Selective Activation of Lattice Oxygen Site Through Coordination Engineering to Boost the Activity and Stability of Oxygen Evolution Reaction.

Although Ru-based materials are among the outstanding catalysts for the oxygen evolution reaction (OER), the instability issue still haunts them and impedes the widespread application. The instability of Ru-based OER catalysts is generally ascribed to the formation of soluble species through the over-oxidation of Ru and structural decomposition caused by involvement of lattice oxygen. Herein, an effective strategy of selectively activating the lattice oxygen around Ru site is proposed to improve the OER activity and stability.

A Volcano Correlation between Catalytic Activity for Sulfur Reduction Reaction and Fe Atom Count in Metal Center.

Sulfur reduction reaction (SRR) facilitates up to 16 electrons, which endows lithium-sulfur (Li-S) batteries with a high energy density that is twice that of typical Li-ion batteries. However, its sluggish reaction kinetics render batteries with only a low capacity and cycling life, thus remaining the main challenge to practical Li-S batteries, which require efficient electrocatalysts of balanced atom utilization and site-specific requirements toward highly efficient SRR, calling for an in-depth understanding of the atomic structural sensitivity for the catalytic active sites. Herein, we manipulated the number of Fe atoms in iron assemblies, ranging from single Fe atom to diatomic and triatomic Fe atom groupings, all embedded within a carbon matrix.

Spectroscopic visualization of reversible hydrogen spillover between palladium and metal-organic frameworks toward catalytic semihydrogenation.

Hydrogen spillover widely occurs in a variety of hydrogen-involved chemical and physical processes. Recently, metal-organic frameworks have been extensively explored for their integration with noble metals toward various hydrogen-related applications, however, the hydrogen spillover in metal/MOF composite structures remains largely elusive given the challenges of collecting direct evidence due to system complexity. Here we show an elaborate strategy of modular signal amplification to decouple the behavior of hydrogen spillover in each functional regime, enabling spectroscopic visualization for interfacial dynamic processes.

Tuning Hole Transport Properties and Perovskite Crystallization via Pyridine-Based Molecules for Quasi-2D Perovskite Solar Cells.

Quasi-2D perovskites show great potential as photovoltaic devices with superior stability, but the power conversion efficiency (PCE) is limited by poor carrier transport. Here, it is simultaneously affected the hole transport layer (HTL) and the perovskite layer by incorporating pyridine-based materials into poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) to address the key problem above in 2D perovskites. With this approach, the enhanced optoelectronic performance of the novel PEDOT:PSS is due to electron transfer between the additives and PEDOT or PSS, as well as a dissociation between PEDOT and PSS based on experimental and theoretical studies, which facilitates the charge extraction and transfer.

Artificial neural network for deciphering the structural transformation of condensed ZnO by extended x-ray absorption fine structure spectroscopy.

Pressure-induced structural phase transitions play a pivotal role in unlocking novel material functionalities and facilitating innovations in materials science. Nonetheless, unveiling the mechanisms of densification, which relies heavily on precise and comprehensive structural analysis, remains a challenge. Herein, we investigated the archetypal4 →1 phase transition pathway in ZnO by combining x-ray absorption fine structure (XAFS) spectroscopy with machine learning.

Boosted hydrogen evolution kinetics of heteroatom-doped carbons with isolated Zn as an accelerant.

Carbon-based single-atom catalysts, a promising candidate in electrocatalysis, offer insights into electron-donating effects of metal center on adjacent atoms. Herein, we present a practical strategy to rationally design a model catalyst with a single zinc (Zn) atom coordinated with nitrogen and sulfur atoms in a multilevel carbon matrix. The Zn site exhibits an atomic interface configuration of ZnNS, where Zn's electron injection effect enables thermal-neutral hydrogen adsorption on neighboring atoms, pushing the activity boundaries of carbon electrocatalysts toward electrochemical hydrogen evolution to an unprecedented level.

Ru Single Atoms Integrated into Cobalt Oxide Spinel Structure with Interstitial Carbon for Enhanced Electrocatalytic Water Oxidation.

Oxygen evolution reaction (OER) plays a critical role in energy conversion technologies. Significant progress has been made in alkaline conditions. In contrast, it remains a challenge to develop stable OER electrocatalysts in acidic conditions.

