Patent Application
20230264972
This disclosure concerns a process to fabricate a novel low-temperature oxygen transporter in nano-thin (1-5 nm) morphology.
Our material is a compound of BixOySez and R
The material transports oxygen rapidly (3.11e-18 m2 s−1) at room temperature under low-power laser exposure. When combined with two-dimensional (2D) materials, the compound BixOySez and R
The changes to the 2D material are reversible and the material is reusable.
Our new material has potential to be used for a host of applications requiring oxygen transport membranes, including fuel cells and oxygen separation. Materials that enable rapid oxygen diffusion are becoming increasingly important as the world transitions to renewable energy. Oxygen transport membranes and oxygen ion conductors enable several technologies that manufacture carbon-neutral syngas and efficiently convert it into energy, solving a host of challenges where current battery technology is impractical, including long-duration and high-density energy storage.
Two-dimensional (2D) materials have demonstrated promise for a spectrum of applications, including superconductivity, quantum information science, DNA sequencing, catalysts, transistors, renewable energy, and COVID-19 sensing. Controlling the properties of the 2D material with high precision and spatial selectivity has the potential to advance these technologies.
Materials that enable rapid oxygen diffusion are becoming increasingly important as the world transitions to renewable energy. Oxygen transport membranes and oxygen ion conductors enable several technologies that manufacture carbon-neutral syngas and efficiently convert it into energy, solving a host of challenges where current battery technology is impractical, including long-duration and high-density energy storage.
We synthesized a nano-thin compound composed of a rare R
As oxygen is transported through the BixOySez, it fills the interlayer region, thereby modulating the monolayer TMD properties and brightening the PL. The oxygen can be controllably intercalated (deintercalated) to brighten (darken) the PL intensity, where the diffusion profile follows Fick's 2nd Law of Diffusion. Using laser-patterning, the diffusion can be controlled with submicron spatial resolution, where changes are stable for more than 221 days.
Our work indicates nano-thin BixOySez is a promising unexplored room-temperature oxygen transporter, raising the prospect that it can advance low-temperature SOFC technology and improve syngas production, thereby facilitating renewable energy. Additionally, we believe BixOySez and the interlayer intercalation mechanism can be applied generally to 2D materials to precisely manipulate their properties on the submicron scale, raising the possibility for a host of spatially-selective and tunable properties, including long-lived interlayer excitons, magnetism, and ferroelectricity.
Oxygen ion transport for solid oxide fuel cells (SOFCs). SOFCs are expected to play a critical role as the world transitions to clean and sustainable energy. SOFCs are not subject to Carnot cycle limitations, efficiently producing electricity without moving parts from direct fuel oxidation. Additionally, they are scalable, modular, low-noise, and can be operated in reverse to produce syngas and oxygen.
Purified Oxygen is required for numerous industrial and medical applications. Further, the demand for pure oxygen is expected to increase as the world transitions to renewable energy. The compound BixOySez and R
The technology can be applied to power generation exhaust to efficiently remove excess unreacted oxygen, thereby increasing the concentration of exhaust pollutants for more efficient carbon and pollutant capture.
The material can be applied as an oxygen carrier in a biomass chemical looping gasification system to produce carbon-neutral syngas.
Our approach modulates the properties of 2D material with high precision and spatial selectivity. The changes to the 2D material are reversible and the material is reusable. They have demonstrated application in a spectrum of disciplines, including superconductivity, quantum information science, DNA sequencing, catalysts, transistors, renewable energy, and COVID-19 sensing. Additionally, 2D materials have demonstrated promise for a host of advanced computing schemes, including valleytronics, twistronics, spintronics, neuromorphic computing, and quantum computing.
This disclosure concerns a process to fabricate a novel low-temperature oxygen transporter in nano-thin (1-5 nm) morphology.
