Profesor Hongjie Dai, Stanford University. "Nanoscience, Biological Imaging and Renewable Energy."  Special Seminar/Student Hosted.This talk present our recent work in several areas of nanosciences. I will first briefly review our earlier work of carbon based nanomaterials, and then focus on fluorescence biological imaging in the newly coined 1000-1700 nm NIR-II window to benefit from suppressed light scattering at long wavelengths. I will show in vivo NIR-II imaging with millimeter tissue depth, single-cell spatial resolution, and real-time temporal resolution using a wide range of fluorescent/luminescent probes emitting > 1000 nm including carbon nanotubes, quantum dots, rare-earth down-conversion nanoparticles, and donor-acceptor organic molecules. Our latest work on NIR-II light sheet microscopy (LSM), voltage-sensitive dyes for neuroscience, and rare-earth probes for cancer immuno-therapy will be presented. If time permits, I will briefly show our recent work on rechargeable Al ion battery and solar driven seawater splitting.