Cascaded Hot Electrons Transfer within Plasmonic Ag@Pt Heterostructure for Enhanced Electrochemical Reactions

Abstract

A popular strategy for constructing localized surface plasmon resonance (LSPR) enhanced plasmonic metal heterostructure catalysts is to fabricate a composite of highly active materials with plasmonic metal nanomaterials. However, this kind of combination not only decreases the LSPR response intensity but also changes the hot electron transport pathway inside the heterogeneous structure, which induces the ineffective transfer of plasmonic hot electrons to the surface of the heterostructures and hinders the effective enhancement of catalytic activity. Herein, simple Ag@Pt bimetallic nanocubes are selected to explore the mechanism of hot electrons from excitation and transmission within a plasmonic metal heterostructure and their contribution to the electrochemical hydrogen evolution reaction (HER). The corresponding experimental and theoretical results confirm that the HER can be significantly enhanced by hot electrons via a cascaded manner, i.e. first being pumped from Ag atoms to Pt atoms, and then accumulated hot electrons on Pt transferring into the adsorbed H atoms. Compared with pure Pt, the Tafel slope of Ag@Pt bimetallic nanocubes is reduced by 55.4%, and the turnover frequency is increased by 590.8% upon 660 nm laser irradiation (101 mW·cm-2 ). This work provides an important reference for the design and application of plasmonic metal heterostructure catalysts.

Keywords: LSPR, hot electrons, plasmonic metal heterostructures, transport pathway, electrochemical reactions, cascaded transfer