A sample of a photoelectric cell in a lab environment. Catalysts are added to the cell, which is submerged in water and illuminated by simulated sunlight. The bubbles seen are oxygen (forming on the front of the cell) and hydrogen (forming on the back of the cell).

Artificial photosynthesis is a chemical process that replicates the natural process of photosynthesis, a process that converts sunlight, water, and carbon dioxide into carbohydrates and oxygen. The term is commonly used to refer to any scheme for capturing and storing the energy from sunlight in the chemical bonds of a fuel (a solar fuel). Photocatalytic water splitting converts water into protons (and eventually hydrogen) and oxygen, and is a main research area in artificial photosynthesis. Light-driven carbon dioxide reduction is another studied process, replicating natural carbon fixation.

Research developed in this field encompasses design and assembly of devices (and their components) for the direct production of solar fuels, photoelectrochemistry and its application in fuel cells, and engineering of enzymes and photoautotrophic microorganisms for microbial biofuel and biohydrogen production from sunlight. Many, if not most, of the artificial approaches are bio-inspired, i.e., they rely on biomimetics.

Overview[link]

The photosynthetic reaction can be divided into two half-reactions (oxidation and reduction), both of which are essential to producing fuel. In plant photosynthesis, water molecules are photo-oxidized to release oxygen and protons. The second stage of plant photosynthesis (also known as the Calvin-Benson cycle) is a light-independent reaction that converts carbon dioxide into glucose. Researchers of artificial photosynthesis are developing photocatalysts to perform both of these reactions separately. Furthermore, the protons resulting from water splitting can be used for hydrogen production. These catalysts must be able to react quickly and absorb a large percentage of solar photons.^[1]

Whereas photovoltaics can provide direct electrical current from sunlight, the inefficiency of fuel production from photovoltaic electricity (indirect process) and the fact sunshine is not constant throughout time sets a limit to its use.^[2][3] A way of using natural photosynthesis is via the production of biofuel through biomass, also an indirect process that suffers from low energy conversion efficiency (due to photosynthesis' own low efficiency in converting sunlight to biomass), and clashes with the increasing need of land mass for human food production.^[4] Artificial photosynthesis aims then to produce a fuel from sunlight that can be stored and used when sunlight is not available, by using direct processes, that is, to produce a solar fuel. With the development of catalysts able to reproduce the key steps of photosynthesis, water and sunlight would ultimately be the only needed sources for clean energy production. The only by-product would be oxygen, and production of a solar fuel has the potential to be cheaper than gasoline.^[5]

One process for the creation of a clean and affordable energy supply is the development of photocatalytic water splitting under solar light. This method of sustainable hydrogen production is a key objective in the development of alternative energy systems of the future.^[6] It is also predicted to be one of the more, if not the most, efficient ways of obtaining hydrogen from water.^[7] The conversion of solar energy into hydrogen via a water-splitting process assisted by photosemiconductor catalysts is one of the most promising technologies in development. This process has the potential for large quantities of hydrogen to be generated in an ecologically sound method. The conversion of solar energy into a clean fuel (H₂) under ambient conditions is one of the greatest challenges facing scientists in the twenty-first century.^[8]

Two approaches are generally recognized in the construction of solar fuel cells for hydrogen production:^[9]

• A homogeneous system is one where catalysts are not compartmentalized, that is, components are present in the same compartment. This means that hydrogen and oxygen are produced in the same location. This can be a drawback, since they compose an explosive mixture, demanding further gas purification. Also, all components must be active in approximately the same conditions (e.g., pH).
• A heterogeneous system has two separate electrodes, an anode and a cathode, making possible the separation of oxygen and hydrogen production. Furthermore, different components do not necessarily need to work in the same conditions. However, the increased complexity of these systems makes them harder to function and they are more costly.

