Scientists mimic essence of plants' energy storage system

A breakthrough of the MIT Solar Revolution Project mimic essence of plants energy storage system, in a simple, inexpensive, highly efficient process for storing solar energy.

Scientists Daniel Nocera and Matthew Kanan, discovered how to mimic a plant's energy storage using ordinary materials in everyday conditions. It can be a very important breakthrough - to electrolyse water into hydrogen and oxygen in a cheaply manner - it means we can effectively store solar energy without big losses. The key components in Nocera and Kanan's work are the two catalysts that produce valuable oxygen gas and hydrogen gas from water.

'Giant leap' for clean energy !
Sunlight has the greatest potential of any power source to solve the world's energy problems, said Nocera. In one hour, enough sunlight strikes the Earth to provide the entire planet's energy needs for one year. James Barber, the Ernst Chain Professor of biochemistry at Imperial College London, a leader in the study of photosynthesis, not involved in this research, called the discovery by Nocera and Kanan a "giant leap" toward generating clean, carbon-free energy on a massive scale.

Inspired by the photosynthesis performed by plants, Nocera and Kanan, have developed an unprecedented process that will allow the split of water into hydrogen and oxygen gases. Later, the oxygen and hydrogen may be recombined inside a fuel cell, creating carbon-free electricity to power your house or your electric car, day or night. The new catalyst works at room temperature, in neutral pH water, and it's easy to set up. The system uses small amounts of electricity to split water into hydrogen and oxygen, just as plant leaves that use a similar reaction. Nocera said "That's why I know this is going to work. It's so easy to implement!".

The key component in Nocera and Kanan's new process is a new catalyst that produces oxygen gas from water; another catalyst produces valuable hydrogen gas. The new catalyst consists of cobalt metal, phosphate and an electrode, placed in water. When electricity -- whether from a photovoltaic cell, a wind turbine or any other source -- runs through the electrode, the cobalt and phosphate form a thin film on the electrode, and oxygen gas is produced. Combined with another catalyst, such as platinum, that can produce hydrogen gas from water, the system can duplicate the water splitting reaction that occurs during photosynthesis.

The system allows small amounts of electricity from solar panels to split water into hydrogen and oxygen. A similar water-splitting reaction occurs during photosynthesis. Later, the gases can be recombined in a fuel cell to produce carbon-free electricity.

Here’s part of the MIT press release on the research findings: “Requiring nothing but abundant, non-toxic natural materials, this discovery could unlock the most potent, carbon-free energy source of all: the sun. ‘This is the nirvana of what we’ve been talking about for years,’ said MIT’s Daniel Nocera, the Henry Dreyfus Professor of Energy at MIT and senior author of a paper describing the work in the July 31 issue of Science. ‘Solar power has always been a limited, far-off solution. Now we can seriously think about solar power as unlimited and soon’.”

As published in the Science Magazine the utilization of solar energy on a large scale requires its storage. In natural photosynthesis, energy from sunlight is used to rearrange the bonds of water to O2 and H2-equivalents. The realization of artificial systems that perform similar "water splitting" requires catalysts that produce O2 from water without the need for excessive driving potentials. In the Science artilce, they also "report such a catalyst that forms upon the oxidative polarization of an inert indium tin oxide electrode in phosphate-buffered water containing Co2+. A variety of analytical techniques indicates the presence of phosphate in an approximate 1:2 ratio with cobalt in this material. The pH dependence of the catalytic activity also implicates HPO42– as the proton acceptor in the O2-producing reaction. This catalyst not only forms in situ from arth-abundant materials but also operates in neutral water under ambient conditions."

With Daniel Nocera's and Matthew Kanan's new catalyst, homeowners could use their solar panels during the day to power their home, while also using the energy to split water into hydrogen and oxygen for storage. At night, the stored hydrogen and oxygen could be recombined using a fuel cell to generate power while the solar panels are inactive.

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