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KTH team develops new cost-effective water-splitting electrocatalyst for H2 production

27 June 2016

Researchers at KTH Royal Institute of Technology in Stockholm have developed a new cost-effective electrocatalyst for water-splitting to produce hydrogen.

The monolayer of nickel–vanadium-layered double hydroxide shows a current density of 27 mA cm−2 (57 mA cm−2 after ohmic-drop correction) at an overpotential of 350 mV for water oxidation. This performance is comparable to those of the best-performing electrocatalysts that are composed of non-precious materials—nickel–iron-layered double hydroxides for water oxidation in alkaline media—the researchers report in an open access paper in Nature Communications.

The new catalyst also offers a competitive, cheap alternative to catalysts that rely on more expensive, precious materials, such as iridium oxide (IrO2) or ruthenium oxide (RuO2).

Water splitting is considered one of the most promising strategies to produce chemical fuels such as hydrogen. The half reaction of the water splitting process, water oxidation, remains the bottleneck of the whole process at present. Therefore, developing highly efficient water oxidation catalysts is crucial. Some precious metal-based electrocatalysts, such as IrO2 and RuO2, have shown excellent performance for water oxidation; however, they suffer from high-cost and relative scarcity of precious metals, which limits their applications. Although some first-row transition metal oxides (for example, NiOx, NiFeOx, CoOx and MnOx) had been developed as low-cost electrocatalysts for water oxidation, most of them still cannot compete with IrO2 and RuO2.

Recently, the earth-abundant Ni–Fe double-layered hydroxide (NiFe-LDH) catalysts have attracted attention … it is nowadays known as one of the most active catalysts with a low overpotential and high electrolysis current. Since then tremendous efforts have been devoted to further improve the activity of NiFe-LDH, such as exfoliation and hybridization, to the extent that LDH catalysts can now outperform IrO2 in alkaline media; however, the aforementioned methods are still too complicated for large-scale applications.

It is already known that Fe(III) incorporated in Ni(II)-based LDH is the key aspect for the high catalytic performance, although the role of Fe in LDH is still ambiguous. … Up until now, there has been no reported earth-abundant metal element that can outperform Fe incorporated Ni-based LDHs. Searching for an earth-abundant metal to form efficient Ni-based LDH comparable to NiFe-LDH is still the state-of-the-art in this area of energy research.

In this work, we incorporate another earth-abundant element into Ni(OH)2: vanadium, and succeed in forming NiV-LDH as an efficient catalyst for the water oxidation reaction. A simple one-step hydrothermal method is employed to synthesize NiV-LDH. Without need for exfoliation or hybridization with other materials, the resulting monolayer NiV-LDH catalyst exhibits comparable activity to the best-performing NiFe-LDH for water oxidation in alkaline electrolyte.

—Fan et al.

The research team, led by KTH Professor Licheng Sun, had earlier developed molecular catalysts for water oxidation with an efficiency approaching that of natural photosynthesis. The new material, composed of common earth-abundant elements, could help change the economics of large-scale hydrogen fuel production.

This is the first time that the metal, vanadium, has been used to dope nickel hydroxide to form a water oxidation catalyst, and it works very well—even beyond our expectations. No doubt this material can greatly expand the scope of non-precious metal elements of electrocatalysts, and it opens new areas for water splitting.

—lead author Ke Fan

The material possesses a layered structure with monolayer nickel-vanadium oxygen polyhedron connected together with a thickness below 1 nanometer. This monolayer feature not only increases the active surface area, but also enhances the electron transfer within the material, said researcher Hong Chen.

Professor Sun expects the research to “open a new area of low-cost water oxidation catalysts, featuring stability and efficiencies that equal or even surpass some of today’s best catalysts including RuO2 and IrO2.

Resources

  • Ke Fan, Hong Chen, Yongfei Ji, Hui Huang, Per Martin Claesson, Quentin Daniel, Bertrand Philippe, Håkan Rensmo, Fusheng Li, Yi Luo & Licheng Sun (2016) “Nickel–vanadium monolayer double hydroxide for efficient electrochemical water oxidation” Nature Communications 7, Article number: 11981 doi: 10.1038/ncomms11981

June 27, 2016 in Catalysts, Hydrogen Production | Permalink | Comments (13)

Comments

Another much lower cost to split water?

A small home unit + a small high pressure compressing unit and tank may eventually supply/store all the H2 required (overnight) for the family FCEVs at an affordable price?

Would you really want a 10,000 PSI compressor operating in your garage, or your neighbor's garage?

