Hierarchically Structured Catalysts Toward Sustainable Hydrogen Economy: Electro- and Thermo-Chemical Pathways.

Hydrogen, as an important clean energy source, plays a more and more crucial role in decarbonizing the planet and meeting the global climate challenge due to its high energy density and zero-emission. The demand for sustainable hydrogen is increasing drastically worldwide as driven by the global shift towards low-carbon energy solutions. Thermochemical catalysis process dominates hydrogen production at scale given its relatively mature technology and commercialization status, as well as the established manufacturing infrastructure.

Enhancing sorption kinetics by oriented and single crystalline array-structured ZSM-5 film on monoliths.

To enhance the reaction kinetics without sacrificing activity in porous materials, one potential solution is to utilize the anisotropic distribution of pores and channels besides enriching active centers at the reactive surfaces. Herein, by designing a unique distribution of oriented pores and single crystalline array structures in the presence of abundant acid sites as demonstrated in the ZSM-5 nanorod arrays grown on monoliths, both enhanced dynamics and improved capacity are exhibited simultaneously in propene capture at low temperature within a short duration. Meanwhile, the ZSM-5 array also helps mitigate the long-chain HCs and coking formation due to the enhanced diffusion of reactants in and reaction products out of the array structures.

Unraveling Anisotropic and Pulsating Etching of ZnO Nanorods in Hydrochloric Acid via Correlative Electron Microscopy.

Despite much technical progress achieved so far, the exact surface and shape evolution during wet chemical etching is less unraveled, especially in ionically bonded ceramics. Herein, by using liquid cell transmission electron microscopy, a repeated two-stage anisotropic and pulsating periodic etching dynamic is discovered during the pencil shape evolution of a single crystal ZnO nanorod in aqueous hydrochloric acid. Specifically, the nanopencil tip shrinks at a slower rate along [0001̅] than that along the ⟨101̅0⟩ directions, resulting in a sharper ZnO pencil tip.

Signal Generation, Acquisition, and Processing in Brain Machine Interfaces: A Unified Review.

Brain machine interfaces (BMIs), or brain computer interfaces (BCIs), are devices that act as a medium for communications between the brain and the computer. It is an emerging field with numerous applications in domains of prosthetic devices, robotics, communication technology, gaming, education, and security. It is noted in such a multidisciplinary field, many reviews have surveyed on various focused subfields of interest, such as neural signaling, microelectrode fabrication, and signal classification algorithms.

Low-Concentration NO Gas Analysis Using Single Bimodular ZnO Nanorod Sensor.

Quantitative measurement of the nitrogen oxide mixture (NO, usually of NO and NO) usually relies on sophisticated, space-consuming, and expensive spectroscopy techniques such as gas chromatography (GC), Fourier-transform infrared spectroscopy (FTIR), and chemi-luminescence detection (CLD). The direct and portable measurement solutions are lacking in this regard. In this work, by utilizing the bimodular sensing strategy, we successfully demonstrated the differential measurement of NO with errors smaller than 8.

Toward Long-Term Accurate and Continuous Monitoring of Nitrate in Wastewater Using Poly(tetrafluoroethylene) (PTFE)-Solid-State Ion-Selective Electrodes (S-ISEs).

Long-term accurate and continuous monitoring of nitrate (NO) concentration in wastewater and groundwater is critical for determining treatment efficiency and tracking contaminant transport. Current nitrate monitoring technologies, including colorimetric, chromatographic, biometric, and electrochemical sensors, are not feasible for continuous monitoring. This study addressed this challenge by modifying NO solid-state ion-selective electrodes (S-ISEs) with poly(tetrafluoroethylene) (PTFE, (CF)).

Enhancing ZnO nanowire gas sensors using Au/FeO hybrid nanoparticle decoration.

Heterojunctions are an important strategy for designing high performance electrical sensor materials and related devices. Herein, a new type of metal-semiconductor hybrid nanoparticle has been successfully used to remarkably sensitize the surface of ZnO nanowires for detecting NO with high responses over a broad temperature window ranging from room temperature to 600 °C. These hybrid nanoparticles are comprised of iron oxide nanowires with well dispersed single crystalline Au nanoparticles.

Author Correction: Activating low-temperature diesel oxidation by single-atom Pt on TiO nanowire array.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Activating low-temperature diesel oxidation by single-atom Pt on TiO nanowire array.

