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Scientists at Stanford develop water splitter that runs on ordinary AAA battery

news.stanford.edu

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Re: Scientists at Stanford develop water splitter that runs on ordinary AAA battery

#21

Post by crististm »

nardi wrote: post #12

I'm amazed at the ignorance in these comments. First, yes this is cool new science. No one imagined nickel would work as a water-splitting electrocatalyst. This is very surprising, and awesome. Second, the point of water-splitting is obviously not power generation . It's power storage , just like a battery, but with better transport and storage characteristics.

I don't know about ignorance, but basically, the energy you get from splitting the water molecule (in the form of H2 and O2) is lower than the energy consumed to make the split. For storage you will also have to deeply freeze the gases unless you want to have huge tanks for storage

So what makes a hydrogen exposed freezing tank better suited for transport and storage than a chemical battery?

Re: Scientists at Stanford develop water splitter that runs on ordinary AAA battery

#22

Post by nardi »

mikexstudios wrote: post #20
nardi wrote: post #12

I'm amazed at the ignorance in these comments. First, yes this is cool new science. No one imagined nickel would work as a water-splitting electrocatalyst. This is very surprising, and awesome. Second, the point of water-splitting is obviously not power generation . It's power storage , just like a battery, but with better transport and storage characteristics.

"No one imagined nickel would work as a water-splitting electrocatalyst." Not true. It has been known since the 1950s (and likely earlier) that Ni oxides can function as water splitting catalysts (both for hydrogen evolution and oxygen evolution half reactions).

Of course you're right. I meant that no one thought nickel oxides would be practical compared to noble metal catalysts. I haven't read the article, but I assume they're using some kind of novel nanostructuring to increase the catalytic activity.

Re: Scientists at Stanford develop water splitter that runs on ordinary AAA battery

#23

Post by nardi »

crististm wrote: post #21
nardi wrote: post #12

I'm amazed at the ignorance in these comments. First, yes this is cool new science. No one imagined nickel would work as a water-splitting electrocatalyst. This is very surprising, and awesome. Second, the point of water-splitting is obviously not power generation . It's power storage , just like a battery, but with better transport and storage characteristics.

I don't know about ignorance, but basically, the energy you get from splitting the water molecule (in the form of H2 and O2) is lower than the energy consumed to make the split. For storage you will also have to deeply freeze the gases unless you want to have huge tanks for storage So what makes a hydrogen exposed freezing tank better suited for transport and storage than a chemical battery?

This is just pessimism. Yes, there are other hurdles to overcome for hydrogen. But this is a major advance in one of the primary pieces necessary for a hydrogen economy. What makes you think advances in other areas are impossible?

And to answer your question, much better energy density by mass.

Re: Scientists at Stanford develop water splitter that runs on ordinary AAA battery

#24

Post by lutorm »

nardi wrote: post #15
lutorm wrote: post #6

... and not a single word about how the necessary electricity needed to make this "zero emission fuel" is supposed to be produced. Plus, all I know about hydrogen points to it not being anything close to "an ideal fuel for powering vehicles, buildings and storing renewable energy". It has very low density, requires cryogenic storage or very heavy pressure vessels, migrates through materials, and is explosive when mix…

This is like commenting on a battery tech article with, "Yes, but how are we going to charge all of those batteries?!" Or power grid technology, "Great, but where is the electricity going to come from ?!?!"

Well, if they claimed that using batteries was "emissions free", I would complain about that, too.

With hydrogen, the issue issue is that (at least to my understanding) if you have electricity, we already have a far more efficient solution: put the electricity directly into a battery and use it to power a motor. Going the route over electrolysis->hydrogen storage->fuel cell imposes such efficiency penalties that it would need extremely compelling other advantages to be competitive, and I don't see them.

