Ted Sargent: Saving the planet with nanoscience



As Ted Sargent explains it, when he started out in his nanoscience lab at University of Toronto 18 years ago, his group was made up of “a team of talented experimentalists.” The laborious experiments were yielding results, but, at the same time, the group knew there were exciting things starting to happen in computational material science that might provide shortcuts and acceleration to experiments.

“We wondered: Can you do an experiment without doing an experiment?” Sargent says. “Can you predict a new material for a solar cell, or how a new light emitter or a new catalyst might work, without actually doing the experimental legwork? In other words, can you predict these things by solving big computational equations with a lot of atoms?”

It turns out that with enough computational power and theory-based studies, increasingly you can. Fast forward to today: the Sargent group is now an integrated team that uses computational materials science and experimental materials fabrication to make better devices for its three main areas of research. Broadly defined, they include cost-efficient solar cells, brighter light emitters and more energy-efficient catalysts.

When it comes to solar cells, the group is working to give the world more efficient ones, using the new alternative materials.

“To be competitive with fossil fuels, we need to convert the energy from the sun to electrical power with greater efficiency than we do today. This requires precision tuning of the materials used in the solar cell,” Sargent says, and adds that his team is making good advances in this area.

On the light-emission front, Sargent’s group looks at green options for things like computing displays, data projectors and lighting.

“Green technologies promise really good power efficiency, but to capture the interest of consumers, we need to make advances in colour purity, true-life resolution in displays, and lighting that is as natural as possible.”

On the catalyst file, the project is all about storing energy.

“Solar energy reaching the Earth’s surface varies over time, because, for example, the sun sets at night, or a cloud goes by, or, we have fewer hours of sun in the winter,” Sargent says. “The timing of how the electricity from the sun varies doesn’t correspond to our demand patterns because we need more energy in the winter when it’s cold. So there’s an interest in storing energy over the very long term. Our project provides a chemical approach. We use solar electricity to synthesize fuel and then we can consume the fuels whenever we want them.”

One of the great things about this approach, Sargent says, is that it takes CO2 from the atmosphere, or from an industrial flue, and uses renewable energy to upgrade it to a carbon-based fuel or chemical feedstocks.

“These carbon-based chemicals are the ones we already work with when we combust existing fossil fuels,” he says, “except ours are synthesized instead by consuming renewable electricity and CO2. This closes the carbon cycle, decarbonizing electricity.”

One of the catalysts converts carbon dioxide into carbon monoxide, which is essential to make valuable chemical fuels such as methanol and diesel. The Sargent team’s simulations and studies figured out how ultra sharp electrodes — which are effectively nanoscale lightning rods — increase the rate of these important reactions. It was published in the journal Nature and made news around the world.

The physicists’ initial experiments yielded exciting results, but to improve the materials further, they needed to understand how they work at an atomic level.

“Splitting water into hydrogen and oxygen is another half of the reaction involved in producing fuels. We’ve made the best catalyst for evolving oxygen gas, but we didn’t fully understand why that was the case, so we couldn’t make further progress,” Sargent says. “We collaborated with another group from Stanford that predicts how good a catalyst will be and we were able to explain the physics of why the ones we made worked better than any before.” Understanding this heightened the value of the work, which was published in March 2016 in the journal Science.

To work on all of its advances, the group uses Compute Canada resources, which touch everything it does, Sargent says — significantly improving the group’s global competitiveness.

“Without Compute Canada, we would have less of a competitive advantage in the global research landscape,” he says. “Having access to great computational abilities and having really smart people to work on them allows us to move faster than some of our colleagues. We can cycle faster and develop physical models faster than we otherwise would. The world is racing to make better catalysts for solar fuels and we can win.”

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