Importance of Hot Spots in Gold Nanostructures on Direct Plasmon-Enhanced Electrochemistry

Recently, the direct utilization of plasmonic metal nanostructures in accelerating the electrochemical reactions reveals the importance of hot charge carriers generated by localized surface plasmon resonance (LSPR). However, the effect of morphological forms of the same metal element on direct plasmon-enhanced electrocatalytic activity has not yet been well documented. Herein, four kinds of Au nanostructures with different morphologies of nanospheres (NSPs), nanorods (NRs), nanostars (NSs), and triangular nanoplates (NPLs) were synthesized. The shape-dependent plasmonic enhancement effect of Au nanostructures toward the electrooxidation of ascorbic acid (AA) was studied. We find that the electrochemistry of AA oxidation on these Au nanostructures can be enhanced upon light irradiation with the higher enhancement effect of the Au NPLs and NSs than the Au NSPs and NRs. This shape-dependent enhancement effect is suggested to be related to the number of “hot spots” in different NP surfaces generated from Au LSPR. Thus, the present work would shed new light on the direct plasmon-enhanced electrochemistry, which helps in widening the potential applications of plasmonic materials in electrochemical sensors and electrochemical energy conversion.