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2.
Dig Dis Sci ; 69(5): 1852-1862, 2024 May.
Article En | MEDLINE | ID: mdl-38514499

BACKGROUND: Early rebleeding is a significant complication of endoscopic treatment for esophagogastric variceal hemorrhage (EGVH). However, a reliable predictive model is currently lacking. AIMS: To identify risk factors for rebleeding within 6 weeks and establish a nomogram for predicting early rebleeding after endoscopic treatment of EVGH. METHODS: Demographic information, comorbidities, preoperative evaluation, endoscopic features, and laboratory tests were collected from 119 patients who were first endoscopic treatment for EGVH. Independent risk factors for early rebleeding were determined through least absolute shrinkage and selection operator logistic regression. The discrimination, calibration, and clinical utility of the nomogram were assessed and compared with the model for end-stage liver disease (MELD), Child-Pugh, and albumin-bilirubin (ALBI) scores using receiver-operating characteristic (ROC) curves, calibration plots, and decision curve analyses (DCA). RESULTS: Early rebleeding occurred in 39 patients (32.8%) within 6 weeks after endoscopic treatment. Independent early rebleeding factors included gastric variceal hemorrhage (GVH), concomitant hepatocellular carcinoma (HCC), international normalized ratio (INR), and creatinine. The nomogram demonstrated exceptional calibration and discrimination capability. The area under the curve for the nomogram was 0.758 (95% CI 0.668-0.848), and it was validated at 0.71 through cross-validation and bootstrapping validation. The DCA and ROC curves demonstrated that the nomogram outperformed the MELD, Child-Pugh, and ALBI scores. CONCLUSIONS: Compared with existing prediction scores, the nomogram demonstrated superior discrimination, calibration, and clinical applicability for predicting rebleeding in patients with EGVH after endoscopic treatment. Therefore, it may assist clinicians in the early implementation of aggressive treatment and follow-up.


Esophageal and Gastric Varices , Gastrointestinal Hemorrhage , Nomograms , Recurrence , Humans , Esophageal and Gastric Varices/surgery , Esophageal and Gastric Varices/diagnosis , Esophageal and Gastric Varices/etiology , Male , Female , Middle Aged , Gastrointestinal Hemorrhage/etiology , Gastrointestinal Hemorrhage/surgery , Gastrointestinal Hemorrhage/diagnosis , Aged , Risk Factors , Retrospective Studies , ROC Curve , Predictive Value of Tests , Adult
3.
J Am Chem Soc ; 146(3): 1926-1934, 2024 Jan 24.
Article En | MEDLINE | ID: mdl-38193748

Dielectric capacitors are highly desired in modern electronic devices and power systems to store and recycle electric energy. However, achieving simultaneous high energy density and efficiency remains a challenge. Here, guided by theoretical and phase-field simulations, we are able to achieve a superior comprehensive property of ultrahigh efficiency of 90-94% and high energy density of 85-90 J cm-3 remarkably in strontium titanate (SrTiO3), a linear dielectric of a simple chemical composition, by manipulating local symmetry breaking through introducing Ti/O defects. Atomic-scale characterizations confirm that these Ti/O defects lead to local symmetry breaking and local lattice strains, thus leading to the formation of the isolated ultrafine polar nanoclusters with varying sizes from 2 to 8 nm. These nanoclusters account for both considerable dielectric polarization and negligible polarization hysteresis. The present study opens a new realm of designing high-performance dielectric capacitors utilizing a large family of readily available linear dielectrics with very simple chemistry.

4.
Science ; 382(6676): 1265-1269, 2023 Dec 15.
Article En | MEDLINE | ID: mdl-38096375

Effective control of heat transfer is vital for energy saving and carbon emission reduction. In contrast to achievements in electrical conduction, active control of heat transfer is much more challenging. Ferroelectrics are promising candidates for thermal switching as a result of their tunable domain structures. However, switching ratios in ferroelectrics are low (<1.2). We report that high-quality antiferroelectric PbZrO3 epitaxial thin films exhibit high-contrast (>2.2), fast-speed (<150 nanoseconds), and long-lifetime (>107) thermal switching under a small voltage (<10 V). In situ reciprocal space mapping and atomistic modelings reveal that the field-driven antiferroelectric-ferroelectric phase transition induces a substantial change of primitive cell size, which modulates phonon-phonon scattering phase space drastically and results in high switching ratio. These results advance the concept of thermal transport control in ferroic materials.