Supported metal single atom catalysts (SACs) present an emerging class of low-temperature catalysts with high reactivity and selectivity, which, however, face challenges on both durability and practicality. Herein, we report a single-atom Pt catalyst that is strongly anchored on a robust nanowire forest of mesoporous rutile titania grown on the channeled walls of full-size cordierite honeycombs. This Pt SAC exhibits remarkable activity for oxidation of CO and hydrocarbons with 90% conversion at temperatures as low as ~160 C under simulated diesel exhaust conditions while using 5 times less Pt-group metals than a commercial oxidation catalyst.

Elucidating the Nature of the Cu(I) Active Site in CuO/TiO for Excellent Low-Temperature CO Oxidation.

Stabilized Cu species have been widely considered as catalytic active sites in composite copper catalysts for catalytic reactions with industrial importance. However, few examples comprehensively explicated the origin of stabilized Cu in a low-cost and widely investigated CuO/TiO system. In this study, mass producible CuO/TiO catalysts with interface-stabilized Cu were prepared, which showed excellent low-temperature CO oxidation activity.

Ion-Exchange Loading Promoted Stability of Platinum Catalysts Supported on Layered Protonated Titanate-Derived Titania Nanoarrays.

Supported metal catalysts are one of the major classes of heterogeneous catalysts, which demand good stability in both the supports and catalysts. Herein, layered protonated titanate-derived TiO (LPT-TiO) nanowire arrays were synthesized to support platinum catalysts using different loading processes. The Pt ion-exchange loading on pristine LPTs followed by thermal annealing resulted in superior Pt catalysts supported on the LPT-TiO nanoarrays with excellent hydrothermal stability and catalytic performance toward CO and NO oxidations as compared to the Pt catalysts through wet-impregnation on the anatase TiO (ANT-TiO) nanoarrays resulted from thermal annealing of LPT nanoarrays.

Direct Synthesis of Conformal Layered Protonated Titanate Nanoarray Coatings on Various Substrate Surfaces Boosted by Low-Temperature Microwave-Assisted Hydrothermal Synthesis.

Layered protonated titanates (LPTs) are promising support materials for catalytic applications because their high surface area and cation exchange capacity provide the possibility of achieving a high metal dispersion. However, the reported LPT nanomaterials are mainly limited to free-standing nanoparticles (NPs) and usually require high temperature and pressure conditions with extended reaction time. In this work, a high-throughput microwave-assisted hydrothermal method was developed for the direct synthesis of conformal LPT nanoarray coatings onto the three-dimensional honeycomb monoliths as well as other substrate surfaces at low temperature (75-95 °C) and pressure (1 atm).

Template-Guided Programmable Janus Heteronanostructure Arrays for Efficient Plasmonic Photocatalysis.

Janus heteronanostructures (HNs), as an important class of anisotropic nanomaterials, could facilitate synergistic coupling of diverse functions inherited by their comprised nanocomponents. Nowadays, synthesizing deterministically targeted Janus HNs remains a challenge. Here, a general yet scalable technique is utilized to fabricate an array of programmable Janus HNs based on anodic aluminum oxide binary-pore templates.

Ni- and Mn-Promoted Mesoporous Co3O4: A Stable Bifunctional Catalyst with Surface-Structure-Dependent Activity for Oxygen Reduction Reaction and Oxygen Evolution Reaction.

Efficient bifunctional catalysts for electrochemical oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are highly desirable due to their wide applications in fuel cells and rechargeable metal air batteries. However, the development of nonprecious metal catalysts with comparable activities to noble metals is still challenging. Here we report a one-step wet-chemical synthesis of Ni-/Mn-promoted mesoporous cobalt oxides through an inverse micelle process.

Perovskite Nanoparticle-Sensitized Ga2O3 Nanorod Arrays for CO Detection at High Temperature.

Noble metal nanoparticles are extensively used for sensitizing metal oxide chemical sensors through the catalytic spillover mechanism. However, due to earth-scarcity and high cost of noble metals, finding replacements presents a great economic benefit. Besides, high temperature and harsh environment sensor applications demand material stability under conditions approaching thermal and chemical stability limits of noble metals.

Manganese Oxide Nanoarray-Based Monolithic Catalysts: Tunable Morphology and High Efficiency for CO Oxidation.

