Charge-Sensitive Cluster−π Interactions Cause Altered Reactivity of Aln±,0 Clusters with Benzene: Enhanced Stability of Al13+Bz

Hydrogen Evolution Reactions of Hydrocarbons and Hydroborons Promoted by Superatomic Nbn- Clusters

Hydrogen evolution reactions (HER) are crucial for producing renewable and ecological hydrogen energy. Here we report the finding that ethyl acetylene (C2H2), borane (B2H6), and benzene (C6H6) undergo drastic dehydrogenation reactions upon interaction with niobium cluster anions (Nbn-). This finding was enabled by our very sensitive and specialized mass spectrometer, which monitored the cluster ions and the resulting metal carbide and boride products in real time. Through mass spectrometry experiments and density functional theory computations, we delved into the varying reactivities of these common gas molecules with small Nbn- clusters and elucidated the underlying reaction mechanisms. These findings shed light on the HER mechanisms of hydrocarbon and hydroboron molecules on superatomic Nbn- clusters, furnishing valuable insights pertinent to the advancement of hydrogen energy resources.

Design of High-Performance Inorganic-Organic Hybrid Nonlinear Optical Materials Using Superhalogen Al13 and Dianhydrides

Novel inorganic-organic hybrid complexes Al13-X (X represents the dianhydrides PMDA, NTCDA, and PTCDA) are theoretically designed and studied using density functional theory (DFT) and time-dependent DFT. These conjugated dianhydrides containing four acceptor carbonyl groups are commonly used as electron acceptor materials. These compounds possess large binding energies, reflecting the sufficient binding of Al13 to the dianhydride molecule. The binding nature of the complexes is of charge transfer type, i.e., electrons are transferred from the aluminum cluster to the dianhydride. All of the aimed complexes have large mean polarizability (α0) and first hyperpolarizability (β0). The β0 values are explained on the basis of electronic transitions in crucial excited states using the TD-DFT method. Additionally, the hole-electron distribution was analyzed, revealing the nature of electronic excitation. Absorption spectra analysis shows that these complexes have an excellent infrared (IR) transparent region (1000-5000 nm). Therefore, these inorganic-organic hybrid complexes with high stability can be considered as potential candidates for new IR nonlinear optical molecules.

On the nature of Con±/0 clusters reacting with water and oxygen

Bulk cobalt does not react with water at room temperature, but cobalt nanometals could yield corrosion at ambient conditions. Insights into the cobalt cluster reactions with water and oxygen enable us to better understand the interface reactivity of such nanometals. Here we report a comprehensive study on the gas-phase reactions of Con±/0 clusters with water and oxygen. All these Con±/0 clusters were found to react with oxygen, but only anionic cobalt clusters give rise to water dissociation whereas the cationic and neutral ones are limited to water adsorption. We elucidate the influences of charge states, bonding modes and dehydrogenation mechanism of water on typical cobalt clusters. It is unveiled that the additional electron of anionic Con- clusters is not beneficial to H2O adsorption, but allows for thermodynamics- and kinetics-favourable H atom transfer and dehydrogenation reactions. Apart from the charge effect, size effect and spin effect play a subtle role in the reaction process. The synergy of multiple metal sites in Con- clusters reduces the energy barrier of the rate-limiting step enabling hydrogen release. This finding of water dissociation on cobalt clusters put forward new connotations on the activity series of metals, providing new insights into the corrosion mechanism of cobalt nanometals.

Assessing the Performance of Al12N12 and Al12P12 Nanostructured Materials for Alkali Metal Ion (Li, Na, K) Batteries

This study focused on the potential of aluminum nitride (Al₁₂N₁₂) and aluminum phosphide (Al₁₂P₁₂) nanomaterials as anode electrodes of lithium-ion (Li-ion), sodium-ion (Na-ion), and potassium-ion (K-ion) batteries as investigated via density functional theory (DFT) calculations at PBE0-D3, M062X-D3, and DSDPBEP86 as the reference method. The results show that the Li-ion battery has a higher cell voltage with a binding energy of -1.210 eV and higher reduction potential of -6.791 kcal/mol compared to the sodium and potassium ion batteries with binding energies of -0.749 and -0.935 eV and reduction potentials of -6.414 and -6.513 kcal/mol, respectively, using Al₁₂N₁₂ material. However, in Al₁₂P₁₂, increases in the binding energy and reduction potential were observed in the K-ion battery with values -1.485 eV and -7.535 kcal/mol higher than the Li and Na ion batteries with binding energy and reduction potential -1.483, -1.311 eV and -7.071, -7.184 eV, respectively. Finally, Al₁₂N₁₂ and Al₁₂P₁₂ were both proposed as novel anode electrodes in Li-ion and K-ion batteries with the highest performances.