Correlating Structural Disorder in Metal (Oxy)hydroxides and Catalytic Activity in Electrocatalytic Oxygen Evolution.

Understanding the correlation between the structural evolution of electrocatalysts and their catalytic activity is both essential and challenging. In this study, we investigate this correlation in the context of the oxygen evolution reaction (OER) by examining the influence of structural disorder during and after dynamic structural evolution on the OER activity of Fe-Ni (oxy)hydroxide catalysts using operando X-ray absorption spectroscopy, alongside other experiments and theoretical calculations. The Debye-Waller factors obtained from extended X-ray absorption fine structure analyses reflect the degree of structural disorder and exhibit a robust correlation with the intrinsic OER activities of the electrocatalysts.

Reversely Trapping Isolated Atoms in High Oxidation State for Accelerating the Oxygen Evolution Reaction Kinetics.

Developing efficient electrocatalysts for the oxygen evolution reaction (OER) is paramount to the energy conversion and storage devices. However, the structural complexity of heterogeneous electrocatalysts makes it a great challenge to elucidate the dynamic structural evolution and OER mechanisms. Here, we develop a controllable atom-trapping strategy to extract isolated Mo atom from the amorphous MoO -decorated CoSe (a-MoO @CoSe ) pre-catalyst into Co-based oxyhydroxide (Mo-CoOOH) through an ultra-fast self-reconstruction process during the OER process.

Strong metal oxide-support interaction in MoO/N-doped MCNTs heterostructure for boosting lithium storage performance.

The low-rate capability and fast capacity decaying of the molybdenum dioxide anode material have been a bottleneck for lithium-ion batteries (LIBs) due to low carrier transport, drastic volume expansion and inferior reversibility. Furthermore, the lithium-storage mechanism is still controversial at present. Herein, we fabricate a new kind of MoO nanoparticles with nitrogen-doped multiwalled carbon nanotubes (MoO/N-MCNTs) as anode for LIBs.

Toward Highly Selective Heteroatom Dopants in Hard Carbon with Superior Lithium Storage Performance.

Hard carbons (HCs) have gained much attention for next-generation high energy density lithium-ion battery (LIB) anode candidates. However, voltage hysteresis, low rate capability, and large initial irreversible capacity severely affect their booming application. Herein, a general strategy is reported to fabricate heterogeneous atom (N/S/P/Se)-doped HC anodes with superb rate capability and cyclic stability based on a three-dimensional (3D) framework and a hierarchical porous structure.

Approach to electrochemical modulating differential extended X-ray absorption fine structure.

The differential XAFS technique holds promise for detecting surface changes, which benefits many chemical applications. Phase-sensitive detection (PSD) analysis based on modulated excitation spectroscopy experiments is expected to obtain a high-quality difference spectrum, while the mathematical relationship and experiment parameters remain to be discussed. In this article, an approach to obtaining the difference spectrum from the PSD demodulated spectrum is described and its applicability in different experiment settings is discussed.

Direct Synthesis of Stable 1T-MoS Doped with Ni Single Atoms for Water Splitting in Alkaline Media.

Metallic MoS (i.e., 1T-MoS ) is considered as the most promising precious-metal-free electrocatalyst with outstanding hydrogen evolution reaction (HER) performance in acidic media comparable to Pt.

Visible light driven photocatalytic removal of uranium(VI) in strongly acidic solution.

Photocatalytic reduction and removal of toxic uranium(VI) from aqueous solution is a highly economic, non-pollutant and efficient strategy. However, most uranium containing waste waters are highly acidic, but current photocatalysts are still restricted in slightly acidic or neutral media (pH ≥ 4). Herein, a conjugated microporous polymer (CMP), pTTT-Ben, was used for visible light driven photocatalytic reduction of U(VI) in highly acidic condition (pH = 1).

Tritium trapping and migration mechanisms in LiO: a first-principles study.

The tritium recovery behaviors and related mechanisms in lithium-based breeding materials are the major concerns in fusion reactors. In the present work, the energetics of intrinsic point defects and H-related defects in Li2O has been investigated by the first-principles method. The results show that the formation energies, charge states and relative stability of the intrinsic point defects and H-related defects in Li2O under working conditions vary with the energy level.

Bioengineering Bacterially Derived Immunomodulants: A Therapeutic Approach to Inflammatory Bowel Disease.

