

 - Study on food stuff for animal(2005)

 - Study on rice breeding for export and domestic consumption(2005)

VIFOTEC Award

- Hybrid Maize by Single Cross V2002 (2003)

- Tomato Grafting to Manage Ralstonia Disease(2005)

- Cassava variety KM140(2010)

Centres
Website links
Vietnamese calendar
Library
Visitors summary
 Curently online :  4
 Total visitors :  4506251

From photosynthesis to photocatalysis: Dual catalytic oxidation/reduction in one system
Thursday, 2020/04/23 | 05:42:19

Lin X. Chen

PNAS April 21, 2020 117 (16) 8672-8673

 

Natural photosynthetic systems and photocatalysis share several fundamental processes in common including light energy conversion and utilization, such as exciton (excited state) generation/splitting and charge migration. The high efficiency of light conversion to chemical redox equivalents in natural photosynthesis is achieved by an electron transfer cascade resulting in a long-distance hole and electron separation across the membrane. Consequently, the charge geminate recombination is minimized, and the loss is reduced. The machinery of natural photosynthesis enables high-quantum yields of photon to electron/charge conversion efficiency facilitated by a fine-tuned local potential energy gradient by the protein surrounding each chlorophyll or its derivative to ensure unidirectional electron transfer and efficient final charge separation across the membrane. The holes and electrons separated far away from each other can thus go their separate ways to drive water oxidation and quinone reduction, respectively. Using the functions of metal oxide cluster or multiple reduction equivalents in molecules like quinones, natural photosynthesis succeeds in coupling multiple single-photon events with generation of multiple redox equivalents for catalytic reactions, such as water splitting.

 

Inspired by natural photosynthesis, many artificial photosynthetic systems have been designed to achieve similar functions in photoinduced sequential, unidirectional, and long-distance electron transfer for simultaneous oxidation and reduction reactions at the both ends of the electron transfer chain. However, it has been a long struggle to effectively couple multiple single-photon events with multiple redox equivalent generation required for catalytic reaction such as water splitting. Frequently, only one of the two single half-reactions may take place, which not only uses only electrons or holes but also causes charge imbalance. Some systems may suffer the loss from charge recombination due to insufficient hole/electron separation after the exciton splitting and from the lack of directionality of charge separation. Thus, it has been a dream for photocatalysis or solar fuel community to design and synthetize platforms capable of accumulating both well-separated holes and electrons from photoinduced charge separation for sufficiently long time to carry out effective and simultaneous reduction and oxidation reactions in a single system.

In summary, Chu et al. in their study (22) simultaneously tackle the following challenges in photocatalysis in a platform of Co1/AQ/C3N4: 1) moving hole and electron away from where they are generated via exciton splitting upon light absorption to minimize the loss due to geminate recombination via a semiconductor 2D C3N4 nanosheet; 2) segregating the photocatalytic oxidation cobalt site in the middle and reduction AQ site at the edge so that the two reactions can simultaneously take place without the needs for sacrificial donor/acceptor and external wiring; and 3) selecting proper AQ reduction site so that the reaction of forming H2O2 is competitive with other reactions in both energetic and kinetic standpoints.

 

Because of the above key advances, this research opens an approach for achieving both efficient oxidation and reduction reactions on 2D photocatalysts for many possible reactions that can be driven by renewable solar energy. We look forward to seeing more successful artificial photosynthetic systems and photocatalytic systems for fuel generation to store solar energy effectively.

 

See https://www.pnas.org/content/117/16/8672

 

(22). C. Chu et al. Spatially separating redox centers on 2D carbon nitride with cobalt single atom for photocatalytic H2O2 production. Proc. Natl. Acad. Sci. U.S.A. 117, 6376–6382 (2020).

 

Figure: (Left) Directional photoinduced electron transfer among bacterial chlorophylls and pheophytins in a sphaerodis bacterial reaction center protein results in charge separation across the membrane (not shown) with positive charges on one side and negative charges on the other side with reduced quinone derivative. (Right) Similarly, the Co1C3N4AQ system by Chu et al. (22) also achieved directional electron and hole transfer resulting in two catalytic centers with Co to perform oxidative reaction and the AQ to perform reduction reaction in the same system. Right: Adapted from ref. 22, licensed under CC BY-NC-ND 4.0.

Back      Print      View: 41

[ Other News ]___________________________________________________
  • Egypt Holds Workshop on New Biotech Applications
  • UN Agencies Urge Transformation of Food Systems
  • Taiwan strongly supports management of brown planthopper—a major threat to rice production
  • IRRI Director General enjoins ASEAN states to invest in science for global food security
  • Rabies: Educate, vaccinate and eliminate
  • “As a wife I will help, manage, and love”: The value of qualitative research in understanding land tenure and gender in Ghana
  • CIP Director General Wells Reflects on CIP’s 45th Anniversary
  • Setting the record straight on oil palm and peat in SE Asia
  • Why insect pests love monocultures, and how plant diversity could change that
  • Researchers Modify Yeast to Show How Plants Respond to Auxin
  • GM Maize MIR162 Harvested in Large Scale Field Trial in Vinh Phuc, Vietnam
  • Conference Tackles Legal Obligations and Compensation on Biosafety Regulations in Vietnam
  • Iloilo Stakeholders Informed about New Biosafety Regulations in PH
  • Global wheat and rice harvests poised to set new record
  • GM Maize Harvested in Vietnam Field Trial Sites
  • New label for mountain products puts premium on biological and cultural diversity
  • The Nobel Prize in Physiology or Medicine 2016
  • Shalabh Dixit: The link between rice genes and rice farmers
  • People need affordable food, but prices must provide decent livelihoods for small-scale family farmers
  • GM Seeds Market Growth to Increase through 2020 Due to Rise in Biofuels Use
Designed & Powered by WEBSO CO.,LTD