ISaaC · In Situ Nanoscale Mapping of CO2 Photoreduction over Low-Dimensional Semiconductor Photocatalysts

The conversion of the greenhouse gas carbon dioxide (CO2) into high-value chemicals and fuels by using solar-powered devices represents a promising and sustainable strategy to achieve the target of climate neutrality by 2050. The development of an efficient technology for photocatalytic CO2 reduction (CO2RR) requires an in-depth knowledge of the reaction mechanism, which is, to date, still elusive. In particular, photocatalysts often consist of nanomaterials which are difficult to study at the single-entity level. In this context, ISaaC represents an effective solution to unlock the working principles of photocatalytic devices for CO2RR. To guide the design of future advanced photocatalysts with improved performances, this project proposes an in situ photochemical nanoscopy of CO2RR over low-dimensional semiconductors and plasmonic metal-semiconductor heterojunctions judiciously designed through top-down nanofabrication. Based on a unique nanoprobe, combining at-source photonic and electrochemical functionalities, ISaaC aims at realizing via light-assisted scanning electrochemical microscopy (Photo-SECM) in situ photochemical analysis of individual nanocatalyst entities, as well as mapping with unprecedented local illumination conditions (sub-100 nm). The collected nanoscale information will be correlated with data provided by operando Raman spectroscopy to confirm the role of the device towards CO2RR. ISaaC identifies three objectives to enable mechanistic insights into individual nanoscale photocatalysts for CO2RR: 1) development of a Photo-SECM plasmonic probe as an individual photocatalyst. Investigation of its plasmon-assisted photochemical response; 2) development of optimized Photo-SECM nanotip with nanoscale light irradiation. Demonstration of improved spatial mapping of nanostructured semiconductor photocatalysts; 3) investigation of CO2RR over nanoengineered photocatalysts via combined in situ Photo-SECM and operando Raman spectroscopy.