Visualizing electron transfer at semiconductor–metal interface by surface plasmon resonance imaging

Abstract

• SPRi has response to electron transfer at both ZnO/Au and TiO 2 /Au interfaces. • Electron mobility and concentration in ZnO and TiO 2 films can be estimated by SPR signals. • BPE arrays can be used to map electron transfer at the two interfaces simultaneously. We report on plasmonic imaging of electron transfer at a semiconductor–metal interface by combining principles of surface plasmon resonance imaging (SPRi) and a closed bipolar electrode (CBPE). In the two-cell configuration, one cell was deposited with thin films of semiconductor-based photocatalysts and the other cell without any modification. By this configuration, electron transfer at the semiconductor–metal interface was coupled with interfacial charging in the latter cell, which was read out optically by SPRi. Two different semiconductor–metal interfaces, that were ZnO/Au and TiO 2 /Au were investigated respectively. Both of their SPR signals increased when light on and decreased when light off. And light intensity increased the corresponding SPR responses. Finally taking advantage of the high-throughput features of SPRi, electron transfer at the two interfaces were visualized simultaneously. This work expands applications of SPRi and provides a new route to investigate electron transfer at semiconductor–metal interfaces.