Getting a permit would be very... Interesting.

No need for high-pressure home tank. When the home Natural Gas piping will be converted to Hydrogen, then the H2 produced will just go down the piping and the meter will run in reverse to give you production credit, kinda like net metering.

To fill up your FCEV, a small compressor can use the very low-pressure home H2 piping to compress over night, just like charging your Plug-in EV.

A home-based Fuel Cell can give out waste heat for hot water and home heating, thus can elevate the efficiency of H2 to nearly 100%. With modern electrolysis at over 80% efficiency on Higher Heating Value, the round-trip efficiency of H2 production and consumption can be as high as 80%, to be competitive with other forms of e-storage.

I love your rich imagination, Roger, and your ceaseless optimism for a better future.

It will be very interesting to see if the prospective technology you describe can economically compete with the much simpler and safer electric distribution grid, solar, and batteries.

At the basic physics level, it's a competition between then cost of moving atoms and electrons. Generally, electrons win.

>>>>>>>>eci stated: "It will be very interesting to see if the prospective technology you describe can economically compete with the much simpler and safer electric distribution grid, solar, and batteries."

It is NOT a competition. It is a cooperation.

1) We will still need the electric grid like we do today to transmit Solar and Wind electricity as it is being produced in real time. This is the most efficient way and least expensive way to use Solar and Wind (S&W) electricity. In the Springs and Falls, you will charge your Plug-in FCV (PFCV) with those abundant S&W electricity to get the highest efficiency out of it. Any excess S&W electricity in Springs and Falls will be used to make H2 and stored away in vast underground reservoirs.

2) Now, then, we will have winters with cloudy days and shorter days and many low-wind days with a lot of electricity demand for lighting and industrial use PLUS the need for home and office heating. That's when the H2 underground piping will come into play, with home-based Fuel Cells (FC) to provide both power and heat, or just heat when not a lot of power is needed.

Of course, you will charge your PFCV on a winter night using the electricity from a home-based FC, while releasing the waste heat to keep your house warm. However, if there is a need to keep the windshield and the cabin warm while on the road, to avoid ice re-accumulation, then you will power your PFCV initially with H2-FC whenever waste heat will be necessary. You will use battery power when heating will no longer be needed. Or, you just turn on the FC a little bit to get just the amount of heat needed, while use battery power to supply the rest of power demand of the car.

3) We will have many very hot summer days and summer nights with low wind and very high electricity demand, even late into the nights when people sleep, they crank up their A/C to beat the heat and humidity. During those times, the PFCV will NOT be charged from the grid, but will use Hydrogen made from other seasons for power to spare the grid of being overloaded. Those overhead transformers will blow if overheated, so summer heat won't help.

Of course, a better strategy for shifting day-time solar energy into night-time cooling would be the use of thermal cold storage (Ice). You make the ice using daytime solar energy, then use that ice to cool your house in the evening. But, we can't count on all the houses will have this thermal ice e-storage.

So, the best strategy is not whether battery or H2-FC, but BOTH. Battery energy or direct S&W whenever heat is not needed, while H2-FC energy when waste heat is needed. Even in the summers, you will need to hot water for dish washing, laundry, and bathing. Thermal ice storage can handle A/C needs during summer evenings and nights.

I must hasten to add to the above that with wide-spread Solar PV carport charging for the PFCV that can bypass the grid completely, then the grid will be spared of PEV charging at night, when the power transformer must cool off to get ready for another hot summer day, without having to use less-efficient Hydrogen reserve.

So, widespread Supercharging of long-range BEV on a hot summer day with power drawn from the grid is not in the best interest of grid stability.
A PFCV has the advantage of being capable of using H2 during the grid's peak power demand, hence sparing the grid from brown out.
A PFCV has the advantage of capable of being charged with Solar PV carport energy during sunny days, while not being charged during cloudy days. The solar car-port DC charging socket will not supply energy during low-solar-energy day, thus will not add burden to the power grid.

However, if you have a BEV and must drive a lot that day, you have no other option but require SuperCharging, thus adding on to the power demand burden of the grid during periods of peak demand.
Even worse, SuperCharging must also go on during periods of low Solar and Wind, forcing back-up power generation on the grid that is expensive to invest and to maintain.

With a PFCV, your FC on board is your backup power generator, and completely spare the grid of excessive power demand nor of requiring expensive backup power generation capacity.

Well, it is competition in the sense that a typical person will choose between a BEV, PHEV or FCV, whether or not that FCV has a larger battery and plug.