Another area of research within artificial photosynthesis is the selection and manipulation of photosynthetic microorganisms, namely green microalgae and cyanobacteria, for the production of solar fuels. Many strains are able to produce hydrogen naturally, and focus exists to improve on these.^[10] Algae biofuels such as butanol and methanol are produced both at laboratory and commercial scales. This approach has benefited with the development of synthetic biology,^[10] which is also being explored by the J. Craig Venter Institute to produce a synthetic organism capable of biofuel production.^[11][12]

History[link]

In the late 60s, Akira Fujishima discovered photocatalytic properties in titanium dioxide, the so-called Honda-Fujishima effect, which could be used for hydrolysis.^[13]

The Swedish Consortium for Artificial Photosynthesis, the first of its kind, was established in 1994 as collaboration between groups of three different universities, Lund, Uppsala and Stockholm, being presently active around Lund and the Ångström Laboratories in Uppsala^[14] The consortium was built with a multidisciplinary approach to focus on learning from natural photosynthesis and applying this knowledge in biomimetic systems.^[15] Research in artificial photosynthesis undergoes a boom in the beginning of the 21st century.^[2] In 2000, Commonwealth Scientific and Industrial Research Organisation (CSIRO) researchers publicize their intent to focus on carbon dioxide capture and conversion to hydrocarbons.^[16][17] In 2003, the Brookhaven National Laboratory announced the discovery of an important intermediate step in the reduction of CO₂ to CO (the simplest possible carbon dioxide reduction reaction), which could lead to better catalyst designing.^[18][19]

One of the drawbacks of artificial systems for water-splitting catalysts is their general reliance on scarce, expensive elements, such as ruthenium or rhenium.^[2] With the funding of the United States Air Force Office of Scientific Research,^[20] in 2008, MIT chemist and head of the Solar Revolution Project Daniel G. Nocera and postdoctoral fellow Matthew Kanan attempted to circumvent this issue by using a catalyst containing the cheaper and more abundant elements cobalt and phosphate.^[21][22] The catalyst was able to split water into oxygen and protons using sunlight, and could potentially be coupled to a hydrogen-producing catalyst such as platinum. Furthermore, while the catalyst broke down during catalysis, it could self-repair.^[23] This experimental catalyst design was considered a major breakthrough in the field by many researchers.^[24][25]

Whereas CO is the prime reduction product of CO₂, more complex carbon compounds are usually desired. In 2008, Princeton chemistry professor Andrew B. Bocarsly reported the direct conversion of carbon dioxide and water to methanol using solar energy in a highly efficient photochemical cell.^[26]

While Nocera and coworkers had accomplished water splitting to oxygen and protons, a light-driven process to produce hydrogen from protons still needed to be developed. In 2009, the Leibniz Institute for Catalysis reported inexpensive iron carbonyl complexes able to do just this.^[27][28] In the same year, researchers at the University of East Anglia use also iron carbonyl compounds to achieve photoelectrochemical hydrogen production with a 60% efficiency, this time using a gold electrode covered with layers of indium phosphide to which the iron complexes were linked.^[29] Both these processes used a molecular approach, where discrete nanoparticles are responsible for catalysis.

Hydrogen photoproduction in heterogeneous systems is also possible, even if not directly mimicking photosynthesis. Also in 2009, F. del Valle and K. Domen showed the impact of the thermal treatment in a closed atmosphere using Cd1-xZnxS photocatalysts. Cd1-xZnxS solid solution reports high activity in hydrogen production from water splitting under sunlight irradiation.^[30] A mixed heterogeneous/molecular approach by researchers at the University of California, Santa Cruz in 2010, using both nitrogen-doped and cadmium selenide quantum dots-sensitized titanium dioxide nanoparticles and nanowires, also yielded photoproduced hydrogen.^[31]

Artificial photosynthesis remained an academic field for many years. However, in the beginning of 2009, Mitsubishi Chemical Holdings was reported to be developing its own artificial photosynthesis research by using sunlight, water and carbon dioxide to "create the carbon building blocks from which resins, plastics and fibers can be synthesized."^[32] This was confirmed with the establishment of the KAITEKI Institute later that year, with carbon dioxide reduction through artificial photosynthesis as one of the main goals.^[33][34]

Funded by the DOE as one of its Energy Innovation Hubs, the Joint Center for Artificial Photosynthesis^[35] is set up in 2010 by Caltech and Lawrence Berkeley National Laboratory.^[36]

