Faculty

Publications

Hongmei An, Paul J. McGinn. Catalytic Behavior of Potassium Containing Compounds for Diesel Soot Combustion. Applied Catalysis B, 62:46-56, 2006. view abstract // link Alkali doped oxides were synthesized and tested as catalysts for diesel soot combustion using a combinatorial method. It has been found that potassium shows better promotion of the catalytic activity than other alkali elements, and most of the potassium-rich oxides showed similar catalytic behaviors when catalysts and soot were mixed in a slurry. The influence of different mixing methods, including loose contact, tight contact and slurry (wet) mixing with different soot suspensions, on the catalytic behavior of some transition metal oxides, alkali metal carbonates and potassium-containing oxides were studied through thermogravimetry and XRD. The high activity of potassium-containing catalysts is found to be due to the intimate contact between soot and potassium cations caused by polar solvents. Potassium containing catalysts degraded after repeated thermal cycles due to the loss of potassium. It was also found that the addition of transition elements can inhibit the loss of potassium.

James S. Cooper, Paul J. McGinn. Combinatorial screening of fuel cell cathode catalyst compositions. Applied Surface Science, 254:662-668, 2007. view abstract // link An improved fuel cell cathode catalyst composition was pursued by fabricating and screening thin film combinatorial libraries. Results from the Pt–Ru, Pt–Co–Ti, Pt–Co–Cu and Pt–Co–Cr systems are reported. The discrete composition combinatorial libraries were fabricated by plasma sputtering through shadow masks. Each combinatorial library was tested by cyclic voltammetry in a multichannel electrochemical cell. Compositions were ranked based on the onset potential of the oxygen reduction reaction. Several compositions exhibited better onset potentials than pure Pt. The optimum composition from the Pt–Co–Ti system was Pt44Ti12Co44 but showed signs of corrosion after prolonged testing. A wide range of Pt–Co–Cu compositions also outperformed Pt initially, but ultimately failed due to poor corrosion resistance. Among all of the compositions that were screened, the best performance was demonstrated by Pt28Co36Cr36, with an onset potential 107 mV higher than pure Pt and no sign of corrosion.

James S. Cooper, Min Ku Jeon, Paul J. McGinn. Combinatorial screening of ternary Pt-Ni-Cr catalysts for methanol electro-oxidation. Electrochemistry Communications, 10:1545-1547, 2008. view abstract // link Methanol electro-oxidation activity of ternary Pt–Ni–Cr system was studied by using a combinatorial screening method. A Pt–Ni–Cr thin-film library was prepared by sputtering and quickly characterized by a multichannel multielectrode analyzer. Among the 63 different composition thin-film catalysts, Pt28Ni36Cr36 showed the highest methanol electro-oxidation activity and good stability. This new composition was also studied in its powder form by synthesizing and characterizing Pt28Ni36Cr36/C catalyst. In chronoamperometry testing, the Pt28Ni36Cr36/C catalyst exhibited "decay-free" behavior during 600 s operation by keeping its current density up to 97.1% of its peak current density, while the current densities of Pt/C and Pt50Ru50/C catalysts decreased to 14.0% and 60.3% of their peak current densities, respectively. At 600 s operation, current density of the Pt28Ni36Cr36/C catalyst was 23.8 A gnoble metal−1, while that of those of the Pt/C and Pt50Ru50/C catalysts were 2.74 and 18.8 A gnoble metal−1, respectively.

