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Search Publications by Andrei Kolmakov

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Displaying 1 - 25 of 33

Probing Electrified Liquid-Solid Interfaces with Scanning Electron Microscopy

December 2, 2020
Hongxuan Guo, Alexander Yulaev, Evgheni Strelcov, Alexander Tselev, Christopher M. Arble, Andras Vladar, John S. Villarrubia, Andrei A. Kolmakov
The mean free path of secondary electrons in aqueous solutions is on the order of a nanometer, making them a suitable probe of ultrathin electrical double layers at solid-liquid electrolyte interfaces. Employing graphene as an electron-transparent

Electron and x-ray focused beam-induced cross-linking in liquids: Toward rapid continuous 3D nanoprinting and interfacing using soft materials

September 16, 2020
Tanya Gupta, Evgheni Strelcov, Glenn E. Holland, Joshua D. Schumacher, Yang Yang, Mandy B. Esch, Vladimir A. Aksyuk, Patrick Zeller, Matteo Amati, Luca Gregoratti, Andrei A. Kolmakov
Additive fabrication of biocompatible 3D structures out of liquid hydrogel solutions has become pivotal technology for tissue engineering, soft robotics, biosensing, drug delivery etc. Electron and X-ray lithography are well suited to pattern nanoscopic

Extraordinary performance of semiconducting metal oxide gas sensors using dielectric excitation

May 11, 2020
Andrei A. Kolmakov, Radislav A. Potyrailo, Steven Go, Daniel Sexton, Xiaxi Li, Nasr Alkadi, Bruce Amm, Richard St-Pierre, Brian Scherer, Majid Nayeri, Guang Wu, Christopher Collazo-Davila, Doug Forman, Chris Calvert, Craig Mack, Philip Mcconnell
Electrical response of metal oxide semiconducting (MOS) materials to gases was discovered 70 years ago [1] and miniature low-cost MOS chemiresistors became the most popular gas sensors when chemical selectivity is not required [2, 3]. When discrimination

Radiation damage of liquid electrolyte during focused X-ray beam photoelectron spectroscopy

April 12, 2020
Christopher M. Arble, Hongxuan Gou, Evgheni Strelcov, Brian D. Hoskins, Patrick Zeller, Matteo Amati, Luca Gregoratti, Andrei A. Kolmakov
Ambient pressure X-ray photoelectron spectroscopy (APXPS) has become an effective tool to interrogate chemical states at surfaces relevant to real operational conditions. Herein we employ a graphene-capped microvolume array sample platform for scanning

Nanoscale mapping of the double layer potential at the graphene-electrolyte interface

January 28, 2020
Evgheni Strelcov, Christopher M. Arble, Hongxuan Guo, Brian D. Hoskins, Alexander Yulaev, Ivan Vlassiouk, Nikolai B. Zhitenev, Alexander Tselev, Andrei A. Kolmakov
The structure and potential drop across the electrical double layer (EDL) govern the operation of multiple electrochemical devices, determine reaction potentials and condition ion transport through the cellular membranes in living organisms. Despite more

Engineered Sulfur-MoS2-Graphene Heterostructure Cathodes for Diagnostics of Nanoscale Electrochemical Processes in High Energy Density Li-S Batteries

August 5, 2019
Vladimir P. Oleshko, William R. McGehee, Saya Takeuchi, Siyuan Zhang, Andrei A. Kolmakov, Jabez J. McClelland, Christopher L. Soles
Lithium-sulfur (Li-S) batteries have recently attracted enormous attention because of high theoretical specific energy (2600 Wh kg-1) and high specific capacity (1672 mAhg-1), as well as the low cost, natural abundance, and nontoxicity of elemental sulfur

In-situ near-field probe microscopy of plasma processing

December 27, 2018
Alexander Tselev, Jeffrey A. Fagan, Andrei A. Kolmakov
There exists a great necessity for in situ nanoscale characterization of surfaces and thin films during plasma treatments. To address this need, the current approaches rely on either ‘post mortem’ sample microscopy, or in situ optical methods. The latter

In aqua electrochemistry probed by XPEEM: experimental setup, examples, and challenges

November 10, 2018
Slavomir Nemsak, Evgheni Strelcov, Hongxuan Guo, Brian D. Hoskins, Tomas Duchon, D Muller, Alexander Yulaev, Ivan Vlassiouk, Alexander Tselev, Andrei A. Kolmakov
Recent developments in environmental and liquid cells equipped with electron transparent graphene windows have enabled traditional surface science spectromicroscopy tools, such as XPS, PEEM, and SEM to be applied to study solid-liquid and liquid-gas

From Microparticles to Nanowires and Back: Radical Transformations in Plated Li Metal Morphology Revealed via in situ scanning electron microscopy

February 3, 2018
Alexander Yulaev, Vladimir P. Oleshko, Paul M. Haney, Jialin Liu, Yue Qi, Talin Alec, Leite Marina, Andrei A. Kolmakov
Li metal is the preferred anode material for all-solid-state Li batteries due to its high theoretical capacity and low voltage vs. standard hydrogen electrode. However, stable plating and stripping of Li metal in contact with a solid electrolyte at high

