Yet Another Sustainable Hydrogen Breakthrough By U.S. Researchers

The pace of progress on renewable hydrogen may slow down after president-elect Donald Trump takes office next year, but for now things have really been heating up. In the latest development, a team of researchers based at the Energy Department's Lawrence Berkeley National Laboratory is on the trail of a new solar cell that mimics the natural process of photosynthesis. The goal is to produce hydrogen and other fuels from nothing more than sunlight, water and carbon dioxide.

If the new Berkeley Lab research continues to receive funding, the result will be an efficient, durable "water-splitting" solar cell that could have a productive lifespan of 20 years or more. That's a huge leap forward from the state of today's technology.

Hydrogen from artificial photosynthesis

Hydrogen is the most abundant element on Earth -- no, make that in the entire universe. That makes it attractive as a fuel, for generating electricity in a fuel cell.

Hydrogen fuel cells produce no emissions other than water, so that takes care of the sustainability angle -- or not, as the case may be.

The problem is that hydrogen does not exist naturally on Earth as a standalone element. It has to be extracted from other compounds.

Currently the compound of choice is natural gas. That's two big strikes against hydrogen: extracting hydrogen from natural gas is an energy-intensive process, and  the natural gas lifecycle contributes methane to the global warming mix.

Extracting hydrogen from water is one sustainable alternative. One method, electrolysis, involves applying an electrical current to water. That current is source-neutral, which means that solar power and other renewables can be deployed instead of fossil fuels.

The Berkeley team has been exploring a second angle, which is to wrench hydrogen from water through a photochemical reaction. Basically, that involves immersing a specialized solar cell in water and exposing it to sunlight.

The goal is to create an "artificial leaf" that mimics the natural process of photosynthesis.

The artificial leaf approach has the potential to be scalable and cost-effective, but there is one important holdup.

Like natural photosynthesis, the artificial variety requires a catalyst to push the process forward. The catalyst requires an "active" chemical environment, but that's exactly the kind of environment that damages the semiconductors that harvest solar energy in a solar cell.

Leaping the hydrogen hurdle

Berkeley Lab staff scientist Ian Sharp elaborates on the problem from the catalyst side:

“The most efficient catalysts tend to be permeable and easily transform from one phase to another. These types of materials would usually be considered poor choices for protecting electronic components.”

...and here's how it looks from the protective side:

“Good protection layers are dense and chemically inactive. That is completely at odds with the characteristics of an efficient catalyst, which helps to split water to store the energy of light in chemical bonds.”

The new Berkeley Lab study details how the team solved both problems. You can find it in the journal Nature under the title, "A multifunctional biphasic water splitting catalyst tailored for integration with high-performance semiconductor photoanodes."

That's a mouthful, right? Basically it means that the researchers developed a new catalyst that also serves as a protective coating for the solar cell's semiconductors.

They weren't just shooting in the dark. They relied on previous studies on water-splitting reactions, which enabled them to focus their efforts on the most promising materials.

The new catalyst is an ultra-thin film consisting of a cobalt dihydroxide materials layered over a form of cobalt oxide.

By ultra-thin, we do mean ultra-thin as in atomic level. The thin films were created practically atom by atom, borrowing a technique from the semiconductor industry called plasma-enhanced atomic layer deposition.

So far the researchers have demonstrated that their new catalyst can run for three days, and potentially longer. That doesn't sound like much of a big deal at first glance, but it's on a much higher plane than any other similar system. According to Berkeley Lab, such systems usually fall apart after just a few seconds.

The next steps -- of which there are many -- include assembling a more thorough understanding of the factors that make water-splitting solar cells degrade.

About that funding stream...

This could be the last step for a promising line of research if the Trump Administration decides to cut the Energy Department's hydrogen budget,

That's not the only such program that could fall under the axe. The Energy Department has a whole raft of research programs for sustainable hydrogen and other fuels that can be generated from sunlight, water and carbon dioxide.

Many of those programs are linked under the umbrella of the Energy Department's Joint Center for Artificial Photosynthesis. Established in 2010 as part of the new national "Energy Hub" network established by President Obama, it currently enrolls a roster of more than 100 researchers drawn from the California Institute of Technology, UC-Irvine and UC-San Diego as well as Berkeley Lab.

The National Accelerator Laboratory at Stanford is also part of the JCAP mission, which is dedicated to finding "new and effective ways to produce fuels using only sunlight, water, and carbon dioxide."

The Obama Administration also just established the new "HydroGEN" initiative to accelerate the development of water-splitting technology, but that's contingent on the availability of funding.

Even if President-elect Trump decides to eliminate the entire Energy Department, that will not stop the hydrogen economy.

Advanced water-splitting research is going on in other countries all around the globe, and that will continue regardless of what happens to the Energy Department.

Hopefully the U.S. will not be left behind. Fingers crossed!

Image (cropped): "Schematic of the multi-functional water splitting catalyst layer engineered using atomic layer deposition for integration with a high-efficiency silicon cell" by Ian Sharp/Berkeley Lab.

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