
UH Researchers Report New, More Efficient Catalyst for Water Splitting - weston
http://www.uh.edu/news-events/stories/2017/April/05152017Ren-Water-Catalyst.php
======
subnaught
Some background and context from someone tangentially related to the field:

1\. The overall idea here is to take an intermittent energy source (e.g. solar
power) and "store" it as chemical fuel, in this case hydrogen and oxygen. This
is what plants do, and we can also view fossil fuels as resulting from the
"storage" of millions of years of solar energy. Note also that you get the
water back when you burn the hydrogen, so there is no net consumption of
water, it's just a carrier.

2\. While you can split water without a catalyst, most of the energy gets
wasted as heat, so this is not a great way to go if you're trying to do energy
storage.

3\. Efficient catalysts exist for this reaction, but they are based on rare
and expensive metals, typically Pd, Pt, and Ir. As a result, there has been a
search for catalysts involving "first-row" metals such as Fe, Co, Ni, etc.

4\. There are variety of metrics for an electrocatalyst (efficiency,
stability, cost, etc), but it's a fair bet that if this were significantly
better than state-of-the-art, it would be in Science or Nature rather than
PNAS.

~~~
dnautics
Beyond the expensive of the metals another problem is duty cycles. Most
transition metal catalysis is oxygen sensitive, and it seems like for some
reason the first step of splitting water is creating oxygen. Plants go through
great lengths to separate oxygen synthesis (photosystem II) from electron
consumption. Most hydrogen production in lower organisms (like e coli) occurs
entirely in anoxic conditions. Engineered systems for generating hydrogen via
algae typically are temporally segregated (harvest light during day, produce
hydrogen at night) which defeats the purpose and is also chemically steppy
(carbohydrate intermediates).

~~~
novaleaf
> and it seems like for some reason the first step of splitting water is
> creating oxygen

good laugh on that :)

~~~
nine_k
Consider a split to H + OH as a first step, as opposed to H + H + O.

~~~
dnautics
What exactly are you proposing? What do you do with the OH?

~~~
nine_k
This is a possible first step of a water-splitting reaction that does not
produce oxygen.

~~~
dnautics
I suggest going back to your chemistry text and reviewing mass balance,
conservation of matter, and balancing equations.

What is that OH? Is it hydroxide radical? Hydroxide? Hydroxyl radical? Where
does it go? Does it recombine to make hydrogen peroxide?

Btw... To make oxygen from water the first part of the first step is to split
it into H and HO. You can't really break two bonds simultaneously, or anyways
it's equivalent to doing them stepwise by the principle of microscopic
reversibility.

------
voicedYoda
I emailed Jeannie and she sent me the paper. I'm an idiot about finding a
place to post it or host it (or find it), but the title of the paper is:
"Highly active catalyst derived from a 3D foam of Fe(PO3)2/Ni2P for extremely
efficient water oxidation"

Searched for that and got this:
[http://www.pnas.org/content/early/2017/05/10/1701562114.abst...](http://www.pnas.org/content/early/2017/05/10/1701562114.abstract)

~~~
JumpCrisscross
How much more efficient is this than existing catalysts? Any obvious scaling
impediments?

~~~
drewbuschhorn
As a former chemist in another but related field, this phrase is telling and
part of why it is not in a higher impact journal: "We find that this catalyst,
which may be associated with the in situ generated nickel–iron oxide/hydroxide
and iron oxyhydroxide catalysts at the surface". This is generally code for
"we're getting some sort of nano surface effect we're not 100% sure we
understand or can replicate." I can't access the full paper, but the downfall
of catalysts are usually: cost, durability, or unreproduciblity\creation cost.
Getting nano surfaces to grow properly at industrial (10s of grams scale as
one researcher said to me) is still more of an art than a science, with maybe
one guy in a 10 person group able to get the substrate to perform.

Not super aimed at this particular paper, but those are probably the reasons
you don't see fireworks going off over inorganic labs around the country about
this paper.

------
EvanAnderson
I am really miffed at this quote:

"Hydrogen is the cleanest primary energy source we have on earth,” said Paul
C. W. Chu, TLL Temple Chair of Science and founding director and chief
scientist of the Texas Center for Superconductivity at UH.

This seems like sensationalism and poor science communication to me. Hydrogen
isn't a primary energy source.

~~~
akiselev
Primary in the sense that we can utilize hydrogen directly for energy
(terrestrial fusion and fuel cell) just like with coal and other fossil fuels

It has nothing to do with market share

~~~
EvanAnderson
"Primary energy source" is a term with a specific meaning. I'm not talking
about market share.

