Local Photochemical Nanoscopy of Hot-Carrier-Driven Catalytic Reactions Using Plasmonic Nanosystems.

Henrotte, Olivier; Santiago, Eva Yazmin; Movsesyan, Artur; Mascaretti, Luca; Afshar, Morteza; Minguzzi, Alessandro; Vertova, Alberto; Wang, Zhiming M et al. · ACS Nano · 2023

basic_science · Level V

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Abstract

Nanoscale investigation of the reactivity of photocatalytic systems is crucial for their fundamental understanding and improving their design and applicability. Here, we present a photochemical nanoscopy technique that unlocks the local spatial detection of molecular products during plasmonic hot-carrier-driven photocatalytic reactions with nanometric precision. By applying the methodology to Au/TiO<sub>2</sub> plasmonic photocatalysts, we experimentally and theoretically determined that smaller and denser Au nanoparticle arrays present lower optical contribution with quantum efficiency in hot-hole-driven photocatalysis closely related to the population heterogeneity. As expected, the highest quantum yield from a redox probe oxidation is achieved at the plasmon peak. Investigating a single plasmonic nanodiode, we unravel the areas where oxidation and reduction products are evolved with subwavelength resolution (∼200 nm), illustrating the bipolar behavior of such nanosystems. These results open the way to quantitative investigations at the nanoscale to evaluate the photocatalytic reactivity of low-dimensional materials in a variety of chemical reactions.