skip to main content

Title: Vapor-Phase-Infiltrated AlO x /PIM-1 “Hybrid Scaffolds” as Solution-Processable Amine Supports for CO 2 Adsorption
Energy-efficient adsorptive CO2 capture requires both adsorbent materials with high CO2 capacity and structured adsorption contactors possessing fast mass transfer kinetics and low pressure drop. The state-of-the-art research primarily focuses on “hard” adsorbents such as mesoporous zeolites and metal–organic frameworks, which exhibit high CO2 capacities but are challenging to translate into structured contactors. Polymer of intrinsic microporosity 1 (PIM-1), a solution-processable microporous polymer, is a “softer” alternative that can be easily fabricated into structured adsorption contactors. In prior research, PIM-1 has been utilized as a “molecular basket” for poly(ethylene imine) (PEI). Despite nanoscale amine dispersion and excellent processability, PEI/PIM-1 composites possess an unstable micropore structure, which collapses at high PEI loadings (∼30%) and results in lower CO2 adsorption capacity than PEI-loaded hard oxides. Here, we applied a post-fabrication polymer stabilization method, vapor phase infiltration (VPI), to improve the CO2 capacity of the PEI/PIM-1 composite without sacrificing its processibility. PIM-1 is fabricated into structured adsorption contactors and then reinforced with amorphous aluminum oxyhydroxide (AlOx) nanostrands via VPI. The resulting AlOx/PIM-1 is a stable, hierarchically porous support, which can be loaded with 40% PEI without pore collapse. Owing to the combination of processibility, comparable CO2 capacity, and high amine efficiency, PEI/AlOx/PIM-1 composites more » are a promising alternative to PEI-loaded mesoporous oxides. « less
; ; ; ; ; ;
Award ID(s):
Publication Date:
Journal Name:
ACS Applied Polymer Materials
Sponsoring Org:
National Science Foundation
More Like this
  1. Copper oxide nanostructures are widely used for various applications due to their unique optical and electrical properties. In this work, we demonstrate an atmospheric laser-induced oxidation technique for the fabrication of highly electrochemically active copper oxide hierarchical micro/nano structures on copper surfaces to achieve highly sensitive non-enzymatic glucose sensing performance. The effect of laser processing power on the composition, crystallinity, microstructure, wettability, and color of the laser-induced oxide on copper (LIO-Cu) surface was systematically studied using scanning electron microscopy (SEM), grazing incidence X-ray diffraction (GI-XRD), Raman spectroscopy, energy dispersive X-ray spectroscopy (EDX), EDX-mapping, water contact angle measurements, and optical microscopy. Results of these investigations showed a remarkable increase in copper oxide composition by increasing the laser processing power. The pore size distribution and surface area of the pristine and LIO-Cu sample estimated by N 2 adsorption–desorption data showed a developed mesoporous LIO-Cu structure. The size of the generated nano-oxides, crystallinity, and electroactivity of the LIO-Cu were observed to be adjustable by the laser processing power. The electrocatalytic activity of LIO-Cu surfaces was studied by means of cyclic voltammetry (CV) within a potential window of −0.8 to +0.8 V and chronoamperometry in an applied optimized potential of +0.6 V, in 0.1more »M NaOH solution and phosphate buffer solution (PBS), respectively. LIO-Cu surfaces with optimized laser processing powers exhibited a sensitivity of 6950 μA mM −1 cm −2 within a wide linear range from 0.01 to 5 mM, with exceptional specificity and response time (<3 seconds). The sensors also showed excellent response stability over a course of 50 days that was originated from the binder-free robust electroactive film fabricated directly onto the copper surface. The demonstrated one-step LIO processing onto commercial metal films, can potentially be applied for tuneable and scalable roll-to-roll fabrication of a wide range of high surface area metal oxide micro/nano structures for non-enzymatic biosensing and electrochemical applications.« less
  2. Heavy metal contamination is one of the leading causes of water pollution, with known adverse effects on human health and the environment. This work demonstrates a novel custom-made 3D printable eco-friendly hydrogel and fabrication process that produces stable biocompatible adsorbents with the ability to capture and remove heavy metals from aqueous environments quickly and economically. The 3D printable ink contains alginate, gelatin, and polyethyleneimine (PEI), which binds heavy metals through primary and secondary amine side chains favoring heavy metal adsorption. The ink's rheological properties are optimized to create mechanically stable constructs, in the form of 3D-printed tablets, fabricated entirely by printing. The optimized tablets have high porosity and accessible surface area with multiple binding sites for heavy metal ion adsorption while the printing process enables rapid and affordable production with the potential for scale-up. The results demonstrate the contribution of hydrogel composition and rheology in determining the printability, stability, and heavy metal binding characteristics of the