523 Chemistry Building
B.S. Lebanon Valley College, 1998
Ph.D. Penn State University, 2001
Honors and Awards:
NSF Graduate Research Fellowship, 1999
NSF CAREER Award, 2006
Beckman Young Investigator Award, 2006
DuPont Young Professor Grant, 2006
Alfred P. Sloan Research Fellow, 2007
Camille Dreyfus Teacher-Scholar Award, 2007
Research Corporation Scialog Award, 2010
National Fresenius Award, 2011
Penn State Faculty Scholar Medal in the Physical Sciences, 2012
S.-I. In, D.D. Vaughn II, and R.E. Schaak, “Hybrid CuO-TiO2-xNx Hollow
Nanocubes for Photocatalytic CO2 Conversion to Methane under Solar
Irradiation,” Angew. Chem. Int. Ed. 2012, in press.
J.F. Bondi, and R.E. Schaak, “A total synthesis framework for the
construction of high-order colloidal hybrid nanoparticles,” Nature
Chemistry 2012, 4, 37-44.
D.D. Vaughn II and R.E. Schaak, “A
Precursor-Limited Nanoparticle Coalescence Pathway for Tuning the
Thickness of Laterally-Uniform Colloidal Nanosheets: The Case of SnSe,”
ACS Nano 2011, 5, 8852-8860.
J.S. Beveridge, M.R. Buck, J.F.
Bondi, R. Misra, P. Schiffer, R.E. Schaak, and M.E. Williams,
“Purification and Magnetic Interrogation of Hybrid Au-Fe3O4 and
FePt-Fe3O4 Nanoparticles,” Angew. Chem. Int. Ed. 2011, 50, 9875-9879.
I.T. Sines and R.E. Schaak, “Phase-Selective Chemical
Extraction of Selenium and Sulfur from Nanoscale Metal Chalcogenides: A General Strategy for Synthesis,
Purification, and Phase Targeting,” J.
Am. Chem. Soc. 2011, 133, 1294-1297.
Vaughn II and R.E. Schaak, “Single Crystal Colloidal Nanosheets of GeS and
GeSe,” J. Am. Chem. Soc. 2010, 132, 15170-15172.
Schaefer, M.L. Gross, M.A. Hickner, and R.E. Schaak, “Uniform Hollow Carbon
Shells: Nanostructured Graphitic
Supports for Improved Oxygen-Reduction Catalysis,” Angew. Chem. Int. Ed. 2010,
I.T. Sines, R. Misra,
P. Schiffer, and R.E. Schaak, “Colloidal Synthesis of Non-Equilibrium
Wurtzite-Type MnSe,” Angew. Chem. Int.
Ed. 2010, 49, 4638-4640.
K.N. Avery, J.E. Schaak, and R.E. Schaak, “M13 Bacteriophage as a Biological
Scaffold for Magnetically-Recoverable Metal Nanowire Catalysts: Combining Specific and Non-Specific
Interactions to Design Multi-Functional Nanocomposites,” Chem. Mater. 2009, 21, 2176-2178.
interests: The intersection of
solid-state chemistry, materials chemistry, molecular inorganic chemistry, and
nanoscience; new low-temperature routes to bulk and nanoscale solid-state
materials, particularly non-equilibrium solids made by direct solution methods,
reactive structural intermediates, and biological templating; mechanistic
studies of nanocrystal reactivity and formation; synthesis and self-assembly of
shape-controlled nanocrystals, including nanocomposites and hybrid systems with
catalytic, magnetic, optical, and superconducting properties.
Synthesis and Applications of
Nanoscale Inorganic Solids
Our research is driven by synthesis – developing new
synthetic methodologies that fill critical gaps in the current toolbox of
techniques available in the solid-state chemistry and nanoscience communities,
and applying these new synthetic tools to important problems in both
fundamental and applied science. In all
of our endeavors, we integrate ideas and techniques from solid-state chemistry,
solution (molecular) chemistry, and nanoscience, and this allows us to tackle
important and often longstanding scientific problems that lie at the interface
between chemistry, physics, materials science, and various engineering
disciplines. Our current focus areas,
which are integrated by the central theme of low-temperature chemical routes to
solid-state materials, are described below.