Daniel Nocera and his research team announced in 2011 the first practical artificial leaf. In a speech at the 241st National Meeting of the American Chemical Society, Nocera described an advanced solar cell the size of a poker card capable of splitting water into oxygen and hydrogen, approximately ten times more efficient than natural photosynthesis.^[37] The cell is mostly made of inexpensive materials that are widely available, works under simple conditions, and shows increased stability over previous catalysts: in laboratory studies, the authors demonstrated that an artificial leaf prototype could operate continuously for at least forty-five hours without a drop in activity.^[38]

Current research[link]

In energy terms, natural photosynthesis can be divided in three steps:^[9][15]

• Light-harvesting complexes in bacteria and plants capture photons and transduce them into electrons, injecting them into the photosynthetic chain.
• Proton-coupled electron transfer along several cofactors of the photosynthetic chain, causing local, spatial charge separation.
• Redox catalysis, which uses the aforementioned transferred electrons, to oxidize water to dioxygen and protons; these protons can in some species be utilized for dihydrogen production.

A triad assembly, with a photosensitizer (P) linked in tandem to a water oxidation catalyst (D) and a hydrogen evolving catalyst (A). Electrons flow from D to A when catalysis occurs.

Using biomimetic approaches, artificial photosynthesis tries to construct systems doing the same type of processes. Ideally, a triad assembly could oxidize water with one catalyst, reduce protons with another and have a photosensitizer molecule to power the whole system. One of the simplest designs is where the photosensitizer is linked in tandem between a water oxidation catalyst and a hydrogen evolving catalyst:

• The photosensitizer transfers electrons to the hydrogen catalyst when hit by light, becoming oxidized in the process.
• This drives the water splitting catalyst to donate electrons to the photosensitizer. In a triad assembly, such a catalyst is often referred to as a donor. The oxidized donor is able to perform water oxidation.

The state of the triad with one catalyst oxidized on one end and the second one reduced on the other end of the triad is referred to as a charge separation, and is a driving force for further electron transfer, and consequently catalysis, to occur. The different components may be assembled in diverse ways, such as supramolecular complexes, compartmentalized cells, or linearly, covalently linked molecules.^[9]

Research into finding catalysts that can convert water, carbon dioxide, and sunlight to carbohydrates or hydrogen is a current, active field. By studying the natural oxygen-evolving complex, researchers have developed catalysts such as the "blue dimer" to mimic its function. Photoelectrochemical cells that reduce carbon dioxide into carbon monoxide (CO), formic acid (HCOOH) and methanol (CH₃OH) are under development.^[39] However, these catalysts are still very inefficient.^[5]

Hydrogen catalysts[link]

Hydrogen is the simplest solar fuel to synthesize, since it involves only the transference of two electrons to two protons. It must however be done stepwise, with formation of an intermediate hydride anion:

2 e⁻ + 2 H⁺ ↔ H⁺ + H⁻ ↔ H₂

The proton-to-hydrogen converting catalysts present in nature are hydrogenases. These are enzymes that can either reduce protons to molecular hydrogen or oxidize hydrogen to protons and electrons. Spectroscopic and crystallographic studies spanning several decades have resulted in a good understanding of both the structure and mechanism of hydrogenase catalysis.^[40][41] Using this information, several molecules mimicking the structure of the active site of both nickel-iron and iron-iron hydrogenases have been synthesized.^[9][42] Other catalysts are not structural mimics of hydrogenase but rather functional ones. Synthesized catalysts include structural H-cluster models,^[9][43] a dirhodium photocatalyst,^[44] and cobalt catalysts.^[9][45]

Water-oxidizing catalysts[link]

Water oxidation is a more complex chemical reaction than proton reduction. In nature, the oxygen-evolving complex performs this reaction by accumulating reducing equivalents (electrons) in a manganese-calcium cluster within photosystem II (PS II), then delivering them to water molecules, with the resulting production of molecular oxygen and protons:

2 H₂O → O₂ + 4 H⁺

Without a catalyst (natural or artificial), this reaction is very endothermic, requiring high temperatures (at least 2500 K).^[7]

