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Poly(3,4-ethylene dioxythiophene) (PEDOT) has a high theoretical charge storage capacity, making it of interest for electrochemical applications including energy storage and water desalination. Nanoscale thin films of PEDOT are particularly attractive for these applications to enable faster charging. Recent work has demonstrated that nanoscale thin films of PEDOT can be formed using sequential gas-phase exposures via oxidative molecular layer deposition, or oMLD, which provides advantages in conformality and uniformity on high aspect ratio substrates over other deposition techniques. But to date, the electrochemical properties of these oMLD PEDOT thin films have not been well-characterized. In this work, we examine the electrochemical properties of 5–100 nm thick PEDOT films formed using 20–175 oMLD deposition cycles. We find that film thickness of oMLD PEDOT films affects the orientation of ordered domains leading to a substantial change in charge storage capacity. Interestingly, we observe a minimum in charge storage capacity for an oMLD PEDOT film thickness of ∼30 nm (60 oMLD cycles at 150 °C), coinciding with the highest degree of face-on oriented PEDOT domains as measured using grazing incidence wide angle X-ray scattering (GIWAXS). Thinner and thicker oMLD PEDOT films exhibit higher fractions of oblique (off-angle) orientations and corresponding increases in charge capacity of up to 120 mA h g −1 . Electrochemical measurements suggest that higher charge capacity in films with mixed domain orientation arise from the facile transport of ions from the liquid electrolyte into the PEDOT layer. Greater exposure of the electrolyte to PEDOT domain edges is posited to facilitate faster ion transport in these mixed domain films. These insights will inform future design of PEDOT coated high-aspect ratio structures for electrochemical energy storage and water treatment. 

Homogeneous molecular catalysts are valued for their reaction specificity but face challenges in manufacturing scale-up due to complexities in final product separation, catalyst recovery, and instability in the presence of water. Heterogenizing these molecular catalysts, by attachment to a solid support, could transform the practical utility of molecular catalysts, simplify catalyst separation and recovery, and prevent catalyst decomposition by impeding bimolecular catalyst interactions. Previous strategies to heterogenize molecular catalysts via ligand-first binding to supports have suffered from reduced catalytic activity and leaching (loss) of catalyst, especially in environmentally friendly solvents like water. Herein, we describe an approach in which molecular catalysts are first attached to a metal oxide support through acidic ligands and then “encapsulated” with a metal oxide layer via atomic layer deposition (ALD) to prevent molecular detachment from the surface. For this initial report, which is based upon the well-studied Suzuki carbon–carbon cross-coupling reaction, we demonstrate the ability to achieve catalytic performance using a non-noble metal molecular catalyst in high aqueous content solvents. The catalyst chosen exhibits limited catalytic reactivity under homogeneous conditions due to extremely short catalyst lifetimes, but when heterogenized and immobilized with an optimal ALD layer thickness product yields >90% can be obtained in primarily aqueous solutions. Catalyst characterization before and after ALD application and catalytic reaction is achieved with infrared, electron paramagnetic resonance, and X-ray spectroscopies. 

The effects of sequential n-doping on a high-electron-mobility naphthalene-diimide-based copolymer poly[( N , N ′-bis(2-decyltetradecyl)-naphthalene-1,8:4,5-bis(dicarboximide)-2,6-diyl)-(selenophene-2,5-diyl)-(benzo[ c ][1,2,5]thiadiazole-4,7-diyl)-(selenophene-2,5-diyl)], PNBS, are reported. Grazing-incidence XRD measurements show that PNBS doped with 2,2′-bis(4-(dimethylamino)phenyl)-1,1′,3,3′-tetramethyl-2,2′,3,3′-tetrahydro-1 H ,1′ H -2,2′-bibenzo[ d ]imidazole, (N-DMBI) 2 , has increased order relative to both the pristine polymer and a film doped with ruthenium pentamethylcyclopentadienyl mesitylene dimer. Films of PNBS optimally doped with (N-DMBI) 2 show electrical conductivities approaching 2 mS cm −1 in air. Temperature-dependent electrical measurements suggest that the polaronic charge carriers are highly localized, which is consistent with the moderate conductivity values obtained.