The rapidly growing concentration of carbon dioxide (CO2) in the Earth’s atmosphere is one of the most urgent issues humanity must address to avoid a climate catastrophe. Thanks to greenhouse gases like CO2, the heat from the Sun is remaining trapped in the atmosphere, warming the planet. Researchers developed a method to break CO2 apart and convert the greenhouse gas into useful materials like fuels or consumer products ranging from pharmaceuticals to polymers.
Typically, this process requires a tremendous amount of energy; however, the team used a more sustainable ally: the Sun. Specifically, they demonstrated that ultraviolet (UV) light could be very effective in exciting an organic molecule, oligophenylene. Upon exposure to UV, oligophenylene becomes a negatively charged anion, readily transferring electrons to the nearest molecule such as CO2, thereby making the CO2 reactive and able to be reduced and converted into things like plastics, drugs, or even furniture.
Many research teams are looking at methods to convert CO2 that has been captured from emissions into fuels or carbon-based feedstocks for consumer products ranging from pharmaceuticals to polymers. The process traditionally uses either heat or electricity along with a catalyst to speed up CO 2 conversion into products; however, many of these methods are often energy intensive, which is not ideal for a process aiming to reduce environmental impacts. Using sunlight instead to excite the catalyst molecule is attractive because it is energy efficient and sustainable.
Most other methods also involve using metal-based chemicals and those metals are rare earth metals that can be expensive, hard to find, and potentially toxic. The alternative is to use carbon-based organic catalysts for carrying out this light-assisted conversion. This method presents challenges of its own. The team used quantum chemistry simulations to understand how electrons move between the catalyst and CO 2 to identify the most viable catalysts for this reaction.
The team found they can carry out systematic modifications to the oligophenylene catalyst by adding groups of atoms that impart specific properties when bonded to molecules that tend to push electrons towards the center of the catalyst to speed up the reaction. The team is exploring catalyst design strategies that not only lead to high reaction rates but also allow for the molecule to be excited by visible light, using both quantum chemistry and genetic algorithms.