Juergen Biener

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Papers by Juergen Biener

Electrochemical CO2 to CO reduction at high current densities using a nanoporous gold catalyst

Materials Research Letters

We report on integrating ultrathin monolithic nanoporous gold (npAu) catalyst coatings for CO 2 r... more We report on integrating ultrathin monolithic nanoporous gold (npAu) catalyst coatings for CO 2 reduction in a large electrode area (25 cm 2) electrochemical membrane reactor with gas diffusion electrodes at 100 mA/cm 2. The CO Faraday efficiency increases with increasing thickness, from 65% to 75% and 80% for 1, 5, and 10 layers of npAu leaves where each npAu leaf layer is 100 nm thick. For the one npAu leaf layer configuration, this corresponds to an extremely high CO current density of 955 A/g gold thus demonstrating the potential for commercial applications. IMPACT STATEMENT By device level optimization of catalyst integration we significantly improved the utilization of gold catalysts for electrochemical CO 2 reduction to syngas at industrial relevant current densities of 100 mA/cm 2 .

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Stabilization of a nanoporous NiCu dilute alloy catalyst for non-oxidative ethanol dehydrogenation

Catalysis Science & Technology

In situ and ex situ X-ray photoelectron spectroscopy and electron-microscopy reveal that the stab... more

Interfacial Charge Induced Phenomena in Porous Graphene-Based Bulk Materials

ECS Meeting Abstracts

Mesoporous Graphene-Based Bulk Materials With Hierarchical Morphologies for Energy Applications

ECS Meeting Abstracts

Evolution of steady-state material properties during catalysis: Oxidative coupling of methanol over nanoporous Ag0.03Au0.97

Journal of Catalysis

Integration of Fullerenes as Electron-Acceptors in 3D Graphene Networks: Enhanced Charge Transfer and Stability Through Molecular Design

ACS Applied Materials & Interfaces

Direct Laser Writing of Low-Density Interdigitated Foams for Plasma Drive Shaping

Advanced Functional Materials

Origins and Implications of Interfacial Capacitance Enhancements in C60-Modified Graphene Supercapacitors

ACS Applied Materials & Interfaces

Understanding and controlling the electrical response at a complex electrode-electrolyte interfac... more Understanding and controlling the electrical response at a complex electrode-electrolyte interface is key to the development of next-generation supercapacitors and other electrochemical devices. In this work, we apply a theoretical framework based on the effective screening medium and reference interaction site model to explore the role of electrical double-layer (EDL) formation and its interplay with quantum capacitance in graphene-based supercapacitors. In addition to pristine graphene, we investigate a novel C-modified graphene supercapacitor material, which promises higher charge-storage capacity. Beyond the expected enhancement in the quantum capacitance, we find that the introduction of C molecules significantly alters the EDL response. These changes in EDL are traced to the interplay between surface morphology and charge localization character and ultimately dominate the overall capacitive improvement in the hybrid system. Our study highlights a complex interplay among surface morphology, electronic structure, and interfacial capacitance, suggesting general improvement strategies for optimizing carbon-based supercapacitor materials.

Radiopaque resists for two-photon lithography to enable submicron 3D imaging of polymer parts via X-ray computed tomography

ACS applied materials & interfaces, Jan 24, 2017

Two-photon lithography (TPL) is high-resolution additive manufacturing (AM) technique capable of ... more Two-photon lithography (TPL) is high-resolution additive manufacturing (AM) technique capable of producing arbitrarily complex 3D micro-structures with features two to three orders of magnitude finer than a human hair. This process finds numerous applications as a direct route towards the fabrication of novel optical and mechanical metamaterials, miniaturized optics, microfluidics, biological scaffolds and various other intricate 3D parts. As TPL matures, metrology and inspection become a crucial step in the manufacturing process to ensure that the geometric form of the end-product meets design specifications. X-ray based computed tomography (CT) is a non-destructive technique that can provide this inspection capability for evaluation of complex internal 3D structure. However, polymeric photoresists commonly used for TPL, as well as other forms of stereolithography, poorly attenuate X-rays due to the low atomic number (Z) of their constituent elements and therefore appear relatively...

