System for Harvesting Oriented Light - Water Splitting

Abstract

A system and method for splitting water to produce hydrogen and oxygen employing focused polarized sunlight energy is disclosed. Hydrogen and oxygen may then be stored for later use as fuels. The system and method use inorganic capping agents that cap the surface of semiconductor nanocrystals to form photocatalytic capped colloidal nanocrystals, which may be deposited and oriented on a substrate to form an oriented photoactive material. The oriented photoactive material may be employed in the system to harvest sunlight and produce energy necessary for water splitting. The system may also include a light polarization system and elements necessary to collect, transfer, and store hydrogen and oxygen, for subsequent transformation into electrical energy.

What's claimed is: 
     
         1 . A water splitting system comprising:
 an oriented photoactive material, wherein the oriented photoactive material includes oriented photocatalytic capped colloidal nanocrystals;   a reaction vessel housing the oriented photoactive material and configured to receive water through a nozzle and facilitate a water splitting reaction when the water reacts with the photocatalytic capped colloidal nanocrystals, wherein the reaction occurs when the photocatalytic capped colloidal nanocrystals absorb irradiated light; and   a collector connected to the reaction vessel and comprising a reservoir that includes a hydrogen permeable membrane and an oxygen permeable membrane for collecting hydrogen gas and oxygen gas.   
     
     
         2 . The water splitting system of  claim 1 , further comprising
 a first mirror that collects and linearly polarizes the irradiated light irradiated by a light source.   
     
     
         3 . The water splitting system of  claim 2 , further comprising:
 a first steering mirror that direct the linearly polarized light received from the first mirror toward the oriented photoactive material at an optimum angle of incidence, wherein the optimum angle of incidence depends on the orientation of the photocatalytic capped colloidal nanocrystals.   
     
     
         4 . The water splitting system of  claim 2 , wherein the first mirror is connected to a sun tracking system so that the first mirror receives sunlight at Brewster's angle. 
     
     
         5 . The water splitting system of  claim 2 , wherein the first mirror is a focusing mirror. 
     
     
         6 . The water splitting system of  claim 1 , further comprising:
 a heater that heats the water entering the reaction vessel so that the water boils and is in a gaseous state when reacting with the photocatalytic capped colloidal nanocrystals in the reaction vessel.   
     
     
         7 . The water splitting system of  claim 1 , further comprising:
 a filter that collects impurities from the water.   
     
     
         8 . The water splitting system of  claim 1 , further comprising:
 a recirculation tube connected to the collector that transports exhaust gas that was not collected by either the hydrogen permeable membrane or the oxygen permeable membrane back into the reaction vessel.   
     
     
         9 . The water splitting system of  claim 1 , further comprising:
 a flow regulator that controls the flow of the water that enters the reaction vessel.   
     
     
         10 . The water splitting system of  claim 1 , further comprising:
 a solar reflector positioned within the reaction vessel such that irradiated light that is not absorbed by the oriented photoactive material is reflected back into the reaction vessel.   
     
     
         11 . The water splitting system of  claim 1 , wherein the photocatalytic capped colloidal nanocrystals comprise a first semiconductor nanocrystal capped with a first inorganic capping agent. 
     
     
         12 . The water splitting system of  claim 11 , wherein the photocatalytic capped colloidal nanocrystals further comprise a second semiconductor nanocrystal capped with a second inorganic capping agent. 
     
     
         13 . The water splitting system of  claim 12 , wherein the first inorganic capping agent is a reduction photocatalyst and the second inorganic capping agent is an oxidation photocatalyst. 
     
     
         14 . The water splitting system of  claim 1 , wherein at least a portion of the reaction vessel is formed of a transparent material. 
     
     
         15 . The water splitting system of  claim 1 , wherein a morphology of the photocatalytic capped colloidal nanocrystals is chosen based on a desired wavelength of the irradiated light usable by the semiconductor nano crystals. 
     
     
         16 . The water splitting system of  claim 15 , wherein the morphology of the photocatalytic capped colloidal nanocrystals comprise one morphology from a group consisting of a core/shell configuration, a nanowire configuration, or a nanospring configuration. 
     
     
         17 . The water splitting system of  claim 1 , wherein the oriented photocatalytic capped colloidal nanocrystals are oriented by applying an electric field, and the direction of the electric field is substantially parallel with a desired electric dipole moment of the photocatalytic capped colloidal nanocrystals. 
     
     
         18 . The water splitting system of  claim 1 , wherein the photocatalytic capped colloidal nanocrystals include charged ligands that assist in controlling the orientation of the photocatalytic capped colloidal nanocrystals. 
     
     
         19 . The water splitting system of  claim 1 , wherein the oriented photocatalytic capped colloidal nanocrystals are oriented according to a combing deposition technique. 
     
     
         20 . The water splitting system of  claim 1 , wherein the oriented photocatalytic capped colloidal nanocrystals are oriented by employing a Langmuir Blodgett method to form a Langmuir Blodgett film.