Greenhouse gas repurposed in University of Auckland experiments

Cutting-edge University of Auckland research converted waste carbon dioxide into a potential precursor for chemicals and carbon-free fuel.

Dr Ziyun Wang’s researchers in the School of Chemical Sciences, in collaboration with researchers at Chinese institutions, have demonstrated a method for turning CO₂ into formic acid, reported in the journal Nature.

In benchtop experiments, a catalyst made from waste lead-acid batteries enabled a transformation which hadn’t been possible using previous catalysts.

Formic acid – the same substance produced by ants (formica is the Latin word for ant) – is a colourless and pungent liquid with potential as a transportation fuel, for storing electrical energy and for enabling the petrochemical industry to cut CO₂ emissions.

As emissions of carbon dioxide, the primary greenhouse gas, rise each year, scientists are looking into options for the capture and storage of CO_2, for repurposing CO_2, and for pursuing a carbon-free economy.

Wang’s group is one of the world leaders in research into CO₂ electrochemical reduction (CO₂RR) using acidic rather than alkaline conditions.

“This innovation opens up exciting possibilities for carbon-neutral technologies,” he says.  “In the future, cars and gas stations could be using repurposed carbon dioxide_.” 

In tests, the new method efficiently converted CO_2. for more than 5,000 hours, and the researchers’ calculations suggest it can be cost-effectively scaled up for industry.

The experiments used a proton exchange membrane electrolyser. Carbon dioxide flowed into an electrochemical cell and was converted into formic acid, just like charging a battery.

Two PhD students, Chengyi Zhang and Ruihu Lu, and a research fellow, Dr Yu Mao, worked on the project.