Atomic Scale Responses of High Entropy Oxides to Redox Environments.

The potential of high entropy oxides (HEOs) as high-performance energy storage materials and catalysts has been mainly understood through their bulk structures. However, the importance of their surfaces, which may play an even more critical role, remains largely unknown. In this study, we employed advanced scanning transmission electron microscopy to investigate the atomic-scale structural and chemical responses of CeYLaHfTiZrO HEOs to high-temperature redox environments.

Synthesis of Perdeuterated Alkyl Amines/Amides with Pt/C as Catalyst under Mild Conditions.

A convenient method for the synthesis of perdeuterated alkyl amides/amines is disclosed. Perdeuterated acetyl amides can be achieved by a hydrogen-deuterium (H/D) exchange protocol with Pt/C as a catalyst and DO as a deuterium source under mild conditions. After removal or reduction of the acetyl group, this protocol can provide perdeuterated primary, secondary, and tertiary amines, which are difficult to achieve via other methods.

Active sites of atomically dispersed Pt supported on Gd-doped ceria with improved low temperature performance for CO oxidation.

"Single - atom" catalysts (SACs) have been the focus of intense research, due to debates about their reactivity and challenges toward determining and designing "single - atom" (SA) sites. To address the challenge, in this work, we designed Pt SACs supported on Gd-doped ceria (Pt/CGO), which showed improved activity for CO oxidation compared to its counterpart, Pt/ceria. The enhanced activity of Pt/CGO was associated with a new Pt SA site which appeared only in the Pt/CGO catalyst under CO pretreatment at elevated temperatures.

Hydrogen-mediated polarity compensation on the (110) surface terminations of ABO3 perovskites.

Polar surfaces undergo polarity compensation, which can lead to significantly different surface chemistry from their nonpolar counterparts. This process in turn can substantially alter the binding of adsorbates on the surface. Here, we find that hydrogen binds much more strongly to the polar (110) surface than the nonpolar (100) surface for a wide range of ABO3 perovskites, forming a hydroxyl layer on the O24- termination and a hydride layer on the ABO4+ termination of the (110) surface.

Significant Roles of Surface Hydrides in Enhancing the Performance of Cu/BaTiO H Catalyst for CO Hydrogenation to Methanol.

Tuning the anionic site of catalyst supports can impact reaction pathways by creating active sites on the support or influencing metal-support interactions when using supported metal nanoparticles. This study focuses on CO hydrogenation over supported Cu nanoparticles, revealing a 3-fold increase in methanol yield when replacing oxygen anions with hydrides in the perovskite support (Cu/BaTiO H yields ~146 mg/h/gCu vs. Cu/BaTiO yields ~50 mg/h/gCu).

ALBSNN: ultra-low latency adaptive local binary spiking neural network with accuracy loss estimator.

Spiking neural network (SNN) is a brain-inspired model with more spatio-temporal information processing capacity and computational energy efficiency. However, with the increasing depth of SNNs, the memory problem caused by the weights of SNNs has gradually attracted attention. In this study, we propose an ultra-low latency adaptive local binary spiking neural network (ALBSNN) with accuracy loss estimators, which dynamically selects the network layers to be binarized to ensure a balance between quantization degree and classification accuracy by evaluating the error caused by the binarized weights during the network learning process.

Neutron Scattering Studies of Heterogeneous Catalysis.

Understanding the structural dynamics/evolution of catalysts and the related surface chemistry is essential for establishing structure-catalysis relationships, where spectroscopic and scattering tools play a crucial role. Among many such tools, neutron scattering, though less-known, has a unique power for investigating catalytic phenomena. Since neutrons interact with the nuclei of matter, the neutron-nucleon interaction provides unique information on light elements (mainly hydrogen), neighboring elements, and isotopes, which are complementary to X-ray and photon-based techniques.

Construction of Boron- and Nitrogen-Enriched Nanoporous π-Conjugated Networks Towards Enhanced Hydrogen Activation.

Boron-enriched scaffolds have demonstrated unique features and promising performance in the field of catalysis towards the activation of small gas molecules. However, there is still a lack of facile approaches capable of achieving high B doping and abundant porous channels in the targeted catalysts. Herein, construction of boron- and nitrogen-enriched nanoporous π-conjugated networks (BN-NCNs) was achieved via a facile ionothermal polymerization procedure with hexaazatriphenylenehexacarbonitrile [HAT(CN) ] sodium borohydride as the starting materials.

Engineering a Self-Grown TiO /Ti-MOF Heterojunction with Selectively Anchored High-Density Pt Single-Atomic Cocatalysts for Efficient Visible-Light-Driven Hydrogen Evolution.

