N2O + CO reaction over a single Si or P atom incorporated nitrogen-doped graphene: A comparative DFT study

Investigation of a Single Atom Iron Catalyst for the Electrocatalytic Reduction of Nitric Oxide to Hydroxylamine: A DFT Study

Hydroxylamine, as an important reducing agent, disinfectant, foaming agent, and biocide, plays a role in both human life and industrial production. However, its synthesis is confronted with challenges, such as high pollution and large consumption. Here, we propose a coordination tailoring strategy to design 47 graphene-supported single iron atom catalysts (SACs), namely, Fe@CxZy (Z = B, N, O, P, and S), for the reduction of nitric oxide to hydroxylamine. Using density functional theory calculations, we demonstrated the great impact of the coordination environment on the stability, catalytic selectivity, and activity of the Fe site. We identified that the experimentally available Fe@N4 possesses an ultralow theoretical limiting potential of -0.32 V compared to that of other catalysts. A comprehensive investigation of the electronic properties elucidates the underlying active origin and reaction mechanism of the nitric oxide reduction reaction to hydroxylamine on Fe@N4. These results not only explain the catalytic origin of synthesized SACs for the NH2OH production but also offer theoretical guidance for further optimizing high-performance catalysts.

Progress and challenges in nitrous oxide decomposition and valorization

Nitrous oxide (N2O) decomposition is increasingly acknowledged as a viable strategy for mitigating greenhouse gas emissions and addressing ozone depletion, aligning significantly with the UN's sustainable development goals (SDGs) and carbon neutrality objectives. To enhance efficiency in treatment and explore potential valorization, recent developments have introduced novel N2O reduction catalysts and pathways. Despite these advancements, a comprehensive and comparative review is absent. In this review, we undertake a thorough evaluation of N2O treatment technologies from a holistic perspective. First, we summarize and update the recent progress in thermal decomposition, direct catalytic decomposition (deN2O), and selective catalytic reduction of N2O. The scope extends to the catalytic activity of emerging catalysts, including nanostructured materials and single-atom catalysts. Furthermore, we present a detailed account of the mechanisms and applications of room-temperature techniques characterized by low energy consumption and sustainable merits, including photocatalytic and electrocatalytic N2O reduction. This article also underscores the extensive and effective utilization of N2O resources in chemical synthesis scenarios, providing potential avenues for future resource reuse. This review provides an accessible theoretical foundation and a panoramic vision for practical N2O emission controls.

Exploring Si-centered phthalocyanine as a single atom catalyst for N2O reduction: a DFT study

To remove the greenhouse gas N2O from the environment, recently, researchers have taken great interest in single-atom catalysts (SACs). In this study, we investigated various reaction pathways and barrier energies for the N2O reduction process onto Si-coordinated phthalocyanine (Si@PthC) employing density functional theory. The outcomes validate that Si decoration in PthC is energetically stable while the corresponding electronic properties show that the Si atom acts as the reactive site for catalytic activity. The N2O molecule exhibits spontaneous dissociation over the catalyst surface from the O-end with -4.01 eV dissociation energy. Meanwhile, N2O dissociation via the N-end involves chemisorption onto the Si@PthC surface with an adsorption energy (Ead) of -1.16 eV, and the dissociation needs an energy barrier of 0.51 eV. The bond distances and negative adsorption energies (-1.11 and -2.40 eV) evince that CO and O2 species chemisorbed onto the Si@PthC surface. However, these energies are smaller than the N2O dissociation energy, which demonstrates that the presence of CO and O2 molecules cannot interrupt the N2O reduction process. Additionally, the CO + O* → CO2 reaction was executed for catalyst recovery, and the reaction proceeds very quickly on the Si@PthC catalyst, with a very small energy barrier (0.37 eV), indicating the excellent catalytic reactivity of the studied catalyst. These results propose that the designed catalyst can be valuable in the progress of novel noble metal-free catalysts for the elimination of harmful N2O from the environment.

B, N, and Si Single-Doping at Graphene/Cu (111) Interfaces to Adjust Electrical Properties

We investigated the structural and electrical properties of B-, N-, and Si-doped graphene/Cu interfaces through density functional theory. B-doping enhances the interfacial bonding strength, N-doping has little effect on the interfacial interaction, and Si-Cu bonds are formed in the Si-doped interface. The energy bands and density of states show that the pristine and N-doped graphene/Cu interfaces exhibit n-type semiconductor properties, and the B-doped and Si-doped graphene/Cu interfaces exhibit p-type semiconductor properties. According to the Mulliken charge populations and charge properties, B-doping and Si-doping improve the ability of charge transport and orbital hybridization at the interface. Graphene doping has a significant effect on the interfacial work function. This result will help to understand the contact between B-, N-, and Si-doped graphene and Cu surfaces and to predict the performance of related micro-nano electronic devices.