Electrochemical CO2 reduction provides a desirable pathway to convert greenhouse gas into useful chemicals. It is a great challenge to reduce CO2 efficiently in aqueous solution, especially on commercial bulk metal electrodes. Here, we report substantial improvement in CO2 reduction on bulk silver electrode through the introduction of ionic surfactant in aqueous electrolyte. The hydrogen evolution on the electrode surface is greatly suppressed by the surfactant, while the catalytic ability of silver towards CO2 reduction is maintained. The Faradaic efficiency for CO is greatly enhanced from 50% to 95% after the addition of this low-cost surfactant. This study may provide new pathways towards efficient CO2 reduction through the inhibition of proton reduction. (C) 2016 Elsevier B.V. All rights reserved.