Hybrid CO2 capture materials, solvent impregnated polymers (SIPs), are developed based on a simple and scalable encapsulation technique to enhance CO2 capture kinetics of water‐lean solvents with ...high viscosity. Liquid‐like nanoparticle organic hybrid materials functionalized with polyethylenimine (NOHM‐I‐PEI) are incorporated into a shell material and UV‐cured to produce gas‐permeable solid sorbents with uniform NOHMs loading (NPEI‐SIPs). The CO2 capture kinetics of NPEI‐SIPs show a remarkable 50‐fold increase compared to that of neat NOHM‐I‐PEI due to a large increase in the NOHMs‐CO2 interfacial surface area provided by the SIP design. The optimum NOHM‐I‐PEI loading and sorption temperature are found to be ≈49 wt% and 50 °C, respectively, and NPEI‐SIPs exhibit great thermal stability over 20 CO2 capture/sorbent regeneration temperature swing cycles. The pseudoequilibrium CO2 loadings of NPEI‐SIPs under humid conditions are as high as 3.1 mmol CO2 g−1NPEI − SIPs for 15 vol% CO2 (postcombustion capture) and 1.7 mmol CO2 g−1NPEI − SIPs for 400 ppm (direct air capture). These findings suggest that NPEI‐SIPs can effectively capture CO2 from a wide range of CO2 concentrations including direct air capture while allowing the flexible design of CO2 capture reactors by combining the benefits of liquid solvents and solid sorbents.
Hybrid CO2 capture materials combining the benefits of liquid solvents and solid sorbents are proposed for postcombustion and direct air capture. Nanoparticle organic hybrid materials (NOHMs) functionalized with polyethylenimine are incorporated into UV‐curable CO2‐permeable polymers as microdroplets to increase the interfacial area. NOHMs functionalized with polyethylenimine‐solvent impregnated polymers particles achieve significantly enhanced CO2 capture kinetics via the synergistic effect between NOHMs and the gas permeable polymer.
As a result of the growing need for direct air capture (DAC) and integrated carbon capture and conversion technologies, CO2 capture materials that can withstand a wide range of environmental ...conditions, including fluctuating ambient temperatures and high concentrations of oxidizing agents (i.e., oxygen and moisture), are critically needed. Liquid-like nanoparticle organic hybrid materials (NOHMs) have been proposed as candidates for DAC and electrolyte additives, enabling sustainable energy storage (i.e., integrated CO2 capture and conversion and flow batteries). Liquid-like NOHMs functionalized with an ionic bond have been shown to display greatly enhanced oxidative thermal stability compared to the untethered polymer. However, previous studies were limited in terms of reaction conditions, and the detailed mechanisms of the oxidative thermal degradation were not reported. In this work, a kinetic thermal degradation analysis was performed on NOHM-I-HPE and the neat polymer, Jeffamine M2070 (HPE), in both non-oxidative and oxidative conditions. NOHM-I-HPE displayed thermal stability similar to the untethered polymer in a nitrogen environment, but interestingly, the thermal stability of the ionically tethered polymer was significantly enhanced in the presence of air. This observed enhancement of oxidative thermal stability is attributed to the orders of magnitude larger viscosity of the liquid-like NOHMs compared to the untethered polymer and the bond stabilization of the ionically tethered polymer in the NOHM canopy. Spectroscopic analyses of the liquid residue revealed that, in the presence of oxygen, the degradation of HPE and NOHM-I-HPE occurs through the formation of trace amounts of carbonyls. This study illustrated that NOHMs can serve as functional materials for sustainable energy storage applications because of their excellent oxidative thermal stability.