The exact structure of the oxygen-evolving complex has been hard to determine experimentally.^[46] As of 2011, the most detailed model was from a 1.9Å resolution crystal structure of photosystem II.^[47] The complex is a cluster containing four manganese and one calcium ions, but the exact location and mechanism of water oxidation within the cluster is unknown. Nevertheless, bio-inspired manganese and manganese-calcium complexes have been synthesized, such as [Mn₄O₄] cubanes, some with catalytic activity.^[48]

Some ruthenium complexes, such as the dinuclear µ-oxo-bridged "blue dimer" (the first of its kind to be synthesized), are capable of light-driven water oxidation, thanks to being able to form high valence states.^[9] In this case, the ruthenium complex acts as both photosensitizer and catalyst.

Many metal oxides have been found to have water oxidation catalytic activity, including ruthenium(IV) oxide (RuO₂), iridium(IV) oxide (IrO₂), cobalt oxides (including nickel-doped Co₃O₄), manganese(III) oxide (Mn₂O₃), and a mix of Mn₂O₃ with CaMn₂O₄. Oxides are easier to obtain than molecular catalysts, especially those from relatively abundant transition metals (cobalt and manganese), but suffer from low turnover frequency and slow electron transfer properties, and their mechanism of action is hard to decipher and, therefore, to adjust.^[6]

Photosensitizers[link]

Structure of [Ru(bipy)₃]²⁺, a broadly used photosensitizer.

Nature uses pigments, mainly chlorophylls, to absorb a broad part of the visible spectrum. Artificial systems can use either one type of pigment with a broad absorption range or combine several pigments for the same purpose.

Ruthenium polypyridine complexes, in particular tris(bipyridine)ruthenium(II) and its derivatives, have been extensively used in hydrogen photoproduction due to their efficient visible light absorption and long-lived consequent metal-to-ligand charge transfer excited state, which makes the complexes strong reducing agents.^[9] Other noble metal-containing complexes used include ones with platinum, rhodium and iridium.^[9]

Metal-free organic complexes have also been successfully employed as photosensitizers. Examples include eosin Y and rose bengal.^[9] Pyrrole rings such as porphyrins have also been used in coating nanomaterials or semiconductors for both homogeneous and heterogeneous catalysis.^[6][39]

Carbon dioxide reduction catalysts[link]

In nature, carbon fixation is done on green plants using the enzyme RuBisCO as a part of the Calvin cycle. RuBisCO is a rather slow catalyst compared to the vast majority of other enzymes, incorporating only a few molecules of carbon dioxide into ribulose-1,5-bisphosphate per minute, but does so at atmospheric pressure and in mild, biological conditions.^[49] The resulting product is further reduced and eventually used in the synthesis of glucose, which in turn is a precursor to more complex carbohydrates, such as cellulose and starch. The process consumes energy in the form of ATP and NADPH.

Artificial CO₂ reduction for fuel production aims mostly at producing reduced carbon compounds from atmospheric CO₂. Some transition metal polyphosphine complexes have been developed for this end; however, they usually require previous concentration of CO₂ before use, and carriers (molecules that would fixate CO₂) that are both stable in aerobic conditions and able to concentrate CO₂ at atmospheric concentrations haven't been yet developed.^[50] The simplest product from CO₂ reduction is carbon monoxide (CO), but for fuel development, further reduction is needed, and a key step also needing further development is the transfer of hydride anions to CO.^[50]

Other materials and components[link]

Charge separation is a key property of dyad and triad assemblies. Some nanomaterials employed are fullerenes (such as carbon nanotubes), a strategy that explores the pi-bonding properties of these materials.^[6] Diverse modifications (covalent and non-covalent) of carbon nanotubes have been attempted to increase the efficiency of charge separation, including the addition of ferrocene and pyrrole-like molecules such as porphyrins and phthalocyanines.^[6]

Since photodamage is usually a consequence in many of the tested systems after a period of exposure to light, bio-inspired photoprotectants have been tested, such as carotenoids (which are used in photosynthesis as natural protectants).^[51]

Light-driven methodologies under development[link]

Photoelectrochemical cells[link]