5.
Adv Mater ; 35(42): e2305383, 2023 Oct.
Article En | MEDLINE | ID: mdl-37578079

The heterogeneous nature, local presence, and dynamic evolution of defects typically govern the ionic and electronic properties of a wide variety of functional materials. While the last 50 years have seen considerable efforts into development of new methods to identify the nature of defects in complex materials, such as the perovskite oxides, very little is known about defect dynamics and their influence on the functionality of a material. Here, the discovery of the intermittent behavior of point defects (oxygen vacancies) in oxide heterostructures employing X-ray photon correlation spectroscopy is reported. Local fluctuations between two ordered phases in strained SrCoOx with different degrees of stability of the oxygen vacancies are observed. Ab-initio-informed phase-field modeling reveals that fluctuations between the competing ordered phases are modulated by the oxygen ion/vacancy interaction energy and epitaxial strain. The results demonstrate how defect dynamics, evidenced by measurement and modeling of their temporal fluctuations, give rise to stochastic properties that now can be fully characterized using coherent X-rays, coupled for the first time to multiscale modeling in functional complex oxide heterostructures. The study and its findings open new avenues for engineering the dynamical response of functional materials used in neuromorphic and electrochemical applications.

6.
Scand J Gastroenterol ; 58(11): 1228-1236, 2023.
Article En | MEDLINE | ID: mdl-37317530

BACKGROUND: Rivaroxaban is a direct oral anticoagulant with the highest risk of anticoagulant-induced major gastrointestinal bleeding (MGIB). Currently, there is a lack of tools to identify patients at high risk of rivaroxaban-induced MGIB. OBJECTIVE: To establish a nomogram model to predict the risk of MGIB in patients receiving rivaroxaban. METHODS: Demographic information, comorbidities, concomitant medications, and laboratory test results were collected from 356 patients (178 diagnosed with MGIB) who were taking rivaroxaban between January 2013 and June 2021. Univariate and multivariate logistic regression analyses were used to identify the independent predictors of MGIB, and a nomogram was constructed based on these predictors. A receiver operating characteristic curve, Brier score, calibration plot, decision curve, and internal validation was used to evaluate the calibration, discrimination, and clinical usefulness of the nomogram. RESULTS: Age, haemoglobin level, platelet count, creatinine level, prior peptic ulcer disease, prior bleeding, prior stroke, proton pump inhibitor use, and antiplatelet agent use were independent predictors of rivaroxaban-induced MGIB. These risk factors were used to establish the nomogram. The area under the curve of the nomogram was 0.833 (95%CI, 0.782-0.866), the Brier score was 0.171, the internal validation accuracy was 0.73, and the kappa value was 0.46. CONCLUSION: The nomogram demonstrated good discrimination, calibration, and clinical applicability. Therefore, it could accurately predict the risk of MGIB in patients treated with rivaroxaban.


Peptic Ulcer , Rivaroxaban , Humans , Rivaroxaban/adverse effects , Nomograms , Gastrointestinal Hemorrhage/chemically induced , Anticoagulants/adverse effects , Retrospective Studies
7.
Science ; 379(6638): 1218-1224, 2023 Mar 24.
Article En | MEDLINE | ID: mdl-36952424

Atomic-scale ferroelectrics are of great interest for high-density electronics, particularly field-effect transistors, low-power logic, and nonvolatile memories. We devised a film with a layered structure of bismuth oxide that can stabilize the ferroelectric state down to 1 nanometer through samarium bondage. This film can be grown on a variety of substrates with a cost-effective chemical solution deposition. We observed a standard ferroelectric hysteresis loop down to a thickness of ~1 nanometer. The thin films with thicknesses that range from 1 to 4.56 nanometers possess a relatively large remanent polarization from 17 to 50 microcoulombs per square centimeter. We verified the structure with first-principles calculations, which also pointed to the material being a lone pair-driven ferroelectric material. The structure design of the ultrathin ferroelectric films has great potential for the manufacturing of atomic-scale electronic devices.

