First-Principles Microkinetic Modeling Unravelling the Performance of Edge-Decorated Nanocarbons for Hydrogen Production from Methane

Abstract

The doping of graphitic and nanocarbon structures with nonmetal atoms allows for the tuning of surface electronic properties and the generation of new active sites, which can then be exploited for several catalytic applications. In this work, we investigate the direct conversion of methane into H2 and C2H x over Klein-type zigzag graphene edges doped with nitrogen, boron, phosphorus and silicon. We combine Density Functional Theory (DFT) and microkinetic modeling to systematically investigate the reaction network and determine the most efficient edge decoration. Among the four edge-decorated nanocarbons (EDNCs) investigated, N-EDNC presented an outstanding performance for H2 production at temperatures over 900 K, followed by P-EDNC, Si-EDNC and B-EDNC. The DFT and microkinetic analysis of the enhanced desorption rate of atomic hydrogen reveal the presence of an Eley–Rideal mechanism, in which P-EDNC showed higher activity for H2 production in this scenario. Coke deposition resistance in the temperature range between 900 and 1500 K was evaluated, and we compared the selectivity toward H2 and C2H4 production. The N-EDNC and P-EDNC active sites showed strong resistance to carbon poisoning, whereas Si-EDNC showed higher propensity to regenerate its active sites at temperatures over 1100 K. This work shows that decorated EDNCs are promising metal-free catalysts for methane conversion into H2 and short-length alkenes.

Theoretical insights into the methane catalytic decomposition on graphene nanoribbons edges

“…Our results were compared with literature reports, aiming to provide a full assessment of GNRs as catalysts for methane dissociation and hydrogen evolution and to provide insights for future works on the catalyst engineering of graphene-based materials. In our previous work ( Xavier et al, 2023 ), we found that decoration of non-metallic heteroatoms on the nanocarbons edges can dramatically increase the regeneration of carbonaceous catalysts, however, the performance for methane decomposition reported here on the pure carbon edges was found to be superior. We expect that the insights provided here aid the engineering of carbon-based catalysts for the catalytic methane decomposition.…”

Bridging Together Theoretical and Experimental Perspectives in Single‐Atom Alloys for Electrochemical Ammonia Production

“…At the same time, DFT calculations have shortcomings, such as difficulty in accurately predicting weak dispersion forces or high computational demand for larger systems. [123,124] Nevertheless, the combination of DFT and microkinetic modeling is a powerful tool for revealing the working principles of SAAs catalysts and guiding the design of advanced catalysts for sustainable NH 3 production. As the field advances, improvements in computational methods and algorithms for model validation, along with more sophisticated experimental techniques, will further enhance the value of this integrated approach.…”

Li‐Mediated Electrochemical Nitrogen Fixation: Key Advances and Future Perspectives

“…By quantifying the rates at which these reactions occur, kinetic models provide valuable insights into the fundamental steps involved in complex electrochemical processes. [ 45 ] Essentially, kinetic modeling for Li‐mediated NRR involves creating mathematical equations that represent the mechanistic steps of the nitrogen fixation process. These steps may include nitrogen and lithium ions being adsorbed onto the catalyst surface, the transformation of these adsorbed species into reaction intermediates, and their subsequent conversion into ammonia or other products.…”