Renewable fuel from sunlight, water and CO2 using non-noble metal catalysis

Purpose and goal:

The global drive to replace fossil fuels by renewable energy sources has created a critical need to develop advanced energy conversion methods. Artificial photosynthesis, where sunlight is used as a virtually endless source of energy and abundant substrates as a cheap source of electrons for CO2 reduction, has emerged as a possible path towards carbon neutrality.

In this project, funded by Vinnova, we design and fabricate next-generation photosensitive materials for the conversion of solar energy into fuels. These materials should have important implications for solar fuel cells. Expected results and effects:

While the photoelectrode materials in most state-of-the-art solar fuel cells are based on scarce noble metals, mainly iridium, we utilize catalysts based on first-row transition metals. Our materials are recyclable, environmentally benign and cheap, which is a prerequisite for the solar cells scalability. Specifically, we have designed water oxidation and CO2 reduction catalysts based on iron, the most abundant transition metal on Earth.

The ligand family we use can be easily obtained in one-pot synthesis starting from cheap chemicals under mild conditions. Approach and implementation:

The first step in our design process was the selection of appropriate catalysts for the critical reactions involved in fuel cells: water oxidation and CO2 reduction. To enhance the catalytic performance of the Fe-based photoelectrodes, we designed a family of ligands that stabilize the Fe center and optimize its catalytic activity. The implementation phase involved the fabrication of photoelectrodes, using anchoring techniques to integrate the catalysts onto the electrode substrates. They were tested in water oxidation and CO2 reduction reactions under simulated solar light.