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Kreller C.R.,Los Alamos National Laboratory | Sekhar P.K.,Washington State University | Li W.,ESL ElectroScience | Palanisamy P.,ESL ElectroScience | And 3 more authors.
ECS Transactions | Year: 2012

Commercial manufacturing methods have been used to fabricate a planar, self-heated, tape-cast, mixed-potential NOx sensor for application in vehicle on-board emission control systems. The device consists of dense La 0.8Sr0.2CrO3 (LSCrO) and Pt electrodes and a porous YSZ electrolyte on one side of a dense ceramic substrate and a Pt-heater with independent leads on the backside of the substrate. These planar mixed-potential sensors are capable of selectively detecting ppm levels of NOx when operated at a positive bias. Additionally, the device has yielded stable performance under months of testing as a result of the stable morphology of the electrode/electrolyte/gas phase interface. © 2012 The Electrochemical Society. Source


Kreller C.R.,Los Alamos National Laboratory | Praveen K.S.,Washington State University | Spernjak D.,Los Alamos National Laboratory | Li W.,ESL ElectroScience | And 4 more authors.
ECS Transactions | Year: 2013

Commercial tape casting and screen-printing methods have been used to fabricate a planar, self-heated, mixed-potential NOx sensor for application in vehicle on-board emission control systems. The device consists of dense La0.8Sr0.2CrO3 (LSCrO) and Pt electrodes and a porous YSZ electrolyte on one side of a dense ceramic substrate and a Pt-heater with independent leads on the backside of the substrate. While these sensors have demonstrated high sensitivity and selectivity to NOx when operated at a positive bias, optimization of the sensor device geometry remains an open question. In this work, we used circular cells of dense YSZ with LSCrO working and Pt counter electrodes in order to identify the impedance response of each individual sensor component. The impedance response measured on the cell was then used to identify the rate-limiting processes underlying the response of the planar sensor device. © 2014 The Electrochemical Society. Source


Sekhar P.K.,Los Alamos National Laboratory | Brosha Eric.L.,Los Alamos National Laboratory | Mukundan R.,Los Alamos National Laboratory | Li W.,ESL ElectroScience | And 3 more authors.
Sensors and Actuators, B: Chemical | Year: 2010

The article details the application of commercial manufacturing methods towards the development of NOx/NH3 sensors for vehicle on-board emissions control. These sensors possess a unique mixed potential sensor design. This unique LANL (Los Alamos National Laboratory) design results in improved sensitivity, selectivity and response time over conventional mixed potential sensors incorporating a stable three-phase interface using a porous electrolyte coated over a dense electrode. A prototype gas sensing platform conducive to large-scale manufacturing and commercialization is also been presented. The observed results indicate the possibility of evolution towards a combined NOx/NH3 sensor on the same platform. Finally, critical challenges towards developing field deployable mixed potential NOx/NH3 sensors are identified and discussed. © 2009 Elsevier B.V. All rights reserved. Source


Kreller C.R.,Los Alamos National Laboratory | Spernjak D.,Los Alamos National Laboratory | Li W.,ESL ElectroScience | Palanisamy P.,ESL ElectroScience | And 3 more authors.
ECS Transactions | Year: 2014

Meeting EPA Tier 3 emissions reduction requirements while simultaneously increasing fuel economy to meet new CAFE standards will require optimization of advanced combustion strategies and emissions control technologies. There is an immediate need for suitable exhaust gas sensor technologies to monitor internal combustion engine tailpipe emissions and to control and maintain efficient operation of the engine and exhaust after treatment systems. NH3, NOx, and HC sensors could enable onboard diagnostics and combustion control in lean-burn engines, analogous to the role of O2 sensors in stoichiometric burn engines. Commercial manufacturing methods have been used to fabricate self-heated mixed-potential sensors in a planar automotive configuration. By altering materials composition and operating conditions, we are able to obtain sensitivity/selectivity to each NH3, NOx and HCs. Additionally, these devices exhibit stable performance over months of testing as a result of the stable morphology of the electrode/electrolyte/gas three-phase interface. © The Electrochemical Society. Source


Li W.,ESL ElectroScience | Palanisamy P.,ESL ElectroScience | Webb R.,ESL ElectroScience | Minh N.,University of California at San Diego
ECS Transactions | Year: 2013

Optimized performance of a fuel cell membrane electrode assembly (MEA) depends on several factors. Key among them are the electrolyte density and the interface between the electrolyte and electrodes (anode and cathode). In this work, SOFC half cells were fabricated by tape casting, lamination, and co-sintering with constraint. These half-cells were then printed with cathode material and re-fired to form the MEA. The effect of both constraint and firing profile were investigated. Optimization of firing profile and constraint load facilitated production of MEA's with minimal camber. Study of these cells, fired in different profiles, displayed that interface issues easily overshadow the effect of electrolyte density with regard to cell performance and stability in use. In addition, infiltration was performed on the as-fabricated single cell samples. The performance of the infiltrated cell conducted in 100% hydrogen as well as in 7.3% ethanol in helium will be presented. © The Electrochemical Society. Source

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