Rational designed Co@N-doped carbon catalyst for high-efficient H2S selective oxidation by regulating electronic structures

H2S selective catalytic oxidation, regarded as a green purification technology, has attracted much attention due to its ability to convert H2S to elemental S directly without thermodynamic limitation. Herein, we report for the first time that Co nanoparticles (NPs) with different Co content were encapsulated by N-doped graphitic carbon (3-5 layers) for H2S selective oxidation. The catalytic performance of Co@NC catalysts increases at first and then decreases by increasing the content of Co. It is found that Co@NC-4 with a suitable Co content shows an optimal H2S conversion ratio of nearly 100% with the weight hourly space velocity of 18000 mL g(-1) h(-1) at 190 degrees C for 28 h. This high performance may be due to optimal mesopore size and abundant pyridinic N. In contrast, NC sample without Co has conversed nearly 95% of H2S at 250 degrees C. The theoretical calculation indicates that N doped graphene can regulate the electron density around the Co NPs, which promotes the adsorption of H2S. We believe that the unique electronic and geometrical configurations improve the activity and stability. Our finding provides a new reference for the study of H2S selective oxidation.