8.
Front Pharmacol ; 14: 1304552, 2023.
Article En | MEDLINE | ID: mdl-38273830

Background: Lansoprazole, a proton-pump inhibitor (PPI), is the primary therapy for peptic ulcers (PU). Potassium competitive acid blockers (P-CAB) offer an alternative for acid suppression. However, the efficacy and safety of P-CABs versus lansoprazole in the management of PU has not been evaluated. Methods: Five databases were searched for randomized clinical trials in English until 31 August 2023. Data extraction provided outcome counts for ulcer healing, recurrent NSAID-related ulcer, and adverse events. The pooled effect, presented as rate difference (RD), was stratified by ulcer location, follow-up time, and the types of P-CAB, along with their corresponding 95% confidence intervals (95% CI). Results: The pooled healing rates of peptic ulcers were 95.3% (1,100/1,154) and 95.0% (945/995) for P-CABs and lansoprazole, respectively (RD: 0.4%, 95% CI: -1.4%-2.3%). The lower bounds of the 95% CI fell within the predefined non-inferiority margin of -6%. In subgroup analyses base on ulcer location, and follow-up time also demonstrated non-inferiority. The drug-related treatment-emergent adverse events (TEAEs) did not differ significantly among groups (RR: 0.997, 95% CI: 0.949-1.046, p = 0.893). However, P-CAB treatment was associated with an increased risk of the serious adverse events compared to lansoprazole (RR: 1.325, 95% CI: 1.005-1.747, p = 0.046). Conclusion: P-CABs demonstrated non-inferiority to lansoprazole in the management of peptic ulcer. The safety and tolerability profile are comparable, with similar TEAEs rates. However, P-CABs appear to have a higher risk of serious adverse events. Systematic Review Registration: https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=458361 Identifier: PROSPERO (No. CRD42023458361).

9.
Phys Rev Lett ; 129(23): 235701, 2022 Dec 02.
Article En | MEDLINE | ID: mdl-36563221

Understanding the behavior of defects in the complex oxides is key to controlling myriad ionic and electronic properties in these multifunctional materials. The observation of defect dynamics, however, requires a unique probe-one sensitive to the configuration of defects as well as its time evolution. Here, we present measurements of oxygen vacancy ordering in epitaxial thin films of SrCoO_{x} and the brownmillerite-perovskite phase transition employing x-ray photon correlation spectroscopy. These and associated synchrotron measurements and theory calculations reveal the close interaction between the kinetics and the dynamics of the phase transition, showing how spatial and temporal fluctuations of heterointerface evolve during the transformation process. The energetics of the transition are correlated with the behavior of oxygen vacancies, and the dimensionality of the transformation is shown to depend strongly on whether the phase is undergoing oxidation or reduction. The experimental and theoretical methods described here are broadly applicable to in situ measurements of dynamic phase behavior and demonstrate how coherence may be employed for novel studies of the complex oxides as enabled by the arrival of fourth-generation hard x-ray coherent light sources.

10.
ACS Appl Mater Interfaces ; 14(45): 51096-51104, 2022 Nov 16.
Article En | MEDLINE | ID: mdl-36318085

Antiferroelectric PbZrO3 has attracted renewed interest in recent years because of its unique properties and wide range of potential applications. However, the nature of antiferroelectricity and its evolution with the electric field and temperature remain controversial, mostly due to the difficulty of obtaining high-quality single-crystal samples. The lack of consensus regarding the phase transition in PbZrO3 is not only important on a fundamental side but also greatly hinders further applications. Herein, high-quality PbZrO3 epitaxial thin films are successfully fabricated by pulsed laser deposition. The structural and physical properties of the films are systematically studied via a combination of electric property measurements, X-ray diffraction, scanning transmission electron microscopy imaging, and second-harmonic generation studies. Our studies unveil the noncentrosymmetric nature of PbZrO3 films at room temperature. Moreover, the Curie temperature increased to 270°, ∼40° higher than that in the bulk, and no intermediate ferroelectric phase was observed. Besides, an incipient ferroelectric with relaxor-like behavior above the Curie temperature due to the existence of a local polar cluster in the high-temperature paraelectric phase is experimentally observed for the first time. Our studies provide a better understanding of PbZrO3 thin films and pave the way for practical applications of antiferroelectric material in modern electronic devices.

