Director of Graduate Recruitment
and Associate Professor
Oliver Hall 4025
B.S., University of Kelaniya, Sri Lanka, 2001
Ph.D., Wayne State University, Detroit, MI, 2007
Postdoctoral Fellow, Northwestern University, Evanston, IL, 2007-2009
Research Associate, Los Alamos National Laboratory, Los Alamos, NM, 2009-2011
Honors, Awards, and Fellowships
VCU College of Humanities and Sciences – Excellence in Scholarship, 2017
Esther and Stanley Kirschner Outstanding Graduate Student Award, Wayne State University, 2007
Wilfred Heller Outstanding Graduate Research Fellowship, Wayne State University, 2006-2007
Dissertation Research Fellowship, Graduate School, Wayne State University, 2006
Undergraduate Educational Fellowship, Department of Education, Sri Lanka, 1996-2000
Research efforts in Arachchige group are focused on the synthesis, characterization, and assembly of novel inorganic nanomaterials with unique and tunable physical properties; fundamental investigation of how the structure, morphology, composition, and physical properties are related; in order to advanced technologies such as chemical sensing, cellular imaging, energy conversion, and heterogeneous catalysis. The synthesis of nanoscale materials with unique physical properties and their self-assembly into functional nanostructures is a critical field of endeavor today. However, precise control over nanomaterials properties and their interactions in nanostructured assemblies has proven a challenging task that hinder widespread application of nano-science/technology. In response to these critical needs, a highly interdisciplinary program is developed, spanning chemistry, physics, engineering, and medicine, working towards the overarching goal of enabling “novel efficient materials” for advanced technological applications. There are three main thrusts of the research.
- Direct-Gap Si1-xSnx and Ge1-xSnx Nanocrystals for High-Efficiency Optoelectronics
Low-cost, non-toxic and abundantly-produced, Group IV semiconductors are the ideal active components for a broad range of devices. However, Si and Ge are of limited use in optoelectronics (solar cells, light emitting diodes, sensing, and imaging) because of their indirect energy-gaps, which make their interactions with light much less efficient than many other semiconductors. We propose to develop nanocrystalline Group IV semiconductors with direct energy-gaps that will greatly enhance the efficiency of Si and Ge optoelectronics. This will be accomplished through concerted influences of quantum confinement and alloying with Sn, and will result in SixSn1-X and GexSn1-x alloy nanocrystals (NCs) with significant potential in visible to near-infrared optoelectronics. This research addresses the major bottleneck (indirect energy-gaps) for efficient use of Si and Ge in optoelectronics and establishes a strikingly new technology that combines the unique advantages of nanoscale device design and fabrication with attractive technological features of low-cost, non-toxic Group IV semiconductors potentially impacting the future design of high-efficiency optoelectronics.
- Direct Self-Supported Assembly of Metal and Semiconductor Nanoparticles into Porous Nanostructures for Surface Enhanced Raman Scattering and Heterogeneous Catalysis
Nanomaterials often exhibit unique properties that hold enormous potential in breakthrough technologies. However, advances in nanotechnology are predicated on our ability to create, manipulate, and organize nanoscale materials into functional superstructures with useful and controllable physical properties. To address this issue, Arachchige group is developing innovative strategies for direct hardwiring of metal and semiconductor NCs into high-surface-area, highly-conductive, hierarchically-porous nanostructures (aerogels), with no use of intervening ligands and substrate supports. The resultant aerogels are expected to exhibit optical transparency or opacity, high surface area and hierarchical porosity, and superior electrical transport properties, making them promising for application in a number of new (chemical sensing and electrocatalysis) technologies.
This work builds fundamental understanding of the integration of chemically similar/dissimilar systems into macroscopic nanostructures, and of the emerging optical/electronic properties and chemical functionalities. It also enables traditional sol-gel chemistry to emerge as a versatile route for NC self-assembly and offers new perspectives to build confined nanostructures as self-supported monoliths or nanostructured thin films. These efforts will result in a truly new class of high-surface-area, highly-conductive, hierarchically-porous metal and semiconductor nanostructures that exhibit maximum surface area per unit mass for efficient and sustainable application in future technologies.
