The research performed advanced the field by discovering catalytic nanomaterials that outperform those reported in the literature on the electrocatalytic conversion of renewable electricity and carbon dioxide to solar fuels. In particular, we optimized colloidal quantum dots of InP (a non-toxic semiconductor). We integrated them in electrodes for selective CO2-to-formate production at high rates (selectivity above 90%, rate above 1 A cm-2). In addition, we demonstrated high selectivity in the 8-electron reduction of carbon monoxide to acetate by controlling the adsorption of the intermediates via surface atomic modification of copper oxide. Finally, cooperative catalysis between copper and nitrogen-doped carbon nanoparticles achieved high selectivity in the 12- and 8-electron reduction toward propanol and ethanol, respectively.
In the last year of the project, we studied the effects of catalysts' oxidation state on the reactivity in different local environments with in-situ XAS at the European Synchrotron Radiation Facility (ESRF). Advanced in-situ XAS is one of the few techniques that enables observing the oxidation state during the reaction, which has crucial impacts on the catalytic reaction and the catalyst's long-term stability. Lastly, we developed a shielding strategy to avoid undesired charge recombination in heterojunction systems, such as WO3/BiVO4 for water splitting.
The results of this project were disseminated through five papers in high-impact journals: one on CO2 reduction to formate in ACS Energy Letters, four papers on solar light-driven water splitting for hydrogen production (on ACS Applied Energy Materials, Applied Surface Science, and The Journal of Physical Chemistry C). Furthermore, one article has been recently accepted on Nature Synthesis.
The research carried out during the project directly addresses issues related to climate change and industrial and societal needs. Using renewable electricity to produce fuels and chemicals from CO2 and water will be essential to achieve carbon neutrality by still increasing the current welfare standards and manufacturing commodity chemicals and materials such as polymers, cosmetics, and highly energy-dense fuels without employing fossil resources.
Modular electrolyzes can be stacked in series to build facilities with size on demand. They can be deployed close to CO2 emitting points (cement factories, bio-refineries, bio-treatment plants, bio-alcohol production sites as the most common CO2 emitters) in plants that can adapt to regional conditions, for example, the abundance of renewable energies and CO2 point sources. Advances in this field can open technical, industrial, societal, and economic opportunities in a 10-year timescale. Looking ahead, progresses in the circular carbon economy will reduce the reliance on foreign resources and stimulate the job market by designing new highly-skilled job positions: for example, in the infrastructure sectors for energy distribution and storage, in the automotive and net-zero emission plastics and polymers industry.
