1. Rietveld Refinement
Rietveld refinement allows for the calculation of lattice parameters per pattern. Future research will observe how the
nickel content changes the lattice parameters of the nickel-ruthenium crystal.
Synthesis
Nickel phosphide was prepared by depositing a mixture of nickel (II) hyroxide and hypophosphorous acid directly
onto titania/zirconia. A consistent P/Ni molar ratio was prepared while varying the loading of 15 wt. % and 25 wt.%
Ni2P. Following temperature-programmed reduction (TPR), a 1 mol% O2/He mixture was used to create a thin oxide
layer on the surface of the Nickel phosphide particles. This process is called passivation.
+++
The National Science Foundation
Western Washington University Chemistry Department and Advanced Materials
Science and Engineering Center
Bussell Research Group
Acknowledgements
X-Ray Diffraction Analysis
Lower reduction temperatures can be achieved when using phosphorus in the form of hypophosphorous acid
as opposed to Phosphoric acid, because hypophosphorous acid has a lower oxidation state. As a result,
catalyst particle sizes are smaller, and the process is conducive to industry standards.
Phosphoric acid Hypophosphorous acid
Photocatalysis
Ni2P
Ni2P
CO2 + 4H2 CH4 + 2H2O
Future work
FeP
Electrocatalysis
Hydrogen Evolution Reaction
30 40 50 60 70
15 wt.% Ni2
P
Bragg Angle (2)
Ni2P Ref.
25 wt.% Ni2
P
Ni2
P/TiO2
P/Ni = 2
Reduction Temperature: 400C
TiO2
XRD analysis suggests that Ni2P is present on TiO2 and ZrO2. Performing
reductions at higher temperatures (500-600 °C) result in sharper peaks. However
the higher the reduction temperature the larger the catalyst particles, which is
undesirable due to the low surface area to volume ratio that results from high
temperature reductions. The next step is to increase the reduction temperature
to 500°C, in order to strengthen the evidence of the presence of Ni2P on ZrO2 and
TiO2.
30 40 50 60 70
25 wt.% Ni2
P
Bragg Angle (2)
Ni2P Ref.
15 wt.% Ni2
P
ZrO2
Ni2
P/ZrO2
P/Ni = 2.0
Reduction Temperature: 400C
Introduction
Nanoscale metal phosphide particles on metal oxide supports are promising catalysts for hydrodesulfurization (HDS), hydrodenitrogenation (HDN), and
hydrodeoxygenation (HDO) reactions. In recent studies, however, it was shown that metal phosphide catalysts on metal oxide supports can be used for
photocatalysis as well.1 Chemical reactions such as the photocatalytic reduction of CO2 to produce methane can be driven by Ni2P on metal oxide supports
(e.g. TiO2).1 In photocatalysis a photon strikes the support and excites electrons that travel into the metal of the metal phosphide catalyst and can drive a
reduction reaction. Since metal oxide supports have different photocatalytic effects, my task was to explore the effects of two supports: TiO2 and ZrO2.
Currently, platinum is the most widely used catalyst for the hydrogen-evolution reaction, but earth abundant metal phosphides are being explored as an
alternative due to the scarceness and high-cost of platinum. It has been shown that iron (III) phosphide can facilitate both photocatalysis and electrocatalysis
at rates almost as promising as platinum.4
5
Photocatalytic Reactor
Harrick Photocatalytic Reactor
References
1. Sastre, F., Puga, A., Liu, L., Corma, A., Garcia, H. J. Am. Chem. Soc. 2014, 136, 6798-6801.
2. Prins, R., Bussell, M. Catal Lett. 2012, 142: 1413-1436.
3. Munoz-Batista, M., Kubacka, A., Fernandez-Garcia, M. ACS Catal. 2014, 4, 4277-4288
4. Callejas, J., McEnaney, J., Read, G., Crompton, J., Biacchi, A., Popczun, E., Gordon, T.,
Lewis, N., Schaak, R. ACS Nano., 2014, 8:11, 11101-11107.
5. Christopher, P.; Xing, H.; Linic, S. Nature Chemistry 2011, 3, 467 - 491
6. P. Kamat Faculty Webpage,
http://www3.nd.edu/~kamatlab/research_lightEnergyConversion.html,
accessed 06/29/15.
TiO2
Incident photon
Ni2P/TiO2 and Ni2P/ZrO2 for Photocatalysis
Ashraf Faraj and Mark E. Bussell
Department of Chemistry, Western Washington University, Bellingham, WA 98225
6
Western Washington University Department of Geology