- Nanostructured Transition Metal Phosphides for Photocatalysis and Electrocatalysis
Transition metal phosphides (TMPs) are a class of materials that have been historically important across many societally relevant applications, and remain at the forefront of modern science and technology, specifically as nanostructured materials. Vast majority of TMPs exhibit a range of physical properties of both fundamental and technological interest depending on their chemical identity and crystal phase. Underpinning their application is the ability to synthesize TMPs with precisely controlled features –including crystal structure, morphology, and composition– that directly impact their physical properties and chemical reactivity. Arachchige group is developing novel and efficient wet-chemical syntheses for size, shape, and phase controlled nanostructured TMPs (Zn3P2, Ni2-xMoxP, Co2-xMoxP, Ni2-xWxP and Co2-xMoxP) that exhibit tremendous potential in photo-/electro-chemical water splitting, alcohol oxidation and oxygen reduction fuel cell reactions. This research will build new knowledge, capabilities, and high-efficiency nanostructured metal phosphides of broad importance to chemists, physicists, and engineers while impacting diverse applications in photocatalysis and electrocatalysis.
- Independent Research Publications at VCU
Tallapally, Venkatesham; Nakagawara, Tanner A.; Demchenko, Denis O.; Ümit Özgür; Arachchige, Indika U.* “Ge1-xSnx Alloy Quantum Dots with Composition-Tunable Energy Gaps and Near-Infrared Photoluminescence” Nanoscale, 2018, 10, 20296–20305.
Ohlhaver, Christopher M.; Rutan, Sarah A., Bertino; Massimo F.; Wijesinghe, Dayanjan S.; Arachchige, Indika U.* “Applications of Surface Enhanced Raman Scattering toward the Detection of the Bioactive Lipid 20-HETE” ACS Appl. Nano Mater. 2018, 1, 4064–4072.
Nahar, Lamia; Farghaly, Ahmed A.; Esteves, Richard A; Arachchige, Indika U. “Shape Controlled Synthesis of Au/Ag/Pd Nanoalloys and Their Oxidation-Induced Self-Assembly into Electrocatalytically Active Aerogel Monoliths” Chem. Mater. 2017, 29, 7704–7715.
Demchenko, Denis O.; Tallapally, Venkatesham; Esteves, Richard J.; Hafiz, Shopan; Nakagawara, Tanner A.; Arachchige, Indika U.; Ümit Özgür “Optical Transitions and Excitonic Properties of Ge1-xSnx Alloy Quantum Dots” J. Phys. Chem. C 2017, 121, 18299–18306.
Arachchige, Indika U.; Armatas G. S.; Biswas, K.; Subrahmanyam, K. S.; Latturner, S.; Malliakas, C. D.; Manos, M. J.; Oh, Y.; Polychronopoulou, P.; Poudeu, P. F. P.; Trikalitis, P. N.; Zhang, Q.; Zhao, L.-D.; Peter, S. C., “Mercouri G. Kanatzidis: Excellence and Innovations in Inorganic and Solid State Chemistry” Inorg. Chem. 2017, 56, 7582–7597.
Esteves, Richard J.; Hafiz, Shopan A.; Demchenko, Denis O.; Özgür, Ümit; Arachchige, Indika U. “Ultra-Small Ge1-xSnx Quantum Dots with Visible Photoluminescence” Chem. Commun. 2016, accepted.
Hafiz, Shopan A.; Esteves, Richard J.; Demchenko, Denis O.; Arachchige, Indika U.; Özgür, Ümit “Band-Gap Engineering and Carrier Dynamics in Colloidal Ge1−xSnx Quantum Dots” J. Phys. Chem. Lett. 2016, 7, 3295-3301.
Tallapally, Venkatesham; Esteves, Richard J.; Nahar, Lamia; Arachchige, Indika U. “Multivariate Synthesis of Tin Phosphide Nanoparticles: Temperature, Time, and Ligand Control of Size, Shape, and Crystal Structure” Chem. Mater. 2016, 28, 5406−5414.
