The low-temperature plasma secret to artificial photosynthesis

December 14, 2023

Maik Budde defended his PhD thesis at the department of Applied Physics and Science Education on December 12th.

Photo: iStockPhoto

Climate change is in the news daily, and the subject of discussions between politicians, scientists, and lots of stakeholders in society. The process of climate change is influenced by our activities, part of which has involved increased emission of CO2. One obvious way to potentially deal with this CO2 is to plant more trees to absorb excess CO2, but this process can be somewhat inefficient. For his PhD research, Maik Budde investigated so-called artificial photosynthesis in the form of the combined conversion of CO2 and H2O in a low-temperature plasma.

Low-temperature plasmas (LTPs) are partially ionized gases, generated by applying a voltage across a gas-filled gap. They form highly reactive environments that can promote the conversion of CO2 in a very efficient way.

Furthermore, LTPs run on electricity, for example originating from photovoltaic cells where sunlight is converted into electricity.

To date, the combined conversion of CO2 and H2O has not been studied by many researchers, which means that some fundamental work is necessary large-scale uses are possible.

Artificial photosynthesis

With this in mind, for his PhD research, Maik Budde explored the concept of artificial photosynthesis. To achieve this, Budde fired a laser at the plasma and used the response of particles in the plasma to probe the physics of the process.

However, even the niftiest diagnostic method cannot observe everything. Therefore, Budde turned to computer simulations of plasma and established a set of so-called collision cross sections of electrons with H2O molecules.

As an ionized gas, LTPs are dominated by their electrons and the cross sections give the probability for a certain collision process to occur.

With this, a firm basis for the experimental as well as computational study of CO2-H2O plasmas is established that can now serve as the starting point for attempts to optimize the process.

Title of PhD thesis: In Uncharted Waters – Energy transfer processes in H2O-containing low-temperature CO2 conversion plasmas. Supervisors: Erwin Kessels, Vasco Guerra, and Richard Engeln.