Growth mechanism, electronic properties and spectra of aluminum clusters

Density functional theory (DFT) and particle swarm optimization (PSO) have been applied to study the growth behavior, electronic properties and spectra of neutral, anionic and cationic aluminum clusters with 3-20 atoms. Many isomers have been obtained through a comprehensive structural search. The results indicate that the ground state structures of neutral and anionic aluminum clusters follow an identical periodic growth law. When the number of atoms is 6-11 and 13-18, Al atoms in these clusters grow around an octahedral cluster nucleus and an icosahedral cluster nucleus, respectively. For Al_n⁺ (n ≤ 14 and n ≠ 7) clusters, the most stable structure is different from that of Al_n or Al_n^-clusters. When n > 14, the ground state structure of Al_n⁺ clusters is similar to that of Al_n or Al_n^-clusters. The electronic properties of aluminum clusters have been analyzed by the averaged binding energy, second-order difference of energy, energy gap and dissociation energy. It is found that the Al₇⁺ and Al₁₃^- clusters have very high stability and a large energy gap and can be regarded as two superatoms. The aluminum cluster with 18 or 40 valence electrons are the least likely to lose an electron. The dissociation behavior of Al_n⁺ clusters caused by collision is reasonably explained by means of the dissociation energy. The optical absorption spectra of neutral aluminum clusters have been simulated by using the time-dependent density functional theory. The ground states of anionic aluminum clusters have been determined by comparing theoretical photoelectron spectra (PES) with experimental findings. Infrared and Raman spectra of cationic aluminum clusters have been forecasted and can assist in identifying the most stable structure in future experiments.

Remarkable static and dynamic nonlinear optical responses of Al13-TCNQ/F4-TCNQ complexes: a quantum chemical study

Al13-TCNQ/F4-TCNQ complexes, which exhibit excellent stability and first hyperpolarizabilities, can be considered as candidates for UV and IR NLO materials.

Cyclotrimerization of Acetylene on Clusters Con+/Fen+/Nin+(n = 1-16)

Cyclotrimerization of acetylene to benzene has attracted significant interest, but the role of geometric and electronic effects on catalytic chemistry remains unclear. To fully elucidate the mechanism of catalytic acetylene-to-benzene conversion, we have performed a gas-phase reaction study of the Fe_n⁺, Co_n⁺, and Ni_n⁺ (n = 1-16) clusters with acetylene utilizing a customized mass spectrometer. It is found that their reactions with acetylene are initiated by C₂H₂ molecular adsorption and allow for dominant dehydrogenation with the relatively low partial pressure of the acetylene gas. However, at high acetylene concentrations, the cyclotrimerization in M_n⁺ + 3C₂H₂ (M = Fe, Co, Ni) becomes the dominant reaction channel. We demonstrate theoretically the favorable thermodynamics and reaction dynamics leading to the formation of the M⁺(C₆H₆) products. The results are discussed in terms of a cluster-catalyzed multimolecule synergistic effect and the cation-π interactions.

Probing Cluster-π Interactions between Cun- and C2H2/C2H4 for Gas Separation

Copper-related materials are used for separation of ethylene and acetylene gases in chemistry; however, the precise mechanism regarding selectivity is elusive to be fully understood. Here, we have conducted a joint experimental and theoretical study of the Cu_n^- (n = 7-30) clusters in reacting with C₂H₄ and C₂H₂. It is found that all of the Cu_n^- clusters readily react with C₂H₂, giving rise to C₂H₂-addition products; however, Cu₁₈^- and Cu₁₉^- do not react with C₂H₄. We illustrate the superatomic stability of Cu₁₈^- and advocate its availability to separate C₂H₄ from C₂H₂. Further, we demonstrate the atomically precise mechanism regarding selectivity by fully unveiling the size-dependent cluster-π interactions.