Electronic Charge Transfer Properties Research Articles

Causal Paths Allowing Simultaneous Control of Multiple Nanoparticle Properties Using Multi‐Target Bayesian Inference

AbstractMachine learning can extract complex structure/property relationships but is often insufficient to explain how to control or tune the properties of materials, particularly when they are multi‐functional. This study demonstrates the value of combining multi‐target regression and multi‐target causal graphs to address the need to simultaneously control multiple properties of nanomaterials, and the need to translate these relationships into actionable insights. Using nanodiamonds as an exemplar, recursive feature elimination is first used to identify nine structural features that allow simultaneous prediction of their electron charge transfer properties and thermochemical stability to high accuracy by an interpretable random forest regressor. A multi‐target Bayesian network with domain knowledge incorporated via interactive learning using a hill‐climbing algorithm then determines how these important structural features of nanodiamonds relate to their functional properties, proposing causal paths that can be used to inform experimental design.

Electronic charge transfer properties of COF-5 solutions and films with intercalated metal ions

To investigate the manipulation of electromagnetic properties of two-dimensional materials, this effort characterizes charge transfer behavior of colloidal COF-5 (covalent organic framework) in the presence of various metal ions. A series of metal chloride compounds was introduced to COF-5 in solution and solid film phases and the interaction of the material with electromagnetic radiation was monitored across the visible region using electronic absorption spectroscopy. Notable changes were observed, quantified, and discussed for copper (II) chloride (CuCI2), chromium (III) chloride (CrCI3), and iron (III) chloride (FeCI3) with COF-5. Ligand-to-metal and metal-to-ligand charge transfer are explored as a possible mechanism for the observed electronic behaviors.

The impact of size and shape distributions on the electron charge transfer properties of silver nanoparticles.

Many applications of silver nanoparticles are moderated by the electron charge transfer properties, such as the ionization potential, electron affinity and Fermi energy, which may be tuned by controlling the size and shape of individual particles. However, since producing samples of silver nanoparticles that are perfectly monodispersed in terms of both size and shape can be prohibitive, it is important to understand how these properties are impacted by polydispersivity, and ideally be able to predict the tolerance for variation of different geometric features. In this study, we use straightforward statistical methods, together with electronic structure simulations, to predict the electron charge transfer properties of different types of ensembles of silver nanoparticles and how restricting the structural diversity in different ways can improve or retard performance. In agreement with previous reports, we confirm that restricting the shape distribution will tune the charge transfer properties toward specific reactions, but by including the quality factors for each case we go beyond this assessment and show how targeting specific classes of morphologies and restricting the distribution of size can impact sensitivity.

A glassy carbon electrode modified with a nanocomposite consisting of carbon nanohorns and poly(2-aminopyridine) for non-enzymatic amperometric determination of hydrogen peroxide

The authors describe a composite material prepared from carbon nanohorns and poly(2-aminopyridine) that was obtained by electrochemical polymerization of 2-aminopyridine on carbon nanohorns. The material was used to modify a glassy carbon electrode (GCE) to obtain a sensor for non-enzymatic determination of hydrogen peroxide. The modified GCE was characterized by cyclic voltammetry, electrochemical impedance spectroscopy and chronoamperometry. The modified electrode is shown to display excellent electrical conductivity and catalytic activity towards hydrogen peroxide, mainly due to the large specific surface area of carbon nanohorns, the good electron charge transfer properties resulting from the use of poly(2-aminopyridine), and their synergistic effect. The response of the modified GCE (best operated at a working potential of −0.45 V vs. SCE) to H2O2 is linear in the 0.05 to 8 mM concentration range. The limits of detection (LOD) and quantitation (LOQ) are 3.6 μM and 12.4 μM, respectively. The electrode is selective, stable and reproducible, this making it a promising tool for non-enzymatic determination of hydrogen peroxide.

Impact of speciation on the electron charge transfer properties of nanodiamond drug carriers.

Unpassivated diamond nanoparticles (bucky-diamonds) exhibit a unique surface reconstruction involving graphitization of certain crystal facets, giving rise to hybrid core-shell particles containing both aromatic and aliphatic carbon. Considerable effort is directed toward eliminating the aromatic shell, but persistent graphitization of subsequent subsurface-layers makes perdurable purification a challenge. In this study we use some simple statistical methods, in combination with electronic structure simulations, to predict the impact of different fractions of aromatic and aliphatic carbon on the charge transfer properties of the ensembles of bucky-diamonds. By predicting quality factors for a variety of cases, we find that perfect purification is not necessary to preserve selectivity, and there is a clear motivation for purifying samples to improve the sensitivity of charge transfer reactions. This may prove useful in designing drug delivery systems where the release of (selected) drugs needs to be sensitive to specific conditions at the point of delivery.