Green Car Congress  
Home Topics Archives About Contact  RSS Headlines

« BorgWarner supplying customized dual-clutch and control modules to Great Wall Motors; higher fuel efficiency | Main | BMW Group, Intel and Mobileye bringing Delphi in as partner in autonomous driving platform work »

Print this post

UH team develops new, highly efficient and durable OER catalyst for water splitting

16 May 2017

Researchers at the University of Houston have developed a catalyst—composed of easily available, low-cost materials and operating far more efficiently than previous catalyst—that can split water into hydrogen and oxygen.

The robust oxygen-evolving electrocatalyst consists of ferrous metaphosphate on self-supported conductive nickel foam that is commercially available in large scale. The catalyst yields current densities of 10 mA/cm2 at an overpotential of 177 mV, 500 mA/cm2 at only 265 mV, and 1,705 mA/cm2 at 300 mV, with high durability in alkaline electrolyte of 1 M KOH even after 10,000 cycles. This represents an activity enhancement by a factor of 49 in boosting water oxidation at 300 mV relative to the state-of-the-art IrO2 catalyst. A paper on their work is published in Proceedings of the National Academy of Sciences (PNAS).

To realize the overall water electrolysis for H2 production, oxygen evolution reaction (OER), also named water oxidation, plays another key role. OER is also an important oxidative reaction in obtaining carbon fuels from CO2 reduction and achieving rechargeable metal–air batteries, and it has been meticulously studied for more than half a century. However, owing to the sluggish four-proton-coupled electron transfer and rigid oxygen–oxygen bonding, this key process remains a major bottleneck in the water-splitting process.

State-of-the-art OER catalysts, such as iridium dioxide (IrO2) and ruthenium dioxide (RuO2), still require overpotentials of around 300 mV to achieve current densities on the order of 10 mA/cm2, not to mention their scarcity and high costs, which severely hinder the substantial market penetration of this technique. Thus, it is highly desirable and imperative to develop robust and stable oxygen-evolving electrocatalysts from earth-abundant and cost-effective elements.

Commercial water electrolyzers require a competent electrocatalyst that can efficiently deliver an oxidative current density above 500 mA/cm2 with long-term stability at overpotentials < 300 mV. Although various earth-abundant materials have been proven to be efficient catalysts for oxygen evolution, such as transition metal oxides, hydroxides, oxyhydroxides, phosphates, phosphides, metal–organic frameworks, and carbon nanomaterials, many of them cannot meet the aforementioned commercial criteria for water–alkali electrolyzers, and, most importantly, they may not survive long in high-current operation. To this end, we report a highly efficient electrocatalyst for oxygen evolution reaction yielding current densities of 10 and 500 mA/cm2 at overpotentials of 177 and 265 mV, respectively, both of which are the lowest overpotential values for the corresponding current densities ever reported, and showing excellent long-term stability.

—Zhou et al.

Although it is simple in theory, splitting water into hydrogen and oxygen is a complex process, requiring two separate reactions—a hydrogen evolution reaction and an oxygen evolution reaction, each requiring a separate electrode. While hydrogen is the more valuable component, it can’t be produced without also producing oxygen. And while efficient hydrogen catalysts are available, the lack of an inexpensive and efficient oxygen catalyst has created a bottleneck in the field.

Co-author Shuo Chen said oxygen evolution reactions often depend upon an electrocatalyst using a noble metal—iridium, platinum or ruthenium. But those are expensive and not readily available.

In this work, we discovered a highly active and stable electrocatalyst based on earth-abundant elements, which even outperforms the noble metal based ones. Our discovery may lead to a more economic approach for hydrogen production from water electrolysis.

—Shuo Chen

The fabrication process for such an exceptional electrocatalyst is compatible with industrial standards and is economically viable for large-scale production. We believe our finding is a giant step toward practical and economic production of hydrogen by water splitting, which will significantly contribute to the effort to reduce the consumption of fossil fuels.

—Zhou et al.

Resources

  • Haiqing Zhou, Fang Yu, Jingying Sun, Ran He, Shuo Chen, Ching-Wu Chu, and Zhifeng Ren (2017) “Highly active catalyst derived from a 3D foam of Fe(PO3)2/Ni2P for extremely efficient water oxidation” PNAS doi: 10.1073/pnas.1701562114

May 16, 2017 in Catalysts, Hydrogen, Hydrogen Production | Permalink | Comments (8)

Comments

As far as I can tell from the write up, this is more or less immediately deployable with no long process of further development needed.