Our material is a compound of BixOySez and R
The material transports oxygen rapidly (3.11e-18 m2 s−1) at room temperature under low-power laser exposure. When combined with two-dimensional (2D) materials, the compound BixOySez and R
The changes to the 2D material are reversible and the material is reusable.
We synthesized a nano-thin compound composed of a rare R
As oxygen is transported through the BixOySez, it fills the interlayer region, thereby modulating the monolayer TMD properties and brightening the PL. The oxygen can be controllably intercalated (deintercalated) to brighten (darken) the PL intensity, where the diffusion profile follows Fick's 2nd Law of Diffusion. Using laser-patterning, the diffusion can be controlled with submicron spatial resolution, where changes are stable for more than 221 days.
The following description and drawings set forth certain illustrative implementations of the disclosure in detail, which are indicative of several exemplary ways in which the various principles of the disclosure may be carried out. The illustrated examples, however, are not exhaustive of the many possible embodiments of the disclosure. Other objects, advantages and novel features of the disclosure will be set forth in the following detailed description when considered in conjunction with the drawings.
This disclosure concerns a process to fabricate a novel low-temperature oxygen transporter in nano-thin (1-5 nm) morphology.
Our material is a compound of BixOySez and R
The material transports oxygen rapidly (3.11e-18 m2 s−1) at room temperature under low-power laser exposure. When combined with two-dimensional (2D) materials, the compound BixOySez and R
The changes to the 2D material are reversible and the material is reusable.
We synthesized a nano-thin compound composed of a rare R
As oxygen is transported through the BixOySez, it fills the interlayer region, thereby modulating the monolayer TMD properties and brightening the PL. The oxygen can be controllably intercalated (deintercalated) to brighten (darken) the PL intensity, where the diffusion profile follows Fick's 2nd Law of Diffusion. Using laser-patterning, the diffusion can be controlled with submicron spatial resolution, where changes are stable for more than 221 days.
Our work indicates nano-thin BixOySez is a promising unexplored room-temperature oxygen transporter, raising the prospect that it can advance low-temperature SOFC technology and improve syngas production, thereby facilitating renewable energy. Additionally, we believe BixOySez and the interlayer intercalation mechanism can be applied generally to 2D materials to precisely manipulate their properties on the submicron scale, raising the possibility for a host of spatially-selective and tunable properties, including long-lived interlayer excitons, magnetism, and ferroelectricity.
Oxygen ion transport for solid oxide fuel cells (SOFCs). SOFCs are expected to play a critical role as the world transitions to clean and sustainable energy. SOFCs are not subject to Carnot cycle limitations, efficiently producing electricity without moving parts from direct fuel oxidation. Additionally, they are scalable, modular, low-noise, and can be operated in reverse to produce syngas and oxygen.
Purified Oxygen is required for numerous industrial and medical applications. Further, the demand for pure oxygen is expected to increase as the world transitions to renewable energy. The compound BixOySez and R
The changes to the 2D material are reversible and the material is reusable.
We synthesized a nano-thin compound composed of a rare R
As oxygen is transported through the BixOySez, it fills the interlayer region, thereby modulating the monolayer TMD properties and brightening the PL. The oxygen can be controllably intercalated (deintercalated) to brighten (darken) the PL intensity, where the diffusion profile follows Fick's 2nd Law of Diffusion. Using laser-patterning, the diffusion can be controlled with submicron spatial resolution, where changes are stable for more than 221 days in our novel oxygen transport material: Nano-thin compound containing R
Oxygen transporters and ion conductors—materials that facilitate rapid oxygen diffusion—enable key technologies that are expected to play a critical role as the world transitions to clean and renewable energy, including solid oxide fuel cells (SOFCs) and synthesis gas (syngas) production.