Photoelectrochemical cells are a heterogeneous system that use light to produce either electricity or hydrogen. The vast majority of photoelectrochemical cells use semiconductors as catalysts.^[39] There have been attempts to use synthetic manganese complex-impregnated Nafion as a working electrode, but it has been since shown that the catalytically active species is actually the broken-down complex.^[52]

A promising, emerging type of solar cell is the dye-sensitized solar cell. This type of cell still depends on a semiconductor (such as TiO₂) for current conduction on one electrode, but with a coating of an organic or inorganic dye that acts as a photosensitizer; the counter electrode is a platinum catalyst for H₂ production.^[39] These cells have a self-repair mechanism and solar-to-electricity conversion efficiencies rivaling those of solid-state semiconductor ones.^[39]

Photocatalytic water splitting in homogeneous systems[link]

Direct water oxidation by photocatalysts is a more efficient usage of solar energy than photoelectrochemical water splitting because it avoids an intermediate thermal or electrical energy conversion step.^[53]

Bio-inspired manganese clusters have been shown to possess water oxidation activity when adsorbed on clays together with ruthenium photosensitizers, although with low turnover numbers.^[9]

As mentioned above, some ruthenium complexes are able to oxidize water under solar light irradiation.^[9] Although their photostability is still an issue, many can be reactivated by a simple adjustment of the conditions they work in.^[9] Improvement of catalyst stability has been tried resorting to polyoxometalates, in particular ruthenium-based ones.^[6][9]

Whereas a fully functional artificial system is usually envisioned when constructing a water splitting device, some mixed approaches have been tried. One of these involve the use of a gold electrode to which photosystem II is linked; an electrical current is detected upon illumination.^[54]

Hydrogen-producing artificial systems[link]

A H-cluster FeFe hydrogenase model compound covalently linked to a ruthenium photosensitizer. The ruthenium complex absorbs light and transduces its energy to the iron compound, which can then reduce protons to H₂.

The simplest photocatalytic hydrogen production unit consists of a hydrogen-evolving catalyst linked to a photosensitizer.^[55] In this dyad assembly, a so-called sacrificial donor for the photosensitizer is needed, that is, one that is externally supplied and replenished; the photosensitizer donates the necessary reducing equivalents to the hydrogen-evolving catalyst, which uses protons from a solution where it is immersed or dissolved in. Cobalt compounds such as cobaloximes are some of the best hydrogen catalysts, having been coupled to both metal-containing and metal-free photosensitizers.^[9][56] The first H-cluster models linked to photosensitizers (mostly ruthenium photosensitizers, but also porphyrin-derived ones) were prepared in the early 2000s.^[9] Both types of assembly are under development to improve their stability and increase their turnover numbers, both necessary for constructing a sturdy, long-lived solar fuel cell.

As with water oxidation catalysis, not only fully artificial systems have been idealized: hydrogenase enzymes themselves have been engineered for photoproduction of hydrogen, by coupling the enzyme to an artificial photosensitizer, such as [Ru(bipy)₃]²⁺ or even photosystem I.^[9][55]

[edit] NADP⁺/NADPH coenzyme-inspired catalyst

In natural photosynthesis, the NADP⁺ coenzyme is reducible to NADPH through binding of a proton and two electrons. This reduced form can then deliver the proton and electrons, potentially as a hydride, to reactions that culminate in the production of carbohydrates (the Calvin cycle). The coenzyme is recyclable in a natural photosynthetic cycle, but this process is yet to be artificially replicated.

A current goal is to obtain an NADPH-inspired catalyst capable of recreating the natural cyclic process. Utilizing light, hydride donors would be regenerated and produced where the molecules are continuously used in a closed cycle. Brookhaven chemists are now using a ruthenium-based complex to serve as the acting model. The complex is proven to perform correspondingly with NADP+/NADPH, behaving as the foundation for the proton and two electrons needed to convert acetone to isopropanol.

