•The oscillations appear in the coverage-dependent activation energy model.•The bifurcation point is close to experimental barrier and theory barrier.•Adding a stochastic component to system leads to the generation of oscillation.•Fluctuation-driven oscillation appears with a maximum signal-to-noise ratio.The oscillations of N2O decomposition over Cu-ZSM-5 are investigated by considering the relationship of activation energy and coverage of copper. It is found that the bifurcation point is 146 kJ mol−1, close to the theoretical calculation barrier and the experimental apparent activation barrier. Then adding a stochastic component to activation energy leads to a broader range of parameters that support oscillation, a form of fluctuation-driven oscillation (FDO). The signal-to-noise ratio of FDO reaches a maximum at the particular noise intensity. The presence of FDO makes the stochastic model show oscillations at a more extended region than the deterministic one.

The N2O decomposition mechanism is investigated over Cu-ZSM-5 using density functional theory (DFT). Though the mechanism is extended from Fe/Co-ZSM-5, the results show that a different step may be rate-determining over Cu-ZSM-5 compared to the Fe/Co-ZSM-5 system. In the beginning, Z[Cu] as active center decomposes the first N2O and generates Z[CuO] (process 1), and the energy barrier of N2O dissociation is 35.18 kcal/mol. Then Z[CuO] could decompose the second N2O and generate Z[CuOO] (process 2), and the energy barrier of N2O dissociation is 28.07 kcal/mol. In process 2, oxygen could desorb from Z[CuOO], and the desorption energy is 39.48 kcal/mol, which is only higher 4.30 kcal/mol than 35.18 kcal/mol in the process 1. However the corresponding rate constants show approximately that the rate-limiting step is O2 desorption in process 2 and not the N2O dissociation in process 1. Next, if Z[CuOO] could not desorb O2, it could decompose the third N2O and generate Z[CuO(O2)] (process 3). In this process, the energy barrier for N2O dissociation and the O2 desorption energy from Z[CuO(O2)] are 42.10 and 63.42 kcal/mol, respectively, which are much higher than the former processes. It indicates the presence of O2 could inhibit the N2O decomposition over Cu-ZSM-5, which is in line with the kinetic experiment. The results suggest the process 1 and 2 are the main catalytic cycle in N2O decomposition. Importantly, O2 desorption from Z[CuOO] shows that the mechanism over Cu-ZSM-5 is different from that over Fe/Co-ZSM-5 system.

•A general strategy of fabricating heteroatom doped carbon materials was developed.•The fabrication procedures could be fulfilled within 5 min at room temperatures.•Major byproducts was KCl and H2O, which could be eco-friendly disposed.•N, S, or P-doped carbon materials were investigated as demonstrations.Heteroatom doped carbon materials (DCM) have gained tremendous attention due to their highly promising applications as well as low costs, therefore, time-/cost-/operation-effective fabrication of doped carbon materials holds great meanings to both scientific and practical fields. Here in this study, metal-free DCM could be fabricated rapidly (<5 min) at room-temperature, which could engage the efficient incorporation of heteroatom during the dechlorination of polyvenyldichloride (PVDC) by strong alkaline (like KOH). Cases of N, S, or P-DCM were investigated as demonstrations, which proofed our strategy being capable of effectively incorporating in-situ dehalogenated carbon sites with any available hetero-elements. Meanwhile, major byproduct, as investigated, were KCl and water, which could be eco-friendly disposed. Since the in-situ dehalogenated carbon sites are very reactive, our strategy should be not limited to the fabrication of single or two heteroelements, and it should fit the synthesis of multiple heteroelement DCM for broad interests of DCM investigations and application explorations.Figure optionsDownload full-size imageDownload high-quality image (362 K)Download as PowerPoint slide