SOFCs are not subject to Carnot cycle limitations, efficiently producing electricity without moving parts from direct fuel oxidation. Additionally, they are scalable, modular, low-noise, and can be operated in reverse to produce syngas and oxygen. Oxygen transport membranes and oxygen carriers can also be applied in other processes to produce carbon-neutral syngas using biomass or solar heating. Syngas, and its conversion to liquid hydrocarbons, has demonstrated potential as a carbon-neutral fuel for long-duration and high-density energy storage, solving a host of challenges where current battery technology is impractical, including (1) intermittent and seasonal energy production; (2) long refueling times; and (3) heavy-duty and long-distance transportation (e.g., buses, trucks, trains, forklifts, and ships). A critical limitation of SOFCs are the high operating temperatures (˜800° C.), which decrease lifetime and increase start-up times, constraining greater adoption.
In this work, we synthesized a novel nano-thin oxygen transporter composed of a rare R
Our findings demonstrate it is able to rapidly diffuse oxygen at room temperature under laser exposure.
Bismuth oxide-based materials have demonstrated exceptional oxygen transport and ion conducting properties, and are a leading material for advanced SOFCs and oxygen separation membranes.
Additionally, they have demonstrated promise for spectrum of technologies, including photocatalysts, multiferroics, and gas sensors.
To synthesize nano-thin R
Nano-thin BixOySez can modulate 2D material properties.
We demonstrated oxygen transport through nano-thin BixOySez by combining it with monolayer transition metal dichalcogenides (TMDs), whose properties are sensitive to the adjacent environment.
We were able to controllably transport oxygen into and out of the interlayer region, thereby reversibly modulating the 2D material's properties higher and lower with high precision.
Further, the changes are confined to the laser spot, enabling submicron patterning.
Our findings indicate BixOySez and the mechanism can be applied to other 2D materials as a generalized method to reversibly and precisely manipulate the properties with submicron spatial resolution.
Two-dimensional (2D) materials have made a notable impact across numerous disparate fields, including superconductivity, quantum information science, DNA sequencing, catalysts, transistors, renewable energy, and COVID-19 sensing. 2D Materials are highly sensitive to their environment, providing a pathway to modulate their properties across wide ranges and tailor them to specific applications. Monolayer TMDs have demonstrated particular promise, in part due to their strong light-matter interaction, stable valley polarization, and bright photoluminescence (PL). Additionally, they contain tightly-bound excitons, which can reside at different valleys within the band structure, due in part to broken inversion symmetry and spin-orbit coupling. These valleys, and excitons therein, can be selectively addressed using circularly polarized light, enabling a host of advanced computing schemes, including valleytronics, twistronics, spintronics, and quantum computing.
Here, we combined BixOySez with different monolayer TMDs (i.e., WSe2 and WS2) to form 2D heterostructures, whose PL can be reversibly modulated using controlled oxygen intercalation and deintercalation into the interlayer region. As oxygen is intercalated (deintercalated), the PL is brightened (darkened), due to changing exciton recombination pathways. The PL evolution follows Fick's 2nd Law of Diffusion, enabling us to measure the oxygen diffusion speed through the BixOySez.
Our findings indicate oxygen diffuses very fast through BixOySez at room temperature under laser exposure (3.11e-18 m¬2 s-1), raising the prospect that it could advance low-temperature SOFC technology and improve syngas production.
Separately, our work suggests BixOySez can be applied generally to 2D materials to precisely manipulate their properties on the submicron scale, raising the possibility for a host of spatially-selective and tunable properties, including long-lived interlayer excitons, magnetism, and ferroelectricity.
Our findings indicate laser exposure in an oxygen atmosphere converts few-layer Bi2Se3 into a nano-thin compound containing a rare R
Our work indicates R
Previous work showed that the interlayer coupling strength of layered materials can be modulated by intercalating oxygen or other compounds.
Below are the fabrication steps for BixOySez.
We demonstrated BixOySez can be fabricated by numerous different methods. Importantly, BixOySez requires a precursor Bi2Se3, which is grown prior to laser-oxygen processing, which is the final fabrication step where the selenium is mostly removed and oxygen is incorporated.