Coupling renewable energy with the electrochemical conversion of CO2 to chemicals and fuels has been proposed as a strategy to achieve a new circular carbon economy and help mitigate the effects of ...anthropogenic CO2 emissions. Liquid‐like Nanoparticle Organic Hybrid Materials (NOHMs) are composed of polymers tethered to nanoparticles and are previously explored as CO2 capture materials and electrolyte additives. In this study, two types of aqueous NOHM‐based electrolytes are prepared to explore the effect of CO2 binding energy (i.e., chemisorption versus physisorption) on CO2 electroreduction over a silver nanoparticle catalyst for syngas production. Poly(ethylenimine) (PEI) and Jeffamine M2070 (HPE) are ionically tethered to SiO2 nanoparticles to form the amine‐containing NOHM‐I‐PEI and ether‐containing NOHM‐I‐HPE, respectively. At less negative cathode potentials, PEI and NOHM‐I‐PEI‐based electrolytes produce CO at higher rates than 0.1 molal. KHCO3 due to favorable catalyst‐electrolyte interactions. Whereas at more negative potentials, H2 production is favored because of the carbamate electrochemical inactivity. Conversely, HPE and NOHM‐I‐HPE‐based electrolytes display poor CO2 reduction performance at less negative potentials. At more negative potentials, their performance approached that of 0.1 molal. KHCO3, highlighting how the polymer functional groups of NOHMs can be strategically selected to produce value‐added products from CO2 with highly tunable compositions.
NOHMs (Nanoparticle Organic Hybrid Materials) consist of a polymer canopy tethered to a nanoparticle core and are proposed for combined CO2 capture and electrochemical conversion. The ionic conductivity and CO2 binding energy of the polymer canopy are identified as critical design parameters for the production of highly tunable syngas compositions over a silver nanoparticle catalyst in CO2 electroreduction.
A critical concern regarding electrolyte formulation in an electrochemical environment is the impact of the interaction of the multiple components (
i.e.
, supporting electrolyte or additive) with ...the electrode surface. Recently, liquid-like neat Nanoparticle Organic Hybrid Materials (NOHMs) have been considered as an electrolyte component to improve the transport of redox-active species to the electrode surface. However, the structure and assembly of the NOHMs near the electrode surface is unknown and could significantly impact the electrode-electrolyte interface. Hence, we have investigated the depth profile of polyetheramine (HPE) polymer and NOHM-I-HPE (nanoparticles with ionically bonded HPE polymer) in deuterated water (D
2
O) in the presence of two different salts (KHCO
3
and ZnCl
2
) near two different electrode surfaces using neutron reflectometry. Moreover, the depth profile of the NOHM-I-HPE near the electrode surface in a potential has also been studied with
in situ
reflectivity experiments. Our results indicate that a change in the chemical structure/hydrophilicity of the electrode surface does not significantly impact the ordering of HPE polymer or NOHM-I-HPE near the surface. This study also indicates that the NOHM-I-HPE particles form a clear layer near the electrode surface immediately above an adsorbed layer of free polymer on the electrode surface. The addition of salt does not impact the layering of NOHM-I-HPE, though it does alter the conformation of the polymer grafted to the nanoparticle surface and free polymer sequestered near the surface. Finally, the application of negative potential results in an increased amount of free polymer near the electrode surface. Correlating the depth profile of free polymer and NOHM-I-HPE particles with the electrochemical performance indicates that this assembly of free polymer near the electrode surface in NOHM-I-HPE solutions contributes to the higher current density of the system. Therefore, this holistic study offers insight into the importance of the assembly of NOHM-I-HPE electrolyte and free polymer near the electrode surface in an electrochemical milieu on its performance.
Schematic showing the ordering of free HPE polymer in D
2
O (left), static NOHM-I-HPE in D
2
O (middle), and NOHM-I-HPE in a negative potential in D
2
O (right) near a gold electrode.
An emerging area of sustainable energy and environmental research is focused on the development of novel electrolytes that can increase the solubility of target species and improve subsequent ...reaction performance. Electrolytes with chemical and structural tunability have allowed for significant advancements in flow batteries and CO2 conversion integrated with CO2 capture. Liquid-like nanoparticle organic hybrid materials (NOHMs) are nanoscale fluids that are composed of inorganic nanocores and an ionically tethered polymeric canopy. NOHMs have been shown to exhibit enhanced conductivity making them promising for electrolyte applications, though they are often challenged by high viscosity in the neat state. In this study, a series of binary mixtures of NOHM-I-HPE with five different secondary fluids, water, chloroform, toluene, acetonitrile, and ethyl acetate, were prepared to reduce the fluid viscosity and investigate the effects of secondary fluid properties (e.g., hydrogen bonding ability, polarity, and molar volume) on their transport behaviors, including viscosity and diffusivity. Our results revealed that the molecular ratio of secondary fluid to the ether groups of Jeffamine M2070 (λSF) was able to describe the effect that secondary fluid has on transport properties. Our findings also suggest that in solution, the Jeffamine M2070 molecules exist in different nanoscale environments, where some are more strongly associated with the nanoparticle surface than others, and the conformation of the polymer canopy was dependent on the secondary fluid. This understanding of the polymer conformation in NOHMs can allow for the better design of an electrolyte capable of capturing and releasing small gaseous or ionic species.