11.
Front Cardiovasc Med ; 9: 966890, 2022.
Article En | MEDLINE | ID: mdl-36312293

Background: Sortilin, a protein that regulates glucose and lipid metabolism, has recently been linked to cardiovascular diseases (CVDs) such as coronary heart disease and carotid artery stenosis. In this study, we measured circulating sortilin concentrations in essential hypertensive (EH) patients, and evaluated the association between sortilin, hypertension, and subclinical carotid atherosclerosis in hypertensive individuals. Methods: This cross-sectional study included 336 individuals, including 186 newly diagnosed EH patients and 150 age-and-sex-matched normotensive healthy subjects (NT). Plasma sortilin and adiponectin (ADI) levels were measured using ELISA kits. In the EH group, high-resolution B-mode ultrasound was used to detect the existence of subclinical carotid atherosclerosis (subAS), which was defined as having a carotid intima-media thickness (cIMT) ≥ 1.0 mm and/or plaque on the carotid artery without any clinical manifestations. Results: Our findings showed that plasma sortilin concentrations ranged from 3.34-11.34 ng/ml for all subjects. Sortilin levels were significantly higher in the EH group than in the NT group (8.10 ± 1.82 ng/ml vs. 6.37 ± 1.52 ng/ml, P < 0.001) and were further upregulated in the EH with subclinical carotid atherosclerosis (EH + subAS) group compared to the EH without subclinical carotid atherosclerosis (EH-subAS) group (8.42 ± 1.75 ng/ml vs. 7.79 ± 1.84 ng/ml, P < 0.05). In correlation analysis, sortilin was positively correlated with systolic blood pressure (SBP), diastolic blood pressure (DBP), triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), white blood cell (WBC), endothelin-1 (ET-1), high-sensitivity C-reactive protein (hsCRP), interleukin-6 (IL-6), and cIMT (all P < 0.05) and negatively associated with NO and ADI (P < 0.001). Multiple linear regression analysis revealed that SBP, LDL-C, and ET-1 were independently associated with plasma sortilin levels. Increased sortilin levels were independently associated with the risk of EH (OR: 1.86, 95%CI: 1.56-2.20, P < 0.001) and EH + subAS (OR: 1.33, 95%CI: 1.07-1.66, P = 0.011), after adjustment for multiple risk factors. Restricted spline curve showed that elevated sortilin levels increase the odds of having EH. Conclusion: Elevated sortilin levels are associated with an increased risk of essential hypertension and subclinical carotid atherosclerosis in hypertensive patients.

12.
Adv Mater ; 34(35): e2203209, 2022 Sep.
Article En | MEDLINE | ID: mdl-35796130

Neuromorphic computing provides a means for achieving faster and more energy efficient computations than conventional digital computers for artificial intelligence (AI). However, its current accuracy is generally less than the dominant software-based AI. The key to improving accuracy is to reduce the intrinsic randomness of memristive devices, emulating synapses in the brain for neuromorphic computing. Here using a planar device as a model system, the controlled formation of conduction channels is achieved with high oxygen vacancy concentrations through the design of sharp protrusions in the electrode gap, as observed by X-ray multimodal imaging of both oxygen stoichiometry and crystallinity. Classical molecular dynamics simulations confirm that the controlled formation of conduction channels arises from confinement of the electric field, yielding a reproducible spatial distribution of oxygen vacancies across switching cycles. This work demonstrates an effective route to control the otherwise random electroforming process by electrode design, facilitating the development of more accurate memristive devices for neuromorphic computing.


Artificial Intelligence , Neural Networks, Computer , Multimodal Imaging , Oxygen , X-Rays
13.
Clin Appl Thromb Hemost ; 28: 10760296211064897, 2022.
Article En | MEDLINE | ID: mdl-35037779

Whether the use of acid suppressants can reduce non-vitamin K oral anticoagulants (NOACs)-related gastrointestinal bleeding (GIB) remains unclear. To systemically evaluate the effect of acid suppressants on the risk of GIB in patients treated with NOACs. All related studies were searched in four databases (Cochrane, Embase, PubMed, and Web of Science) from their establishment to August 10, 2021. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement was used to identify studies and Stata 16.0 software was used for meta-analysis, including sensitivity and subgroup analysis. Six retrospective cohort studies were included in this study. The use of acid suppressants significantly reduced the GIB risk in patients taking NOACs, with an overall relative risk (RR) of 0.70 (95% confidence interval [CI]: 0.61-0.82; P < 0.001; I2 = 56.3%). This trend of reduced risk for GIB in NOACs was more significant in upper GIB (UGIB; RR: 0.45; 95%CI: 0.22-0.90; P = 0.025; I2 = 71.1%). The reduction was stronger for dabigatran than for rivaroxaban and apixaban. The least reduction in the risk of GIB with acid suppressant co-therapy was rivaroxaban (dabigatran: RR: 0.53; 95% CI: 0.45-0.62; P = <0.001; I2 = 39.8%; apixaban: RR: 0.67; 95% CI: 0.54-0.84; P = <0.001; I2 = 0; rivaroxaban: RR: 0.73; 95% CI: 0.66-0.81; P = <0.001; I2 = 37.6%). The included studies revealed the protective effect of acid suppressants against NOACs-related GIB, especially in the upper gastrointestinal tract. The protective effect was even stronger in patients using dabigatran than in those using Xa inhibitors (rivaroxaban and apixaban).


