Chemical properties of superatomic Li3O clusters from a density functional theory perspective: formation of chloride and adsorption behavior on graphynes

Superatomic clusters have received a lot of attention due to their ability to mimic the electronic configurations of individual atoms. Despite numerous studies of these clusters, their ability to mimic the chemical properties of individual atoms is still unclear. This also applies for Li3O/Li3O+ clusters which simulate the Na atom and its ion, but their capabilities to form a salt or be adsorbed on surfaces remain unexplored. In this work, a density functional theory investigation was performed to study the chemical formation and adsorption behavior of the superatomic Li3O cluster. The results show that Li3O mimics the chemical properties of the sodium element to form Li3O chloride and be adsorbed on graphdiyne and γ-graphyne with similar binding energy as the sodium adsorbate cases. Beyond the isolated cluster individuals, superatoms are demonstrated as elements from the 3D periodic table to construct compounds and attach onto solid surfaces.

Prediction of bimetal embedded in two-dimensional materials for CO2 reduction electrocatalysis with a new integrated descriptor

CO₂ reduction catalysis plays an important role in the process of converting harmful exhaust gas into useful fuels. However, the product complexity and the difficult hydrogenation in critical steps make it difficult to find a suitable catalyst for CO₂ reduction. In this work, we report homo/hetero bimetal embedded in two-dimensional materials for electrocatalysis and discovered a new descriptor. We chose β₁₂-borophene accommodating two transition metal atoms for efficient CO₂RR as a model system. We found that MnCo and VV systems are promising for CO₂ reduction with good stability and high selectivity over HER. Through least absolute shrinkage and selection operator (LASSO) regression, we discovered a new integrated descriptor containing the spin moment of the metals and the descriptor is linked with the performance of the first step of CO₂ hydrogenation. The MnCo system could catalyze a C1 process with low free energy change of the rate determining step. The VV system could also conduct the C2 process with low free energy change of the rate determining step. Bader charge analysis shows the ability of the borophene substrate to provide or hold electrons. This work demonstrates homonuclear and heteronuclear biatomic catalysts with high activity for CO₂RR.

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.