Currently, Brookhaven researchers are aiming to find ways for light to generate the hydride donors. The general idea is to use this process to produce fuels from carbon dioxide.^[57]

Photobiological production of fuels[link]

Some photoautotrophic microorganisms can, under certain conditions, produce hydrogen. Nitrogen-fixing microorganisms, such as filamentous cyanobacteria, possess the enzyme nitrogenase, responsible for conversion of atmospheric N₂ into ammonia; molecular hydrogen is a byproduct of this reaction, and is many times not released by the microorganism, but rather taken up by a hydrogen-oxidizing (uptake) hydrogenase. One way of forcing these organisms to produce hydrogen is then to annihilate uptake hydrogenase activity. This has been done on a strain of Nostoc punctiforme: one of the structural genes of the NiFe uptake hydrogenase was inactivated by insertional mutagenesis, and the mutant strain showed hydrogen evolution under illumination.^[58]

Many of these photoautotrophs also have bidirectional hydrogenases, which can produce hydrogen under certain conditions. However, other energy-demanding metabolic pathways can compete with the necessary electrons for proton reduction, decreasing the efficiency of the overall process; also, these hydrogenases are very sensitive to oxygen.^[10]

Several carbon-based biofuels have also been produced using cyanobacteria, such as 1-butanol.^[59]

Synthetic biology techniques are predicted to be useful in this field. Microbiological and enzymatic engineering have the potential of improving enzyme efficiency and robustness, as well as constructing new biofuel-producing metabolic pathways in photoautotrophs that previously lack them, or improving on the existing ones.^[10][59] Another field under development is the optimization of photobioreactors for commercial application.^[60]

Employed research techniques[link]

Research in artificial photosynthesis is necessarily a multidisciplinary field, requiring a multitude of different expertise.^[10] Some techniques employed in making and investigating catalysts and solar cells include:

• Organic and inorganic chemical synthesis.
• Electrochemistry methods, such as photoelectrochemistry, cyclic voltammetry, and bulk electrolysis.
• Spectroscopic methods:
  • fast techniques, such as time-resolved spectroscopy and ultrafast laser spectroscopy;
  • magnetic resonance spectroscopies, such as nuclear magnetic resonance, electron paramagnetic resonance;
  • X-ray absorption methods, such as EXAFS.
• Crystallography.
• Molecular biology, microbiology and synthetic biology methodologies.

Advantages, disadvantages, and efficiency[link]

Advantages of solar fuel production through artificial photosynthesis include:

• The solar energy can be immediately converted and stored. In photovoltaic cells, sunlight is converted into electricity and then converted again into chemical energy for storage, with some necessary loss of energy associated with the second conversion.
• The byproducts of these reactions are environmentally friendly. Artificially photosynthesized fuel would be a carbon-neutral source of energy, which could be used for transportation or homes.

Disadvantages include:

• Materials used for artificial photosynthesis often corrode in water, so they may be less stable than photovoltaics over long periods of time. Most hydrogen catalysts are very sensitive to oxygen, being inactivated or degraded in its presence; also, photodamage may occur over time.^[9][55]
• The overall cost is not yet advantageous enough to compete with fossil fuels as a commercially viable source of energy.^[3]

A concern usually addressed in catalyst design is efficiency, in particular how much of the incident light can be used in a system in practice. This is comparable with photosynthetic efficiency, where light-to-chemical-energy conversion is measured. Photosynthetic organisms are able to collect about 50% of incident solar radiation,^[61] but photochemical cells could use materials absorbing a wider range of solar radiation. It is however not straightforward to compare overall fuel production between natural and artificial systems: for example, plants have a theoretical threshold of 12% efficiency of glucose formation from photosynthesis, while a carbon reducing catalyst may go beyond this value.^[61] However, plants are efficient in using CO₂ at atmospheric concentrations, something that artificial catalysts still cannot perform.^[62]

Potential global impact[link]

Professor Dan Nocera (MIT), Professor Peidong Yang (UC Berkeley), and Assoc. Prof Thomas Faunce (ANU), Towards Global Artificial Photosynthesis Conference, Lord Howe Island, 16 August 2011.