Re: Scientists at Stanford develop water splitter that runs on ordinary AAA battery

#25

Post by justin66 »

lutorm wrote: post #6

... and not a single word about how the necessary electricity needed to make this "zero emission fuel" is supposed to be produced. Plus, all I know about hydrogen points to it not being anything close to "an ideal fuel for powering vehicles, buildings and storing renewable energy". It has very low density, requires cryogenic storage or very heavy pressure vessels, migrates through materials, and is explosive when mix…

> ... and not a single word about how the necessary electricity needed to make this "zero emission fuel" is supposed to be produced.

At some point you have to trust the reader to understand things that are completely obvious. That's a necessary quality of good writing, even if you're adhering to the newspaper standard of targeting someone at the 8th grade reading level.

Re: Scientists at Stanford develop water splitter that runs on ordinary AAA battery

#26

Post by nardi »

sirdogealot wrote: post #9

This isn't news. "The researchers also plan to develop a water splitter than runs on electricity produced by solar energy." Unfortunately that approach would be less efficient that simply transferring the electrical energy to an electric motor. Light > Electricity > Hydrogen > Electricity > Electric Motor is longer than Light > Electricity > Electric Motor

Ignorance. The news here isn't "we discovered electrolysis!" It's "we developed a new, efficient, and cheap electrocatalyst!"

Did you do that when you were 9 too?

Re: Scientists at Stanford develop water splitter that runs on ordinary AAA battery

#27

Post by mikexstudios »

digikata wrote: post #3
partacus wrote: post #2

How is this a story? Did someone at Stanford open up a grade 10 Chemistry textbook?

From the article: "Using nickel and iron, which are cheap materials, we were able to make the electrocatalysts active enough to split water at room temperature with a single 1.5-volt battery. This is the first time anyone has used non-precious metal catalysts to split water at a voltage that low. It's quite remarkable, because normally you need expensive metals, like platinum or iridium, to achieve that voltage."

They're overselling the science. This is certainly not the first time anyone has used non-precious metals to split water at low voltages. Both Ni oxide and Ni-Fe oxide systems that they use in their paper are well known in the literature. Ni oxides have been published back in the 1950s while Ni-Fe oxide catalysts were introduced in the 1980s. However, they do claim that their NiO/Ni/CNT system is novel, which may be true.

In their experimental setup, they target 20 mA/cm2 current density. To achieve that, they can just increase the amount of catalyst they use. The geometric area (cm2) will remain the same, but the surface area will increase which will correspondingly raise current density. For example, one can stack sheets of carbon aerogel to achieve the same current density.

Re: Scientists at Stanford develop water splitter that runs on ordinary AAA battery

#28

Post by nardi »

lutorm wrote: post #24
nardi wrote: post #15

Earlier quoted context omitted.

This is like commenting on a battery tech article with, "Yes, but how are we going to charge all of those batteries?!" Or power grid technology, "Great, but where is the electricity going to come from ?!?!"

Well, if they claimed that using batteries was "emissions free", I would complain about that, too. With hydrogen, the issue issue is that (at least to my understanding) if you have electricity, we already have a far more efficient solution: put the electricity directly into a battery and use it to power a motor. Going the route over electrolysis->hydrogen storage->fuel cell imposes such efficiency penalties that it w…

Hey, I like chemical batteries too, but they're not capacitors. You don't put electricity into them. You drive an electrochemical reaction with them, which is subject to its own inefficiencies, as well as wear and tear on the battery, which isn't a problem with hydrogen fuel cells.

Hydrogen fuel cells also tend to be highly efficient.

Re: Scientists at Stanford develop water splitter that runs on ordinary AAA battery

#30

Post by petersellers »

alex_duf wrote: post #18
nardi wrote: post #12

I'm amazed at the ignorance in these comments. First, yes this is cool new science. No one imagined nickel would work as a water-splitting electrocatalyst. This is very surprising, and awesome. Second, the point of water-splitting is obviously not power generation . It's power storage , just like a battery, but with better transport and storage characteristics.

right, but using a AAA battery which is already storing energy doesn't serve any purpose. But I agree with you, efficient-cheap catalyst is needed indeed. I'd like to know the efficiency of the system though...

Using a AAA battery demonstrates that the process can be done using low voltage.
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