Liquid-like Nanoscale Organic Hybrid Materials or NOHMs consisting of polymer grafted nanoparticles have shown great promise in applications, such as electrochemistry and gas separation, due to their ...enhanced conductivity, tunability, and negligible vapor pressure. Recently, NOHMs are considered to be used as novel electrolytes in Redox Flow Batteries (RFBs). However, to employ NOHMs in redox flow batteries as electrolytes, it is important to understand the conformation and dispersion of NOHMs in the electrochemical milieu. Here, we report the use of small-angle neutron scattering to probe the structure and dispersion of Jeffamine M2070 polymer grafted to a SiO2 nanoparticle in an aqueous solution with and without the presence of a supporting electrolyte. Our results indicate that, in the aqueous environment, there exists a large amount of free polymer in the solution that is not grafted to the functionalized nanoparticles. These protonated free polymers, dispersed in the aqueous solvent, may also strongly interact with the grafted polymer layer and greatly affect the neat structure of NOHMs. Thus, there also exist polymers identified as “interacting” polymers to distinguish them from tethered or truly free polymers in the fluid system. The presence of supporting electrolyte shows a greater effect on the structure of NOHMs-based fluid as it not only alters the structure of the free polymer but also hinders the interaction of the polymer with the functionalized nanoparticles. Moreover, the change in the interaction of the Jeffamine M2070 with the functionalized nanoparticles due to the addition of supporting electrolyte has revealed a drastic change in the viscosities of NOHM solutions. Overall, the dispersion of the free polymer, the interaction of the interacting polymer with grafted polymer, and the change in conformation of free polymer and grafted layers with the addition of supporting electrolyte provide valuable insight into the overall scenario of the electrochemical environment of NOHMs. These results can be applied to fine-tune the structure of liquid-like NOHMs and will aid in a better understanding of their performance as potential electrolytes in RFBs.
Nanoparticle organic hybrid materials (NOHMs) are liquid-like materials composed of an inorganic core to which a polymeric canopy is ionically tethered. NOHMs have unique properties including ...negligible vapor pressure, high oxidative thermal stability, and the ability to bind to reactive species of interest due to the tunability of their polymeric canopy. This makes them promising multifunctional materials for a wide range of energy and environmental technologies, including electrolyte additives for electrochemical energy storage (e.g., flow batteries) and the electrochemical conversion of CO2 to chemicals and fuels. Due to their unique transport behaviors in fluid systems, an understanding of the near-electrode surface behavior of NOHMs in electrolyte solutions and their effect on electrochemical reactions is still lacking. In this work, the complexation of zinc (Zn) by NOHMs with an ionically tethered polyetheramine canopy (HPE) (NOHM-I-HPE) was studied using attenuated total reflectance Fourier transform infrared and Carbon-13 nuclear magnetic resonance spectroscopy. Additionally, various electrochemical techniques were employed to discern the role of NOHM-I-HPE during zinc electrodeposition, and the results were compared to those of the electrochemical system containing untethered HPE polymers. Our findings confirmed that NOHM-I-HPE and HPE reversibly complex zinc in the aqueous electrolyte. NOHM-I-HPE and HPE were found to block some of the electrode active sites, reducing the overall current density during electrodeposition, while facilitating the formation of smooth zinc deposits, as revealed by surface imaging and diffraction techniques. Observed variations in the current density responses and the degree of passivation created by the NOHM-I-HPE and HPE adsorbed on the electrode surface revealed that their different packing behaviors at the electrode–electrolyte interface influence the zinc deposition mechanism. The presence of the nanoparticle and ordering offered by the NOHMs as well as the structured conformation of the polymeric canopy allowed the formation of void spaces and free volumes for enhanced transport behaviors. These findings provided insights into how structured electrolyte additives such as NOHMs can allow for advancements in electrolyte design for controlled deposition of metal species from energy-dense electrolytes or for other electrochemical reactions.
