Hydrogen adsorption and dissociation on Pd19 cluster using density functional calculations

Self-enhanced Electrochemiluminescence Luminophore Based on Pd Nanocluster-Anchored Metal Organic Frameworks via Ion Annihilation for Sensitive Cell Assay of Human Lung Cancer

Electrochemiluminescence (ECL) has attracted significant interest in the analysis of cancer cells, where the ruthenium(II)-based emitter demonstrates urgency and feasibility to improve the ECL efficiency. In this work, the self-enhanced ECL luminophore was prepared by covalent anchoring of Pd nanoclusters on aminated metal organic frameworks (Pd NCs@MOFs), followed by linkage with bis(2,2'-bipyridine)-5-amino-1,10-phenanthroline ruthenium(II) (RuP). The resultant luminophore showed 214-fold self-magnification in the ECL efficiency over RuP alone, combined by promoting the interfacial photoelectron transfer. The enhanced mechanism through ion annihilation was critically proved by controlled experiments and density functional theory (DFT) calculations. Based on the above, a "signal off" ECL biosensor was built by assembly of tyrosine kinase 7 (PTK-7) aptamer (Apt) on the established sensing platform for analysis of human lung cancer cells (A549). The built sensor showed a lower detection limit of 8 cells mL-1, achieving the single-cell detection. This work reported a self-enhanced strategy for synthesis of advanced ECL emitters, combined by exploring the ECL biosensing devices in the single-cell analysis of cancers.

A quantum chemical study of hydrogen adsorption on carbon-supported palladium clusters

A key step for achieving better insight into catalytic hydrogenation reactions is to understand in detail the process of hydrogen adsorption on the catalyst. The present article focuses on hydrogen adsorption on carbon-supported palladium clusters, which are nowadays one of the most common catalysts in industrial applications. Density functional theory is applied to study Pd₆ and Pd₂₁ clusters to reveal the influence of the carbon support material on the properties of the catalyst as well as on the mechanisms and energetics of the hydrogen adsorption. In general, a stepwise hydrogen adsorption process is observed consisting of molecular adsorption followed by dissociative chemisorption. The carbon support material does not noticeably affect the reaction mechanisms, but has a large influence on energy barriers and preferential adsorption sites. Our comparison of Pd₆ and Pd₂₁ systems reveals that small clusters, such as Pd₆, are able to model some but not all important properties of palladium nanoparticles and, therefore, it is essential to also study larger cluster sizes.

The DFT study of Si-doped Pd6Si clusters for selective acetylene hydrogenation reaction

Recently, it has been demonstrated that Si-modified Pd catalyst shows excellent selectivity and produces less amount of green oil than the unmodified Pd catalyst in acetylene hydrogenation. Motivated by experiment works, we systematically investigate the mechanism of the selective acetylene hydrogenation reactions over pristine Pd₇ and Si-doped Pd₆Si clusters by using the B3LYP method of density functional theory. Our result confirms that both the Pd₇ and Pd₆Si clusters catalytic hydrogenation of acetylene are mainly through two different pathways and a series of intermediates can be transformed into each other by proton transfer, which link the two independent reaction paths into a network path. Among these reaction paths, activation energies for all steps of the reaction have been calculated and it is illustrated that the lowest activation energy in the process of ethylene generation are 22.59 kcal/mol for Pd₇ cluster and 11.25 kcal/mol for Pd₆Si cluster, which indicate that the Pd₆Si cluster perform better than Pd₇ cluster in the aspect of catalytic activity. Besides, it has also been demonstrated that the selectivity for the reaction is enhanced after doping a Si atom.