This article reviews the progress made in CO2 separation and capture research and engineering. Various technologies, such as absorption, adsorption, and membrane separation, are thoroughly discussed. New concepts such as chemical-looping combustion and hydrate-based separation are also introduced briefly. Future directions are suggested. Sequestration methods, such as forestation, ocean fertilization and mineral carbonation techniques are also covered. Underground injection and direct ocean dump are not covered.

Progress in carbon dioxide separation and capture: a review.

Porous Inorganic Membranes for CO2 Capture: Present and Prospects

In the past decade, atomic layer deposition (ALD) has become an important thin film deposition technique for applications in nanoelectronics, catalysis, and other areas due to its high conformality...

Synthesis of doped, ternary, and quaternary materials by atomic layer deposition: a review

The overall objective of this project is to develop a simple and inexpensive process to separate carbon dioxide (CO2) as an essentially pure stream from a fossil fuel combustion gases using a regenerable sodium-based sorbent. This objective of this phase of the project is to evaluate CO2 capture using sodium-based sorbents in single-cycle and multicycle tests as a function of calcination and carbonation conditions. The sorbent precursors investigated were sodium bicarbonates supplied by Church and Dwight, Inc., and natural trona supplied by Solvay. All precursors were first calcined to sodium carbonate and then converted to sodium bicarbonate (NaHCO3) or Wegscheider’s salt (Na2CO3•3NaHCO3) through reaction with carbon dioxide and water vapor. Both sodium bicarbonate and Wegscheider’s salt are regenerated to sodium carbonate when heated, producing a nearly pure CO2 stream after condensation of water vapor. An electrobalance reactor (thermogravimetric analyzer) and a fixed-bed reactor system were used to study the reaction rate and achievable sorbent capacity as a function of carbonation temperature, carbonation gas composition, and calcination temperature and atmosphere. Sorbent reproducibility and durability were studied in multi-cycle tests. Electrobalance tests show that sodium bicarbonate (SBC) samples had better performance than Trona samples. Lower carbonation temperature (60C) and higher CO2/H2O concentrations resulted in faster reaction rate and larger sorbent capacity. More severe calcination conditions had a more significant negative effect on Trona than SBC sorbents. In addition, a small amount SO2 (<0.1%) resulted in a cumulative decrease in CO2 removal capacity with increasing carbonation cycle number.

/pdf/carbon-dioxide-capture-from-flue-gas-using-regenerable-17bypdj9yz.pdf

Carbon dioxide capture from flue gas using regenerable sodium-based sorbents

Hydrogen separation from reforming gas using organic templating silica/alumina composite membrane

Enhancing the dielectric constant (k) of conventional gate dielectric materials such as HfO2 and ZrO2 is one of the important requirements for further scaling down of devices in future years. One promising approach for achieving this is to incorporate a specific element in the high-k host material for stabilizing a particular higher-k crystalline phase. Although Ge has been theoretically suggested as a stabilizer for ZrO2, there are no experimental studies correlating the structure of ZrO2 films fabricated by atomic layer deposition (ALD) with their electrical properties. In this work, we systematically investigated the structural and electrical properties of Ge-doped ZrO2 films prepared by ALD. We used germanium butoxide (Ge(OnBu)4) and Zr tris(dimethylamino)cyclopentadienyl zirconium as the Ge and Zr precursors, respectively, with O3 as a reactant. We controlled the ALD cycle ratio using a supercycle process (GeO2/ZrO2 = 1:128, 1:64, 1:32, 1:16, 1:8, 1:4, and 1:2) to produce the alloy films. Electrical properties of these samples were evaluated by measuring the electrical characteristics of metal-oxide-semiconductor (MOS) capacitors based on them, and the results are discussed together with crystallographic analysis. The results revealed that Ge incorporation into ZrO2 induced the stabilization of the cubic/tetragonal phase of the ZrO2 film at low temperatures and improved its dielectric properties. Consequently, this is a systematic and facile method to optimize the dielectric properties of Ge-doped ZrO2 prepared by varying the ALD cycle ratio, and these films could be applied in future nanoscale devices.

