Insights into Highly-Efficient CO 2 Electroreduction to CO on Supported Gold Nanoparticles in an Alkaline Gas-Phase Electrolyzer

Abstract

Electrochemical conversion of CO 2 to fuels powered by renewable energy is an attractive technology for carbon emission reduction and renewable energy utilization elevation. Here, electrochemical reduction of CO 2 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 g Au −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 CO 2 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 CO 2 electrolyzer performance was revealed, and its stability can be greatly improved by using deionized water instead of KOH solution.