Min Ku Jeon, Yuan Zhang, Paul J McGinn. Effect of reduction conditions on electrocatalytic activity of a ternary PtNiCr/C catalyst for methanol electro-oxidation. Electrochimica Acta, 54:2837-2842, 2009. view abstract // link The effect of reduction conditions on a Pt28Ni36Cr36/C catalyst was investigated by using two different reduction methods: hydrogen reduction and NaBH4 reduction. In hydrogen reduced catalysts, dissolution of metallic Ni and Cr was observed during cyclic voltammetry (CV) tests, and a larger amount of Ni and Cr was dissolved when reduced at higher temperatures. For methanol electro-oxidation, the highest specific current density of 1.70 A m−2 at 600 s of the chronoamperometry tests was observed in the catalyst reduced at 300 °C, which was not, vert, similar24 times that of a Pt/C catalyst (0.0685 A m−2). In NaBH4 reduced catalysts, formation of an amorphous phase and a more Pt-rich surface was observed in X-ray diffraction and CV results, respectively, with increasing amounts of NaBH4. When reduced by 50 times of the stoichiometric amount of NaBH4, the PtNiCr/C catalyst (PtNiCr-50t) showed a current density of 34.1 A gnoble metal−1, which was 81% higher than the 18.8 A gnoble metal−1 value of a PtRu/C catalyst at 600 s of the chronoamperometry tests. After 13 h of chronoamperometry testing, the activity of the PtNiCr-50t (15.0 A gnoble metal−1) was 110% higher than the PtRu/C catalyst (7.15 A gnoble metal−1). The PtNiCr/C catalyst shows promise as a Ru-free methanol oxidation catalyst.

Hongmei An, Changsheng Su, Paul J. McGinn. Application of Potash Glass as a Catalyst For Diesel Soot Oxidation. Catalysis Communications, 10:509-512, 2009. view abstract // link A novel approach for catalyzing diesel soot oxidation with a potash glass is reported. A simple potash glass (35K2O:2SiO2:13CaO weight ratio) was synthesized and examined for activity for the combustion of diesel soot under various contact and atmospheric conditions by thermogravimetric analysis (TGA). The glass was found to be an effective soot oxidation catalyst. Leaching of potassium from the glass helps to mitigate the effect of potassium loss during combustion, offering an effective means to maintain the surface activity of the glass catalyst, as seen from repeated TGA cycling.

James S. Cooper, Paul J. McGinn. Combinatorial Screening of Thin Film Electrocatalysts for a Direct Methanol Fuel Cell Anode. Journal of Power Sources, 163:330-338, 2006. view abstract // link The Pt-Ru-W and Pt-Ru-Co ternary alloy systems were investigated for use as anode catalysts in direct methanol fuel cells. Plasma sputtering through shadow masks was used to deposit discrete composition combinatorial libraries. Post-deposition annealing promoted multilayer homogenization, with interdiffusion of the layers confirmed by X-ray diffraction. The short term methanol oxidation activities of the different compositions were compared in parallel by cyclic voltammetry with a multichannel electrochemical cell. It was found that the optimum composition changed from initial to final tests. Initially Pt25Ru0W75 and Pt17Ru17Co66 outperformed the best binary Pt-Ru catalyst by 3× and 20×, respectively. Cycling the potential at 60 °C was found to change the performance of some compositions. The performance of Pt-Ru binary catalysts were improved by this conditioning and the optimum ternary compositions shifted to Pt44Ru12W44 and Pt12Ru50Co38. The optimum Pt-Ru-W composition had a peak methanol oxidation current density that was 1.5× more than the best Pt-Ru binary composition. The peak methanol oxidation current density of the best Pt-Ru-Co composition was 2.5× more than the best Pt/Ru binary composition and had a substantially lower onset potential.

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Courses

• CBE 40461 - Structure of Solids - This class seeks to provide students with an understanding of the structure of solids, primarily as found in metals, alloys, and ceramics applied in technological applications. The structure of cry... more >
• CBE 41362 - Laboratory Technology in Materials Science - This course is intended for junior chemical engineering majors who are participating in the materials certificate program. The goal of the course is to introduce students to instrumentation they wi... more >
• CBE 60561 - Structure of Solids - This class seeks to provide students with an understanding of the structure of solids, primarily as found in metals, alloys, and ceramics applied in technological applications. The structure of cry... more >
• CBE 60910 - Selected Topics in Material Processing - This course covers a limited number of materials processing techniques used by materials researchers as well as industrial manufacturers. The primary areas to be covered include thin film processin... more >

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Pulsed laser deposition (PLD) system for synthesis of combinatorial libraries