Being a renewable and carbon-neutral source of solar fuels, producing either hydrogen or carbohydrates, artificial photosynthesis is set apart from other popular renewable energy sources, specifically hydroelectric, solar photovoltaic, geothermal, and wind — which produce electricity directly with no fuel intermediate. As such, artificial photosynthesis may become a very important source of fuel for transportation. Unlike biomass energy, it does not require arable land and, consequently, will not compete with the food supply.

At the fifteenth meeting of the International Congress of Photosynthesis Research (ISPR) in Beijing 27 August 2010, a proposal was made for a "macroscience" Global Artificial Photosynthesis (GAP) Project, with seven models being presented for evaluation.^[63][64] An international conference on the subject took place between the fourteenth and eighteenth of August 2011 at Lord Howe Island under the auspices of the UNESCO Natural Sciences Sector with subsequent meetings planned.^[65] The meeting featured presentations from both scientists and non-scientific members of the society from across the globe, such as Peidong Yang, Dan Nocera and Michael Kirby.^[66] It has been argued that photosynthesis in its natural and artificial forms should be considered a common heritage of humanity.^[67]

See also[link]

• AlgaePARC
• Carbon footprint
• Fuel cell
• Hydrogen economy
• List of emerging technologies
• Metabolic engineering
• Photovoltaic cell
• Photovoltaic module

References[link]

External links[link]

• Engineering light-activated metalloproteins to split water at Australia National University
• Daniel Nocera describes new process for storing solar energy at Massachusetts Institute of Technology.
• Paul Alivisatos on Artificial Photosynthesis at Lawrence Berkley National Laboratory
• Nanocapsules for artificial photosynthesis a Nanowerk News article
• MIT Solar Revolution Project

Paul Alivisatos in 2003

Armand Paul Alivisatos is an American scientist of Greek descent, researching the structural, thermodynamic, optical, and electrical properties of nanocrystals. In 2009, he was named the Director of the Lawrence Berkeley National Laboratory.^[1]

Alivisatos graduated with a bachelors in chemistry from the University of Chicago in 1981, and with a doctorate in physical chemistry from the University of California, Berkeley in 1986, where he worked under Charles Harris.

In 1986 he joined AT&T Bell Labs working with Louis E. Brus, and began research in the field of nanotechnology. He returned to Berkeley in 1988 as an Assistant Professor of Chemistry, becoming associate Professor in 1993 and Professor in 1995. He was Chancellor's Professor for 1998-2001.

In January 2003 he was appointed director of the Materials Sciences Division at the Lawrence Berkeley National Laboratory. He is also director of LBNL's Molecular Foundry. Alivisatos was elected a Fellow of the American Academy of Arts and Sciences in 2004.^[2]

He is a Fellow of the National Academy of Sciences, American Physical Society and the American Association for the Advancement of Science, and is a co-editor of the scientific journal Nano Letters.

He has served as a member of the Defense Sciences Study Group, and on panels of the Defense Science Board. As of 2000, he was a member of the Department of Energy Council on Materials Sciences.

"Paul Alivisatos has been a world leader in the synthesis of artificial nanostructures and quantum dot technology, and one of the principal scientific drivers behind the use of nanoscience technologies to create a new generation of solar photovoltaic cells," Steve Chu said when he named Alivisatos as Berkeley Lab’s deputy director in 2008. Alivisatos has directed the Laboratory since 2009. ^{[3] [4]} He has been ranked 5th in the list of the 100 top chemists of the past decade released by Thomson-Reuters. ^[5]

Early Life[link]

A. Paul Alivisatos was born in Chicago on November 12, 1959. He lived there until the age of 10, when his family moved to Athens, Greece, where he would remain through high school. Alivisatos has said of his years in Greece that it was a great experience for him because he had to learn the Greek language and culture then catch up with the more advanced students. "When I found something very interesting it was sometimes a struggle for me to understand it the very best that I could," he has said of that experience. "That need to work harder became an important motivator for me." Alivisatos returned to the United States to attend the University of Chicago in the late seventies. ^[6]

Awards[link]

