Chemists turn gold to purple -- on purpose

Jan 26, 2011
BYU chemists developed a method of artificial photosynthesis, and proved it by turning gold atoms (left) into purple-colored nanoparticles (right). Credit: Mark Philbrick/BYU

Professor Richard Watt and his chemistry students suspected that a common protein could potentially react with sunlight and harvest its energy – similar to what chlorophyll does during photosynthesis.

The story of how they proved it sounds as colorful as the legend of the leprechaun who hid his pot of at the end of the rainbow.

They started with citric acid from oranges and mixed it with the protein. Next they dissolved gold powder into the solution. Then they put vials of the yellow-colored mixture in direct sunlight and crossed their fingers in the hope that it would turn purple.

Here's the reason why: If it turned purple, that would signal that the gold atoms had received electrons and used the donated energy to bunch together as small, purple-colored . And that would mean that the protein used the sunlight to excite the citric acid and trigger a transfer of energy.

While direct sunlight did the trick in about 20 minutes, a high-powered tungsten mercury lamp worked much faster.

"We set the system up, turned on the light, and the solution turned purple," Watt said. "We knew that we'd proved the concept."

The beauty of this experiment lies not in its colors – unless, of course, you're thinking of it as a potential "green" energy source that keeps the environment clean.

The BYU researchers published their experiments in the Journal of Nanoparticle Research. The final step of this project will involve connecting the to an electrode to channel the energy into a battery or fuel cell. The BYU chemists will partner with Jae-Woo Kim of the National Institute of Aerospace for this next stage of the work.

Professor Watt's pedigree includes a post-doc at Princeton, a father who developed a fuel cell that runs on sugar and weed-killer and a more distant ancestor credited with inventing the first practical steam engine. That ancestor is also the Scottish engineer for whom the unit of power "watt" is named.

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User comments : 12

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Quantum_Conundrum
1.8 / 5 (10) Jan 26, 2011
Surely you must be joking. Solar panels currently cost around $440 per square meter.

Gold costs $1300 per ounce.
J-n
5 / 5 (9) Jan 26, 2011
Surely YOU must be joking.Don't tell me you believe that the gold was there as a part of the reaction, instead of just there to show that the reaction happened.

The gold was there to show that the energy was created, the protein and the citric acid plus the sunlight created the energy that was then transferred to the gold, which clumped together to show the energy was created.

I hope that helps clear things up for you.
panorama
not rated yet Jan 26, 2011
Interesting, but hopefully they can achieve the same process with cheaper materials.

edit: That makes much more sense, J-n, thanks for explaining that.
AlexanderThink
5 / 5 (2) Jan 26, 2011
Interesting, but hopefully they can achieve the same process with cheaper materials.

edit: That makes much more sense, J-n, thanks for explaining that.


Copper maybe? Also one wandering electron in the valence shell.
Quantum_Conundrum
1 / 5 (5) Jan 26, 2011
Surely YOU must be joking.Don't tell me you believe that the gold was there as a part of the reaction, instead of just there to show that the reaction happened.

The gold was there to show that the energy was created, the protein and the citric acid plus the sunlight created the energy that was then transferred to the gold, which clumped together to show the energy was created.

I hope that helps clear things up for you.


Gold is chemically inert in most situations.

I'm not sure what you are going on about here.
nuge
5 / 5 (5) Jan 26, 2011
Surely YOU must be joking.Don't tell me you believe that the gold was there as a part of the reaction, instead of just there to show that the reaction happened.

The gold was there to show that the energy was created, the protein and the citric acid plus the sunlight created the energy that was then transferred to the gold, which clumped together to show the energy was created.

I hope that helps clear things up for you.


Gold is chemically inert in most situations.

I'm not sure what you are going on about here.


Quantum Conundrum, did you actually bother to read the article? It describes how the team tested whether a common protein could capture solar energy by seeing whether it could give energy to citric acid molecules which would in turn clump gold atoms to form purple nanoparticles. The gold was not part of the reaction being tested, it was just used to signal the result. This was what the majority of the article was actually about.
stealthc
not rated yet Jan 27, 2011
yes the gold wasn't part of the reaction....

So which protein is this, or are they not mentioning it on purpose? Can anybody find out? I bet you it is readily obtainable since it is so common and we can build these things ourselves without their help.
stealthc
not rated yet Jan 27, 2011
I did my own research, without purchasing the article for $34 LOL. What a scam.
"ferritin protein shell".
I would expect that this publication not withhold the information, but then again, you wouldn't want ordinary people to start ordering the stuff themselves as this might make it possible to build such a device easily at home. That is your common protein.
stealthc
not rated yet Jan 27, 2011
it is a health supplement you can buy it for cheap.

theregister dot co dot uk/2011/01/27/watt_gold_purple/

a better article in my books. Any feed back guys, how can we take this and build our own cheap solar cells ? Would appreciate your input on this.....
shavera
5 / 5 (1) Jan 27, 2011
@stealthc: the world is not a giant conspiracy to prevent you from getting your free electricity. How do you intend to connect this protein to an electrical grid? Just smear it on and hope that works? They've managed to show a protein can energize electrons from light, a big step forward, but not everything. They probably need to align the proteins in the right way on the electrical connections, determine what molecules are best suited for making such a connection, what environment these proteins are ideal in etc. These researchers are doing a commendable job for advancing scientific frontiers and sometimes the rest of us just have to be patient for discovery to happen
trekgeek1
5 / 5 (1) Jan 27, 2011
Surely you must be joking. Solar panels currently cost around $440 per square meter.

Gold costs $1300 per ounce.


As others have said, the Gold isn't a reactant. But, just for fun, we can see what would happen if they were going to make panels out of Gold. You are comparing the area of a solar panel to the mass of Gold. We need to compare area to area. 1oz of Gold is 28.3 grams of Gold. Due to it's ductility, a gram of Gold can be worked into one square meter. So 1oz of Gold can make 28.3 square meters. 1300 dollars/28 square meters is 46 dollars per panel for the Gold. So it wouldn't be that bad if that is what they were doing anyway.
pauljpease
1 / 5 (1) Jan 28, 2011
The problem is, proteins aren't cheap. Not on the scale necessary to generate useful amounts of electricity. Plus, they don't last long, or operate over a wide range of conditions (temperature, pH, etc.). They would constantly need to be replaced, and the denatured molecules would gum up the electrode they are feeding with electrons. You'd run into the same problem as with organic electronics (like OLEDs), they don't last as long. It's still a neat experiment though...