Carbon dioxide can be used as a co-factor for catalytic reactions allowing cyclic alkenes to be converted with higher conversion rates at lower pressures, according to chemists in South Korea. Sang-Eon Park and colleagues at Inha University, in Incheon, used carbon nitrides containing surface groups to activate carbon dioxide and thence to promote oxidation. Carbon dioxide has been investigated in the past as a "green" chemistry reagent or solvent in dense and supercritical form, respectively. However, it can act as an oxygen source even at low pressure, Park explains. Further spectroscopic and computational studies are now under way to glean details of the precise mechanism allowing the gas to behave in this way and so help the researchers fine tune the oxidation reactions and perhaps even extend the range of reactions amenable to this approach.