Single Metal Atoms on Oxide Surfaces: Assessing the Chemical Bond through 17O Electron Paramagnetic Resonance

Metal-support interactions in metal oxide-supported atomic, cluster, and nanoparticle catalysis

Supported metal catalysts are essential to a plethora of processes in the chemical industry. The overall performance of these catalysts depends strongly on the interaction of adsorbates at the atomic level, which can be manipulated and controlled by the different constituents of the active material (i.e., support and active metal). The description of catalyst activity and the relationship between active constituent and the support, or metal-support interactions (MSI), in heterogeneous (thermo)catalysts is a complex phenomenon with multivariate (dependent and independent) contributions that are difficult to disentangle, both experimentally and theoretically. So-called "strong metal-support interactions" have been reported for several decades and summarized in excellent review articles. However, in recent years, there has been a proliferation of new findings related to atomically dispersed metal sites, metal oxide defects, and, for example, the generation and evolution of MSI under reaction conditions, which has led to the designation of (sub)classifications of MSI deserving to be critically and systematically evaluated. These include dynamic restructuring under alternating redox and reaction conditions, adsorbate-induced MSI, and evidence of strong interactions in oxide-supported metal oxide catalysts. Here, we review recent literature on MSI in oxide-supported metal particles to provide an up-to-date understanding of the underlying physicochemical principles that dominate the observed effects in supported metal atomic, cluster, and nanoparticle catalysts. Critical evaluation of different subclassifications of MSI is provided, along with discussions on the formation mechanisms, theoretical and characterization advances, and tuning strategies to manipulate catalytic reaction performance. We also provide a perspective on the future of the field, and we discuss the analysis of different MSI effects on catalysis quantitatively.

Spin-Lattice Relaxation and Spin-Phonon Coupling of ns1 Metal Ions at the Surface

To use transition metal ions for spin-based applications, it is essential to understand fundamental contributions to electron spin relaxation in different ligand environments. For example, to serve as building blocks for a device, transition metal ion-based molecular qubits must be organized on surfaces and preserve long electron spin relaxation times, up to room temperature. Here we propose monovalent group 12 ions (Zn+ and Cd+) as potential electronic metal qubits with an ns1 ground state. The relaxation properties of Zn+ and Cd+, stabilized at the interface of porous aluminosilicates, are investigated and benchmarked against vanadium (3d1) and copper (3d9) ions. The spin-phonon coupling has been evaluated through DFT modeling and found to be negligible for the ns1 states, explaining the long coherence time, up to 2 μs, at room temperature. These so far unexplored metal qubits may represent viable candidates for room temperature quantum operations and sensing.

Computational innovation of in situ metallic elements with zirconia as a novel possible carrier for chemotherapeutic medication

CONTEXT

Electronic sustainable behavior on the material surface and in situ metal configuration were accompted with some metal atoms like Li, Na, and K elements. Metal-doped ZrO2 crystal exported modified characteristics related to electronic conduction and exhibited some dynamic modification around the surface of the metal oxide. Computational perturbations were considered to discuss the modification behavior in addition to the studied Li, Na, and K metals. Optimization of the three doping systems was achieved followed by generating DOS and electronic band structure maps. A dynamic simulation was performed with temperature over 2000 k: the presence of the metal on the surface and prediction of its ZrO2 inclusion leading to access adsorption behavior, besides generating predictive designed models described the adsorption affinity on the solid-state surface. It cannot be neglected the importance of various metals as a main role in chemotherapy. Molecular docking investigation was considered to predict the binding behavior of the studied metal ZrO2 carrier system as an anticancer agent. Also, docking affinity was helpful in comparing the active sites binding for the studied metals, resulting in a notable binding affinity for both Li- and Na-zirconia incorporation.

METHODS

The program PWSCF, which is a component of the quantum ESPRESSO suite for quantum simulation of materials, was used to construct geometric systems. The generalized gradient approximation in the Perdew-Burke-Ernzerhof (GGA/PBE) function with D3 correction (Becke-Jonson damping) was applied to the exchange-correlation energy. As the last step in the DFT postulation and design, adsorption locator annealing was carried out on the convergent models using the Materials Studio simulation package. The main roles played by metal atoms are in protein binding and the suppression of bio-active regions. For the docking process, the protein was produced using AutoDock 4.2 and Discovery Studio software in accordance with the usual methodology. Chimera and Discovery Studio were used to examine the docking data that was processed after generating specific grid box dimensions for 7BTN.

Short-Range Electronic Interactions between Vanadium and Molybdenum in Bimetallic SAPO-5 Catalysts Revealed by Hyperfine Spectroscopy

Engineering two cooperative sites into a catalyst implies the onset of synergistic effects related to the existence of short-range electronic interactions between two metal components. However, these interactions and the relative structure-property correlations are often difficult to obtain. Here we show that hyperfine spectroscopy has the potential to reveal the presence of V⁴⁺-O-Mo⁶⁺ linkages assessing the degree of spin density transfer from paramagnetic V⁴⁺ species to proximal oxo-bridged Mo⁶⁺ metal ions. The dimer species were prepared by adsorption of Mo(CO)₆ in the pores of SAPO-5, followed by thermal decomposition and oxidation and subsequent grafting of anhydrous VCl₄(g) followed by hydrolysis and dehydration. The metal species react with SAPO protons during the exchange process and generate new Lewis acid sites, which act as redox centers. X- and Q-band EPR and HYSCORE experiments have been employed to monitor the local environment of V⁴⁺ species obtaining direct evidence for spin delocalization over ²⁷Al, ³¹P, ⁹⁵Mo, and ⁹⁷Mo nuclei, demonstrating the presence of bimetallic V-O-Mo well-defined structures.