Anticoagulants/administration & dosage , Atrial Fibrillation/drug therapy , Gastrointestinal Hemorrhage/prevention & control , Administration, Oral , Atrial Fibrillation/complications , Humans , Stroke/etiology , Stroke/prevention & control
14.
Adv Mater ; 34(13): e2108419, 2022 Apr.
Article En | MEDLINE | ID: mdl-35092066

Oxide nanosprings have attracted many research interests because of their anticorrosion, high-temperature tolerance, oxidation resistance, and enhanced-mechanic-response from unique helix structures, enabling various applications like nanomanipulators, nanomotors, nanoswitches, sensors, and energy harvesters. However, preparing oxide nanosprings is a challenge for their intrinsic lack of elasticity. Here, an approach for preparing self-assembled, epitaxial, ferroelectric nanosprings with built-in strain due to the lattice mismatch in freestanding La0.7 Sr0.3 MnO3 /BaTiO3 (LSMO/BTO) bilayer heterostructures is developed. It is found that these LSMO/BTO nanosprings can be extensively pulled or pushed up to their geometrical limits back and forth without breaking, exhibiting super-scalability with full recovery capability. The phase-field simulations reveal that the excellent scalability originates from the continuous ferroelastic domain structures, resulting from twisting under co-existing axial and shear strains. In addition, the oxide heterostructural springs exhibit strong resilience due to the limited plastic deformation nature and the built-in strain between the bilayers. This discovery provides an alternative way for preparing and operating functional oxide nanosprings that can be applied to various technologies.

15.
Small ; 18(3): e2104213, 2022 01.
Article En | MEDLINE | ID: mdl-34816590

Multiferroics with simultaneous electric and magnetic orderings are highly desirable for sensing, actuation, data storage, and bio-inspired systems, yet developing flexible materials with robust multiferroic properties at room temperature is a long-term challenge. Utilizing water-soluble Sr3 Al2 O6 as a sacrificial layer, the authors have successfully self-assembled a freestanding BaTiO3 -CoFe2 O4 heteroepitaxial nanostructure via pulse laser deposition, and confirmed its epitaxial growth in both out-of-plane and in-plane directions, with highly ordered CoFe2 O4 nanopillars embedded in a single crystalline BaTiO3 matrix free of substrate constraint. The freestanding nanostructure enjoys super flexibility and mechanical integrity, not only capable of spontaneously curving into a roll, but can also be bent with a radius as small as 4.23 µm. Moreover, piezoelectricity and ferromagnetism are demonstrated at both microscopic and macroscopic scales, confirming its robust multiferroicity at room temperature. This work establishes an effective route for flexible multiferroic materials, which have the potential for various practical applications.


Nanostructures , Barium Compounds/chemistry , Nanostructures/chemistry , Temperature , Titanium/chemistry
16.
Phys Rev Lett ; 127(11): 117204, 2021 Sep 10.
Article En | MEDLINE | ID: mdl-34558947

Dzyaloshinskii-Moriya interaction in magnets, which is usually derived from inversion symmetry breaking at interfaces or in noncentrosymmetric crystals, plays a vital role in chiral spintronics. Here we report that an emergent Dzyaloshinskii-Moriya interaction can be achieved in a centrosymmetric material, La_{0.67}Sr_{0.33}MnO_{3}, by a graded strain. This strain-driven Dzyaloshinskii-Moriya interaction not only exhibits distinctive two coexisting nonreciprocities of spin-wave propagation in one system, but also brings about a robust room-temperature magnetic skyrmion lattice as well as a spiral lattice at zero magnetic field. Our results demonstrate the feasibility of investigating chiral spintronics in a large category of centrosymmetric magnetic materials.

