Trihydrogen cation formation on strong field-ionized gold nanoparticles*

Strong-field interactions with gold nanoparticles (AuNPs) drive charge-induced reaction pathways, making surface morphology crucial for catalytic performance. In this study, we investigate how nanoscale surface features influence catalytic activity at the single-particle level, a challenging area due to the intricate length scales involved. Traditional methods, such as suspending AuNPs in colloidal solutions or depositing them on substrates, can alter intrinsic properties and distort observed catalytic behaviors. To address this, we employed reaction nanoscopy, enabling direct observation and measurement of surface reaction yields at high spatial resolution on individual spherical and faceted citrate-capped AuNPs to investigate trihydrogen cation formation. Our findings reveal how shape variations affect the nanoparticle surface's reaction landscape and highlight the pivotal role of charge localization in driving reaction dynamics. We show that the proton-rich environment created by laser-induced surface ionization enhances the catalytic activity of faceted AuNPs, emphasizing their potential for diverse chemical transformations.