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Associate Professor LOH KIAN PING Ph.D. (Oxford), Postdoc (NIMS, Japan) Contact Information:   Department of Chemistry, NUS 3 Science Drive 3 Singapore 117543 Office: S8-05-08 Tel: (65)-6516-4402 Fax: (65)-6779-1691 Email: chmlohkp@nus.edu.sg

Research Interests

Advanced Functional Materials

Introduction

The unifying theme of our research is the synthesis and modification of functional carbon materials for advanced technological applications. A wide range of synthetic methods ranging from chemical vapor deposition to solution phase synthesis were applied to make designer molecules and structures. These designer molecules range from light harvesting organic molecules, to organic-inorganic hybrid films, molecular wires, and new age condensed phase matter like graphene and boron-doped diamond films. These materials were then alloyed or married together at the surfaces and interfaces to make hybrids in order to target advanced technological applications like photovoltaics or sensing. The modifications of the materials often involve surface functionalization for tailor-made applications. Therefore our research strategies are also characterized by methods and concepts that interface physics and chemistry. We routinely apply surface physics techniques like scanning probe microscopy (STM, AFM), high resolution electron energy loss and photoemission spectroscopy and electrochemistry techniques to study chemical problems at the surfaces and interfaces.

Research Topics

Graphene and related materials
Graphene is single atomic sheet of carbon atoms. It presents a new field of NANOchemistry research.

My research program focuses on developing

• Graphene sol-gel chemistry
• Graphene organic chemistry
• Graphene photovoltaics
• Graphene electrochemistry
• Graphene computational chemistry
• Epitaxial Graphene, Electronics and Surface Science

Our program is funded up to 10 million by National Research Foundation Competitive Research Funding.

"We aim to devise new methods to make graphene-related materials using chemical as well as physical means. The physical methods involve the growth of a monolayer of graphite on semiconductors such as silicon carbide. The chemical method involves organic synthesis to make graphene-like organic compounds, as well as the modification of graphene sheets so that it can be dispersed and assembled on substrates and have their band gaps modified."
"The synthesised materials will be investigated by physicists and engineers in our research team for its magnetic and electronic properties. They will also be integrated into specially created device structures for investigating electron transport."

Diamond and Related Materials

Diamond is a solid organic template. It has negative electron affinity, and an intrinsic diamond can undergo insulator-to-metal transition in solution. The material is becoming increasingly important now with the breakthrough in the growth of transparent diamond thin film at close to room temperature using cooking gas (methane). A recent breakthrough in detonation synthesis allows ton quantities of nanodiamond to be made cheaply, allowing many engineering applications to be enabled (eg, drug delivery). Research interests in diamond in K. P. LOH's group include:

• Detonation diamond sol-gel chemistry
• Diamond-organic interface
• Diamond photovoltaics
• Diamond electrochemistry and sensors
• Diamond computational chemistry
• Developing nano-diamond interface

We have unique expertise in the growth and surface modification of diamond thin films.

[Invited speaker, Berlin, GERMANY, Diamond Related Materials conference Sep 2007 ; Invited speaker, MRS symposium P, November Fall Meeting 2007, BOSTON, USA; Invited speaker, Engineering conference International, June Hongkong 2007, Invited speaker, New Diamond and Nanocarbon conference, Taipei, Taiwan, March 2008]

Molecular electronics
Designing and synthesizing new

• Engineering light-harvesting polymers for photovoltaics
• Self-assembly of organometallic-organic wires
• Self-assembly of donor-acceptor hyperbranced dendrimer structures
• Making hybrid organic-inorganic films for photovoltaics

Nanomaterials

• Synthesis of metal oxide and sulfide nanomaterials with novel optical, electronic, and magnetic properties.
• Synthesis of Nanoclustered films using Nanocluster Beam Deposition

Using hydrothermal synthesis, we can prepare high quality ZnO nanorod array on any substrates. We wish to apply these ZnO nanorods as templates for making organic-hybrid solar cell material.
Although the bulk phase of Molybdenum Sulfide is non-magnetic, the generation of nanostructured form of the material with a high density of edge spins can result in magnetism and giant magnetoresistance. This concept of edge-spins driven magnetism may have general validity for a large class of sulfide materials, and can have implications for magnetic semiconductors. We have developed new methods for MoS₂ nanotubule growth from direct CVD of a single source precursor, and discovered report non-linear scattering properties from these MoS₂ nanotubules.
We have constructed a nanocluster beam deposition system for the deposition of metal nanoclusters. Silver nanoclustered films for example provide excellent template for surface enhanced Raman.