Sahoo, N. G.; Esteves, Richard J.; Punetha, Vinay. D.; Pestov, D.; Arachchige, Indika U.; McLeskey, James. T. “Schottky Diodes from 2D Germanane” Appl. Phys. Lett. 2016, 109, 023507/1-023507/4.
Gao, Xiaonan; Esteves, Richard J.; Nahar, Lamia; Arachchige, Indika U. “Direct Cross-Linking of Au/Ag Alloy Nanoparticles into Monolithic Aerogels for Application in Surface Enhanced Raman Scattering” ACS Appl. Mater. Interfaces 2016, 8, 13076–13085.
Nahar, Lamia; Esteves, Richard J.; Hafiz, Shopan; Ozgur, Umit; Arachchige, Indika U. “Metal-Semiconductor Hybrid Aerogels: Evolution of Optoelectronic Properties in a Low Dimensional CdSe/Ag Nanoparticle Assembly” ACS Nano 2015, 9, 9810-9821.
Ho, Minh Q.; Esteves, Richard J.; Arachchige, Indika U. “Size Dependent Optical Properties of Luminescent Zn3P2 Quantum Dots” J. Phys. Chem. C. 2015, 119, 10576−10584.
Esteves, Richard J.; Ho, Minh Q.; Arachchige, Indika U. “Nanocrystalline Group IV Alloy Semiconductors: Synthesis and Characterization of Ge1–xSnx Quantum Dots for Tunable Bandgaps” Chem. Mater. 2015, 27, 1559–1568.
Altarawneh, S.; Nahar, Lamia; Arachchige, Indika U.; El-Ballouli, Ala’a O.; Hallal, Kassem M.; Kaafarani, Bilal R.; Rabbani, Mohammad G.; Arvapally, Ravi K.; El-Kaderi, Hani M. “Highly Porous and Photoluminescent Pyrenequinoxaline-derived Benzimidazole-linked Polymers” J. Mater. Chem. A 2015, 3, 3006-3010.
Gao, Xiaonan; Esteves, Richard J.; Luong, Thi T. H.; Jaini, Rajendra; Arachchige, Indika U., “Oxidation-Induced Self-Assembly of Ag Nanoshells into Transparent and Opaque Ag Hydrogels and Aerogels” J. Am. Chem. Soc. 2014, 136, 7993-8002.
Kulugammana, Ranmohotti G. S.; Gao, Xiaonan; Arachchige, Indika U., “Salt-mediated Self-Assembly of Metal Nanoshells into Metallic Aerogels” Chem. Mater. 2013, 25, 3528–3534.
Nahar, Lamia; Arachchige, Indika U., “Sol-Gel Methods for the Assembly of Metal and Semiconductor Nanoparticles” JSM Nanotechnol. Nanomed. 2013, 1, 1004/1-1004/6.
- Publications from Undergraduate, Graduate, and Postdoctoral Research
Soriano, Ronlad A.; Arachchige, Indika U.; Malliakas, Christos D.; Wu, Jinsong; Kanatzidis, Mercouri G., “Nanoscale Stabilization of New Phases in the PbTe–Sb2Te3 System: PbmSb2nTem+3n Nanocrystals” J. Am. Chem. Soc. 2013, 135, 768-774.
Ivanov, Sergei A.; Arachchige, Indika U.; Aikens, Christine M., “Density Functional Analysis of Geometries and Electronic Structures of Gold-Phosphine Clusters. The Case of Au4(PR3)42+ and Au4(μ2-I)2(PR3)4” J. Phys. Chem. A 2011, 115, 8017–8031.
Arachchige, Indika U.; Malliakas, Christos D.; Soriano, Ronlad A.; Ivanov, Sergei A.; Kanatzidis, Mercouri G., “Amorphous and Crystalline GeTe Nanoparticles” Adv. Funct. Mater. 2011, 21, 2737–2743.
Wu, Jinsong; He, Jiaqing; Han, Mi-Kyung; Sootsman, Joseph R.; Girard, S.; Arachchige, Indika U.; Kanatzidis, Mercouri G.; Dravid, Vinayak P., “Electron-Beam Activated Thermal Sputtering of Thermoelectric Materials” J. Appl. Phys. 2011, 110, 044325.