The Bi2Se3 films were grown on 10×10 mm2 c-plane (0001) sapphire (Al2O3) substrates using molecular beam epitaxy (MBE) with base pressure below 5×10-10 Torr. The substrates were initially annealed ex-situ at 1,000° C. under the atmospheric pressure, and ozone cleaned in-situ under 200 Torr of oxygen pressure.
It is then annealed at 600° C. for 20 min in the ultra-high vacuum MBE chamber. Individual sources of high-purity (99.999%) Bi and Se were evaporated from standard effusion cells during the film growth.
Se flux was maintained at least ten times higher than Bi's to minimize Se vacancies.
To obtain an atomically sharp interface between the Bi2Se3 layer and the substrate, we adopted the two-step growth scheme. First, the initial 3 QL Bi2Se3 is grown at 170° C. It is slowly annealed to 300° C., and followed by deposition of the remaining 2QL Bi2Se3 layers. 5QL Bi2Se3 was grown.
Monolayer TMDs are synthesized at ambient pressure in 2-inch diameter quartz tube furnaces on SiO2/Si substrates (275 nm thickness of SiO2).
Separate dedicated furnaces are used for the growth of WS2 and WSe2 to prevent cross contamination. Prior to use, all SiO2/Si substrates are cleaned in acetone, IPA, and Piranha etch (H2SO4+H2O2) then thoroughly rinsed in DI water. At the center of the furnace is positioned a quartz boat containing ˜1 g of WO3 powder. Two SiO2/Si wafers are positioned face-down, directly above the oxide precursor. A separate quartz boat containing the appropriate chalcogen powder (S or Se) is placed upstream, outside the furnace-heating zone, for the synthesis of WS2 or WSe2.
The upstream SiO2/Si wafer contains perylene-3,4,9,10-tetracarboxylic acid tetrapotassium salt (PTAS) seeding molecules, while the downstream substrate is untreated. The hexagonal PTAS molecules are carried downstream to the untreated substrate and promote lateral growth of the monolayer TMD.
Pure argon (65 sccm) is used as the furnace heats to the target temperature. Upon reaching the target temperature in the range of 825 to 875° C., 10 sccm H2 is added to the Ar flow and maintained throughout the 10-minute soak and subsequent cooling to room temperature.
Bi2Se3 was grown on top of the monolayer TMDs (i.e., WS2 and WSe2) using chemical vapor deposition (CVD) in a two-zone furnace with a 2″ quartz tube.
High-purity Bi2Se3 flakes are ground using a mortar and pestle into a fine dust. The powdered Bi2Se3 is placed in a ceramic boat and inserted into the furnace's quartz tube, and pushed into the center of the furnace's first zone. The monolayer TMD, which is on an SiO2 substrate, is placed downstream of the Bi2Se3 into the center of the furnace's second zone. The furnace is pumped down to ˜20 mTorr. An argon (Ar) carrier gas is flown into the furnace at 80 sccm.
The Bi2Se3 is heated to 520° C. (550° C.), and the WS2 (WSe2) are heated to 210° C. (245° C.). The ramp rate is ˜55° C./min, and the total growth is 27 min (14 min).
Laser-oxygen processing and heat processing to transform Bi2Se3 into BixOySez.
Applied a low-power 532 nm laser (>2.7 μW and >0.12 μW/μm2) in an environment containing oxygen, transformed Bi2Se3 into BixOySez.
The process can be done with any laser, so long as sufficient energy is imparted to raise the temperature of the sample, enabling transformation.
Our work indicates that the same transformation process is possible using heating using a conventional oven in an environment containing oxygen. The partial pressure of the oxygen and laser power determine the rate of transformation, where higher partial pressure and higher powers increase the rate of transformation.
Our work indicates that heating can be substituted for laser power.
Demonstration and Characterization of BixOySez
BixOySez was fabricated on a TEM mesh support, and studied using Raman spectroscopy and scanning transmission electron microscopy energy-dispersive X-ray spectroscopy (STEM-EDS).
