The Zhang research group is primarily interested in the design, development, characterization, and application of advanced materials with emphasis on optical and electronic nanomaterials (nanocrystals or quantum dots) of both semiconductors and metals. These nanomaterials have novel physical and chemical properties due to quantum confinement and exceedingly large surface to volume ratio. The design and synthesis of the materials are mostly based on inorganic colloidal chemistry methods. The synthesized materials are characterized systematically and extensively using a variety of experimental techniques including SERS (surface-enhanced Raman scattering), optical spectroscopy, ultrafast laser, x-ray (XAFS, XPS), ESR, electrochemical, and microscopy. In the meantime, the group actively explores emerging technological applications of these advanced nanomaterials in areas such as solar energy conversion, hydrogen generation and storage, cancer biomarker detection, photocatalysis, sensors, imaging, detectors, and lasers. A number of projects have been accomplished and several are currently under investigation. Some examples of on-going projects include:
1. Organo-metal perovskites: films, quantum dots, and magic sized clusters: fundamental issues related to stability and solar energy conversion and sensing applications
2. Surface-enhanced Raman scattering (SERS) based on Au and Ag nanoparticles/aggregates and development of SERS sensors for chemical and biomedical detection with emphasis on cancer biomarkers including antigens and antibodies of ovarian and lung cancers.
3. Ultrafast interfacial electron dynamics and surface modification of semiconductor nanoparticles: CdS, CdSe, CdTe, PbS, Ag2S, CuS. Biocnjugation of semiconductor quantum dots to proteins for biomedical cancer detection based on photoluminescence
4. Hydrogen generation and storage based on novel semiconductor, oxide, and metal nanostructures including nanowires and nanorods via photoelectrochemistry or photocatalysis.
5. Photoluminescence and up-conversion luminescence of doped semiconductor nanoparticles: Mn2+ and Cu+ doped ZnS, ZnSe, CdS nanoparticles
6. Solar energy conversion based on dye, polymer, or quantum dot sensitized nanocrystalline TiO2, WO3, or ZnO solar cells, in conjunction with N-doping, using conjugated polymers as solid electrolytes
7. Hot electron relaxation in metal nanoparticles and nanoparticle aggregates: Ag, Au, Pd, and Pt
8. Photothermal imaging and ablation therapy of cancer cells using hollow gold nanoshells (HGNs)