Nanoscale Organic Hybrid Materials (NOHMs) consist of polymers tethered to a nanoparticle surface, and NOHMs formed with an ionic bond between the polymer and nanoparticle have been proposed for ...electrochemical applications. NOHMs exhibit negligible vapor pressure, chemical tunability, oxidative thermal stability, and high ionic conductivity making them attractive in reactive and separation systems. In this study, NOHMs are synthesized by tethering Jeffamine M2070 (HPE) to SiO2 nanocores via ionic (NOHM‐I‐HPE) and covalent (NOHM‐C‐HPE) bonding to investigate the effect of the bond type on the thermal, structural and transport properties of the tethered HPE. In the neat state, NOHM‐C‐HPE displays the highest thermal stability in a nitrogen atmosphere, while NOHM‐I‐HPE is the most stable under oxidative conditions. Small‐angle neutron scattering (SANS) reveals the presence of multiple types of HPE polymers in aqueous solutions of NOHM‐I‐HPE (i.e., tethered, interacting, and free), whereas only tethered HPE is observed in NOHM‐C‐HPE systems. Moreover, the SANS profiles identify clustering of NOHM‐C‐HPE in aqueous solutions, but not in the corresponding NOHM‐I‐HPE solutions, suggesting that the free HPE chains stabilize the dispersion of NOHM‐I‐HPE. The results of this study elucidate how the bond type and grafting density can be used to tune the properties of NOHMs.
Nanoparticle Organic Hybrid Materials (NOHMs) are composed of a polymer ionically or covalently linked to a nanoparticle surface. Distinct thermal stability behaviors, small‐angle neutron scattering profiles, and transport measurements of covalently and ionically tethered polymers suggest that the bond type is a crucial parameter that can be used to tune NOHMs for targeted applications.
As renewable energy is rapidly integrated into the grid, the challenge has become storing intermittent renewable electricity. Technologies including flow batteries and CO2 conversion to dense energy ...carriers are promising storage options for renewable electricity. To achieve this technological advancement, the development of next generation electrolyte materials that can increase the energy density of flow batteries and combine CO2 capture and conversion is desired. Liquid-like nanoparticle organic hybrid materials (NOHMs) composed of an inorganic core with a tethered polymeric canopy (e.g., polyetheramine (HPE)) have a capability to bind chemical species of interest including CO2 and redox-active species. In this study, the unique response of NOHM-I-HPE-based electrolytes to salt addition was investigated, including the effects on solution viscosity and structural configurations of the polymeric canopy, impacting transport behaviors. The addition of 0.1 M NaCl drastically lowered the viscosity of NOHM-based electrolytes by up to 90%, reduced the hydrodynamic diameter of NOHM-I-HPE, and increased its self-diffusion coefficient, while the ionic strength did not alter the behaviors of untethered HPE. This study is the first to fundamentally discern the changes in polymer configurations of NOHMs induced by salt addition and provides a comprehensive understanding of the effect of ionic stimulus on their bulk transport properties and local dynamics. These insights could be ultimately employed to tailor transport properties for a range of electrochemical applications.
Metal-Organic Frameworks (MOFs) have been developed as solid sorbents for CO2 capture applications and their properties can be controlled by tuning the chemical blocks of their crystalline units. A ...number of MOFs (e.g., HKUST-1) have been developed but the question remains how to deploy them for gas–solid contact. Unfortunately, the direct use of MOFs as nanocrystals would lead to serious problems and risks. Here, for the first time, we report a novel MOF-based hybrid sorbent that is produced via an innovative in-situ microencapsulated synthesis. Using a custom-made double capillary microfluidic assembly, double emulsions of the MOF precursor solutions and UV-curable silicone shell fluid are produced. Subsequently, HKUST-1 MOF is successfully synthesized within the droplets enclosed in the gas permeable microcapsules. The developed MOF-bearing microcapsules uniquely allow the deployment of functional nanocrystals without the challenge of handling ultrafine particles, and further, can selectively reject undesired compounds to protect encapsulated MOFs.
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•A novel MOF-based hybrid sorbent is produced via in-situ microencapsulated synthesis.•The proposed method allows a faster synthesis rate and a more flexible reactor application.•HKUST-1 microcapsules show good recyclability and stability.•A broader range of MOFs can be readily explored using this facile approach.
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