Few-layer Bi2Se3—the BixOySez precursor—was grown using molecular beam epitaxy (MBE) and transferred onto a TEM mesh support (see methods). Raman spectroscopy reveals peaks characteristic of few-layer Bi2Se3 (
During laser-air exposure, all the peaks decreased intensity (
Our findings indicate BixOySez exhibits a distinct color from Bi2Se3, enabling laser-patterned areas to be easily identified.
At the edge of each of these holes, we see a clear increase in the oxygen content with a corresponding decrease in selenium. The laser-oxygen-exposed 3×3 grid is also readily observed by the increased oxygen content.
Using the STEM-EDS map in
The change in oxygen (O) and selenium (Se) content correlates with a change in the crystal lattice.
As shown in
The SAED data combine with the STEM-EDS data strongly indicates that the laser-oxygen exposure of the Bi2Se3 is removing Se atoms and replacing them with O atoms, resulting in the production of BixOySez.
STEM-EDS maps of the laser/air exposed Bi2Se3 (
Furthermore, the SAED images show that after laser-air exposure, the hexagonal symmetry of the sample is maintained, while the lattice constant decreases (
These combined results suggest that Se is being removed from the lattice and replaced with oxygen.
To explore this possibility, we used DFT to optimize the lattice constants of a series of monolayer Bi2Se3 crystals in which the selenium atoms are systematically replaced with oxygen atoms (
Demonstration and characterization of BixOySez with a 2D material.
The Bi2Se3 grows at a near ˜0° twist angle, suggesting material interaction is sufficiently strong to steer growth dynamics.
Numerous monolayer TMDs—including WSe2 and WS2—have a direct band gap and tightly-bound excitons, which facilitate a bright PL and strong light matter interaction. The monolayer nature enables the exciton's electric field lines to extend outside the material, making them sensitive to changes in the surrounding dielectric environment. Additionally, they lack an inversion center and contain spin-orbit coupling, enabling valley degree of freedom with valley-dependent optical selection rules, where different band structure valleys—and the spin-dependent excitons therein—can be selectively addressed using circularly polarized light. Together, they are promising materials for a spectrum of optoelectronic and advanced computing applications, including valleytronics, twistronics, spintronics, and quantum information sciences.
We next showed that the WSe2 PL can be recovered by transforming Bi2Se3 into BixOySez, and intercalating oxygen into the interface.
We demonstrated BixOySez transformation (i.e., initial laser-oxygen exposure) restores the WSe2 PL, due to oxygen transport into the interlayer region, which decouples the materials, enabling radiative exciton recombination. We obtained optical and fluorescence images, respectively, of BixOySez patterned as the letters “NRL” into a Bi2Se3-WSe2 2D heterostructure using laser exposure in air, producing a purple-to-white color change and site-selectable WSe2 PL recovery with submicron (740 nm) resolution. We demonstrated PL spectra at multiple laser-air exposure times, revealing time-dependent evolution of the PL intensity, peak position, and spectra shape.
Our findings indicate BixOySez facilitates oxygen intercalation, which decouples the materials, enabling radiative exciton recombination in WSe2. The spectra contain a peak along with two shoulders, suggesting multiple radiative recombination pathways are present, possibly due to various exciton species and phonon side bands.
We measured the PL intensity and peak position evolution, respectively, where each data point is extracted using a robust fitting algorithm written in Python Spyder software, enabling low-error measurements. The spectra are fit with three Lorentzian functions and a linear background, where visual observation and low optimization uncertainty suggest a good fit. The PL intensity evolution is continuous, steadily increasing 43.8× over 342 s (118 data points), demonstrating a continuum of PL values can be accessed. We believe the sporadic deviations (i.e., bumps or indentations that depart from an underlying order) are likely due to chemical and structural changes during the Bi2Se3 to BixOySez transformation. These deviations are not observed in follow-on oxygen deintercalation-intercalation cycles (discussed later). More specifically, in follow-on exposures the PL reliably modulates higher and lower, following Fick's 2nd Law of Diffusion closely. The PL peak position evolution rapidly decreases 23 meV and changes shape during the first 65 s (23 data points), before plateauing and maintaining shape for the remainder of the exposure, a marked departure from the PL intensity evolution.