• Presidential Young Investigator Award
• Alfred P. Sloan Foundation fellowship
• ACS Exxon Solid State Chemistry Fellowship
• Coblentz Award (1994)
• Wilson Prize at Harvard
• Department of Energy Award for Outstanding Scientific Accomplishment in Materials Chemistry (1994)
• Materials Research Society Outstanding Young Investigator Award (1995)
• Department of Energy Award for Sustained Outstanding Research in Materials Chemistry (1997)
• Wolf Prize in Chemistry, 2012

Notable Publications[link]

• Science vol 271 p 933, 1996
• Science vol 295 p 2425, 2002
• Science vol 310 p 5747, 2005

SCIENCE Vol 292 p2060 2001

External links[link]

• Biography (UC Berkeley)

References[link]

For Real was an American R&B and soul quartet, that formed in 1993.^[1] In the latter part of that decade they were nominated for a Grammy, Billboard Music Award, and Soul Train Music Award.

Biography[link]

For Real secured their recording contract by accident. "We were picking up our manager from the airport. So we decided to greet him with an acappella song. Someone from A&M Records just happened to be in the airport and heard them perform. Not long after, they were signed," said Latanyia Baldwin.^[2]

The band released their debut album, It's a Natural Thang, with production from Brian McKnight on A&M Records in 1994, and it became a critical success, including a rare four stars from Rolling Stone magazine.^[3] Their first single, "You Don't Wanna Miss" hit #28 on the Billboard chart, courtesy of a danceable new jack swing remix by Steve "Silk" Hurley, which was featured in the song's video. A second single, "Easy to Love", peaked at #65 on the Billboard Hot 100 chart. The album scored another chart hit with the a cappella love song, "You Don't Know Nothin'", which was written and produced by Mervyn Warren, and which peaked at #27. The song peaked at #54 in the UK Singles Chart in July 1995.^[4] The album sold over one million copies worldwide, and peaked at #80 on the Billboard 200.

In 1995, the band appeared in Italian Vogue, modeling men's suits. They toured alongside Stevie Wonder,^[5] and lent their voices to the Martin Scorsese film project Grace of My Heart. The foursome also forayed into acting with appearances in the film Shake, Rattle and Rock! starring Renée Zellweger and Howie Mandel^[6] on Showtime.

They also hit the US Top 20 with the single "Freedom (Theme from Panther)" featuring Aaliyah, TLC, En Vogue, BlackGirl, SWV, and Vanessa Williams from the film Panther. They also recorded a duet with Stevie Wonder called "Stubborn Kind of Fellow", which appeared on the Marvin Gaye tribute album, Inner City Blues: The Music of Marvin Gaye.^[7] For Real also recorded songs for the soundtracks of the films Waiting to Exhale and Fled.

After a label change from A&M to Dallas Austin's Arista imprint Rowdy Records in 1996, For Real struck again with the Austin-produced, 60s-leaning single "Like I Do", from their second album Free. "Like I Do" hit #10 on the Billboard singles chart. The video also earned a Billboard nomination for Best R&B Clip; the album made the Top 100, and sold nearly 400,000 copies in the US. The album's next and last single was the Diane Warren-penned pop ballad "The Saddest Song I Ever Heard" which hit #65 on the Top 100 singles chart. The band performed "Saddest Song" on the TV series All That. Free included production from top R&B/pop producers like Babyface, Mario Winans, and Jon B..

The band also recorded three songs ("I Do", "Born to Love That Boy" and "Unwanted Number") and appeared in the critically acclaimed film Grace of My Heart. The film's soundstrack won a Satellite Award in 1997.^[9][10]

In January 1997, the band won an American Music Award for their work on the Waiting to Exhale soundtrack, in Summer 1997, the group earned a Soul Train Award nomination for Album of the Year (By a Group, Band or Duo) for Free.

In 1999, Wendi Williams lent her voice to the Emmy-winning film Introducing Dorothy Dandridge with Halle Berry, in which Berry plays a singer but Williams is behind her singing voice.^[11]

In 2002, their song "Love Will Be Waiting at Home" appeared in the film Two Can Play That Game, which starred Vivica A. Fox and Morris Chestnut.

In 2009, CoryLavel began to work with Josina Elder on her new album.

Discography[link]

• It's a Natural Thang (1994)
• Free (1996)

Awards and nominations[link]

References[link]