Low-temperature chemical routes to non-equilibrium solids
The rate-limiting step in traditional solid-state reactions
is solid-solid diffusion, which generally necessitates high reaction
temperatures and usually leads to products that are the most thermodynamically
stable in a particular system. We have
been actively developing alternative low-temperature strategies that side-step
the diffusion problem, with an emphasis on elucidating the reaction pathways
involved in the formation of solid-state materials using these routes. Our focus is on using solution-based nanoparticle
synthesis methods as an alternative low-temperature platform for the synthesis
and discovery of new materials, particularly transition metal intermetallic
compounds and chalcogenides. Some of our
targets are found via focused exploratory investigations, but many are chosen
because of potential technological interest or long-standing fundamental
“Total synthesis” of complex multi-functional inorganic nanostructures
As inorganic nanostructures become more advanced and their
synthesis becomes more mature, the challenges shift toward more complex
materials and architectures than are currently straightforward to prepare. For example, how do we design and synthesize
multi-component nanostructures with controlled and pre-determined compositions,
structures, morphologies, and spatial organization of components, while
simultaneously maintaining robust interfaces (without the use of large organic
or biological molecules to mediate coupling)?
Inspired by organic chemistry, we have been developing “total synthesis”
strategies for the synthesis of complex inorganic nanostructures. The application of ideas such as orthogonal
reactivity, protection/deprotection, and site-specific reactivity (within the
context of all-inorganic solid-state nanostructures) is allowing us to create
exceptionally complex multi-functional nanowires, patterned films, and
nanoparticle heterostructures. Our
target materials will advance applications in sequential multi-step catalysis
and emerging lab-on-a-particle technologies.
Catalytic nanostructures for chemical synthesis and energy applications
Chemical catalysis is an integral component of
pharmaceutical and fine chemical synthesis, as well as facilitating reactions
that will help to meet current and future energy demands. New and improved catalysts can often be
realized by modifying the sizes, morphologies, compositions, structures, and
supports. Simulataneously addressing all
of these issues, which is necessary for achieving optimal performance,
represents a synergistic set of important synthetic challenges. We have been exploring nanostructure design
strategies for improving catalytic performance for the oxygen reduction
reaction (ORR), CO oxidation, direct H2O2 synthesis, and
various hydrogenation and oxidation reactions.
Our efforts focus on catalytic metal nanoparticles and carbon-based
support materials, with a focus on shape-controlled multi-metal nanoparticle
catalysts of non-equilibrium phases that are inspired by model surface studies
and computational investigations.
Colloidal synthesis of size- and shape-controlled nanocrystals
Colloidal routes to many types of size- and shape-controlled
metal and semiconductor nanocrystals have become ubiquitous in recent
years. However, important synthetic
challenges remain. For example, how do
we extend the capabilities developed for benchmark nanomaterials like Au, Ag,
ZnO, CdSe, etc. to early transition metal systems, p-block elements,
non-equilibrium phases, and more complex binary, ternary, and quaternary alloy
phases? How do we achieve similar results
for systems that are chemically challenging to prepare or stabilize, such as
metal phosphides, hydrides, borides, and carbides? Our efforts have centered around the use of
strong reducing agents facilitated by rigorously air-free techniques, as well
as mild low-temperature benchtop strategies.
Biological routes to inorganic solids
Nature facilitates the synthesis of intricate inorganic
nanostructures under ambient conditions, and one of the most significant
current challenges in nanostructure design is to mimic these capabilities
synthetically in “artificial” systems.
To do so requires a detailed understanding of the factors that underpin
the biological templating of inorganic materials, as well as empirical
guidelines for how to achieve the desired results. We have been using M13 bacteriophage as a
biological support for both non-specific and materials-specific templating of
inorganic nanostructures, with a focus on multi-component and
spatially-controllable composite materials with multiple functionalities. Current efforts include expanding the
materials-templating capabilities of M13 bacteriophage, applying the
materials-specific characteristics of polypeptides for applications in
nanoparticle synthesis and assembly, and using proteins and other biomolecules
to direct the synthesis of nanoparticle heterostructures.