Polymeric tungsten carbide nanoclusters as potential non-noble metal catalysts for CO oxidation

A DNA Fishhook Electrochemical Sensor Based on a Potassium Ferricyanide-Mediated Dual-Signal-Correlation Enhanced Electrocatalysis Reaction for a Simultaneous and Correlation Assay of Multiple Biomarkers

Simultaneous detection and correlation analysis of multiple biomarkers in a single run are crucial to improving the detection specificity and indicate disease progression, but they remain a challenge. Herein, we propose a DNA fishhook electrochemical sensor based on the potassium ferricyanide-mediated dual-signal correlation enhanced electrocatalysis reaction (DEER). The designed T-shaped DNA fishhook scaffold has two "hooks" to recruit their respective "fish" (targets) with the help of the "fishing bait" (signal probes, Sp), resulting in the different targets and Sp being specifically captured by the DNA fishhook to the electrode interface, respectively. The proposed DEER not only effectively improves the detection sensitivity without introducing nucleic acid amplification but also can reflect the logical correlation between the targets. As proof of principle, the DNA fishhook sensor was successfully applied in the simultaneous detection of two related gene sequences of SARS-CoV-2 and the active-state assay of the PI3K/AKT signaling pathway. In general, our DNA fishhook sensor provides a meaningful potential tool for the sensitive simultaneous detection and correlation analysis of multiple targets.

The catalytic performance of (ZrO)n (n = 1-4, 12) clusters for Suzuki-Miyaura cross-coupling: a DFT study

Superatoms are special clusters with similar physicochemical properties to individual atoms in the periodic table, which open up new avenues for exploring inexpensive catalysts. Given that the ZrO superatom possesses the same number of valence electrons as a Pd atom, the mechanisms of the Suzuki-Miyaura reaction catalyzed by (ZrO)n (n = 1-4) clusters have been investigated and compared with the corresponding Pdn (n = 1-4) species to explore superatom-based catalysts for the formation of C-C bonds via a density functional theory (DFT) study. It was interesting to find that the catalytic activities of (ZrO)n (n = 1-4) towards the Suzuki-Miyaura reaction gradually improved as the cluster size increased. Therefore, to obtain more efficient catalysts, the catalytic activity of a well-designed (ZrO)12 nanocage towards this cross-coupling reaction has been further evaluated. Gratifyingly, this nanocage shows excellent catalytic performance for the considered coupling reaction, which is even comparable to that of the commonly used Pd catalyst and outperforms the corresponding Pd12 cluster. We hope this study can not only provide valuable guidance for the development of noble metal-like catalysts for C-C bond formation, but also expand the application of superatoms in the catalysis of organic reactions.

Suzuki-Miyaura Cross-Coupling Reaction Catalyzed by Al12M (M = Be, Al, C, and P) Superatoms with Different Numbers of Valence Electrons

The exploration of low-cost, efficient, environmentally safe, and selective catalysts for the activation of carbon-halogen bonds has become an important and challenging topic in modern chemistry. With the help of density functional theory (DFT), it is found that phenyl bromide (PhBr) can be efficiently chemisorbed by the Al12M (M = Be, Al, C, and P) superatoms via forming highly polarized Al-Br covalent bonds, where the C-Br bonds of PhBr can be effectively activated through the electron transfer from Al12M. The different electronic structures of these four Al12M superatoms pose a substantial effect on their performances on the activation of PhBr and the catalytic mechanisms of the Suzuki-Miyaura (SM) reaction. Among them, the alkali-metal-like superatom Al12P exhibits the best performance for the activation of PhBr. In particular, Al13 and Al12P with open-shell electronic structures exhibit catalytic performances comparable to those of previously reported catalysts for this coupling reaction. Hence, it is highly expected that Al13 and Al12P could be used as novel superatom catalysts for C-C coupling reactions and, therefore, open up new possibilities to use nonprecious superatoms in catalyzing the activation and transformation of carbon-halogen bonds.

Theoretical prediction of superatom WSi12-based catalysts for CO oxidation by N2O

Catalytic conversion of N2O and CO into nonharmful gases is of great significance to reduce their adverse impact on the environment. The potential of the WSi12 superatom to serve as a new cluster catalyst for CO oxidation by N2O is examined for the first time. It is found that WSi12 prefers to adsorb the N2O molecule rather than the CO molecule, and the charge transfer from WSi12 to N2O results in the full activation of N2O into a physically absorbed N2 molecule and an activated oxygen atom that is attached to an edge of the hexagonal prism structure of WSi12. After the release of N2, the remaining oxygen atom can oxidize one CO molecule via overcoming a rate-limiting barrier of 28.19 kcal mol-1. By replacing the central W atom with Cr and Mo, the resulting MSi12 (M = Cr and Mo) superatoms exhibit catalytic performance for CO oxidation comparable to the parent WSi12. In particular, the catalytic ability of WSi12 for CO oxidation is well maintained when it is extended into tube-like WnSi6(n+1) (n = 2, 4, and 6) clusters with energy barriers of 25.63-29.50 kcal mol-1. Moreover, all these studied MSi12 (M = Cr, Mo, and W) and WnSi6(n+1) (n = 2, 4, and 6) species have high structural stability and can absorb sunlight to drive the catalytic process. This study not only opens a new door for the atomically precise design of new silicon-based nanoscale catalysts for various chemical reactions but also provides useful atomic-scale insights into the size effect of such catalysts in heterogeneous catalysis.

New Insights into Adsorption Properties of the Tubular Au26 from AIMD Simulations and Electronic Interactions

Recently, we revealed the electronic nature of the tubular Au₂₆ based on spherical aromaticity. The peculiar structure of the Au₂₆ could be an ideal catalyst model for studying the adsorptions of the Au nanotubes. However, through Google Scholar, we found that no one has reported connections between the structure and reactivity properties of Au₂₆. Here, three kinds of molecules are selected to study the fundamental adsorption behaviors that occur on the surface of Au₂₆. When one CO molecule is adsorbed on the Au₂₆, the σ-hole adsorption structure is quickly identified as belonging to a ground state energy, and it still maintains integrity at a temperature of 500 K, where σ donations and π-back donations take place; however, two CO molecules make the structure of Au₂₆ appear with distortions or collapse. When one H₂ is adsorbed on the Au₂₆, the H-H bond length is slightly elongated due to charge transfers to the anti-bonding σ* orbital of H₂. The Au₂₆-H₂ can maintain integrity within 100 fs at 300 K and the H₂ molecule starts moving away from the Au₂₆ after 200 fs. Moreover, the Au₂₆ can act as a Lewis base to stabilize the electron-deficient BH₃ molecule, and frontier molecular orbitals overlap between the Au₂₆ and BH₃.