Photochemical diodes for unassisted biomass valorization coupled with hydrogen production or carbon dioxide fixation

Abstract

This disclosure provides systems, methods, and apparatus related to photochemical diodes. In one aspect, a device include a photoanode, a photocathode, and a bipolar membrane between the photoanode and the photocathode. The photoanode comprises a first semiconductor, the first semiconductor being N-type doped, a first catalyst disposed over the first semiconductor, and the photoanode being disposed in an anolyte. The photocathode comprises a second semiconductor, the second semiconductor being P-type doped, a second catalyst disposed over the second semiconductor, and the photocathode being disposed in a catholyte. The photoanode and the photocathode are in electrical contact. A hydrogen reduction reaction or a carbon dioxide reduction reaction occurs at the photocathode and a chemical oxidation reaction occurs at the photoanode when the photocathode and the photoanode are illuminated with light.

What is claimed is: 
     
         1 . A device comprising:
 a photoanode comprising a first semiconductor, the first semiconductor being N-type doped, a first catalyst disposed over the first semiconductor, the photoanode being disposed in an anolyte;   a photocathode comprising a second semiconductor, the second semiconductor being P-type doped, a second catalyst disposed over the second semiconductor, the photocathode being disposed in a catholyte, the first semiconductor being the same semiconductor material as the second semiconductor, and the photoanode and the photocathode being in electrical contact; and   a bipolar membrane between the photoanode and the photocathode; and   a hydrogen reduction reaction or a carbon dioxide reduction reaction occurs at the photocathode and a chemical oxidation reaction occurs at the photoanode when the photocathode and the photoanode are illuminated with light.   
     
     
         2 . The device of  claim 1 , wherein the bipolar membrane comprises an anion exchange layer and a cation exchange layer. 
     
     
         3 . The device of  claim 2 , wherein the anion exchange layer and a cation exchange layer are both based on hydrocarbon resins. 
     
     
         4 . The device of  claim 1 , wherein the first semiconductor and the second semiconductor both comprise silicon. 
     
     
         5 . The device of  claim 1 , wherein a protective layer is disposed on both the first semiconductor and the second semiconductor. 
     
     
         6 . The device of  claim 5 , wherein the protective layer comprises titanium dioxide (TiO2). 
     
     
         7 . The device of  claim 1 , wherein the first catalyst comprises PtAu, and wherein the second catalyst is a catalyst from a group Pt, Au, and PdAu. 
     
     
         8 . The device of  claim 1 , wherein the anolyte comprises potassium hydroxide, and wherein the catholyte comprises sulfuric acid. 
     
     
         9 . The device of  claim 1 , wherein the anolyte includes glycerol dissolved therein. 
     
     
         10 . The device of  claim 1 , wherein the second semiconductor includes nanowires on a surface of the second semiconductor. 
     
     
         11 . The device of  claim 1 , wherein the chemical oxidation reaction is not an oxygen evolution reaction. 
     
     
         12 . The device of  claim 1 , wherein the chemical oxidation reaction is an oxidation reaction of glucose, 5-hydroxymethylfurfural, or glycerol. 
     
     
         13 . The device of  claim 1 , wherein the chemical oxidation reaction is a glycerol oxidation reaction. 
     
     
         14 . The device of  claim 1 , wherein the chemical oxidation reaction is a glycerol oxidation reaction, and wherein the glycerol oxidation reaction generates glyceraldehyde (GLD), dihydroxyacetone (DHA), glyceric acid (GLA), or lactic acid (LA). 
     
     
         15 . The device of  claim 1 , wherein a surface of the photoanode is heavily doped with a P-type dopant, and wherein up to about 10 nanometers in depth of the surface includes the P-type dopant. 
     
     
         16 . The device of  claim 1 , wherein a surface of the photocathode is heavily doped with a N-type dopant, and wherein up to about 10 nanometers in depth of the surface include the N-type dopant. 
     
     
         17 . A device comprising:
 a photoanode comprising N-type doped silicon, a PtAu catalyst disposed over the photoanode, the photoanode being disposed in an anolyte;   a photocathode P-type doped silicon, a Pt catalyst disposed over the photocathode, the photocathode being disposed in a catholyte, and the photoanode and the photocathode being in electrical contact; and   a bipolar membrane between the photoanode and the photocathode.   
     
     
         18 . A method comprising:
 providing a device, the device including:
 a photoanode comprising a first semiconductor, the first semiconductor being N-type doped, a first catalyst disposed over the first semiconductor, the photoanode being disposed in an anolyte, 
 a photocathode comprising a second semiconductor, the second semiconductor being P-type doped, a second catalyst disposed over the second semiconductor, the photocathode being disposed in a catholyte, the first semiconductor being the same semiconductor and the second semiconductor, and the photoanode and the photocathode being in electrical contact, and 
 a bipolar membrane between the photoanode and the photocathode; and 
   exposing the photoanode and the photocathode to light, a hydrogen reduction reaction or a carbon dioxide reduction reaction occurring at the photocathode, and a chemical oxidation reaction occurring at the photoanode.