Enhanced metal−promoter interaction over Na modified Co2C nanoprisms for high-efficiency hydrogen production from methanol steam reforming

Abstract

As an important application for methanol-based energy-storage systems, methanol steam reforming (MSR) using appropriate catalysts can provide clean hydrogen via onboard production for fuel cells. However, owing to their unsatisfactory activity and stability, the use of the most common catalysts, including Cu-based and groups 8–––10 transition metals, remains challenging. Herein, a series of Na-promoted Co2C nanoprism catalysts containing different Na loadings was used for the first time in MSR. The 1Na/Co2C catalyst showed an excellent activity and stability for MSR, with H2 production rates as high as 4637.9 μmol/gcat/min at 250 °C, which outperforms most of the reported catalysts. In-depth characterizations revealed that a strong interaction between Na and Co2C stabilized the catalyst and promoted the dissociation of CH3OH and H2O. A further investigation of the reaction mechanism revealed that the reaction proceeded via the dehydrogenation of methanol and sequential water−gas shift reactions. Density functional theory calculations revealed that the Co2C (101) surface exhibited the lowest energy barrier and that the methoxy dehydrogenation was the rate-determining step. This work provides further valuable insights into the rational design of transition-metal carbide catalysts for MSR.