hydrogel, and indicate the critical role of the PEI in increasing stability of the printed construct, in addition to its metal binding properties. The highest removal capacity was obtained for copper, followed by cadmium, cobalt, and nickel ions. In the optimized formulation, each hydrogelmore »tablet removed 60% from 100 ppm copper in 5 h and up to 98% in 18 h. For more concentrated solutions (1000 ppm), ∼25% of copper was removed in 18 h. The printed tablets are stable, robust, and can be produced in a single simple step from inexpensive biomaterials. The ink's tunability, excellent printability, and stability offer a universally applicable procedure for creating hydrogel-based structures for environmental remediation. These unique capabilities open new avenues for manufacturing tailor-made constructs with integrated functionality for water treatment and environmental applications.« less
  3. Per- and polyfluoroalkyl substances (PFAS) have been extensively utilized in practical applications that include surfactants, lubricants, and firefighting foams due to their thermal stability and chemical inertness. Recent studies have revealed that PFAS were detected in groundwater and even drinking water systems which can cause severe environmental and health issues. While adsorbents with a large specific surface area have demonstrated effective removal of PFAS from water, their capability in desorbing the retained PFAS has been often neglected despite its critical role in regeneration for reuse. Further, they have demonstrated a relatively lower adsorption capacity for PFAS with a short fluoroalkyl chain length. To overcome these limitations, electric field-aided adsorption has been explored. In this work, reversible adsorption and desorption of PFAS dissolved in water upon alternating voltage is reported. An inexpensive graphite adsorbent is fabricated by using a simple press resulting in a mesoporous structure with a BET surface area of 132.9 ± 10.0 m 2 g −1 . Electric field-aided adsorption and desorption experiments are conducted by using a custom-made cell consisting of two graphite electrodes placed in parallel in a polydimethylsiloxane container. Unlike the conventional sorption process, a graphite electrode exhibits a higher adsorption capacity for PFAS withmore »a short fluoroalkyl chain (perfluoropentanoic acid, PFPA) in comparison to that with a long fluoroalkyl chain (perfluorooctanoic acid, PFOA). Upon alternating the voltage to a negative value, the retained PFPA or PFOA is released into the surrounding water. Finally, we engineered a device module mounted on a gravity-assisted apparatus to demonstrate electrosorption of PFAS and collection of high purity water.« less
  4. Recently, metal–organic framework (MOF)-based polymeric substrates show promising performance in many engineering and technology fields. However, a commonly known drawback of MOF/polymer composites is MOF crystal encapsulation and reduced surface area. This work reports a facile and gentle strategy to produce self-supported MOF predominant hollow fiber mats. A wide range of hollow MOFs including MIL-53(Al)–NH 2 , Al-PMOF, and ZIF-8 are successfully fabricated by our synthetic method. The synthetic strategy combines atomic layer deposition (ALD) of metal oxides onto polymer fibers and subsequent selective removal of polymer components followed by conversion of remaining hollow metal oxides into freestanding MOF predominant hollow fiber structures. The hollow MOFs show boosted surface area, superb porosity, and excellent pore accessibility, and exhibit a significantly improved performance in CO 2 adsorption (3.30 mmol g −1 ), CO 2 /N 2 separation selectivity (24.9 and 21.2 for 15/85 and 50/50 CO 2 /N 2 mixtures), and catalytic removal of HCHO (complete oxidation of 150 ppm within 60 min).
  5. Broadband photodetectors (PDs) have great applications in both industrial and scientific sectors. In this study, solution-processed broadband PDs with an “inverted” vertical photodiode device structure without incorporating transparent conductive oxides electrodes, fabricated by bulk heterojunction (BHJ) composites composed of a low optical gap conjugated polymer blended with highly electrically conductive PbS quantum dots (QDs), operated at room temperature, are reported. The low optical gap conjugated polymer incorporated with PbS QDs contributes to the spectral response from the ultraviolet (UV)-visible to the infrared (IR) range. To realize the IR spectral response and to circumvent the weak IR transparency of the transparent oxide electrodes, the implementation of a photodiode with an “inverted” vertical device structure with the Au anode and the Ba/Al bilayer semitransparent cathode passivated with the MgF 2 layer is demonstrated. Photoinduced charge carrier transfer occurring within the BHJ composite gave rise to decent photocurrent, resulting in detectivities greater than 10 12 Jones (cm Hz 1/2 /W) over the wavelength from the UV-visible to the IR range under low applied bias. Thus, our findings of the utilization of the BHJ composites and an “inverted” vertical photodiode without the incorporation of the transparent conductive oxide electrodes provide a facile way tomore »realize broadband PDs.« less