Unraveling the electro-oxidation steps of methanol on a single nanoparticle by in situ nanoplasmonic scattering spectroscopy

Understanding the mechanism of methanol oxidation reaction (MOR) remains a challenge in the development of direct methanol fuel cells. Large-scale investigations of the MOR encounter issues related to mass transfer and averaging effects. To address these limitations, exploring the MOR on the surfaces of individual nanocatalyst and precisely identifying the reaction steps can yield valuable insights into the underlying pathways. In this study, we employed in situ nanoplasmonic resonance scattering spectroscopy to dynamically monitor the MOR process on single gold nanorod particles (GNPs) and Pt-coated gold nanoparticles (Pt-GNPs). We observed the evolution of metal hydroxides, which was assumed as the active species. Notably, the dynamic behavior of the surface atomic layers revealed the rate-determining steps for both the GNPs and Pt-GNPs, indicating competitive adsorption of intermediates on the nanocatalyst surface. The resulting inherent reaction mechanism highlights the thermodynamics-dependent catalysts’ redox processes and their surface adsorptions, which holds significance for advancing highly active MOR catalysts.