Bacterial enteric pathogens have evolved efficient mechanisms to suppress mammalian inflammatory and immunoregulatory pathways. By exploiting the evolutionary relationship between the gut and pathogenic bacteria, we have developed a potential mucosal therapeutic. Our findings suggest that engineered preparations of the Salmonella acetyltransferase, AvrA, suppress acute inflammatory responses such as those observed in inflammatory bowel disease (IBD).

First principles investigation of helium physisorption on an α-Al2O3(0001) surface.

The interaction of helium with an α-Al2O3(0001) surface was studied by density functional theory (DFT), with consideration of the effects of He-coverage, surface defects, He-coadsorption and van der Waals interaction, respectively. Adsorption energies of helium atoms are very small as expected for a physisorbed state, varying from -20 to -5 meV, which is attributed to the small overlap between Al 3sp, O 2sp and He 1s states. A correlation is obtained for the adsorption energies and the He to nearest-neighbor Al atom distances on a clean (0001) surface.

An insight to the role of Cr in the process of intrinsic point defects in α-Al2O3.

Cr is a commonly existing impurity in α-Al2O3, and thus the role of Cr in the process of intrinsic point defects in α-Al2O3 has been studied based on first-principle calculations. The results show that Cr has significant influence on the formation, charge state, relative stability and equilibrium configuration of isolated intrinsic point defects in α-Al2O3, resulting in the variation of defect process. Specifically, depending on the O-condition, the possible defect types, the dominant defects and the defect formation energies will be altered in α-Al2O3 after Cr doping.

Helium stability and its interaction with H in α-Al2O3: a first-principles study.

Little is known about hydrogen interaction with helium, an extrinsic defect, present in α-Al2O3 TPBs due to tritium decay and (n, a) reaction. Using density functional theory (DFT), the stability, structure and diffusion of He-related complexes at the different positions (VAl(3-), V, Oi(2-) and octahedral interstitial sites (OISs)) in α-Al2O3, as well as the interactions with H, are determined under H2-rich conditions. A He atom favors occupation of Al vacancies, the centers of OISs or forms a dumbbell around Al vacancies, forming Hei, HeAl(3-), Hei-HeAl(3-), [V-Hei](0) and [Oi(2-)-He](2-) complexes, among of which HeAl(3-) forms most readily.

A new perspective on the process of intrinsic point defects in α-Al₂O₃.

First-principles plane-wave pseudopotential calculations have been performed to study the charge states and energetics of intrinsic point defects as vacancies, interstitials and antisite atoms in α-Al2O3, and thus a new perspective on the process of intrinsic point defects has been proposed. Considering the various charge states for each intrinsic point defects, V(Al)(3-), V(O)(0), Al(i)(3+), O(i)(2-), Al(O)(3+), and O(Al)(3-), not all in their fully ionized states are found to be most stable and in pure Al2O3. From the formation energies of individual point defects, the antisite atom O(Al) will be readily formed in α-Al2O3 in an O-rich environment.

Hydrogen interactions with intrinsic point defects in hydrogen permeation barrier of α-Al₂O₃: a first-principles study.

It is crucial to understand hydrogen interactions with intrinsic point defects in the hydrogen permeation barrier (HPB) of α-Al2O3, finding underlying reasons for the not-so-low H-permeability of the barrier, and thereby produce samples with tailored defects for optimal performance. Using density functional theory (DFT), the formation energies of intrinsic point defects in an α-Al2O3 lattice, including extrinsic H-related defects (H(i), V(Al)-H complex, HO(i) and H(O)), in all possible charged states, are first calculated under HPB working conditions, to determine the dominant basic defect species for hydrogen. We find that the stable forms of H-related defects in α-Al2O3 are charged H interstitials (H(i)(q), where q is the charge state of the defect) and hydrogenation of the bulk V(Al)(3-) ([V(Al)(3-)-H(+)](q)), under hydrogen-rich conditions.

The association of TP53 mutations with the resistance of colorectal carcinoma to the insulin-like growth factor-1 receptor inhibitor picropodophyllin.

Background: There is growing evidence indicating the insulin-like growth factor 1 receptor (IGF-1R) plays a critical role in the progression of human colorectal carcinomas. IGF-1R is an attractive drug target for the treatment of colon cancer. Picropodophyllin (PPP), of the cyclolignan family, has recently been identified as an IGF-1R inhibitor.