Synthetic approaches to artificial photosynthesis: general discussion

Abstract

Moritz F. Kuehnel opened a discussion of the paper by Andrew I. Cooper: What do you know about the HOMO and LUMO localisation on the polymers? I suppose this is strongly affected by introducing heteroatoms such as sulfur, and that this causes the changes observed when oxidising the thiophene to sulfolane moieties. Can you use different heteroatoms to tweak the redox potentials? Andrew I. Cooper answered: Yesby changing the heteroatom one can change the catalytic activity, but this can also change a variety of other things such as the surface hydrophilicity and (in some cases) the polymer molecular weight, or, in the case of networks, the surface area. As such, it is oen unclear whether these effects come from changes to the redox potentials or a variety of factors.Moritz F. Kuehnel asked: How much is known about the residual palladium in the polymer? What do you know about its environment, which I assume will depend on functional groups in the polymer backbone, e.g. donor groups? I am wondering if the observed differences in activity for different polymers are a result of the different palladium environments, rather than other, more easily determined factors. such as the band gap, etc. Do you have any EXAFS data?

Polymer photocatalysts for solar-to-chemical energy conversion

“…136 About then, a number of linear poly(phenylene) type polymers had been explored and were found modestly active under UV irradiation (Table 2). 137,138 The field has seen considerable growth in the past few years, 14,15,[139][140][141][142][143][144][145][146][147][148][149] with the pioneering work of Cooper and co-workers who started defining structure-property-activity relationships in the photoactivity of such polymers. As compared to the well-known organic polymers used in photovoltaics, 150 these polymers are typically insoluble.…”

Hydrogen evolution by polymer photocatalysts; a possible photocatalytic cycle

“…Despite a significant uptake of interest in organic materials the exact relationship between their (opto-)electronic/structural properties and the observed hydrogen (HER) and oxygen evolution reaction (OER) rates still remains far from clear. 19 Previously, we demonstrated that empirically the variation in HER/OER rates between polymers can be described in terms of (i) the thermodynamic driving force for proton reduction and water oxidation, controlled by the ionisation potential (IP) and electron affinity (EA) of the neutral polymer, in both the ground state and in the presence of an excited electron-hole pair (exciton), 20,21 (ii) the onset of light absorption and (iii) the dispersability of the polymer particles in suspension. 18,22,23 The dispersability of a polymer probably depends both on the size (distribution) of the polymer particles in suspension and the inherent wettability of the polymer or the sidegroups present.…”

Electrochemical Control of the Morphology and Functional Properties of Hierarchically Structured, Dendritic Cu Surfaces

“…The faradaic efficiency (FE) for each product was then calculated from the overall charge passed as measured by the potentiostat (Equation (3)), where n is the number of moles of each product calculated through quantitative measurements, Z is the number of moles of electrons required per mole of product, F is the Faraday constant (96485.3 C mol −1 ), and Q is the total charge passed in units of coulombs during each 15 min interval. [ 32,33 ] …”