SURFACE SCIENCE

The LOH KP laboratory is currently equipped with two STM (1 air, 1 UHV), one HREELS, one XPS/UPS/IPES system, one SCEM system, two electrochemical workstations, one TPD system, one Nanocluster beam deposition system, one Microwave Plasma enhanced CVD system and one IPCE/Solar cell testing station and photovoltaic film fabrication facilities. We are interested in the assembly of organic molecules on metal surfaces, and on the charge transfer and transfer doping between organic molecules and diamond/graphene surfaces.

Selected Publications

NANOMATERIALS

1. Zhang J, Soon JM, Loh KP, et al. Magnetic molybdenum disulfide nanosheet films. NANO LETTERS 7 (8): 2370-2376 (2007)

2. Soon JM, Wang J, Loh KP, Zhong YL, et al. Bifunctional FePt core-shell and hollow spheres: Sonochemical preparation and self-assembly. CHEMISTRY OF MATERIALS 19 (10): 2566-2572 (2007)

3. Adsorption of molecular oxygen on the walls of pristine and carbon-doped (5,5) boron nitride anotubes: Spin-polarized density functional study. Zhang J, Loh KP, Zheng JW, PHYSICAL REVIEW B, 75, 245301 (2007)

4. Dynamical observation of bamboo-like carbon nanotube growth. Lin M, Tan JPY, Boothroyd C, K.P. Loh et. al., NANO LETTERS, 7, 2234-2238 (2007)

5. Direct observation of single-walled carbon nanotube growth at the atomistic scale. Lin M, Tan JPY, Boothroyd C, K. P. Loh et, al., NANO LETTERS, 6 449-452, (2006)

MOLECULAR ELECTRONICS

1.Chen W, Wang L, Huang C, Loh KP, ATS Wee, Effect of functional group (fluorine) of aromatic thiols on electron transfer at the molecule-metal interface. JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 128 (3): 935-939 (2006)

2. Qi D, Chen W, Gao X, Loh KP, A T S Wee, Surface transfer doping of diamond (100) by tetrafluoro-tetracyanoquinodimethane. JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 129 (26): 8084 (2007)

3. Fluorescent nanoparticles comprising amphiphilic rod-coil graft copolymers. Yao JH, Mya KY, Shen L, K.P. Loh, MACROMOLECULES, 41 1438-1443 (2008)

4. Light scattering and luminescence studies on self-aggregation behavior of amphiphilic copolymer micelles.
Yao JH, Mya KY, Li X, K.P. Loh, JOURNAL OF PHYSICAL CHEMISTRY B, 112, 749-755 (2008)

5. Xuanjun Zhang, Kian Ping Loh, Michael Sullivan, Zhi-Kuan Chen, Minghui Liu, Aggregation dependent S1 and S2 dual emissions of thiophene- acrylonitrile-carbazole. CRYSTAL GROWTH AND DESIGN, in print (2008).

DIAMOND

1. Using Detonanotion Nanodiamond for the Specific Capture of Glycoproteins. Weng Siang Yeap, Yee Ying Tan and Kian Ping Loh, ANALYTICAL CHEMISTRY, in press (2008)

2. Suzuki coupling of Aryl organics on Diamond. Yu Lin Zhong, Kian Ping Loh, Anupam Midya and Zhi-Kuan Chen, CHEMISTRY OF MATERIALS, in press (2008)

3. Chemical Bonding of Fullerene and Fluorinated Fullerene on Bare and Hydrogenated Diamond. Ti Ouyang, Kian Ping Loh, Dong chen Qi, Andrew Thye Shen Wee and Milos Nesladek, CHEMPHYSCHEM, in press (2008)

4. Spatial effect of C-H dipoles on the electron affinity of diamond (100) 2x1 due to the adsorption of organic molecules. Hui Ying Hoh, Kian Ping Loh, Michael B Sullivan and Ping Wu, CHEMPHYSCHEM, in press (2008)

5. Cell adhesion properties on photochemically functionalized diamond. Chong KF, Loh KP, Vedula SRK, et al. LANGMUIR, 23, 5615-5621 (2007)

6.Cycloadditions on diamond(100) 2x1: Observation of lowered electron affinity due to hydrocarbon adsorption, Ouyang T, Gao XY, Qi DC, K. P. Loh, JOURNAL OF PHYSICAL CHEMISTRY B, 110, 5611-5620 (2006)

7. Gu HR, di Su X, Loh KP, Electrochemical impedance sensing of DNA hybridization on conducting polymer film-modiried diamond. JOURNAL OF PHYSICAL CHEMISTRY B 109 (28): 13611-13618 (2005)