The formation and evolution of carbonate species in CO oxidation over mono-dispersed Fe on graphene

Fe is not only the most abundant metal on the planet but is also the key component of many enzymes in organisms that are capable of catalyzing many chemical conversions. Mono-dispersed Fe atoms on carbonaceous materials are single atom catalysts (SACs) that function like enzymes. To take advantage of the outstanding catalytic performance of Fe-based SACs, we extended a CO oxidation reaction network over mono-dispersed Fe atoms on graphene (FeGR) by first-principles based calculations. FeGR-catalyzed CO oxidation is initiated with a revised Langmuir-Hinshelwood pathway through a CO-assisted scission of the O-O bond in peroxide species (OCOO). We showed that carbonate species (CO3), which were previously generally considered as a persistent species blocking reaction sites, may form from CO2 and negatively charged O species. This pathway competes with desorption of CO2 and reduction of the Fe center with gaseous CO, and it is exothermic and inevitable, especially at low temperatures and with high CO2 content. Although direct dissociation of CO3 is demanding on FeGR, further adsorption of CO on Fe in CO3 is plausible and takes place spontaneously. We then showed that adsorbed CO may react with CO3, forming a cyclic-carbonate-like species that dissociates easily to CO2. These findings highlight the reaction condition-dependent formation and evolution of CO3 as well as its contribution to CO conversion, and it may extend the understanding of the performance of SACs in low temperature CO oxidation.

Support effects on adsorption and catalytic activation of O2 in single atom iron catalysts with graphene-based substrates

The adsorption and catalytic activation of O₂ on single atom iron catalysts with graphene-based substrates were investigated systematically by density functional theory calculation.

Interfacial interaction of Ag nanoparticles with graphene oxide supports for improving NH3 and NO adsorption: a first-principles study

The interfacial interaction of Ag nanoparticles with graphene oxide supports improves NH₃ and NO adsorption.

Unique Reactivity of Transition Metal Atoms Embedded in Graphene to CO, NO, O₂ and O Adsorption: A First-Principles Investigation

Taking the adsorption of CO, NO, O₂ and O as probes, we investigated the electronic structure of transition metal atoms (TM, TM = Fe, Co, Ni, Cu and Zn) embedded in graphene by first-principles-based calculations. We showed that these TM atoms can be effectively stabilized on monovacancy defects on graphene by forming plausible interactions with the C atoms associated with dangling bonds. These interactions not only give rise to high energy barriers for the diffusion and aggregation of the embedded TM atoms to withstand the interference of reaction environments, but also shift the energy levels of TM-d states and regulate the reactivity of the embedded TM atoms. The adsorption of CO, NO, O₂ and O correlates well with the weight averaged energy level of TM-d states, showing the crucial role of interfacial TM-C interactions on manipulating the reactivity of embedded TM atoms. These findings pave the way for the developments of effective monodispersed atomic TM composites with high stability and desired performance for gas sensing and catalytic applications.

High stability and superior catalytic reactivity of nitrogen-doped graphene supporting Pt nanoparticles as a catalyst for the oxygen reduction reaction: a density functional theory study

We investigated the structural and electronic properties of Pt₁₃ nanoparticles on various nitrogen (N)-doped graphene and their interaction with O by density functional theory (DFT) calculations.

Copper atoms embedded in hexagonal boron nitride as potential catalysts for CO oxidation: a first-principles investigation

The embedment in h-BN makes Cu states compatible to reactant states and facilitates the charge transfer for reaction to proceed.

CO oxidation catalyzed by Pt-embedded graphene: a first-principles investigation

The combination of reactive Pt atoms and defects over graphene makes Pt-embedded graphene a superior catalyst for low-temperature CO oxidation.

Tuning the reactivity of Ru nanoparticles by defect engineering of the reduced graphene oxide support

The local defect structures on rGO determine the stability, the electronic structure and the reactivity of the Ru/rGO composites.