In this paper, plasmonic photoelectroncatalyst of gold/copper iodide (Au/CuI) was synthesized and fully characterized. Compared to traditional electrocatalytic procedure under dark condition, the photoelectro-catalytic (PEC) activities of Au/CuI towards ethanol oxidation and organic pollutant degradation were distinctly enhanced under visible light irradiation. The advantages of the PEC process were investigated by photocurrent responses, linear sweep voltammetry, chronoamperometric and chronopotentiometry curves, and electrochemical impedance spectroscopy spectra. Finally, the mechanism of plasmon enhanced PEC performance in ethanol oxidation and organic contaminant degradation under visible light irradiation was proposed. The current studies open a new possibility in the application of ethanol oxidation and organic contaminant degradation by using plasmonic photoelectrocatalysts under visible light irradiation. (C) 2017 Elsevier Inc. All rights reserved.