Primary energy sources do not require any type of conversion. Fossil fuels,
nuclear, wind, and solar are all primary energy sources. Free hydrogen isn't
found in nature. It can be made by splitting water using energy from a primary
source. The catalyst described in this press release makes that process more
efficient, but it still takes energy from a primary source to create hydrogen.

Reference:
[https://en.wikipedia.org/wiki/Primary_energy](https://en.wikipedia.org/wiki/Primary_energy)

~~~
derefr
> Free hydrogen isn't found in nature.

Sure it is; you just have to go kind of far out of the solar system before
you'll start running into it. Molecular clouds of hydrogen are what makes
those pretty Hubble pictures of nebulae. :)

~~~
EvanAnderson
Heh heh... you're bringing back memories of "Fuel Scoops" in Elite on my C64!

------
philipkglass
I am (was) a chemist but I find this research area somewhat puzzling.
Electrolytic hydrogen production has been industrialized for more than a
century. Put nickel electrodes in an aqueous solution of potassium hydroxide.
Separate anode and cathode with a porous diaphragm. Run direct current through
it. Get pure hydrogen. "Simple" alkaline electrolysis is only ~50% efficient,
but that means there's only a factor of two efficiency gain possible no matter
how good your catalyst. Large commercial electrolyzers from a decade ago
reached ~70%. Why so much research on further marginal efficiency gains from
new catalysts? Are there other costs that fall faster-than-linearly with
improved efficiency?

~~~
Animats
_Large commercial electrolyzers from a decade ago reached ~70% (efficiency).
"_

That's good to know. No "breakthrough" can improve the process by more than
another 30%. NREL says the best commercial systems are at 73% today.[1]
There's also an additional energy cost for compressing the hydrogen.

That's pretty good. Getting any chemical or electrochemical process up to 73%
efficiency is a good result.

[1]
[http://www.nrel.gov/docs/fy04osti/36705.pdf](http://www.nrel.gov/docs/fy04osti/36705.pdf)

~~~
philipkglass
That was actually the data source I was thinking of. It's reviewing units
commercially available by the end of 2003. More time had passed than I
thought.

I agree that the efficiency is already pretty good and even a "perfect" system
would not drastically lower energy inputs further.

------
ChuckMcM
WSU in 2016: [https://news.wsu.edu/2016/10/25/better-water-splitting-
catal...](https://news.wsu.edu/2016/10/25/better-water-splitting-catalyst/)

Missouri U:
[http://onlinelibrary.wiley.com/doi/10.1002/cssc.201601631/ab...](http://onlinelibrary.wiley.com/doi/10.1002/cssc.201601631/abstract;jsessionid=0CBBE4F0EBB05A15864081DE3851C125.f02t02)

Stanford:
[http://science.sciencemag.org/content/353/6303/1011.full](http://science.sciencemag.org/content/353/6303/1011.full)

Lots and lots and lots of research going on in this space. So far nothing that
can be used to produce hydrogen at scale.

------
mabbo
> That would solve one of the primary hurdles remaining in using water to
> produce hydrogen, one of the most promising sources of clean energy.

What? No. Hydrogen is not a source of energy, it's a storage format. A more
efficient catalyst will certainly help with losses when storing the energy,
but there's no net gain.

~~~
devwastaken
It said sources of clean energy, not a source of clean electricity for the
power grid.

~~~
badosu
Still wrong, this process is a _sink_ of energy, not a source.

------
kylehotchkiss
Some total n00b questions:

Could this also be used in desalination? Turn into hydrogen, burn to convert
back to water, feed it catalyst material like a fuel? (I'm not really sure how
these catalysts work, do you like push water through them? and out comes
gases?)

~~~
astrodust
You can do that already with electrolysis, but why would you? It's way more
expensive than approaches like reverse osmosis.

~~~
ars
If you electrolyze salt water you will generate chlorine and hydrogen gas
(instead of oxygen and hydrogen).

The water will also contain lye from the leftover sodium.

~~~
kylehotchkiss
DOH (to me). This was the answer I needed to see. Thanks for saving me from
this tangent!

------
mmagin
So, uh, do catalysts like this reduce the waste heat you get when
electrolyzing water with a cruder setup? Because there's nothing but a
specific minimum energy input that's going to break the bonds between hydrogen
and oxygen.

