Christopher James Brooks

Synthesis, characterization, and photocatalytic properties of ZnO/(La,Sr)CoO3 composite nanorod arrays

ZnO/(La, Sr) CoO3 (ZnO/LSCO) core-shell composite nanorod arrays have been successfully synthesized by a sequential combination process of a hydrothermal synthesis followed by a pulsed laser deposition (PLD) process (or a colloidal deposition process). Compared to the colloidal deposition process, PLD produces a more uniform and efficient deposition of continuous and mesoporous LSCO thin films onto ZnO nanorod arrays. During the PLD process, the deposited film uniformity was found to be dependent on the nanorod diameter, array density, and thus specific surface area of the nanorod arrays, in addition to the PLD deposition parameters. Field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD) were used to investigate the surface morphologies and orientations of the composite nanorod arrays. With densely packed ZnO nanorod arrays as a unique support structure, the mesoporous LSCO thin film coated on top exhibited better photocatalytic properties than ZnO nanorod arrays and LSCO thin films deposited on flat Si substrates. With optimization of the structure, dimensionality, packing density, as well as the composition and interface structure, these unique composite nanoarchitectures could be a promising class of photocatalyst candidates for organic molecule degradation.

High-performance hybrid oxide catalyst of manganese and cobalt for low-pressure methanol synthesis

Carbon dioxide capture and use as a carbon feedstock presents both environmental and industrial benefits. Here we report the discovery of a hybrid oxide catalyst comprising manganese oxide nanoparticles supported on mesoporous spinel cobalt oxide, which catalyses the conversion of carbon dioxide to methanol at high yields. In addition, carbon-carbon bond formation is observed through the production of ethylene. We document the existence of an active interface between cobalt oxide surface layers and manganese oxide nanoparticles by using X-ray absorption spectroscopy and electron energy-loss spectroscopy in the scanning transmission electron microscopy mode. Through control experiments, we find that the catalysts chemical nature and architecture are the key factors in enabling the enhanced methanol synthesis and ethylene production. To demonstrate the industrial applicability, the catalyst is also run under high conversion regimes, showing its potential as a substitute for current methanol synthesis technologies.

The influence of trace water concentration on iron oxide nanoparticle size.

The size of iron oxide nanoparticles, prepared from the thermal decomposition of Fe(CO)(5) in a high boiling solvent in the presence of oleic acid, is affected by water concentration, giving particles from sizes of 5.6 nm to as low as 2.2 nm.

Discovery of Novel Catalytic Materials for Emissions Control Using High Throughput Scanning Mass Spectrometry

High-throughput approaches were applied to the discovery of more efficient catalysts for various applications in emissions control. The screening approach was based on a hierarchy of qualitative or semi-quantitative primary screens for discovery of hits and quantitative secondary screens for confirmation and scale-up of leads. In this work, primary screening was carried out by fast scanning mass spectrometry (SMS) for NO(x) abatement, low temperature CO oxidation, VOC removal, CO(x) methanation and the water gas shift (WGS) reaction.

High Throughput Discovery of Families of High Activity WGS Catalysts: Part I - History and Methodology

State-of-art water gas shift catalysts (FeCr for high temperature shift and CuZn for low temperature shift) are not active enough to be used in fuel processors for the production of hydrogen from hydrocarbon fuels for fuel cells. The need for drastically lower catalyst volumes has triggered a search for novel WGS catalysts that are an order of magnitude more active than current systems. Novel catalytic materials for the high, medium and low temperature water gas shift reactions have been discovered by application of combinatorial methodologies. Catalyst libraries were synthesized on 4 inch wafers in 16 x 16 arrays and screened in a high throughput scanning mass spectrometer in the temperature range 200 degrees C to 400 degrees C. More than 200 wafers were screened under various conditions and more than 250,000 experiments were conducted to comprehensively examine catalyst performance for various binary, ternary and higher-order compositions.