Stanislaus Wong's Group
Stanislaus S. Wong
B.Sc., 1994, McGill University; A.M., 1996, Harvard University; Ph.D., 1999, Harvard
University; Postdoctoral Research Associate, Columbia University, 1999-2000; Joint
appointment with the Condensed Matter Physics and Materials Sciences Department, Brookhaven
National Laboratory, 2000-2017. Affiliated member of Biomedical Engineering and Biophysics
programs at SUNY Stony Brook.
631-632-1703; 631-344-3178 (at Brookhaven National Laboratory)
The group’s research has focused on two main areas (namely, nanotube chemistry and
nanostructure synthesis) that will broaden the potential impact and practical applicability
A. Carbon Nanotube (CNT) Functionalization: In this work, we have reacted nanotubes as if there were chemical ligands. Indeed,
the protocols that we have created have significantly enhanced the ability to purify,
exfoliate, process, solubilize, and even render biocompatible CNTs, thereby permitting
more facile photophysical and biomedical applications of these systems. This work
is summarized in a number of invited contributions including
Chem. Eur. J.,
v.9, 1898 (2003),
v.17, 17 (2005),
Chem. Soc. Rev.,
v.21, 682 (2009), as well as
v.21, 625 (2009). By providing new ways to isolate, purify, and functionalize CNTs, our
research is bringing their potential for novel technological uses closer to fruition.
Thus, our research accomplishments address key challenges facing the incorporation
of CNTs into practical, functional devices.
Successful Demonstrations of Carbon Nanotube Functionalization:
(i). Inorganic Systems
(ii). Organic Systems
(iii). Nanotube-Nanocrystal Heterostructures
(iv). Biological Systems
B. Green Nanostructure Synthesis: We have also embarked on developing innovative syntheses of nanotubular, nanorod,
and nanocube formulations of oxide (particularly, technologically significant perovskites)
and fluoride materials. This work is summarized in invited contributions including
v. 46, 8093 (2010),
Chem. Commun., 4598 (2005), and
v.3, 1122 (2007). Specifically, we have implemented viable environmentally friendly synthetic
methodologies in the fabrication of a range of ternary/binary metal oxides, titanates,
fluorides, tungstates, zirconates, and ferrites. In fact, most of our processes run
under either ambient conditions or low temperatures, and can be efficiently scaled
up. Moreover, our simple protocols are generally cost-effective; use mainly nontoxic
precursors; limit the numbers of reagents and reaction steps; minimize waste, reagent
use, and power consumption; and involve the development of high-yield processes with
an absence of volatile and toxic byproducts.
In particular, we have made important advances in the use of molten-salt synthetic
methods, hydrothermal protocols, and ambient template-directed techniques as green,
cost-effective methodologies to generate monodisperse nanostructures with precise
size and shape control without sacrificing on sample quality, purity, and crystallinity.
Our as-prepared nanomaterials maintain fundamentally interesting size-dependent electronic,
optical, and magnetic properties. In terms of applications, these nanostructures have
wide-ranging utility in areas as diverse as catalysis, energy storage, fuel cells,
biomedicine, computation, power generation, photonics, remediation, and sensing.
Successful Demonstrations of Nanoscale Metal & Metal Oxide Synthesis:
(iii). Magnetic Nanostructures
(iv). Perovskite Nanostructures
(v). Titanate Nanostructures
vi). Binary Systems
(vii). Nanostructures for Biological Labeling
(viii). Nanomaterials for Fuel Cells
). Nanomaterials for Batteries
C. Near-edge X-ray absorption fine structure (NEXAFS) Studies of Nanomaterials:
We have recently used synchrotron-based near-edge X-ray absorption fine structure
(NEXAFS) spectroscopy as a particularly useful and effective technique for simultaneously
probing the surface chemistry, surface molecular orientation, degree of order, and
electronic structure of carbon nanotubes and related nanomaterials. This work is summarized
in an invited contribution, namely
v.2, 26 (2006). That is, we employed NEXAFS as an exciting, complementary tool to microscopy
and spectroscopy for providing localized information about single-walled carbon nanotube
and multi-walled carbon nanotube (MWNT) powders, films, and arrays as well as of boron
nitride nanotubes. Specifically, for SWNTs, we analyzed their structure as a function
of oxygenation/oxidation (e.g. comparison of wet-air oxidized, ozonized, and pristine
In additional experiments, we compared the degree of order and alignment in nanotube
powder, film, and aligned samples with those of graphite. Specifically, we analyzed
the surface order of vertically-aligned single-walled and multi-walled carbon nanotube
arrays of varying length and composition by means of NEXAFS. Both NEXAFS and scanning
electron microscopy (SEM) studies concluded that the nanotubes in these samples were
oriented vertically to the plane of the surface. However, NEXAFS polarization analysis
provided for a more quantitative and nuanced description of the surface structure,
indicative of far less localized surface order, an observation partially attributed
to misalignment and bending of the tubes. Moreover, it was demonstrated by NEXAFS
that the surface order of the arrays was imperfect and relatively independent of the
height of the nanotube arrays. Furthermore, we have shown that NEXAFS can be used
to correlate the extent of chemical functionalization and oxygenation with disruption
of the electronic and physical structure of nanotubes embedded in array motifs.
(i). Carbon Nanotubes
(ii). Additional Systems
D. Site-Selective Chemistry Induced by Probe Microscopy Techniques.
Working on the nanometer scale requires the ability to synthesize, manipulate, and
organize matter in a controllable manner as well as to predict and understand the
properties of the resulting structure. One means of synthesizing material at the nanoscale
is to actually create it molecule by molecule. In this regard, novel approaches are
needed to understand surface reactions at a molecular scale. Scanning probe techniques
offer the prospect of manipulating atoms and molecules on surfaces. In this regard,
the project herein described involves using an atomic force microscopy (AFM) tip,
derivatized at the end with a catalytic nanocrystal/powder, to initiate and catalyze
localized nanometer-scale chemical reactions on a surface, one molecule at a time.
In effect, this work takes advantage of the ultralow dimension of the functionalized
tip to catalyze reactions on a single molecule level.
(a). Selective Borohydride Reduction Using Functionalized Atomic Force Microscopy
A powder of a selective reducing agent, sodium triacetoxyborohydride (Na(OAc)
BH), was attached to an AFM tip and used to selectively reduce a monolayer of imines
to their corresponding secondary amines within a well-defined region. Reaction completion
was confirmed using surface mid-IR results and the chloranil test.
, 5055 (2002).
(b). Current-less Photoreactivity Catalyzed by Functionalized AFM Tips
Spatially confined photocatalytic oxidation of a synthetic textile azo dye (Procion
Red MX-5B) was carried out using TiO
-functionalized AFM probes on a homogeneous surface of a synthetic textile dye deposited
on a glass substrate. Reaction process was confirmed through optical microscopy and
AFM images and analyses as well as through surface FT-mid-IR spectroscopy studies.
., (36), 4598 (2005).