During the initial phase, the spectra shape appears to evolve from a single exciton fit into a multi exciton fit. The relative intensity, peak position, and FWHM for each Lorentzian evolve as well, thereby changing the spectra shape. Together, our findings suggest the exciton recombination pathways are modified as oxygen is intercalated. Previous work found monolayer WSe2 to have numerous exciton recombination pathways, as well as phonon side bands, which affect spectra shape. Supporting information contains two movies that use all the raw data to display the PL evolution. Control experiments of bare monolayer WSe2 (without BixOySez) under laser-air exposure showed only comparatively very minor changes over 6 min of exposure (<6% increase), demonstrating that BixOySez is required to modulate the TMD PL.
Demonstration of rapid oxygen diffusion at room temperature under laser exposure.
We demonstrated that the PL can be repeatably manipulated higher and lower by intercalating and deintercalating oxygen, where diffusion speeds are atmosphere, pressure, and laser-power dependent. We show the PL intensity and peak position evolution, respectively, from a BixOySez-WSe2 2D heterostructure exposed to multiple atmospheres, pressures, and laser powers. The PL intensity and peak position evolution is dependent on oxygen partial pressure and laser power, which affect the direction and speed of diffusion.
The PL intensity (peak position) are modulated higher (lower) in an atmosphere containing oxygen, but modulated lower (higher) when no oxygen is present. The first laser-air exposure shows an uneven PL intensity curve, due to the Bi2Se3 to BixOySez transformation. In contrast, subsequent laser-atmosphere exposures follow Fick's 2nd Law of Diffusion closely, and without the sporadic deviations observed in the first laser-oxygen exposure. Changes to the peak position are also reversed, where the prominent rapid shift in peak position is consistently observed at low intensities. When sufficient oxygen is deintercalated, BixOySez couples to WSe2, thereby strengthening certain higher-energy exciton recombination pathways.
We demonstrated that a continuum of PL values can be reliably accessed, suggesting the oxygen intercalation can be controlled with high precision. Fluorescence imaging suggests the changes are stable at room temperature in N2 for 221 days.
Together, the technology demonstrates spatially-selective and tunable intensities with write-read-erase-reuse capability and long-term stability.
Fick's 2nd Law of Diffusion—an equation used to describe the change in concentration with respect to time—fits the PL intensity data well, enabling diffusion coefficients to be extracted. We make the ansatz that the PL intensity is proportional to the concentration of oxygen in the interlayer region, and assume fixed concentration boundary conditions at the atmosphere and TMD. When applying boundary conditions, Fick's 2nd Law of Diffusion reduces to Eq. (1), where c is the concentration in the interlayer region, x is the BixOySez thickness, D is the diffusion coefficient, and t is the time. We set x=3 nm based on AFM data (
Considering that the measurements were completed at room-temperature, the material demonstrates exceptionally fast diffusion, suggesting it is a promising low-temperature oxygen transporter for fuel cell applications. A low-temperature laser was used, and no temperature-dependent WSe2 response was detected, suggesting laser heating is minimal (<20° C. change), a conclusion supported by previous work on laser-induced heating in TMDs. For comparison, current SOFC technology operates in excess of 800° C., which impedes wide-spread adoption.
