C₁ Chemistry on Metal Carbide Nanoparticles: Boosting the Conversion of CO₂ and CH₄

Abstract

The studies described in this Perspective show that transition metal carbide (TMC) nanoparticles can be very useful for the activation of three molecules located at the heart of C 1 chemistry: H 2 , CH 4 , and CO 2 . They also can play a major role in the trapping and conversion of two major greenhouse gases. A combination of experiment and theory has shed light on the physical and chemical properties of these systems, which can be very different from those of bulk carbides. Molecular clusters of these compounds, which can be inserted inside the cages of zeolites or carbon nanotubes, have unsaturated metal and carbon atoms that frequently work in a cooperative way when dealing with hard-to-activate molecules, such as CH 4 and CO 2 . These molecular clusters can evolve into nanoparticles of small to medium size (<15 nm) that have unique carbon/metal ratios and structures not seen in the bulk metal carbides. Even when their structures are cuts from bulk lattices, the TMC nanoparticles have corner or edge atoms that are active for the cleavage and conversion of C−H and C−O bonds. Here, we cover experimental and theoretical studies with well-defined metal carbide nanoparticles prepared by different methods, free and supported on diverse substrates. The Perspective ends with a discussion of current challenges and potential applications.

Consecutive Reduction of Five Carbon Dioxide Molecules by Gas-Phase Niobium Carbide Cluster Anions Nb3C4–: Unusual Mechanism for Enhanced Reactivity by the Carbon Ligands

“…In comparison to pure metals, TMCs are considered as superior potential industrial catalysts due to their higher selectivity, durability, and stability. , It is known that the incorporation of carbon changes the electronic properties and crystal structures of TMCs, while the influence of the number of carbon atoms in active sites on catalytic performance is crucial but not yet being well understood . A few reports have shown that the carbon/metal ratio has a significant impact on the reactivity of niobium carbide (Nb x C y ), while the majority of reports focus on molybdenum carbide (Mo x C y ) .…”

Transition Metal Carbides: Emerging CO2 Hydrogenation Catalysts, from Recent Advance to Future Exploration

“…Firstly, nano-TMCs are able to expose active sites more efficiently in the catalytic reaction, and secondly, nano-TMCs are cut from bulk TMCs and have unique metal/C ratios and structures different from bulk TMCs, as well as corner or edge atoms that are active for C-O bond breaking and activation. [85] In view of this, Zhang et al successfully obtained 2D 𝛽-Mo 2 C nanorods with abundantly stacked nanopores by carburizing the hydrothermally synthesized MoO 3 nanorods as precursors (Figure 12a,b). [86] The specific surface area [86] Copyright 2020, Elsevier.…”

Tailoring Titanium Carbide Clusters for New Materials: from Met-Cars to Carbon-Doped Superatoms

“…Another interesting research topic of TMCs pertains to the finding of Ti 8 C 12 as a class of metallocarbohedrenes (Met-Cars) − with a common stoichiometry of M 8 C 12 (M = Ti, V, Cr, Zr, Hf, Nb, Mo, etc. ), − which was repeatedly observed during dehydrogenation reactions of hydrocarbons with metal atoms/ions and small clusters in the plasma atmosphere. − Met-Cars are attractive in the application potentials for hydrogen storage and catalytic reactions including the novel C1 chemistry. − Recently, by downstream reactions of pure Co n – and Ni n – clusters with acetylene, stable M 12 C 12 – (M = Fe, Co, Ni) clusters have also been identified. , However, it is still unclear if super magic TMCs are limited to M 8 C 12 and M 12 C 12 . Further insights into the chemical reactivity, the bonding nature, and the structure–property relationship still need to be further explored. , Also, it is anticipated that stable TMCs can be tailored with tunable structures and properties at atomic precision − as well as novel quantum size effects and superatomic features. − …”