A generic one-pot hydrothermal synthesis route has been successfully designed and utilized to in situ grow uniform manganese oxide nanorods and nanowires onto the cordierite honeycomb monolithic substrates, forming a series of nanoarray-based monolithic catalysts. During the synthesis process, three types of potassium salt oxidants have been used with different reduction potentials, i.e.

Bimodular high temperature planar oxygen gas sensor.

A bimodular planar O2 sensor was fabricated using NiO nanoparticles (NPs) thin film coated yttria-stabilized zirconia (YSZ) substrate. The thin film was prepared by radio frequency (r.f.

Monolithically integrated spinel M(x)Co(3-x)O(4) (M=Co, Ni, Zn) nanoarray catalysts: scalable synthesis and cation manipulation for tunable low-temperature CH(4) and CO oxidation.

A series of large scale Mx Co3-x O4 (M=Co, Ni, Zn) nanoarray catalysts have been cost-effectively integrated onto large commercial cordierite monolithic substrates to greatly enhance the catalyst utilization efficiency. The monolithically integrated spinel nanoarrays exhibit tunable catalytic performance (as revealed by spectroscopy characterization and parallel first-principles calculations) toward low-temperature CO and CH4 oxidation by selective cation occupancy and concentration, which lead to controlled adsorption-desorption behavior and surface defect population. This provides a feasible approach for scalable fabrication and rational manipulation of metal oxide nanoarray catalysts applicable at low temperatures for various catalytic reactions.

A review of helical nanostructures: growth theories, synthesis strategies and properties.

Helical nanomaterials represent an emerging group of nanostructures with unique spiral geometry as well as multiple functionalities owing to their enriched physical and chemical properties. With the novel properties enabled by their nanoscale dimension and unique geometry, the helical nanostructures may open opportunities to develop our understanding of new physics, chemistry and biology, and enable new nanodevice design and fabrication. This review article presents a comprehensive and in-depth overview of the latest progress in helical nanostructures synthesis, properties and potential applications.

Hierarchically nanostructured materials for sustainable environmental applications.

This review presents a comprehensive overview of the hierarchical nanostructured materials with either geometry or composition complexity in environmental applications. The hierarchical nanostructures offer advantages of high surface area, synergistic interactions, and multiple functionalities toward water remediation, biosensing, environmental gas sensing and monitoring as well as catalytic gas treatment. Recent advances in synthetic strategies for various hierarchical morphologies such as hollow spheres and urchin-shaped architectures have been reviewed.

Hierarchical assembly of multifunctional oxide-based composite nanostructures for energy and environmental applications.

Composite nanoarchitectures represent a class of nanostructured entities that integrates various dissimilar nanoscale building blocks including nanoparticles, nanowires, and nanofilms toward realizing multifunctional characteristics. A broad array of composite nanoarchitectures can be designed and fabricated, involving generic materials such as metal, ceramics, and polymers in nanoscale form. In this review, we will highlight the latest progress on composite nanostructures in our research group, particularly on various metal oxides including binary semiconductors, ABO(3)-type perovskites, A(2)BO(4) spinels and quaternary dielectric hydroxyl metal oxides (AB(OH)(6)) with diverse application potential.

Low temperature synthesis and characterization of MgO/ZnO composite nanowire arrays.

Large scale dendritic MgO/ZnO composite nanowire arrays have been successfully synthesized on Si substrates using a two-step sequential hydrothermal synthesis at low temperature for the first time. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), and x-ray photoelectron spectroscopy (XPS) were systematically carried out to confirm and elaborate the potentially localized Mg surface alloying process into the ZnO nanowire arrays. Both room temperature and low temperature (40 K) photoluminescence results revealed an enhanced and blue-shifted near-band-edge (NBE) ultraviolet (UV) emission for the MgO/ZnO nanowires compared to those of the pure ZnO nanowire arrays, indicating the success of Mg alloying into ZnO nanowires.

Electronic transport in superlattice-structured ZnO Nanohelix.

Superlattice-structured ZnO nanohelix is a structure that is made of a coiling nanobelt, which is composed of ZnO nanostripes oriented alternatively in two different orientations (Science 2005, 309, 1700). The nanostripes run almost in parallel to the nanobelt direction but at an offset angle of approximately 5 degrees . We have measured the transport properties of a nanohelix and found its abnormal nonlinear characteristic.