Fabrication of double modified electrocatalyst by dual flame synthesis for enhancing electrochemical reduction of carbon dioxide.

A rapid dual flame synthesis is developed for one-step preparation and modification of double modified ZnO catalysts with carbon doping and oxygen vacancies. The growth mechanism and nanostructure evolution are also investigated. The double modified ZnO with carbon doping and oxygen vacancies exhibies excellent performance in CO 2 reduction to syngas, with a high current density of 14.02 mA/cm2 at −1.1 V vs. RHE and a maximum Faradaic efficiency of 71% for CO production. The maximum adjustable range of the CO/H 2 ratio from 0.5 to 2.7. In a flow cell, the double modified ZnO exhibits a large current density of 126.8 mA/cm2 at −1.2 V vs. RHE. The maximum Faradaic efficiency for CO 2 reduction to CO is 74.8% at 50 mA/cm2. Double modified ZnO maintains stable potential and Faradaic efficiency for over 5 h of electrolysis. Operando X-ray absorption spectroscopy and density functional theory calculations reveal that the active site is the Zn–Zn configuration, and that carbon dopant and oxygen vacancy promote CO 2 activation and CO desorption, and reduce reaction overpotential of CO 2 RR. • The objective is to efficiently convert CO 2 to syngas using renewable energy. • Carbon doping and oxygen vacancy are employed to modify the electrocatalyst. • Dual flame synthesis is proposed for fabricating the double modified catalysts. • Double modifications can enhance catalytic activity and alter selectivity. • Operando XAS reveals that Zn sites serve as the active sites for CO 2 reduction. [ABSTRACT FROM AUTHOR]