Characterisation and predictive modelling of nanodevice components.

Progress in the design and synthesis of nanodevices for solar to fuel conversion needs the concomitant development of computational modeling methods that are able to predict new nanosized materials with specific target properties, with a particular emphasis on nanostructures with desired energy conversion and catalytic properties. In our contribution to theme 1, we focus on two key elements of a novel artificial photosynthesis device, namely guiding the design of the light-harvesting antenna/charge separator in KG2 and the underpinning of the plug-and-play supramolecular catalytic sites for water oxidation and proton reduction that are the focus of the synthesis and design work in KG1.

For the antenna/charge separators we build on our recent analyses of classically coherent phenomena in natural systems, chlorosomes, LH2 antennae and reaction centers. We aim to resolve the most significant design principles that will be the common denominators between artificial and natural photosynthesis. Our recent analyses will guide the design of the first supramolecular dye aggregates for the tandem device in projects C1.3 and C1.4. Subsequently we will participate in the design loop by jumping back and forth between the natural and the artificial systems, in an evidence based approach with dynamic modeling constrained by the results from the experiments in (C1.5, C1.6) Since the capability of copying a biological system is the ultimate form of understanding, the computational characterization of the artificial and the natural systems in a concerted approach will provide a most effective way to optimize the structural and electronic properties of key modules in the artificial device. The focus of this modeling will be on how to integrate electric polarizability in 2-D and 3-D J-aggregate structures and dendrimers for use as a supramolecular dye with directional charge transfer properties (KG2), and on how the structure of the matrix can be designed to support static or classically coherent dynamic heterogeneity for broadening of the optical absorption profiles. The design of such supramolecular dyes is an essential step for a tandem cell incorporating molecular components for sustainable energy supply, which is the focus of theme 1 of TBSC. The modeling will link into the device construction 

with utilization project U1.3 with Sevink and Culgi B.V., focusing on rational design of hybrid organic/inorganic heterojunctions for efficient light-harvesting/charge separation by a dissipative particle dynamics (DPD) model that provides a full hydrodynamic mesoscopic description. The second part of this project C1.9 is to identify the functional principles of recently synthesized homogeneous water oxidation catalysts (WOC) and, by developing novel optimization schemes, provide input for improving the efficiency and stability of the WOC. Here also two elements are important, which is the activation of the catalysts for PCET in the plug-and-play supramolecular cages containing Ru and Ir WOC of KG1, and how transform those into robust structures for multi electron catalysis where rapid PCET is rate-limiting, instead of e.g. slow structural rearrangement or for the WOC, slow access of a second water molecule. The modeling will also help to make the step to Co, and for the investigation of the Fe and Ni centers in the proton reduction systems. The scientific challenge is to exploit experimental constraints to perform the computational modeling of these complexes in order to obtain good accuracy to be predictive, and at the same time being able to include the complexity and multiscale character of the problem. The project will be a success if we can guide the design of (i) an artificial reaction center (KG2) and (ii) efficient and stable catalysts, first for water oxidation and later for proton reduction (KG1).

The work in theis proejct is primarily done at the Leiden Institute of Chemistry, Leiden University

Doorzoek de website