Hematite-based photoanodes with manganese, cobalt, and nickel additives

Abstract

A photoanode, photochemical cell and methods of making are disclosed. The photoanode includes an electrode at least partially formed of hematite and having a surface doped with at least one of nickel, cobalt and manganese. The electrode surface may be doped with nickel. The surface may be doped with cobalt. The electrode surface may be doped with manganese. An aqueous solution may surround the photoanode and a cathode, the photoanode being configured to generate holes upon light absorption and the cathode being configured to emit electrons to the aqueous solution. A voltage source may be electrically coupled between the photoanode and the cathode.

1 . A photoanode comprising an electrode at least partially formed of hematite and having a surface doped with at least one of nickel, cobalt and manganese, the electrode having a (0001) surface Fe bilayer doped with a concentration in the 1/8 to 1/2 range. 
     
     
         2 . The photoanode of  claim 1 , wherein the electrode surface is doped with nickel. 
     
     
         3 . The photoanode of  claim 1 , wherein the electrode surface is doped with cobalt. 
     
     
         4 . The photoanode of  claim 1 , wherein the electrode surface is doped with manganese. 
     
     
         5 . The photoanode of  claim 1 , wherein the electrode is bulk doped with at least one of cobalt and nickel to enhance light absorption. 
     
     
         6 . The photoanode of  claim 1 , wherein the electrode is bulk doped with at least one of silicon and manganese to enhance band alignment and carrier transport. 
     
     
         7 . The photoanode of  claim 1 , further comprising an aqueous solution surrounding the photoanode and a cathode, the photoanode being configured to generate holes upon light absorption and the cathode being configured to emit electrons to the aqueous solution. 
     
     
         8 . The photoanode of  claim 7 , further comprising a voltage source electrically coupled between the photoanode and the cathode. 
     
     
         9 . A photochemical cell configured for electrolysis of water, the photochemical cell comprising:
 a photoanode comprised of hematite and having a surface doped with at least one of nickel, cobalt and manganese configured for immersion in the water; and   a cathode electrically coupled to the photoanode, the cathode being configured for immersion in the water.   
     
     
         10 . The photochemical cell of  claim 9 , wherein the electrode surface is doped with nickel. 
     
     
         11 . The photochemical cell of  claim 9 , wherein the electrode surface is doped with cobalt. 
     
     
         12 . The photochemical cell of  claim 9 , wherein the electrode surface is doped with manganese. 
     
     
         13 . The photochemical cell of  claim 9 , wherein the electrode is bulk doped with at least one of cobalt and nickel to enhance light absorption. 
     
     
         14 . The photochemical cell of  claim 9 , wherein the electrode is bulk doped with at least one of silicon and manganese to enhance band alignment and carrier transport. 
     
     
         15 . The photochemical cell of  claim 9 , wherein the photoanode is configured to generate holes upon light absorption and the cathode is configured to emit electrons to the water. 
     
     
         16 . The photochemical cell of  claim 15 , further comprising a voltage source electrically coupled between the photoanode and the cathode. 
     
     
         17 . A method of making a photoanode, the method comprising:
 providing an electrode at least partially formed of hematite; and   doping a surface of the electrode with at least one of nickel, cobalt and manganese.   
     
     
         18 . The method of  claim 17 , wherein the electrode surface is doped with nickel. 
     
     
         19 . The method of  claim 17 , wherein the electrode surface is doped with cobalt. 
     
     
         20 . The method of  claim 17 , wherein the electrode surface is doped with manganese. 
     
     
         21 . The method of  claim 17 , wherein the electrode is bulk doped with at least one of cobalt and nickel to enhance light absorption. 
     
     
         22 . The method of  claim 17 , wherein the electrode is bulk doped with at least one of silicon and manganese to enhance band alignment and carrier transport. 
     
     
         23 . The method of  claim 17 , further comprising surrounding the photoanode and a cathode with an aqueous solution, the photoanode being configured to generate holes upon light absorption and the cathode being configured to emit electrons to the aqueous solution. 
     
     
         24 . The photoanode of  claim 23 , further comprising electrically coupling a voltage source between the photoanode and the cathode. 
     
     
         25 . A method of making a photochemical cell configured for electrolysis of water, the method comprising:
 providing a photoanode comprised of hematite;   doping a surface of the electrode with at least one of nickel, cobalt and manganese; and   electrically coupling a cathode to the photoanode, the cathode being configured for immersion in the water.   
     
     
         26 . The method of  claim 25 , wherein the electrode surface is doped with nickel. 
     
     
         27 . The method of  claim 25 , wherein the electrode surface is doped with cobalt. 
     
     
         28 . The method of  claim 25 , wherein the electrode surface is doped with manganese. 
     
     
         29 . The method of  claim 25 , wherein the electrode is bulk doped with at least one of cobalt and nickel to enhance light absorption. 
     
     
         30 . The method of  claim 25 , wherein the electrode is bulk doped with at least one of silicon and manganese to enhance band alignment and carrier transport.