Low-temperature thermal reduction of graphene oxide: In situ correlative structural, thermal desorption and electrical transport measurements

January 30, 2018
Alexey Lipatov, Maxime Guinel, Dmitry S. Muratov, Vladislav O. Vanyushin, Peter Wilson, Andrei A. Kolmakov, Alexander Sinitskii
Elucidation of the structural transformations in graphene oxide (GO) upon reduction remains an active and important area of research. We report the results of in situ heating experiments, during which electrical, mass spectrometry, X-ray photoelectron

Interfacial Electrochemistry in Liquids Probed with Photoemission Electron Microscopy

December 20, 2017
Slavomir Nemsak, Evgheni Strelcov, Tomas Duchon, Hongxuan Guo, Johanna Hackl, Alexander Yulaev, Ivan Vlassiouk, David Mueller, Andrei A. Kolmakov
Studies of the electrified solid-liquid interfaces are crucial for understanding of the biological and electrochemical systems. Until recently, the use of photoemission electron microscopy (PEEM) for such purposes has been hampered by the in-compatibility

Stateful characterization of resistive switching TiO2 with electron beam induced currents

December 7, 2017
Brian D. Hoskins, Gina C. Adam, Evgheni Strelcov, Nikolai B. Zhitenev, Andrei A. Kolmakov, Dmitri B. Strukov, Jabez J. McClelland
Metal oxide resistive switches have become increasingly important as possible artificial synapses in next generation neuromorphic networks. Nevertheless, there is still no codified set of tools for studying fundamental properties of the devices. To this

Graphene microcapsule arrays for combinatorial electron microscopy and spectroscopy in liquids

April 27, 2017
Alexander Yulaev, Hongxuan Guo, Evgheni Strelcov, Lei Chen, Ivan Vlasssiouk, Andrei A. Kolmakov
An atomic-scale thickness, molecular impermeability, low atomic number, and mechanical strength make graphene an ideal electron transparent membrane for scanning electron microscopy and spectroscopy in liquids. Here, we present a novel sample platform made

Enabling photoemission electron microscopy in liquids via graphene-capped microchannel arrays

February 8, 2017
Hongxuan Guo, Evgheni Strelcov, Alexander Yulaev, Jian Wang, Narayana Appathurai, Stephen Urquhart, John T. Vinson, Subin Sahu, Michael P. Zwolak, Andrei A. Kolmakov
Photoelectron emission microscopy (PEEM) is a powerful tool to spectroscopically access dynamic surface processes at the nanoscale but is traditionally limited to ultra-high or moderate vacuum conditions. Here, we develop a novel graphene-capped

Imaging and Analysis of Encapsulated Objects through Self-Assembled Electron and Optically Transparent Graphene Oxide Membrane

January 23, 2017
Alexander Yulaev, Alexey Lipatov, Annie Xi Lu, Alexander Sinitskii, Leite Marina, Andrei A. Kolmakov
We demonstrate a technique for facile adhesion and encapsulation of micro- and nano objects on arbitrary substrates, stencils, and micro structured surfaces by ultrathin graphene oxide membranes via a simple drop casting of graphene oxide solution. A

Membrane-Based Environmental Cells for SEM in Liquids

December 1, 2016
Andrei A. Kolmakov
Environmental electron microscopy and Scanning Electron Microscopy (SEM) in liquids are among the most active research areas in modern electron microscopy and spectroscopy. Research interest in these techniques is broad as they are enabling the nanoscale

Fabrication, Testing and Simulation of All Solid State Three Dimensional Li-ion Batteries

November 10, 2016
Talin Alec, Dimitry Ruzmetov, Andrei A. Kolmakov, Kim McKelvey, N Ware, Farid El Gabaly, Bruce Dunn, Henry White
In this paper we demonstrate fully-functional 3D SSLIBs fabricated using materials and thin film deposition methods compatible with semiconductor device processing. These 3D SSLIBs consist of conical or cylindrical Si microcolumns onto which layers

Toward Clean Suspended CVD Graphene

August 26, 2016
Alexander Yulaev, Guangjun Cheng, Angela R. Hight Walker, Ivan Vlassiouk, Alline F. Myers, Marina S. Leite, Andrei A. Kolmakov
The application of suspended graphene as electron transparent supporting media in electron microscopy, vacuum electronics, and micromechanical devices requires the least destructive and maximally clean transfer from their original growth substrate to the

Bridging the Pressure Gap in Electron Beam Induced Current Microscopy: Imaging Charge Transport in Metal Oxide Nanowires under Atmospheric Pressures

July 25, 2016
Ana Stevanovic, Jeyavel Velmurugan, Feng Yi, David A. LaVan, Andrei A. Kolmakov
We developed a versatile environmental cell for ambient pressure scanning electron microscopy (SEM) technique to study the interplay between surface reactivity and electronic properties of metal oxide nanowires such as SnO2, TiO2 and ZnO. We tested