Research on artificial photosynthesis makes progress

Solar energy has attracted much attention because of the huge amount of energy continuously transferred from the sun to the Earth. While numerous photosensitizing systems had been studied over the decades for light harvesting, most photosensitizers possess a large bandgap (> 1.7 eV) requiring ultraviolet and visible light for their activation. Considering that over 46% of solar energy is in the near-infrared (NIR) range, almost half of overall solar spectrum cannot be utilized to activate those photosensitizers. Herein, we first report on NIR light-driven biocatalytic artificial photosynthesis using upconversion nanoparticles. Upconversion refers to nonlinear optical processes that occur through anti-Stokes emission, in which an emitted photon has more energy than the absorbed photon by sequential absorption of photons. For NIR light-driven photoenzymatic synthesis, we synthesized silica-coated upconversion nanoparticles, such as Si-NaYF4:Yb,Er and Si-NaYF4:Yb,Tm, for efficient photon-conversion through Forster resonance energy transfer (FRET) with rose bengal (RB), a photosensitizer. We observed NIR-induced electron transfer using linear sweep voltammetric analysis, which indicated photoexcited electrons of RB/Si-NaYF4:Yb,Er were transferred to NAD+ through a Rh-based electron mediator. RB/Si-NaYF4:Yb,Er nanoparticles, which exhibited higher FRET efficiency due to more spectral overlap than RB/Si-NaYF4:Yb, resulted in much better performance for photoenzymatic conversion. Our work shows that upconversion nanoparticles with anti-Stokes emission are promising light harvesters for versatile usage of NIR light in solar-to-chemical conversion processes.

Artificial photosynthesis - Wikipedia

07/08/2008 · Re: Duplicating MIT's artificial photosynthesis breakthrough ..

A Big Leap for an Artificial Leaf - MIT Technology Review

Artificial photosynthesis is being pursued to make liquid fuel from carbondioxide and water. Researchers at the Berkeley National Laboratory think this is going to be possible since discovering that nano-sized crystals of cobalt oxide can effectively carry out the critical part of the photosynthetic reaction which is the splitting of water molecules. The photo of the water molecule to hydrogen ions and oxygen is a an important half reaction in the process of artificial photosynthesis. The electrons released in this part of the reaction is used to reduce carbondioxide to form fuel. Having a catalyst that can effectively capture the photons and utilize them fast enough so as to not waste the sunlight photons is crucial which scientists think the newly discovered cobalt nano crystals are capable of doing. When micron sized cobalt crystals were used the yield was very less but when the scientists replaced it with nanocrystals of cobalt the yield increased by 1600 times which is commensurate with the sunlight flux at ground level. Photosystem II is a process in which manganese-containing enzymes serve as the catalyst for the photo of water molecules within a complex of . Scientists at he berkeley institute say that the efficiency, speed and size of the cobalt oxide nanocrystal clusters are comparable to Photosystem II. The next step for them to do is have a use this catalytic component to develop a viable integrated solar fuel conversion system.

How photosynthetic pigments harvest light | MIT News

Artificial photosynthesis is an attractive way to utilize solar energy through inspiration from natural photosynthesis in green plants. Water-splitting is critically required to establish an artificial photosynthetic system that consists of sequential charge-obtaining and transferring reactions. The oxidation of water is a limiting step to achieving water-splitting because of its multi-hole-related characteristics. A key to the development of effective water oxidation catalysts is the optimized control of material structure and composition through a facile synthetic method. This work synthesized polycrystalline RuO2/Co3O4 core/shell nanofibers by electrospinning and evaluated their photocatalytic water oxidation performance using a Ru(bpy)32+/persulfate system under visible light illumination. Our results show that RuO2/Co3O4 nanofibers exhibit significantly enhanced efficiency of photocatalytic water oxidation with a higher number of turnover frequency than those of pristine Co3O4 nanoparticles, Co3O4 nanofibers, and RuO2 nanofibers, respectively. The unique core-shell structure of RuO2/Co3O4 nanofibers comprising the inner region of highly conductive RuO2 and the outer region of catalytic Co3O4 provided a fast and effective transport highway for holes to O2-evolving sites. This work highlights the potential of tailored 1D binary composite nanofibers for the development of efficient oxygen-evolving catalysts and offers a new viewpoint for exploring multi-component catalysts through electrospinning.

Duplicating MIT's artificial photosynthesis breakthrough: Sevenhundred Elves: 8/1/08 5:47 …
Researchers from MIT have developed a new model that could help scientists design materials for artificial photosynthesis

JCAP - “innovation hub” on artificial photosynthesis

Efficient harvesting of unlimited solar energy and its conversion into valuable chemicals is one of the ultimate goals of scientists. With the ever-increasing concerns about sustainable growth and environmental issues, numerous efforts have been made to develop artificial photosynthetic process for the production of fuels and fine chemicals mimicking natural photosynthesis. Despite the research progresses made over the decades, the technology is still in its infancy because of the difficulties in kinetic coupling of whole photocatalytic cycles. Here, we report a new type of artificial photosynthesis system that can avoid such problems by integrally coupling biocatalytic redox reactions with photocatalytic water-splitting. We found that photocatalytic water-splitting reaction can be efficiently coupled with biocatalytic redox reactions by using tetra-cobalt polyoxometalate and Rh-based organometallic compound as hole and electron scavengers, respectively, for photoexcited Ru(bpy)32+ dye. Based on these results, we could successfully photosynthesize a model chiral compound (L-glutamate) using a model redox enzyme (glutamate dehydrogenase) upon in-situ photo-regeneration of cofactors.

A recent article in MIT Technology Review describes an exciting new development in clean fuel produced by artificial photosynthesis.

Artificial Photosynthesis Will Power the Future

Although other artificial photosynthesis methods have tried to use the photosynthetic parts of plants, Belcher, the Professor of Materials Science and Engineering and Biological Engineering at MIT and the lead author of the in Nature Nanotechnology, Yoon Sung Nam, pursued the method, plants use of having a natural pigment attract the sunlight and then using a catalyst to split the water into hydrogen and oxygen. Thomas Mallouk, the DuPont Professor of Materials Chemistry and Physics at Pennsylvania State University, describes the work as “an extremely clever piece of work that addresses one of the most difficult problems in artificial photosynthesis, namely, the nanoscale organization of the components in order to control electron transfer rates.” The concept behind artificial photosynthesis is to create a method of energy conversion using sunlight. But this preliminary is a long way from providing an alternative energy source. Belcher believes that within two years, she expects to have a prototype device that can carry out the whole process of splitting water into oxygen and , using a self-sustaining and durable system.

MIT professor Daniel Nocera claims to have created an artificial leaf, made from stable and inexpensive materials, which mimics nature's photosynthesis process

Bionic leaf turns sunlight into liquid fuel | Harvard Gazette

At the March 27, 2011 meeting of the American Chemical Society, Nocera unveiled a prototype artificial leaf that he reports to function at 10 times the photosynthetic efficiency of natural leafs, with no drop in efficiency after 45 hours of operation. Although this technology is in its infancy (the detailed scientific paper is not yet available) the mild conditions under which it is reported to operate, inspiration from natural photosynthesis, self-healing characteristics and fuel-cell like efficiency make this system very attractive for mass implementation. It can be foreseen that such a system could eventually be used to turn homes into their own power plants.