Theme 5

Water is in seriously short supply in many regions of the world.  Both for personal use — drinking, cleaning, cooking, and removal of waste — and large-scale use such as irrigation for agriculture, water must be available and sustainably provided to maintain quality of life.  New technologies for desalinating sea water may be helpful, but small-scale technologies for local water purification may be even more effective for personal needs.  Atmospheric direct current corona discharge from micro-sized objects has been widely used as an ion source in many devices, such as photocopiers, laser printers, and electronic air cleaners.  However, ozone generation from these indoor corona devices poses significant health risks to indoor occupants.  Our research goal is to control, degrade, and remove contaminants in water and air using nanomaterials and nanotechnology.  We have developed a cost-effective route to a promising oxygen reduction reaction (ORR) catalyst, namely the nitrogen-enriched core-shell structured Fe/Fe3C-C (N-Fe/Fe3C@C) nanorods, with high activity and improved kinetics. The N-Fe/Fe3C@C was successfully used as cathode catalysts of microbial fuel cells (MFCs) and performed better than the commercial Pt/C-based cathode at the maximum power output.  We have also demonstrated a highly porous N-doped graphene-based capacitive deionization device, which exhibits a high removal efficiency (90-100%), fast removal (<30 min), and good regeneration performance (10 cycles, 99% retention) for multiple heavy metals (Pb2+, Cd2+, Cu2+, Fe2+, etc.) in water with a wide range of concentrations (0.05-200 ppm).  Finally, we have demonstrated corona discharges from CNTs and vertical graphene to minimize ozone generation from indoor corona devices.