Catalysis plays a key role in the current chemical manufacturing and renewable energy generation sectors. The development of active, efficient and selective catalysts is an essential step in our attempts to achieve sustainability. However, our progress is hindered because of the limited molecular-level knowledge of the surface chemistry occurring when a catalyst is in action. The in-situ investigation of catalysts at the single-nanoparticle level can bridge this knowledge gap by revealing adsorbates and rare intermediates dynamically formed on the surface of the catalyst during the reaction. Additionally, the probing of catalytic activity of individual nanoparticles can discern particle-to-particle variations in catalytic activity, information otherwise masked in ensemble measurements. To this end, we have developed a surface-sensitive, in-situ nanoscale surface enhanced Raman scattering (SERS)-based chemical imaging technique that has single-nanoparticle-level spatial resolution and a 100-ms time-resolution and can be used in aqueous media. Using this technique, we studied the light-excitation-driven CO2 reduction reaction (CO2RR) on individual Ag nanoparticle (NP) catalysts in CO2-saturated water (Figure 1). We discovered a rich array of previously unknown C1 and C2+ surface species formed in the CO2RR. Many of these species are long chain C–C coupled hydrocarbons and alcohols, which are valuable liquefiable, energy-dense fuels that are otherwise kinetically challenging to be produced in electrocatalytic CO2RR on Ag. Additionally, an analysis of catalytic activity from several individual nanoscale locations revealed spatiotemporal variabilities in the species distribution. This work demonstrates the power of high-spatial-resolution operando studies for understanding complex catalytic processes at the molecular level.
References
• Devasia, D.; Jain, P. K. Intrinsic noise in catalysis deduced from single-nanoparticle-level studies (2020), manuscript in preparation
• Devasia, D.; Wilson, A. J.; Jain, P. K. A rich catalog of C–C bonded species formed in CO2 reduction on a plasmonic photocatalyst (2020), ‎Nat. Commun. (under review)
• Devasia, D.; Das, A.; Mohan, V.; Jain, P. K. Control of chemical reaction pathways by light–matter coupling (2020), invited review article, submitted to Annu. Rev. Phys. Chem.
• Wilson, A. J.; Devasia, D.; Jain, P. K. Nanoscale optical imaging in chemistry, Chem. Soc. Rev., 2020, DOI: 10.1039/D0CS00338G
• Kumari, G.; Zhang, X.; Devasia, D.; Heo, J.; Jain, P. K. Watching visible light-driven CO2 reduction on a plasmonic nanoparticle catalyst, ACS Nano, 2018, 12 (8), 8330-8340, DOI: 10.1021/acsnano.8b03617