Multiscale Morphology of Nanoporous Copper Made from Intermetallic Phases

ACS applied materials & interfaces, Jan 2, 2017

Many application-relevant properties of nanoporous metals critically depend on their multiscale a... more Many application-relevant properties of nanoporous metals critically depend on their multiscale architecture. For example, the intrinsically high step-edge density of curved surfaces at the nanoscale provides highly reactive sites for catalysis, whereas the macroscale pore and grain morphology determines the macroscopic properties, such as mass transport, electrical conductivity, or mechanical properties. In this work, we systematically study the effects of alloy composition and dealloying conditions on the multiscale morphology of nanoporous copper (np-Cu) made from various commercial Zn-Cu precursor alloys. Using a combination of X-ray diffraction, electron backscatter diffraction, and focused ion beam cross-sectional analysis, our results reveal that the macroscopic grain structure of the starting alloy surprisingly survives the dealloying process, despite a change in crystal structure from body-centered cubic (Zn-Cu starting alloy) to face-centered cubic (Cu). The nanoscale stru...

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Dynamic restructuring drives catalytic activity on nanoporous gold-silver alloy catalysts

Nature materials, Jan 19, 2016

Bimetallic, nanostructured materials hold promise for improving catalyst activity and selectivity... more Bimetallic, nanostructured materials hold promise for improving catalyst activity and selectivity, yet little is known about the dynamic compositional and structural changes that these systems undergo during pretreatment that leads to efficient catalyst function. Here we use ozone-activated silver-gold alloys in the form of nanoporous gold as a case study to demonstrate the dynamic behaviour of bimetallic systems during activation to produce a functioning catalyst. We show that it is these dynamic changes that give rise to the observed catalytic activity. Advanced in situ electron microscopy and X-ray photoelectron spectroscopy are used to demonstrate that major restructuring and compositional changes occur along the path to catalytic function for selective alcohol oxidation. Transient kinetic measurements correlate the restructuring to three types of oxygen on the surface. The direct influence of changes in surface silver concentration and restructuring at the nanoscale on oxidatio...

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ChemInform Abstract: UHV Study of Hydrogen Atom Induced Etching of Amorphous Hydrogenated Silicon Thin Films

Cheminform, 2010

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Diamond Ablators for Inertial Confinement Fusion

Fusion Science and Technology, 2006

Diamond has a unique combination of physical properties for the inertial confinement fusion ablat... more Diamond has a unique combination of physical properties for the inertial confinement fusion ablator application, such as appropriate optical properties, high atomic density, high yield strength, and high thermal conductivity. Here, we present a feasible concept to fabricate diamond ablator shells. The fabrication of diamond capsules is a multi-step process, which involves diamond chemical vapor deposition on silicon mandrels followed by polishing, microfabrication of holes, and removing of the silicon mandrel by an etch process. We also discuss the pros and cons of coarse-grained optical quality and nanocrystalline chemical vapor deposition diamond films for the ablator application.

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Gold-containing catalyst with porous structure

Evaluating and enhancing quantum capacitance in graphene-based electrodes from first principles

ABSTRACT Graphene derivatives are attractive as supercapacitor electrodes because they are lightw... more ABSTRACT Graphene derivatives are attractive as supercapacitor electrodes because they are lightweight, chemically inert, have high surface area and conductivity, and are stable in electrolyte solutions. Nevertheless, devising reliable strategies for improving energy density relies on an understanding of the specific factors that control electrode performance. We use density-functional theory calculations of pristine and defective graphene to extract quantum capacitance, as well as to identify specific limiting factors. The effect of structural point defects and strain-related morphological changes on the density of states is also evaluated. The results are combined with predicted and measured in situ X-ray absorption spectra in order to give insight into the structural and chemical features present in synthesized carbon aerogel samples.

Nanoporous carbon actuator and methods of use thereof

3D Macroscopic Graphene Assemblies

Nanostructure and Atomic Arrangement, 2016

Solvent-directed sol-gel assembly of 3-dimensional graphene-tented metal oxides and strong synergistic disparities in lithium storage

J. Mater. Chem. A, 2016

The conversion-reaction-based metal oxide/graphene aerogels show much higher capacitive synergy t... more

Method for forming gold-containing catalyst with porous structure

Highly Active Thermally Stable Nanoporous Gold Catalyst

Juergen Biener

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