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Date Permissions Signed


Date of Award

Summer 2020

Document Type

Masters Thesis

Department or Program Affiliation


Degree Name

Master of Science (MS)



First Advisor

Bussell, Mark E.

Second Advisor

Berger, Robert F.

Third Advisor

Rider, David A. (Materials scientist)


This thesis work focuses on the synthesis and characterization of photocatalysts composed of metal phosphide nanoparticles on a titania (TiO2) support for the conversion of carbon dioxide (CO2) to carbon monoxide (CO) via the reverse water gas shift (RWGS) reaction. The CO product can be subsequently converted to solar fuels such as methanol (CH3OH), thus lowering the carbon footprint associated with the combustion of liquid fuels. The photocatalysts are composed of a tunable light absorber, indium-gallium phosphide (InxGa1-xP), and nickel phosphide (Ni2P) as a co-catalyst, on TiO2. The photocatalysts are characterized using diffuse reflectance ultraviolet-visible (UV-Vis) spectroscopy to determine band gaps, and methods such as X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS) to probe structure and composition. This combination of characterization techniques allows for synthetic strategies to probe how varying the In/Ga molar ratio affects photocatalyst properties, which leads to tunability in the band gaps of the materials. The Ni2P cocatalyst has been synthesized onto the InxGa1-xP/TiO2, with the expectation that photoexcited electrons will be transferred to Ni2P with sufficient energy to drive the RWGS reaction. The RWGS activity will be tested in a flow reactor system outfitted with a xenon arc lamp as the light source and a gas chromatograph (GC) for determination of CO2 conversion and product selectivity under light and dark conditions at varying reaction temperatures.




Nickel Phosphide, Indium Phosphide, Gallium Phosphide, Titania, photocatalyst, reverse water gas shift, vegard's law, Ni2P, InP, GaP


Western Washington University

OCLC Number


Subject – LCSH

Phosphides--Synthesis; Water-gas--Reactivity; Catalysts--Absorption and adsorption




masters theses




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