Search for: All records

Electrochemical CO₂separation has drawn attention as a promising strategy for using renewable energy to mitigate climate change. Redox-active compounds that undergo proton-coupled electron transfer (PCET) are an impetus for pH-swing-driven CO₂capture at low energetic costs. However, multiple barriers hinder this technology from maturing, including sensitivity to oxygen and the slow kinetics of CO₂capture. Here, we use vapor phase chemistry to construct a textile electrode comprising an immobilized PCET agent, poly(1-aminoanthraquinone) (PAAQ), and incorporate it into redox flow cells. This design contrasts with others that use dissolved PCET agents by confining proton-storage to the surface of an electrode kept separate from an aqueous, CO₂-capturing phase. This system facilitates carbon capture from gaseous sources (a 1% CO₂feed and air), as well as seawater, with the latter at an energetic cost of 202 kJ/mol_CO2, and we find that quinone moieties embedded within the electrode are more stable to oxygen than dissolved counterparts. Simulations using a 1D reaction-transport model show that moderate energetic costs should be possible for air capture of CO₂with higher loadings of polymer-bound PCET moieties. The remarkable stability of this system sets the stage for producing textile-based electrodes that facilitate pH-swing-driven carbon capture in practical situations. 

Abstract Organized nano‐ and microstructures of molecular semiconductors display interesting optical and photonic properties, and enhanced charge carrier mobilities, as compared to disordered thin films. However, known directed‐growth and self‐organization strategies cannot create structured molecular heterojunctions and cannot be practically incorporated into existing device fabrication routines to create large‐area optoelectronic devices. Here, an ultrathin (<2 nm) seed layer of the compound coronene creates 1D nanostructures of an electron‐transporting molecule (IFD) is shown, which possesses an intrinsic proclivity to form disordered thin films in the absence of the seed layer. It is revealed that nanostructured IFD films exhibit enhanced light absorption and emission, and greater electron mobilities, as compared to amorphous counterparts. This seed layer strategy creates uniform IFD nanowires over large areas of up to 18 mm²at low processing temperatures. Notably, the coronene seed layer creates IFD nanowires when applied over either oxide surfaces or predeposited organic layers, meaning that this structuring approach can be integrated into diode manufacturing routines to realize large‐area flexible optoelectronic devices. Flexible organic light‐emitting diodes and fullerene‐free organic solar cells containing IFD nanowires in the photoactive layer to demonstrate that molecular nanostructures can lead to robust, large‐area device arrays on flexible substrates being fabricated. 

Abstract Wearable electromechanical sensors are essential to improve health monitoring and off‐site point‐of‐care applications. However, their practicality is restricted by narrow ranges of detection, failure to simultaneously sense static and dynamic pressures, and low durability. Here, an all‐fabric pressure sensor with high sensitivity in a broad range of pressures, from subtle heart pulses to body posture, exceeding that of previously‐reported sensors is introduced. By taking advantage of chemical vapor deposition of p‐doped poly(3,4‐ethylenedioxythiophene) chloride (PEDOT‐Cl) on two natural textiles (cotton gauze and cotton balls), multiscale tunable pressure sensitivity with low power demand for data read‐out is obtained. To protect the sensor against humidity induced degradations, the sensor is encapsulated with a hydrophobic coating that leads to ultrastability of the sensor performance even after 1 week of exposure to 100% relative humidity and 20 laundry cycles. The sensor reveals excellent performance retention of >99% over 70 000 bending cycles under ambient conditions. The varied utility of this sensor for health monitoring is demonstrated by recording heartbeats, respiration, and joint movements. Furthermore, using this sensor, grip strength is successfully detected by 93.6% accuracy as compared to commercial dynamometer, speaking of its potential as the first fabric‐based sensor allowing for personalized real‐time grip strength analysis. 

Abstract Wearable thermoelectric generators are a promising energy source for powering activity trackers and portable health monitors. However, known iterations of wearable generators have large form factors, contain expensive or toxic materials with low elemental abundance, and quickly reach thermal equilibrium with a human body, meaning that thermoelectric power can only be generated over a short period of wear. Here, an all‐fabric thermopile is created by vapor printing persistentlyp‐doped poly(3,4‐ethylenedioxythiophene) (PEDOT‐Cl) onto commercial cotton and this thermopile is integrated into a specially designed, wearable band that generates thermovoltages >20 mV when worn on the hand. It is shown that the reactive vapor coating process creates mechanically rugged fabric thermopiles that yield notably high thermoelectric power factors at low temperature differentials, as compared to solution‐processed counterparts. Further, best practices for naturally integrating thermopiles into garments are described, which allow for significant temperature gradients to be maintained across the thermopile despite continuous wear.