Low-platinum catalyst could make hydrogen production cheaper

A new type of catalyst that uses five times less platinum than usual could help make hydrogen production more affordable in the future.

Hydrogen generated by splitting water molecules with electricity (electrolysis) has great potential as a plentiful and green energy source. But the materials needed to accelerate the chemical reaction don’t come cheap: platinum alone currently costs about $85 per gram.

“The process is dependent on platinum, which is scarce and expensive,” said Dr Victor Mashindi, an electrochemist at the University of the Witwatersrand in Johannesburg, South Africa. “We wanted to find an alternative catalyst that doesn’t use as much platinum.”

Mashindi was part of an international team – involving researchers from South Africa, Brazil, Canada, and Germany – that developed the new catalyst. Their work was published recently in ACS Applied Energy Materials.

Previous research has shown that metals like nickel and cobalt provide some catalytic activity in electrolysis, though they are not as effective as platinum. So the team created a catalyst that replaces some of the platinum with nickel and cobalt and mounted it on tiny structures made of carbon (nanospheres), to hold the metals in place and maximize the surface area for the chemical reaction.

While a typical catalyst contains around 20% platinum by weight, the new version uses around five times less platinum – just 4% by weight – which represents big cost savings.

“The catalyst uses the same total amount of material, just with less platinum, to produce the same amount of hydrogen,” said Mashindi, and performs just as well as more platinum-rich catalysts.

The team used the Canadian Light Source at the University of Saskatchewan to study how the various components of the new catalyst are arranged and how they interact.

“The data we obtained from the CLS helped us form a clearer understanding of the atomic structure of the catalyst,” said Dr Dean Barrett, a materials scientist at the University of the Witwatersrand, who led the work. “This information enabled us to finetune the material properties at the nanoscale towards the desired outcome of producing more hydrogen and using less platinum. We can only get that type of data by using a facility like the CLS.”

While the new catalyst shows promise, the work is still at an early stage, said Barrett. The team has identified a local start-up company in South Africa they may work with to develop the idea further. “We work at the level of fundamental science,” he said. “We need to make sure what works in the lab can be scaled up,” he said.