Enhancing Efficiency of Dye Sensitized Solar Cells by Coinage Metal Doping of Cyanidin-Silver Trimer Hybrids at TiO2 Support Based on Theoretical Study.

Identification of a natural-based sensitizer with optimal stability and efficiency for dye-sensitized solar cell (DSSC) application remains a challenging task. Previously, we proposed a new class of sensitizers based on bio-nano hybrids. These systems composed of natural cyanidin dyes interacting with silver nanoclusters (NCs) have demonstrated enhanced opto-electronic and photovoltaic properties. In this study, we explore the doping of silver nanocluster within a cyanidin-Ag3 hybrid employing Density Functional Theory (DFT) and its time-dependent counterpart (TDDFT). Specifically, we investigate the influence of coinage metal atoms (Au and Cu) on the properties of the cyanidin-Ag3 system. Our findings suggest that cyanidin-Ag2Au and cyanidin-AgAuCu emerge as the most promising candidates for improved light harvesting efficiency, increased two-photon absorption, and strong coupling to the TiO2 surface. These theoretical predictions suggest the viability of replacing larger silver NCs with heterometallic trimers such as Ag2Au or AgAuCu, presenting new avenues for utilizing bio-nano hybrids at the surface for DSSC application.

Model systems for dye-sensitized solar cells: cyanidin-silver nanocluster hybrids at TiO2 support.

Theoretical study of structural, optical, and photovoltaic properties of novel bio-nano hybrids (dye-nanocluster), as well as at TiO2 surface model support is presented in the context of the application for dye-sensitized solar cells (DSSC). A group of anthocyanidin dyes (pelargonidin, cyanidin, delphinidin, peonidin, petunidin, and malvidin) represented by cyanidin covalently bound to silver nanoclusters (NCs) with even or odd number of valence electrons have been investigated using DFT and TDDFT approach. The key role of nanoclusters as acceptors in hybrids cyanidin-NC has been shown. The nanoclusters with an even number of valence electrons are suitable as acceptors in hybrids. The interaction of bio-nano (cyanidin-NC) hybrid with the TiO2 surface model has been investigated in the context of absorption in near-infrared (NIR) and charge separation due to donor and acceptor subunits. Altogether, the theoretical concept serves to identify the key steps in the design of novel solar cells based on bio-nano hybrids at TiO2 surface for DSSC application.

Mechanism of Catalytic CO2 Hydrogenation to Methane and Methanol Using a Bimetallic Cu3Pd Cluster at a Zirconia Support.

For very small nanocluster-based catalysts, the exploration of the influence of the particle size, composition, and support offers precisely variable parameters in a wide material search space to control catalysts' performance. We present the mechanism of the CO2 methanation reaction on the oxidized bimetallic Cu3Pd tetramer (Cu3PdO2) supported on a zirconia model support represented by Zr12O24 based on the energy profile obtained from density functional theory calculations on the reaction of CO2 and H2. In order to determine the role of the Pd atom, the performance of Cu3PdO2 with monometallic Cu4O2 at the same support has been compared. Parallel to methane formation, the alternative path of methanol formation at this catalyst has also been investigated. The results show that the exchange of a single atom in Cu4 with a single Pd atom improves catalyst/s performance via lowering the barriers associated with hydrogen dissociation steps that occur on the Pd atom. The above-mentioned results suggest that the doping strategy at the level of single atoms can offer a precise control knob for designing new catalysts with desired performance.

Phenyl argentate aggregates [AgnPhn+1]- (n = 2-8): Models for the self-assembly of atom-precise polynuclear organometallics.

Electrospray ionization of phenyl argentates formed by transmetalation reactions between phenyl lithium and silver cyanide provides access to the argentate aggregates, [AgnPhn+1]-, which were individually mass-selected for n = 2-8 in order to generate their gas-phase Ultraviolet Photodissociation (UVPD) "action" spectra over the range 304-399 nm. A strong bathochromic shift in optical spectra was observed with increasing size/n. Theoretical calculations allowed the assignment of the experimental UVPD spectra to specific isomer(s) and provided crucial insights into the transition from the 2D to 3D structure of the metallic component with the increasing size of the complex. The [AgnPhn+1]- aggregates contain neither pronounced metallic cluster properties nor ligated metallic cluster features and are thus not superatom complexes. They therefore represent novel organometallic characteristics built from Ag2Ph subunits.

Structural characterization and gas-phase studies of the [Ag10H8(L)6]2+ nanocluster dication.

The reactions between silver salts and borohydrides produce a rich set of products that range from discrete mononuclear compounds through to silver nanoparticles and colloids. Previous studies using electrospray ionization mass spectrometry (ESI-MS) to track the cationic products in solutions containing sodium borohydride, silver(i) tetrafluoroborate and the bisphosphine ligands, L, bis(diphenylphosphino)methane (dppm) and bis(diphenylphosphino)amine (dppa) have identified the dications [Ag10H8(L)6]2+. Here we isolate and structurally characterize [Ag10H8(dppa)6](BF4)2, and [Ag10H8(dppa)6](NO3)2via X-ray crystallography. Both dications have nearly identical structural features consisting of a Ag10 scaffold with the atoms lying on vertices of a bicapped square antiprism. DFT calculations were carried out to suggest potential sites for the hydrides. Ion-mobility mass spectrometry experiments revealed that [Ag10H8(dppa)6]2+ and [Ag10H8(dppm)6]2+ have similar collision cross sections, while multistage mass spectrometry experiments were used to compare their unimolecular gas-phase chemistry. Although the same initial sequential ligand loss followed by cluster fission and H2 evolution is observed, the more acidic N-H of the dppa provides a more labile H for H2 loss and H/D scrambling processes as revealed by isotope labelled experiments.