Investigation of the catalytic activity of bifunctional plasmonic nanocatalysts via in situ SERS monitoring

Author(s)

Douglas dos Santos Lopes

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Conjunto das Químicas (IQ e FCF) (CQ/DBDCQ)
• Defense date: 2023-06-16

Examining board members

Paola Corio; Italo Odone Mazali; Henrique Eisi Toma

• Advisor: Paola Corio

Abstract

Considered the development of the Surface Enhanced Raman Scattering (SERS) technique in recent years, the extremely high selectivity in relation to metallic interfaces allows for the in situ monitoring of reactions promoted by heterogeneous catalysis on the surface of nanostructured metals. Important kinetic and reaction parameters can be evaluated in real time via in situ SERS monitoring on the surface of bifunctional plasmonic nanocatalysts. Taking into consideration the mechanisms of excitation and decay of Surface Plasmon Resonances (SPR), dynamic processes of catalysis (conventional or plasmon-induced) can be monitored in situ via SERS, as a direct consequence of the radiative decay of SPR (local field enhancement), and can be driven over the surface of plasmonic metals as a consequence of the non-radiative decay of SPR (hot charge transfer and/or local heating). The present work demonstrates the preparation and characterization of bifunctional catalytic/SERS-active substrates based on different plasmonic metals and, at times, combined with conventional catalysts. The catalytic performance of these substrates is evaluated by obtaining vibrational information of molecular adsorbates, collected in situ during dynamic processes of catalysis, using the SERS technique as a central monitoring tool during chemical processes occurring on the metallic surface. Comprehensively, the results discussed demonstrate the potential of bifunctional catalytic/SERS-active substrates for activating, modulating, and enhancing photocatalytic processes on the metallic surface and show how the in situ SERS monitoring can provide selective and valuable information to unveil unique characteristics of the metallic surface, control and modulate alternative reaction pathways, as well as inventive applications of plasmonic systems involving chemical species of environmental interest. The results discussed herein contributes to the fields of plasmonic catalysis and SERS spectroscopy, as well as the development of methodologies for in situ monitoring of dynamic processes of catalysis and future applications. (AU)

• FAPESP's process: 19/03371-6 - Investigation of the SERS and catalytic activity of plasmonic nanostructures in the degradation of organochlorine and organophosphorus pesticides
• Grantee: Douglas dos Santos Lopes
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)