Efficient electroreduction of CO2 to CO by Ag decorated S-doped g-C3N4/CNT nanocomposites at industrial-scale current density

Abstract

In recent years, the application of graphitic carbon nitride (g-C3N4) for electrochemical CO2 reduction reaction (eCO2RR) has aroused strong interest. However, this material is still facing severe activity issue towards eCO2RR so far, and studies on its catalytic mechanism have not been sufficiently implemented either. Herein, we report an Ag-decorated sulfur-doped graphitic carbon nitride/carbon nanotube nanocomposites (Ag–S–C3N4/CNT) for efficient eCO2RR to carbon monoxide (CO). The resulting Ag–S–C3N4/CNT catalyst exhibits a notable performance in eCO2RR, yielding a high current density of −21.3 mA/cm2 at −0.77 VRHE and maximum CO Faradaic efficiency over 90% in H-type cell. Strikingly, when combining with flow cell configuration, the fabricated nanocomposites permit an industrial scale and cost-effective eCO2RR, showing a current density larger than 200 mA/cm2 and the Faradaic efficiency of CO over 80% in a wide potential window, delivering the best eCO2RR performance among the C3N4-derivatives. Moreover, the catalytic mechanism of this nanocomposite has been further explored through density functional theory (DFT) and electrochemical methods carefully. Our work not only sheds light on industrial scale eCO2RR to CO but also leads to new insights on the application of C3N4-based composite materials in electrocatalytic processes.