Algal protein provides a more efficient way to split water and produce hydrogen

In this world proceeding towards an energy crisis in future, the development of efficient techniques to harness energy from sustainable resources have interested many researchers. Researchers have been striving hard to understand and replicate the natural process of photosynthesis to harness solar energy as efficiently as plants.Now let's see how algae help us in this respect.

 Water splitting in photo-electrochemical cells to yield hydrogen is a promising way to sustainable fuels. A team of Swiss and US scientists now made major progress in developing highly efficient electrodes – made of an algal protein, thus mimicking a central step in natural photosynthesis. Photosynthesis is considered the (Holy Grail) in the field of sustainable energy generation because it directly converts solar energy into storable fuel using nothing but water and carbon dioxide (CO2). Scientists have long tried to mimic the underlying natural processes and to optimize them for energy device applications such as photo-electrochemical cells (PEC), which use sunlight to electrochemically split water – and thus directly generate hydrogen, cutting short the more conventional approach using photovoltaic cells for the electrolysis of water.So lets see how far this algae protein can split up water and produce hydrogen!!!

                                                 

Recently, scientists from the Swiss research institute EMPA, along with colleagues from the University of Basel and the Argonne National Laboratory in Illinois took a cue from photosynthesis and discovered that by coupling a light-harvesting plant protein with their specially designed electrode, they could substantially boost the efficiency of photo-electrochemical cells used to split water and produce hydrogen - a huge step forward in the search for clean, truly green power.Until the discovery of deep sea life forms that thrive in lightless hyrothermal vents, photosynthesis was considered the engine that drives all life on Earth. For those of us not dwelling in the chilly depths, that's still pretty much true - plants use solar energy to combine carbon dioxide and water to build sugars for energy storage (food for us) and structure (wood for heat and shelter) - the ultimate in green. Somewhere in that cascade of reactions, water is quickly and efficiently split into hydrogen and oxygen - a property understandably of great interest to proponents of clean energy.                                  

Iron oxide, in particular hematite (alpha-Fe₂O₃), is a promising electrode material for PEC because it is susceptible to visible wavelengths and thus uses sunlight more efficiently than photocatalysts like TiO₂, which can only use the UV part of solar radiation. What’s more, hematite is a low-cost and abundant material.The second thing in the process is phycocyanin a protein from blue-green algae. Electrolysis the energy for which can be cleanly supplied by photovoltaic cells or hydroelectric power. Another technique, the focus of the Swiss/US collaborators, uses photo-electrochemical cells (PEC), which employ light energy to directly cleave water electrochemically - a process that skips the step of converting the light to electricity first.                                                                                                                           

The material of choice for PEC electrodes (site of the actual water splitting) has centered on metal oxides because some are photocatalytic (activated by light). Recently, titanium dioxide was in the news after it was shown to disperse organic air and water pollutants when activated by UV light. Hematite, a form of iron oxide (otherwise known as rust) proved even more promising because it responds to visible wavelengths and is cheap and abundant.While working on his doctoral thesis at EMPA, scientist Debajeet Bora hit upon the idea of cross-coupling molecules of a light-harvesting plant protein with nanoparticles of hematite.  Somewhat surprisingly, the light harvesting protein complex does not get destroyed while in contact with a photocatalyst in an alkaline environment under strong illumination. Chemists would have predicted the complete denaturation of biomolecules under such corrosive and aggressive conditions.Photocatalysts are designed to destroy organic pollutants, which are a burden to the environment.  There seems to be a delicate balance where organic molecules not only survive harsh photocatalytic conditions, but even convey an additional benefit to ceramic photocatalysts:They double the photocurrent. This is a big step forward and in an area of science where even small incremental increases in efficiency are considered noteworthy, this new plant-assisted boost to hydrogen generation is big news indeed and bodes well for the on-going quest to supply affordable earth-friendly energy for all of us.

[via:gizmag]

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