~~~
jkghsdjklsdgjkl
a catalyst by definition reduces the minimum energy input required for a
chemical reaction to occur

------
xupybd
>And unlike solar power, wind power and other “clean” energy, hydrogen can be
easily stored

Sure it's easier than other forms, but it's my understanding that there are
some significant challenges in storing hydrogen?

~~~
jgamman
hydrogen makes metals brittle and there can be catastrophic failure of valves,
regulators etc.

there are only 3 significant problems with hydrogen as an energy carrier to
solve before it becomes ubiquitous: 1\. how to make it 2\. how to store it &
transport it 3\. how to use it

IMO there was a time in the late 80s, early 90s when there was a chance it
could be useful but the battery tech development over the last 25 years has
nailed the coffin shut - hydrogen research persists because people with jobs
know how to research hydrogen production.

------
gjem97
What are the key metrics for catalysts? Obviously cost is one. Round-trip
energy efficiency? How does this measure up to existing commercial
alternatives? How about against no-catalyst electrolysis?

~~~
marcosdumay
Not round trip efficiency. The reasonable metric is electrolysis-only
efficiency. Longevity is another good one.

------
webkike
Could most uses of natural gas be replaced with hydrogen gas?

~~~
astrodust
There's a reason why different gasses are used in different applications.
Combustiblity, pressure required for liquefaction, flashpoint, safety and so
on.

There's a lot of overlap between these in some areas like home heating and
BBQs, but each application requires some engineering to make it work with any
particular fuel.

The energy storage density of hydrocarbons make them more practical as a fuel
in situations where portability is a concern. For example: You could have a
hydrogen BBQ, but the tank would probably have to be much larger for the same
amount of burn time.

~~~
badosu
> You could have a hydrogen BBQ, but the tank would probably have to be much
> larger for the same amount of burn time.

Isn't the opposite true? I mean, hydrogen at 700 bar has a specific energy of
142 MJ/kg while hydrocarbons in general have less than 60 MJ/kg.

~~~
dmoy
Yup but propane is 20x denser than hydrogen, so even if you have 2x energy per
weight, you have 0.1x energy per volume. Or something like that.

~~~
badosu
Gotcha, thanks!

------
knowaveragejoe
Anyone know what some "bigger picture" uses of this would be? It seems
significant, but I'm not a chemist. Energy sources, desalination, etc?

~~~
badosu
One direct application would be more efficient ways to generate fuel for
Hydrogen vehicles [0].

It would also be essential for mining fuel from asteroids or gas giant's moons
as ice is not so rare, improving the sustainability of space operations.
Hydrogen itself has a pretty big specific impulse, it's just not used more
often than Kerosene for rockets due to safety issues.

If you could achieve Metallic Hydrogen [1][2] then you would have the perfect
fuel for navigating the solar system.

[0]:
[https://en.wikipedia.org/wiki/Hydrogen_vehicle](https://en.wikipedia.org/wiki/Hydrogen_vehicle)

[1]:
[https://en.wikipedia.org/wiki/Metallic_hydrogen](https://en.wikipedia.org/wiki/Metallic_hydrogen)

[2]:
[http://iopscience.iop.org/article/10.1088/1742-6596/215/1/01...](http://iopscience.iop.org/article/10.1088/1742-6596/215/1/012194/meta)

------
24gttghh
Any idea what this catalyst actually is, perhaps a link to a paper, or even
just an actual abstract?

~~~
AdamTReineke
Is it this paper?
[https://scholar.google.com/citations?view_op=view_citation&h...](https://scholar.google.com/citations?view_op=view_citation&hl=en&user=uVxFD-
sAAAAJ&sortby=pubdate&citation_for_view=uVxFD-sAAAAJ:KqnX2w3egDsC)

Direct PDF link:
[https://www.researchgate.net/profile/Zhenhuan_Zhao/publicati...](https://www.researchgate.net/profile/Zhenhuan_Zhao/publication/315612407_A_TiO2FeMnP_CoreShell_Nanorod_Array_Photoanode_for_Efficient_Photoelectrochemical_Oxygen_Evolution/links/58da73c6a6fdccca1c53f8f3/A-TiO2-FeMnP-
Core-Shell-Nanorod-Array-Photoanode-for-Efficient-Photoelectrochemical-Oxygen-
Evolution.pdf)