What makes you certain H2 will be used in an era of Nissan stylr ethanol FCVs? Until H2 is very cheap to generate, distribute, store and convert into electrons, it seems at a distinct disadvantage.

Ethanol is cheap to produce and very easy and inexpensive to distribute, store and dispense.

Ethanol is not produced by magic.

A cheap source of hydrogen is an enabler for its renewable production.

As for the nonsense about hydrogen is impractical as storage at home would be problematic, there is no reason that that is essential, although Honda are doing work in that direction.

A solar array on a residential property just like any other source of power can contribute to the grid, with the difference being that dispersed sources of power avoid much of the need for long distance transmission and conversion losses.

So the power produced locally can be tapped at the filling station for on-site production of hydrogen, which may or may not be further processed for the production of other fuels such as ethanol, although that would presumably be done more centrally with captured CO2.

Since fuel cells using natural gas or biogas output a stream of almost pure CO2 and NG use is not going to vanish overnight, then all the ingredients for a working system are present.

The fact remains that if hydrogen production, distribution, storage and use, as you and Roger Pham describe, is substantially more expensive than ethanol, it will not be competitive and will not gain any kind of relevent market share.

No magic needed. Just good old market forces.

@eci,
I don't understand why you insist on picking winners and losers. I know of people who heat their homes with natural gas, some with electricity, and some with fuel oil, others with wood pellets. It is not either or. If all forms are available, people will make choices based on their needs/knowledge or the availability of resources. Bring them all on.

I actually agree, JMartin. Bring them all on. As I pointed out, the market will decide, despite a heavy thumb on the scale in additional subsidies to FCVs and Hydrogen infrasructure feom state and Federal government.

Ethanol can be distributed at conventional fuel stations, some requiring mild and relatively inexpensive modifications.

H2 stations are far more expensive and require bespoke dispensing equipment. DOE estimates the cost of a nationwide H2 infrastructure to be $500 billion to $1 trillion.

This is a case where it makes sense to "do the math" before getting your hopes up. H2 is wildly impractical. Great as a science research project. By all means.

Harvey hopes for garage H2 refueling, but can't manage to find the funds for 120v or 240v plugs. I just can't help but point out the impracticality of that.

>>>>>>>eci stated: "Well, it is competition in the sense that a typical person will choose between a BEV, PHEV or FCV, whether or not that FCV has a larger battery and plug."

A Plug-in FCV (PFCV) is two vehicles in one: A short-range BEV and a FCV, so you can have a BEV and a FCV all in one vehicle. No need to choose there.

A PHEV is two vehicles in one: A short-range BEV and an ICEV all in one vehicle. No need to choose there.

How about choosing between a PFCV and a PHEV?

1) Many people driving a PHEV have "engine-start anxiety". They feel bad when the engine started and feel bad for having to rely on the engine. A PFCV will solve that problem. Both the battery and the FC will blend in harmoniously and seamlessly unnoticeable by the driver.

2) H2 gives the ability to drive on 100% RE, while a BEV has only 13% RE content average US grid mix, and a ICEV has only 10% ethanol in gasoline, but, since corn farming is fossil-fuel intensive, true RE content of ethanol is much lower. A FCV has much higher green credential than a BEV or a HEV or a PHEV.

3) Home power back up while parked in the garage is possible with a FCV, but not with a PHEV due to exhaust fume accumulation and risk of CO toxicity and death.

4) Permitting the grow of RE to well past 100% in the grid, when grid-excess RE can be used to make H2 and bring back predictable revenue for RE investors.
Only FCV and PFCV can do that. PHEV's do nothing to help ensure continual growth of RE.

5) Fuel Cell and e-motor can be modular in nature, so a car maker will not have to design a new engine and transmission, which can be very costly, plus new emission certification for each new car.
Small FCV's may have one FC stack, mid-size FCV's has two, and large FCV's have 3 FC stacks, etc. Same with big trucks. No need to spend a fortune to design a spanking new diesel engine every time a new model is released.
This will help reduce the cost of new car and truck development and will make FCV cheaper than ICEV in the future.

Have to agree with Roger.

A (2 IN 1) vehicle (FCEV + BEV) in the same vehicle would be ideal for all conditions, including extended range in cold weather.

Something like $2,500 to $4,000 (25 to 40 kWh) of 2020 batteries and a small 25 to 40 kWh FC could supply all the e-range required on a daily basis and another 400+ Km for the occasional long trip while giving the user much higher total range expectation.

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