A photocatalyst TiO /Ti-BPDC-Pt is developed with a self-grown TiO /Ti-metal-organic framework (MOF) heterojunction, i.e., TiO /Ti-BPDC, and selectively anchored high-density Pt single-atomic cocatalysts on Ti-BPDC for photocatalytic hydrogen evolution.

Ultrasonication-Induced Strong Metal-Support Interaction Construction in Water Towards Enhanced Catalysis.

The development of facile methodologies to afford robust supported metal nanocatalysts under mild conditions is highly desirable yet challenging, particularly via strong metal-support interactions (SMSI) construction. State-of-the-art approaches capable of generating SMSI encapsulation mainly focus on high temperature annealing in reductive/oxidative atmosphere. Herein, ultra-stable metal nanocatalysts based on SMSI construction were produced by leveraging the instantaneous high-energy input from ultrasonication under ambient conditions in H O, which could rapidly afford abundant active intermediates, Ti ions, and oxygen vacancies within the scaffolds to induce the SMSI overlayer formation.

Adsorbate-Induced Strong Metal-Support Interactions: Implications for Catalyst Design.

Since the discovery of strong metal-support interactions (SMSIs) over supported metal catalysts in the 1970s, researchers have studied ways to harness this type of catalyst reconstruction to achieve enhanced stability of metal particles against sintering and to create catalytic sites with novel electronic and bonding properties. The motivation to elucidate performance-structure relationships in catalytic transformations has led researchers to take a closer look into catalytic surfaces under reaction conditions rather than a postreaction analysis. These investigations of operating catalysts have made it clear that SMSIs are more common than initially thought.

Defect Engineering of Ceria Nanocrystals for Enhanced Catalysis via a High-Entropy Oxide Strategy.

Introducing transition-metal components to ceria (CeO) is important to tailor the surface redox properties for a broad scope of applications. The emergence of high-entropy oxides (HEOs) has brought transformative opportunities for oxygen defect engineering in ceria yet has been hindered by the difficulty in controllably introducing transition metals to the bulk lattice of ceria. Here, we report the fabrication of ceria-based nanocrystals with surface-confined atomic HEO layers for enhanced catalysis.

Correction: The synergic effect between Mo species and acid sites in Mo/HMCM-22 catalysts for methane aromatization.

Correction for 'The synergic effect between Mo species and acid sites in Mo/HMCM-22 catalysts for methane aromatization' by Ding Ma , , 2005, , 3102-3109, https://doi.org/10.1039/B502794B.

Measuring and directing charge transfer in heterogenous catalysts.

Precise control of charge transfer between catalyst nanoparticles and supports presents a unique opportunity to enhance the stability, activity, and selectivity of heterogeneous catalysts. While charge transfer is tunable using the atomic structure and chemistry of the catalyst-support interface, direct experimental evidence is missing for three-dimensional catalyst nanoparticles, primarily due to the lack of a high-resolution method that can probe and correlate both the charge distribution and atomic structure of catalyst/support interfaces in these structures. We demonstrate a robust scanning transmission electron microscopy (STEM) method that simultaneously visualizes the atomic-scale structure and sub-nanometer-scale charge distribution in heterogeneous catalysts using a model Au-catalyst/SrTiO-support system.

Manipulating Copper Dispersion on Ceria for Enhanced Catalysis: A Nanocrystal-Based Atom-Trapping Strategy.

Due to tunable redox properties and cost-effectiveness, copper-ceria (Cu-CeO ) materials have been investigated for a wide scope of catalytic reactions. However, accurately identifying and rationally tuning the local structures in Cu-CeO have remained challenging, especially for nanomaterials with inherent structural complexities involving surfaces, interfaces, and defects. Here, a nanocrystal-based atom-trapping strategy to access atomically precise Cu-CeO nanostructures for enhanced catalysis is reported.

Ammonia synthesis on BaTiOH: computational insights into the role of hydrides.

Perovskite oxyhydrides such as BaTiOH have been found to be able to catalyze NH synthesis, but the mechanism and the role of the catalyst's lattice hydrides in the catalytic reaction remain unknown. Here we employ first principles density functional theory to investigate the mechanism of ammonia synthesis and the role of lattice hydrides on a prototypical perovskite oxyhydride, BaTiOH (BTOH). Two mechanistic hypotheses, the distal and alternating pathways, have been tested on the TiO termination of the BTOH (210) surface, previously determined to be the most stable surface termination under the reaction conditions considered.

Machine Learning Method Reveals Hidden Strong Metal-Support Interaction in Microscopy Datasets.

Forming an ultra-thin, permeable encapsulation oxide-support layer on a metal catalyst surface is considered an effective strategy for achieving a balance between high stability and high activity in heterogenous catalysts. The success of such a design relies not only on the thickness, ideally one to two atomic layers thick, but also on the morphology and chemistry of the encapsulation layer. Reliably identifying the presence and chemical nature of such a trace layer has been challenging.