Irreversible Lattice Expansion Effects in Nanoscale Indium Oxide for CO Hydrogenation Catalysis.

Thermal energy has been considered the exclusive driving force in thermochemical catalysis, yet associated lattice expansion effects have been overlooked. To shed new light on this issue, variable temperature high-resolution (scanning) transmission electron microscopy (HR-(S)TEM) and electron energy-loss spectroscopy (EELS) were employed to provide detailed information on the structural changes of an archetype nanoscale indium oxide materials and how these effects are manifest in reverse water gas shift heterogeneous catalytic reactivity. It is found that with increasing temperature and vacuum conditions, an irreversible surface lattice expansion is traced to the formation and migration of oxygen vacancies.

Microstructure-Dependent Thermal Stability of Super-Tetragonal Nanocomposite Films through TEM/EELS Study.

Smart microstructure design in nanocomposite films allows us to tailor physical properties such as ferroelectricity and thermal stability to broaden applications of next-generation electronic devices. Here, we study the thermal stability of self-assembled PbTiO (PTO)/PbO nanocomposite films with nano-spherical and nanocolumnar microstructures by utilizing an environmental transmission electron microscopy (TEM) combined with electron energy loss spectroscopy (EELS). The real-time study reveals that the microstructure-dependent interphase strain has an effect on the stabilization of the tetragonal phase.

Heterostructure Engineering of a Reverse Water Gas Shift Photocatalyst.

To achieve substantial reductions in CO emissions, catalysts for the photoreduction of CO into value-added chemicals and fuels will most likely be at the heart of key renewable-energy technologies. Despite tremendous efforts, developing highly active and selective CO reduction photocatalysts remains a great challenge. Herein, a metal oxide heterostructure engineering strategy that enables the gas-phase, photocatalytic, heterogeneous hydrogenation of CO to CO with high performance metrics (i.

Nonlinear fracture toughness measurement and crack propagation resistance of functionalized graphene multilayers.

Despite promising applications of two-dimensional (2D) materials, one major concern is their propensity to fail in a brittle manner, which results in a low fracture toughness causing reliability issues in practical applications. We show that this limitation can be overcome by using functionalized graphene multilayers with fracture toughness ( integral) as high as ~39 J/m, measured via a microelectromechanical systems-based in situ transmission electron microscopy technique coupled with nonlinear finite element fracture analysis. The measured fracture toughness of functionalized graphene multilayers is more than two times higher than graphene (~16 J/m).

Photothermal Catalyst Engineering: Hydrogenation of Gaseous CO with High Activity and Tailored Selectivity.

This study has designed and implemented a library of hetero-nanostructured catalysts, denoted as Pd@NbO, comprised of size-controlled Pd nanocrystals interfaced with NbO nanorods. This study also demonstrates that the catalytic activity and selectivity of CO reduction to CO and CH products can be systematically tailored by varying the size of the Pd nanocrystals supported on the NbO nanorods. Using large Pd nanocrystals, this study achieves CO and CH production rates as high as 0.

Role of graphene in enhancing the mechanical properties of TiO/graphene heterostructures.

Graphene has been integrated in many heterogeneous structures in order to take advantage of its superior mechanical properties. However, the complex mechanical response of heterogeneous films incorporating graphene is not well understood. Here, we studied the mechanical behavior of atomic layer deposition (ALD) synthesized TiO/graphene, as a representative building block of a typical composite, to understand the mechanical behavior of heterostructures using an experiment-computational approach.

Visible and Near-Infrared Photothermal Catalyzed Hydrogenation of Gaseous CO over Nanostructured Pd@NbO.

The reverse water gas shift (RWGS) reaction driven by NbO nanorod-supported Pd nanocrystals without external heating using visible and near infrared (NIR) light is demonstrated. By measuring the dependence of the RWGS reaction rates on the intensity and spectral power distribution of filtered light incident onto the nanostructured Pd@NbO catalyst, it is determined that the RWGS reaction is activated photothermally. That is the RWGS reaction is initiated by heat generated from thermalization of charge carriers in the Pd nanocrystals that are excited by interband and intraband absorption of visible and NIR light.

In situ TEM tensile testing of carbon-linked graphene oxide nanosheets using a MEMS device.

This paper reports in situ transmission electron microscopy (TEM) tensile testing of carbon-linked graphene oxide nanosheets using a monolithic TEM compatible microelectromechanical system device. The set-up allows direct on-chip nanosheet thickness mapping, high resolution electron beam linking of a pre-fractured nanosheet, and mechanical tensile testing of the nanosheet. This technique enables simultaneous mechanical and high energy electron beam characterization of 2D nanomaterials.

Photomethanation of Gaseous CO over Ru/Silicon Nanowire Catalysts with Visible and Near-Infrared Photons.

in the presence of H to CH at millimole per hour per gram of catalyst conversion rates, using visible and near-infrared photons. The catalyst used to drive this reaction comprises black silicon nanowire supported ruthenium. These results represent a step towards engineering broadband solar fuels tandem photothermal reactors that enable a three-step process involving i) CO capture, ii) gaseous water splitting into H, and iii) reduction of gaseous CO2 by H.

Periodic mesoporous organosilicas containing interconnected [Si(CH2)]3 rings.

A periodic mesoporous organosilica composed of interconnected three-ring [Si(CH2)]3 units built of three SiO2(CH2)2 tetrahedral subunits is reported. It represents the archetype of a previously unknown class of nanocomposite materials in which two bridging organic groups are bound to each silicon atom. It can be obtained with powder and oriented film morphologies.

Mechanical stability enhancement by pore size and connectivity control in colloidal crystals by layer-by-layer growth of oxide.

Control of the pore size and connectivity of micro-sphere colloidal crystal lattices has been achieved by a layer-by-layer growth of silica using atmospheric pressure room temperature chemical vapour deposition of silica, a method which largely increases the mechanical stability of the lattice without disrupting its long range order.