We showed laser-power-dependent data replotted. Very low powers (0.636 μW) have no detectable effect, while low powers (6.26 μW) produce much slower diffusion compared to standard powers (27.0 μW). More specifically, lowering laser power 76.8%, slows desorption 76.5%. As the intensity plateaus toward low values, the PL peak position exhibits quasi-binary behavior, vacillating between the higher (1.605 eV) and lower (1.592 eV) energy states before remaining at the higher value. This behavior is also observed in the 1st and 2nd vacuum evolutions, suggesting the radiative recombination pathways and excitons undergo a notable change at the end.
We fabricated BixOySez on top of monolayer WS2, and demonstrated that the WS2 PL intensity and peak position can be reversibly modulated higher and lower comparable to BixOySez-WSe2, establishing that the effect is not confined to WSe2.
After the initial laser-oxygen exposure, all subsequent exposures followed Fick's 2nd Law of Diffusion closely, suggesting the material's evolution under laser exposure is universal. Very notably, the independently measured diffusion constants are comparable to BixOySez-WSe¬2, despite the fact that the growth recipes and underlying TMDs were different, further validating our proposed mechanism, and the very fast diffusion speeds at room temperature. Previous works showed laser-air exposure of various Bi2Se3-TMD 2D heterostructures could increase PL intensity; however, the mechanism was not understood, and a chemical modification of Bi2Se3 was considered unlikely. Together, the BixOySez-WS¬2 experiments substantially reinforce our claims that BixOySez is a promising room-temperature oxygen transporter, and that it can be harnessed to precisely manipulate the properties of 2D materials in general—not just WSe2 and WS2.
The technology can be used to precisely manipulate their properties on the submicron scale, raising the possibility for spatially-selective and tunable magnetism, long-lived interlayer excitons, ferroelectricity, and integrated quantum photonics. Additionally, if the transport properties are modulated across equivalently large ranges, laser-written p-n junctions, neuromorphic computing schemes, and multistate optoelectronic devices are possible.
The PL evolution follows Fick's 2nd Law of Diffusion, enabling us to measure the oxygen diffusion speed through the BixOySez.
Our findings indicate oxygen diffuses very fast through BixOySez at room temperature under laser exposure (3.11e-18 m2 s−1), raising the prospect that it is a low-temperature oxygen ion conductor. Although other materials and Bi2O3 phases (e.g., δ-Bi2O3) have demonstrated much faster diffusion, they generally require temperatures in excess of 500° C. to be stabilized and efficiently operate, limiting material lifetime and greater adoption. Our measured BixOySez values are several orders of magnitude greater than other room-temperature oxygen transporters. A low-temperature oxygen ion conductor breakthrough would resolve the critical limitation of excessive SOFC operating temperatures, facilitating greater adoption of the technology and renewable energy.
Explanation of intercalation-driven photoluminescence, and application to other 2D materials.
Raman data (
This suggests that the changes in PL are dependent on an interaction with oxygen that does not structurally alter either layer in the heterostructure.
This cycling behavior of the PL is consistent with oxygen intercalating and de-intercalating from between the two layers, consistent with previous work. In the pristine Bi2Se3-WSe2, the WSe2 PL is quenched due to hybridization between the WSe2 valence bands and the Bi2Se3 conduction bands, leading to a non-radiative decay pathway for excited carriers in the WSe2. When oxygen is intercalated between the layers, the layers are physically separated, and the two layers no longer hybridize, suggesting a radiative decay pathway is primary. Supercells of zero-degree aligned Bi2O3-WSe2 bilayers are prohibitively large for computing similar band hybridization in the structurally altered heterostructures. However, the band alignment of Bi2O3 and WSe2 is qualitatively the same as the Bi2Se3-WSe2 band alignment, and the orbital weight at the conduction band minimum in both Bi2Se3 and Bi2O3 is on the Bi pz orbitals. Taken together, these facts suggest that the intercalation of oxygen between Bi2O3 and WSe2 layers would lead to similar changes in hybridization—and thus similarly changes in PL—as are seen in the pristine Bi2Se3/WSe2 heterostructure.