Ideally it would be combined with this method of separate generation of hydrogen and oxygen, so that at the hydrogen pump all that would be needed would be needed at the station, with power generated by sometimes far away solar fields:
http://newenergyandfuel.com/http:/newenergyandfuel/com/2017/03/22/separate-cells-for-hydrogen-and-oxygen-in-water-splitting/

' the vision of the Technion researchers is geographic separation between the sites where the oxygen and hydrogen are produced: at one site, there will be a solar farm that will collect the sun’s energy and produce oxygen, while hydrogen is produced in a centralized manner at another site, miles away.
Thus, instead of transporting compressed hydrogen from the production site to the sales point, it will only be necessary to swap the auxiliary electrodes between the two sites. Economic calculations performed in collaboration with research fellows from Evonik Creavis GmbH and the Institute of Solar Research at the German Aerospace Center, indicate the potential for significant savings in the setup and operating costs of hydrogen production.'

@Davemart. It seems very exciting. The current densities from these earth abundant materials are 2+ orders magnitude higher at <300mV over-potentials than the Rare Earth applications. This is good news. They also mentioned 10K cycles in a 1 Molarity KOH alkaline solution and I am assuming the current densities held-up at < 300mV over-potentials, so the substrates seem stable enough under these conditions.

It is nice to see H2 production without iridium and ruthenium based catalysts.

The thing is to make it so cheap that it can only be used when there is excess electricity, rather than having to run it all the time, which does not solve the renewables load balancing problem.

Now, we have to find something useful to do with a glut of H2.
(and O2).

More pure, lower cost O2 should not be a problem in the quantities produced, we can use it to oxygen blow combined cycle power plants for less NOx and more pure CO2 for making fuels.

Don't need liquid fuels or O2 to clean power plants...that's obsolete thinking in today's world. Try to think about wind, solar, hydro, thermal and not about burning carbon fuels. Think about burning H2 and combining O2 and H2 gently to produce energy and water.

Most of our power comes from fossil fueled plants, it will for many decades. Keep dreaming but don't pull the plug just yet or you will be in the dark.

You still need fossil fuels because wind and solar are intermittent, hydro is too limited in terms of sites and biomass does not have the scale.
Also, batteries to not have enough scale, but are very useful for load shaping - to allow the deployment of renewables at higher scale.
The trick is to reduce, but not eliminate, the use of fossil fuels for load balancing.

The problem is that you will always have extreme weather periods, like very calm periods in winter when you have neither wind nor solar and run out of storage in a couple of hours.
Thus, even if you can get through the whole summer on wind, solar and batteries, you have to keep the fossil plant for winter, even if you only use it for a month or two - so all the fixed costs remain.

Hi mahonj.

I am not a great fan of would be universal solutions, and am very optimistic that a sheaf of technologies are becoming available which will offer many options in different circumstances.

So even if fossil fuel use remains substantial, a topping cycle using fuel cells on NG or even coal plants turns the waste stream into more or less pure CO2, much easier to store or utilise to produce fuel etc.

In addition for the areas needing really high amounts of winter power over that needed in the summer, pre-eminently Europe, I remain at least somewhat hopeful that reason even if much delayed will eventually prevail and that some build out of the many excellent nuclear options becoming available will happen, so enormously reducing the need for hydrogen storage etc.

Chemical storage whether hydrogen or other can though do the job of providing cover for calms etc, or even winter power although the latter at considerable cost and loss of efficiency.

Batteries alone can't.
It really is that simple.

Verify your Comment

Previewing your Comment

This is only a preview. Your comment has not yet been posted.

Working...
Your comment could not be posted. Error type:
Your comment has been posted. Post another comment

The letters and numbers you entered did not match the image. Please try again.

As a final step before posting your comment, enter the letters and numbers you see in the image below. This prevents automated programs from posting comments.

Having trouble reading this image? View an alternate.

Working...

Post a comment

Green Car Congress © 2017 BioAge Group, LLC. All Rights Reserved. | Home | BioAge Group