Abstract: A variety of catalysts have recently been developed for
electrocatalytic oxygen evolution, but very few of them can be readily
integrated with semiconducting light absorbers for photoelectrochemical or
photocatalytic water splitting. Here, we demonstrate an eﬃcient core/shell
photoanode with a highly active oxygen evolution electrocatalyst shell (FeMnP)
and semiconductor core (rutile TiO2) for photoelectrochemical oxygen evolution
reaction. Metal−organic chemical vapor deposition from a singlesource
precursor was used to ensure good contact between the FeMnP and the TiO2. The
TiO2/FeMnP core/shell photoanode reaches the theoretical photocurrent density
for rutile TiO2 of 1.8 mA cm−2 at 1.23 V vs reversible hydrogen electrode
under simulated 100 mW cm−2 (1 sun) irradiation. The dramatic enhancement is a
result of the synergistic eﬀects of the high oxygen evolution reaction
activity of FeMnP (delivering an overpotential of 300 mV with a Tafel slope of
65 mV dec−1 in 1 M KOH) and the conductive interlayer between the surface
active sites and semiconductor core which boosts the interfacial charge
transfer and photocarrier collection. The facile fabrication of the TiO2/FeMnP
core/shell nanorod array photoanode oﬀers a compelling strategy for preparing
highly eﬃcient photoelectrochemical solar energy conversion devices.

~~~
pjreddie
I don't think so, Haiqing Zhou is not on that paper. Zhifeng Ren has a number
of papers in this space.

------
vmarsy
mods, the original title should be preserved, currently it is : "U of Houston
discovers catalyst that splits water into hydrogen and oxygen"

But the original title is : "UH Researchers Report New, _More Efficient_
Catalyst for Water Splitting"

catalyst for water splitting aren't new. the article even says it :

>The catalyst, composed of ferrous metaphosphate grown on a conductive nickel
foam platform, is far more efficient than previous catalysts, as well as less
expensive to produce.

~~~
dang
Yes. Thanks.

Submitters: please don't rewrite titles unless they are misleading or
linkbait. This is in the site rules:
[https://news.ycombinator.com/newsguidelines.html](https://news.ycombinator.com/newsguidelines.html).

~~~
weston
Hi Dang, I submitted the article. I was trying to use the r/futurology article
title which was, "University of Houston physicists have discovered a catalyst
that can split water into hydrogen and oxygen, composed of easily available,
low-cost materials and operating far more efficiently than previous catalysts,
reported in the Proceedings of the Natural Academy of Sciences."

HN has an 80 character limit for titles so I had to cut it down drastically
from that.

------
molyss
When I see anything related to splitting water into hydrogen, I'm worried that
we're going to use water for energy on top of using to hydrate people.

Still today, over 10% of the world population don't have access to clean
water. I'm also curious on how clean the water needs to be to be used with
this catalyst. AFAIK, most catalyst conversion need pretty pure water, in
which case, we would not only use water, but use _clean_ water, which is even
more scare than "dirty" water...

~~~
forgotpwagain
You regenerate the water when H2 and O2 are recombined to produce electricity.

Dan Nocera ( [http://nocera.harvard.edu](http://nocera.harvard.edu) ) is very
prominent in the water splitting field and has done a calculation in which a
volume of an olympic sized pool would need to be split every second to replace
all power sources on earth (
[https://poptech.org/blog/daniel_nocera_on_personalized_energ...](https://poptech.org/blog/daniel_nocera_on_personalized_energy)
).

It seems like a lot, but it would presumably be decentralized across many many
locations. Additionally, you don't need 24 * 60 * 60 * olympic pool volumes --
you can cycle the same amount of water into/out of a fuel cell in a closed
system.

~~~
maxerickson
You are talking about several hundred billion liters.

The inland reservoir here is 100 billion liters:

[https://www.google.com/maps/@43.8937611,-86.4337261,8900m/da...](https://www.google.com/maps/@43.8937611,-86.4337261,8900m/data=!3m1!1e3)

It's not very much water.

------
giltleaf
How much water would this process need to make enough energy for this to have
an impact? Presuming we wouldn't use up our fresh water resources for this and
that it would come from the ocean, but would this process create potential
threats to the marine habitat as the mineral/chemical concentrations of the
ocean water shifted?

~~~
AnimalMuppet
We wouldn't "use up" water at all for this. When you burn the hydrogen (to get
the energy from it), it combines with oxygen and forms water.

(Unless you're "burning" the hydrogen in a fusion reactor. But that takes much
less hydrogen...)

