Uncovering the Role of Direct Electron Transfer in Plasmon-Mediated Electrochemical Reactions

The mechanism of the charge and energy flow at the metal-molecule interface has attracted much attention, especially with the recent rise of plasmonic nanomaterials for light-to-chemical conversion. Although numerous studies have demonstrated the irreplaceable effects of energetic electrons on accelerating chemical reactions, detangling the direct electron transfer (DET) from indirect electron transfer (IET) and understanding their roles are still challenging. Here, by combining electrochemical dark field scattering spectroscopy, the photoelectrochemical method, and density functional theory calculation, we provided the evidence of DET during chemical reactions, alongside decoupling the contributions of DET and IET, and then established the relationship between chemical reactivity and DET efficiency. Moreover, we discovered that DET is selective for different reactions, e.g., enhancing the oxygen reduction reaction much more than the hydrogen evolution reaction. This work offers the possibility to optimize reaction selectivity via DET and advances mechanistic insights into plasmonic charge transfer.