Sintering enhances turn-over frequency of nanoparticles: A case study of Fe_xC_y catalyst using reactive MD simulations

The sintering of nanostructured catalysts poses a grand challenge in understanding the complex mechanism in the experimental phenomena, as well as the structure-activity relationship. Here, we systematically investigate the structure-activity relationship of sintered Fe-based catalysts, including Fe₂C, Fe₅C₂, Fe₃C and pure Fe, in the CO activation by reactive molecular dynamics simulations. The results show that the sintering structures can promote the turn-over frequency of Fe₃C compared with its un-sintered near-size structures, which might be attributed to the formation of low-coordination-number atoms. The change of surface area shows a similar trend for Fe_xC_y and pure Fe, and its increased magnitude varies with the content of carbon in the Fe_xC_y bulk. For size effect, the Fe₂C displays the largest turn-over frequency for the 4.34 nm particle. The CO₂ formation mechanism has also been compared for different Fe_xC_y, which may provide critical theoretical insights for industrial reduction of CO₂ emission.