More Efficient Solar Cells

Wednesday, September 16, 2015 @ 09:09 AM gHale

There is now a relatively inexpensive and simple way to split water into hydrogen and oxygen through a new electrodeposition method, which can produce highly efficient solar cells that can gather solar energy for use as fuel.

In addition, the new method could lead to a sizable increase in the amount of hydrogen available for fuel usage, said researchers at Missouri University of Science and Technology.

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“The work helps to solve the problem that solar energy is intermittent,” said Dr. Jay A. Switzer, the Donald L. Castleman/Foundation for Chemical Research Professor of Discovery at Missouri S&T. “Obviously, we cannot have the sun produce energy on one spot the entire day, but our process converts the energy into a form that is more easily stored.”

The “new way” is to use silicon wafers to absorb solar energy. The silicon submerges in water, with the front surface exposed to a solar energy simulator and the back surface covered in electrodes to conduct the energy. The silicon has cobalt nano-islands formed onto it using a process called electrodeposition.

Unlike current research standards that cover the surface of the silicon entirely in a catalyst layer, Switzer has small clusters of cobalt catalysts dotted on the silicon’s surface. This process was just as protective and produced much higher voltages.

The generated voltage from the solar rays splits liquid water into hydrogen and oxygen. Oxygen evolves at the cobalt-coated silicon electrode, and hydrogen evolves at the platinum counter electrode.

“Initially, we had set out to produce a uniform layer of metal that both catalyzed and protected the silicon, but found that this method actually produces a higher voltage and did not need an additional step that typically has to be applied to the silicon,” Switzer said. “These nano-islands of cobalt produce a much more efficient cell.”

Besides solar arrays and energy cells, Switzer sees potential usage of the results in large-scale hydrogen collection and even a fully carbon-neutral travel solution.

“If we use this process in hydrogen-fueled vehicles, the hydrogen would be used as fuel and the only thing dripping out of the tailpipe of the car would be water,” Switzer said.