17.
Nat Commun ; 12(1): 4620, 2021 Jul 30.
Article En | MEDLINE | ID: mdl-34330915

Topologically nontrivial polar structures are not only attractive for high-density data storage, but also for ultralow power microelectronics thanks to their exotic negative capacitance. The vast majority of polar structures emerging naturally in ferroelectrics, however, are topologically trivial, and there are enormous interests in artificially engineered polar structures possessing nontrivial topology. Here we demonstrate reconstruction of topologically trivial strip-like domain architecture into arrays of polar vortex in (PbTiO3)10/(SrTiO3)10 superlattice, accomplished by fabricating a cross-sectional lamella from the superlattice film. Using a combination of techniques for polarization mapping, atomic imaging, and three-dimensional structure visualization supported by phase field simulations, we reveal that the reconstruction relieves biaxial epitaxial strain in thin film into a uniaxial one in lamella, changing the subtle electrostatic and elastostatic energetics and providing the driving force for the polar vortex formation. The work establishes a realistic strategy for engineering polar topologies in otherwise ordinary ferroelectric superlattices.

18.
iScience ; 24(7): 102734, 2021 Jul 23.
Article En | MEDLINE | ID: mdl-34258562

Electric-field (E-field) control of magnetic switching provides an energy-efficient means to toggle the magnetic states in spintronic devices. The angular tunneling magnetoresistance (TMR) of an magnetic tunnel junction (MTJ)/PMN-PT magnetoelectronic hybrid indicates that the angle-dependent switching fields of the free layer can decrease significantly subject to the application of an E-field. In particular, the switching field along the major axis is reduced by 59% from 28.0 to 11.5 Oe as the E-field increases from 0 to 6 kV/cm, while the TMR ratio remains intact. The switching boundary angle decreases (increases) for the parallel (antiparallel) to antiparallel (parallel) state switch, resulting in a shrunk switching window size. The non-volatile and reversible 180° magnetization switching is demonstrated by using E-fields with a smaller magnetic field bias as low as 11.5 Oe. The angular magnetic switching originates from competition among the E-field-induced magnetoelastic anisotropy, magnetic shape anisotropy, and Zeeman energy, which is confirmed by micromagnetic simulations.

19.
ACS Appl Mater Interfaces ; 13(11): 13419-13424, 2021 Mar 24.
Article En | MEDLINE | ID: mdl-33709704

Hydrogenation, an effective way to tune the properties of transition metal oxide (TMO) thin films, has been long awaited to be performed safely and without an external energy input. Recently, metal-acid-TMO has been reported to be an effective approach for hydrogenation, but the requirement of acid limits its application. In this work, the reversible and rapid hydrogen doping of WO3 in NaOH(aq) | Al(s) | WO3(s) is revealed by structural and electrical measurements. Accompanied by the structural phase transition identified by in situ X-ray diffraction, the electric resistance of the WO3 film is found to be able to change by 5 orders of magnitude. A significant electrical response of touching, 8-fold in amplitude and 3 s in a cycle, can be achieved in the low-resistance state. These reactions are reversible at room temperature. This study unambiguously proves that the hydrogenation-driven dynamic phase transition of WO3 in metal-solution-WO3 systems could occur not only in acid solutions but also in some non-acid environments. Unlike the monotonic increase of resistance revealed during HδWO3 to WO3 transition, an intriguing non-monotonic evolution was found for crystal lattice parameter c, indicating that the mechanism of WO3 hydrogenation involves a series of metastable states, more comprehensive and reasonable. This work sheds light on the potential applications of metal-solution-TMO hydrogenation in touching sensors, circuits survey, and information storage.

20.
Sci Adv ; 7(2)2021 Jan.
Article En | MEDLINE | ID: mdl-33523986

The use of renewable electricity to prepare materials and fuels from abundant molecules offers a tantalizing opportunity to address concerns over energy and materials sustainability. The oxygen evolution reaction (OER) is integral to nearly all material and fuel electrosyntheses. However, very little is known about the structural evolution of the OER electrocatalyst, especially the amorphous layer that forms from the crystalline structure. Here, we investigate the interfacial transformation of the SrIrO3 OER electrocatalyst. The SrIrO3 amorphization is initiated by the lattice oxygen redox, a step that allows Sr2+ to diffuse and O2- to reorganize the SrIrO3 structure. This activation turns SrIrO3 into a highly disordered Ir octahedral network with Ir square-planar motif. The final Sr y IrO x exhibits a greater degree of disorder than IrO x made from other processing methods. Our results demonstrate that the structural reorganization facilitated by coupled ionic diffusions is essential to the disordered structure of the SrIrO3 electrocatalyst.

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