Structural and electrical properties of Ge-doped ZrO2 thin films grown by atomic layer deposition for high-k dielectrics

Effects of O2 plasma treatment on moisture barrier properties of SiO2 grown by plasma-enhanced atomic layer deposition

Nanoporous silica composite membranes for gas separation have been synthesized by dip-coating the tetrapropylammonium (TPA)-templating silica sols on tubular alumina supports (pore size 2.8–100 nm), followed by eliminating the template via heat-treating at 550–600°C. The NMR spectroscopy of TPABr-silica hybrid composites obtained from the templated silica sols confirmed that TPA molecules (i.e., final pores) were uniformly distributed in the silica matrix. The average pore size and the specific surface area of an unsupported membrane prepared by firing the TPABr (6 wt%)-silica hybrid composite at 600°C were below 18 A and 830 m2/g, respectively. Any defects such as cracks or pin-holes on the surface of amorphous silica composite membranes were not observed. The CO2/N2 separation factor of their composite membranes varied from 3.2 to 10.3 and their gas permeability from 10−8 to 10−9 mol/m2 · s · Pa depending on the microstructure of aluminar supports.

Organic-templating approach to synthesis of nanoporous silica composite membranes (l): TPA-templating and CO2 separation

We report the hydrogen barrier performance of sputtered La2O3 thin films for the device stability of amorphous indium–gallium–zinc–oxide (a-IGZO) thin-film transistors (TFTs). Hydrogen acts as a shallow donor in a-IGZO films, which makes TFTs conductive, resulting in degradation of their on/off properties. Since hydrogen can be easily incorporated by external environments or post-processing, an appropriate hydrogen barrier is essential for enhancing device stability. La2O3, with its extreme electronegativity, can provide excellent hygroscopic characteristics. Because hydrogen exists in the form of –OH groups inside a-IGZO films, La2O3 is expected to be a promising barrier material for preventing hydrogen incorporation. Therefore, we investigate the growth characteristics of sputtered La2O3 thin films as hydrogen barrier layers, focusing on variations in growth rate, refractive index, and film stress, which depend on various process parameters, such as radio-frequency (RF) power, O2 partial pressure, and substrate temperature during reactive magnetron sputtering. The effects of these parameters on hydrogen barrier properties are systematically investigated and correlated with the microstructures of La2O3 films. The results demonstrate that La2O3 films grown with low RF power and low O2 partial pressure have an amorphous phase and provide excellent hydrogen barrier performance. We anticipate that these experimental results will help improve the environmental stability of a-IGZO TFTs.

Hydrogen barrier performance of sputtered La2O3 films for InGaZnO thin-film transistor

The main issue in developing a quantum dot light-emitting diode (QLED) display lies in successfully replacing heavy metals with environmentally benign materials while maintaining high-quality device performance. Nonradiative Auger recombination is one of the major limiting factors of QLED performance and should ideally be suppressed. This study scrutinizes the effects of the shell structure and composition on photoluminescence (PL) properties of InP/ZnSeS/ZnS quantum dots (QDs) through ensemble and single-dot spectroscopic analyses. Employing gradient shells is discovered to suppress Auger recombination to a high degree, allowing charged QDs to be luminescent comparatively with neutral QDs. The "lifetime blinking" phenomenon is observed as evidence of suppressed Auger recombination. Furthermore, single-QD measurements reveal that gradient shells in QDs reduce spectral diffusion and elevate the energy barrier for charge trapping. Shell composition dependency in the gradience effect is observed. An increase in the ZnS composition (ZnS >50%) in the gradient shell introduces lattice mismatch between the core and the shell and therefore rather reverses the effect and reduces the QD performance.

Yujin Lee

Papers

Structural and electrical properties of Ge-doped ZrO2 thin films grown by atomic layer deposition for high-k dielectrics

Effects of O2 plasma treatment on moisture barrier properties of SiO2 grown by plasma-enhanced atomic layer deposition

Organic-templating approach to synthesis of nanoporous silica composite membranes (l): TPA-templating and CO2 separation

Hydrogen barrier performance of sputtered La2O3 films for InGaZnO thin-film transistor

Effectual Interface and Defect Engineering for Auger Recombination Suppression in Bright InP/ZnSeS/ZnS Quantum Dots.