The vast majority of theses in this collection are open access and freely available. There are a small number of theses that have access restricted to the WWU campus. For off-campus access to a thesis labeled "Campus Only Access," please log in here with your WWU universal ID, or talk to your librarian about requesting the restricted thesis through interlibrary loan.
Date Permissions Signed
Date of Award
Department or Program Affiliation
Master of Science (MS)
Bussell, Mark E.
Emory, Steven R.
Berger, Robert F.
Converting CO2 to CO via the photocatalyzed reverse water gas shift (RWGS) reaction satisfies a critical step in the production of C1 solar fuels (e.g., CH4, CH3OH) and longer hydrocarbons via the Fischer-Tropsch process. Oxide-supported nickel phosphides (NixPy) are an emerging class of photocatalysts with a number of accessible crystalline phases. Additionally, the broad-spectrum absorption of NixPy materials affords photo-induced local heating to drive catalytic processes at mild operating temperatures. In the current project, NixPy with different P/Ni molar ratios were investigated as RWGS catalysts on two types of support materials: 1) silica (SiO2) as a relatively inert support, and 2) a reducible oxide support (TiO2). NixPy/SiO2 catalysts (2.5 wt%) were synthesized via incipient wetness impregnation followed by temperature-programmed reduction (TPR); crystalline phases (Ni2P, Ni12P5, Ni3P) were identified using X-ray diffraction and compositions were determined by inductively coupled plasma optical emission spectroscopy (ICP-OES), and ongoing RWGS studies were carried out in a batch photoreactor using a Xe lamp (300 W) with the gas composition monitored by gas chromatography. Initial studies were executed using a SiO2 support, which is inactive for the RWGS reaction under light exposure, enabling the photocatalytic properties of the different NixPy phases to be probed. Trends of increasing CO selectivity and decreasing CO2 conversion have emerged as the P/Ni molar ratio increases, while the photo enhancement (light/dark activity ratio) decreases. Studies were then repeated for 2.5 wt% NixPy/TiO2 to evaluate the effect of a reducible oxide support and gain insight on the roles of the support and NixPy-support interface in determining the RWGS photocatalytic properties.
nickel phosphide, reducible oxide, RWGS, heterogeneous catalysis
Western Washington University
Subject – LCSH
Phosphides--Synthesis; Water-gas--Reactivity; Cobalt compounds--Synthesis; Catalysts--Absorption and adsorption
Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this document for commercial purposes, or for financial gain, shall not be allowed without the author’s written permission.
Hennig, Hannah K., "Nickel Phosphide Photothermal Catalyst Development for CO2-Derived Solar Fuels" (2022). WWU Graduate School Collection. 1126.
Available for download on Thursday, August 10, 2023