Oxygen transport membranes and oxygen ion conductors have been researched for decades, and there are numerous other materials. We have attempted to concisely summarize the important and applicable discoveries.
Bismuth oxide-based materials have been considered very promising and demonstrated success for decades across the globe; however, the research has focused on bulk bismuth oxide, which often needed to be stabilized using a substrate. Not only is our fabrication process unique, the nano-thin morphology represents a notable step forward.
Oxygen transport membranes are expected to play an important role for CO2 capture and syngas production, where several materials have been demonstrated, including Bi2O3, YxZyOz, Sc2O3, CeO2, and LaGaO3. These materials can also be doped to increase the oxygen transport speed or tailor their properties. Bi2O3 doped with metal oxides such as Y2O3, Gd2O3, Er2O3, Dy2O3, Nb2O5, and Ta2O5, become an oxygen transporter with significantly higher speeds.
In our system material, trace amounts of Se were detected, a novel discovery that raises the possibility the Se facilitates diffusion.
Typically, the prior art Oxygen transport membranes and oxygen ion conductors require very high temperatures, which greatly limits their adoption.
Here, we demonstrate that our material is able to rapidly transport oxygen at or near room temperature, suggesting it could have a notable impact on numerous technologies, including fostering renewable energy.
Of note, the oxygen transport is equivalently fast as other technologies at much higher temperatures (˜500° C.), and several orders of magnitude as other room temperature oxygen transporters.
Oxygen transport membrane with a 2D material.
The system is unique, and, to the best of our knowledge, no one has reported on combining an oxygen transport membrane with a 2D material. However, there have been other technologies that have manipulated 2D materials.
There are many advantages and new features disclosed herein.
Some examples of some advantages of this new material include, but are not limited to, the following.
The oxygen transport through the membrane functions at room temperature, which is ˜800° C. less than SOFC electrolyte materials currently being applied, and ˜500° C. lower than the ideal operating temperature where SOFC are expected to become cost competitive.
For example, lowering the temperature to less than 600° C. enables steel to be used for the interconnects, instead of high-temperature ceramics, greatly lowering cost and increasing resiliancy.
Another advantage includes the material is stable in ambient, whereas other leading oxygen transport membranes require high-temperatures to be stabilized.
Still another advantage includes the fabrication method is highly scalable, requiring only Bi2Se3 as a precursor and low-power laser or heat processing.
Furthermore, the nano-thin morphology allows it to be coupled to 2D materials, enabling oxygen transport into the interlayer region, and subsequent precision control of the interlayer coupling and 2D material properties.
The technology can be used to precisely manipulate their properties on the submicron scale, raising the possibility for spatially-selective and tunable magnetism, long-lived interlayer excitons, ferroelectricity, and integrated quantum photonics.
Additionally, if the transport properties are modulated across equivalently large ranges, laser-written p-n junctions, neuromorphic computing schemes, and multistate optoelectronic devices are possible.
Our technology enables our material to more easily interface with thin films and other nano technology, as it is more flexible and robust than bulk ceramics. Bulk ceramics are inflexible, and can be easily damaged in vibration environments.
The above examples are merely illustrative of several possible embodiments of various aspects of the present disclosure, wherein equivalent alterations and/or modifications will occur to others skilled in the art upon reading and understanding this specification and the annexed drawings. In addition, although a particular feature of the disclosure may have been illustrated and/or described with respect to only one of several implementations, such feature may be combined with one or more other features of the other implementations as may be desired and advantageous for any given or particular application. Also, to the extent that the terms “including”, “includes”, “having”, “has”, “with”, or variants thereof are used in the detailed description and/or in the claims, such terms are intended to be inclusive in a manner similar to the term “comprising”.
This application is a non-provisional of, and claims priority to and the benefits of, U.S. Provisional Patent Application No. 63/313,561 filed on Feb. 24, 2022, the entirety of which is herein incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| 63313561 | Feb 2022 | US |