Wang, Ruomiao; Li, Li; Arachchige, Indika U.; Ganguly, Shreyashi; Brock, Stephanie L.; Mao, Guangzhao, “Nanoparticles Change the Ordering Pattern of n-Carboxylic Acids into Nanorods on HOPG” ACS Nano 2010, 4, 6687-6696.
Pala, Irina R.; Arachchige, Indika U.; Georgiev, Daniel G.; Brock, Stephanie L., “Reversible Gelation of II-VI Nanocrystals: The Nature of Interparticle Bonding and the Origin of Nanocrystal Photochemical Instability” Angew. Chem. Int. Ed. 2010, 49, 3661-3665.
Arachchige, Indika U.; Kanatzidis, Mercouri G., “Anomalous Band Gap Evolution from Band Inversion in Pb1-xSnxTe Nanocrystals” Nano Lett. 2009, 9, 1583-1587.
Yao, Qinghong; Arachchige, Indika U.; Brock, Stephanie L., “Expanding the Repertoire of Chalcogenide Nanocrystal Networks: Ag2Se Gels and Aerogels by Cation Exchange Reactions” J. Am. Chem. Soc. 2009, 131, 2800-2801.
Arachchige, Indika U.; Wu, Jinsong; Dravid, Vinayak P.; Kanatzidis, Mercouri G., “Nanocrystals of the Quaternary Thermoelectric Materials AgPbmSbTem+2 (m=1-18): Phase-Segregated or Solid Solutions?” Adv. Mater. 2008, 20, 3638-3642.
Bag, Santanu; Arachchige, Indika U.; Kanatzidis, Mercouri G., “Aerogels from Metal Chalcogenides and Their Emerging Unique Properties” J. Mater. Chem. 2008, 18, 3628-2632.
Arachchige, Indika U.; Brock, Stephanie L., “Highly Luminescent Quantum Dot Monoliths” J. Am. Chem. Soc. 2007, 129, 1840-1841. (Highlighted by Science 2007, 315, 741).
Arachchige, Indika U.; Brock, Stephanie L., “Sol-Gel Method for the Assembly of Metal-Chalcogenide Quantum Dots” Acc. Chem. Res. 2007, 40, 801-809.
Brock, Stephanie L.; Arachchige, Indika U.; Kalebaila, Kennedy K., “Metal Chalcogenide Gels, Xerogels and Aerogels” Comments Inorg. Chem. 2006, 27, 103-126.
Arachchige, Indika U.; Brock, Stephanie L., “Sol-Gel Assembly of CdSe Nanoparticles to Form Porous Aerogel Networks” J. Am. Chem. Soc. 2006, 128, 7964-7971. (Highlighted by Anal. Chem. 2006, 78, 5975).
Arachchige, Indika U.; Mohanan, Jaya L.; Brock, Stephanie L., “Sol-Gel Processing of Semiconducting Metal Chalcogenide Xerogels: Influence of Dimensionality on Quantum Confinement Effects in a Nanoparticle Network” Chem. Mater. 2005, 17, 6644-6650.
Mohanan, Jaya L.; Arachchige, Indika U.; Brock, Stephanie L., “Porous Semiconductor Chalcogenide Aerogels” Science 2005, 307, 397-400. (Highlighted by Angew. Chem. Int. Ed. 2005, 44, 4839-4841).
Chen, Dongzhong; Wang, Ruomiao; Arachchige, Indika U.; Mao, Guangzhao; Brock, Stephanie L., “Particle–Rod Hybrids: Growth of Arachidic Acid Molecular Rods from Capped Cadmium Selenide Nanoparticles” J. Am. Chem. Soc. 2004, 126, 16290-16291.
Weerasooriya, R.; Tobschall, H. J.; Wijesekara, H. K. D. K; Arachchige, E. K. I. A. U. K.; Pathiratne, K. A. S., “On the Mechanistic Modeling of As(III) Adsorption on Gibbsite” Chemosphere 2003, 51, 1001-1013.