Insights into Highly-Efficient CO2 Electroreduction to CO on Supported Gold Nanoparticles in an Alkaline Gas-Phase Electrolyzer

Abstract

Electrochemical conversion of CO2 to fuels powered by renewable energy is an attractive technology for carbon emission reduction and renewable energy utilization elevation. Here, electrochemical reduction of CO2 to selectively produce CO using a homemade electrolyzer and Au nanocatalyst was investigated. Au nanoparticles were uniformly anchored on N-doped carbon to improve catalytic activity, and the C/N ratio and operating temperature were adjusted to elevate catalytic selectivity. The resulting Au catalyst exhibited a current efficiency for CO production higher than 90% in a wide full cell voltage range (1.8 ∼ 3.0 V), a high mass activity of 900 A gAu −1, and a total current density of 200 mA cm−2 under 3.0 V cell voltage at room temperature. A scale-up 3 × 3 cm CO2 electrolyzer was constructed and tested at 1 A, the current efficiency for CO production reached 93% but decreased within a few hours due to the potassium carbonate precipitation phenomenon at the cathode. The important influence of an unideal ion transport pathway during electrolysis on CO2 electrolyzer performance was revealed, and its stability can be greatly improved by using deionized water instead of KOH solution.