Porous nanomaterial could reduce pollution from cars

An international collaboration involving Australian researchers has developed a nanomaterial that can be used to make markedly more effective catalytic converters for vehicles.
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Dr Hossain (left) and Prof Yamauchi with their nanomaterial. Photo: UOW

An international collaboration involving Australian researchers has developed a nanomaterial that can be used to make markedly more effective catalytic converters for vehicles.

The researchers from the University of Wollongong (UOW) and Australian Nuclear Science Technology Organisation (ANSTO), working with colleagues in Japan, Turkey and Bangladesh, have created porous rhodium (Rh) on a nanoscale. Rhodium is commonly used in catalytic converters to reduce nitrogen oxides (NOx) in exhaust gases. Making it porous increases its surface area, making it more effective.

Professor Yusuke Yamauchi, from the Australian Institute for Innovative Materials (AIIM) at UOW, said the porous rhodium nanoparticles could make a dramatic improvement to air pollution in cities around the world.

“At the moment, the conversion rate of our catalyst is three to four times that of a normal catalyst, the efficiency increase is three to four times,” he said.

Because rhodium, a rare metal, is expensive, Yamauchi said the team was also looking at trialling different alloys to see if they could be of similar efficiency as converters.

“Iron and copper are very cheap materials so we will test some rhodium-copper and rhodium iron alloys - if we can get the same efficiency with an alloy and, at the same time, lower the cost of the material then I think it will be more widely adopted,” he said.

His colleague Dr Md Shahriar Hossain said the new material could already be used to replace conventional catalytic converters, but the team was looking to develop it further to make it more efficient at converting other pollutants in addition to NOx.

“At this moment, with the conventional catalytic converter we can simply replace it no problem. You can just open the existing filters and put it in - plug and play,” Hossain said.

“Another problem is the conversion releases the carbon dioxide as well, which is very bad, so we also want to stop that. We think we can make a hybrid system that can decompose both NOx, SOx (sulphur oxide), and carbon dioxide, so that is the final target.”

Hossain believes the technology could play a big role in reducing air pollution around the world, particularly in South Asia and other parts of the developing world.

“In the West, people will be moving more and more to electric vehicles so there won’t be the same problem. But in Bangladesh, in India and elsewhere in South Asia - where already there are enormous problems with smog and air pollution from car exhaust - petrol and diesel engines will continue to dominate for the next 50 or 60 years,” he said. “This catalytic converter could really solve a lot of problems in that part of the world.”

[Dr Hossain (left) and Prof Yamauchi with their nanomaterial. Photo: UOW]