Electrochemical and photoelectrochemical reduction of furfurals
Electrochemical cells and photoelectrochemical cells for the reduction of furfurals are provided. Also provided are methods of using the cells to carry out the reduction reactions. Using the cells and methods, furfurals can be converted into furan alcohols or linear ketones.
1. A method for the photoelectrochemical reduction of a furfural to a furan alcohol or a linear ketone in a photoelectrochemical cell comprising: an anode in an anode electrolyte solution; and a cathode in a cathode electrolyte solution comprising a furfural, provided that, if the furfural is reduced to the linear ketone, the cathode is a zinc cathode and the cathode electrolyte solution is acidic, wherein at least one of the anode and the cathode is a photoelectrode comprising a semiconductor, the method comprising: exposing the at least one photoelectrode to radiation that is absorbed to produce electron-hole pairs, wherein electrons are transported to the electrolyte-cathode interface where they undergo reduction reactions with the furfural to form the furan alcohol or the linear ketone and holes are transported to the electrolyte-anode interface where they induce an oxidation reaction.
2. The method of claim 1 , wherein the the furfural is reduced to the linear ketone.
3. The method of claim 2 , wherein the furfural is furan-2-carbaldehyde and the linear ketone is 4-oxopentanal.
4. The method of claim 3 , further comprising reducing the 4-oxopentanal to form 5-hydroxy-2-pentanone.
5. The method of claim 1 , wherein the furfural is reduced to the furan alcohol.
6. The method of claim 5 , wherein the cathode comprises silver.
7. The method of claim 5 , wherein the furan alcohol is formed at a yield of at least 90%.
8. The method of claim 7 , wherein the furfural is 5-hydroxymethylfurfural and the furan alcohol is 2,5-bis(hydroxymethyl)furan.
9. The method of claim 7 , wherein the furfural is 5-methylfurfural and the furan alcohol is 5-methylfurfuryl alcohol.
10. The method of claim 7 , wherein the furfural is furan-2-carbaldehyde and the furan alcohol is 2-furanmethanol.
11. The method of claim 7 , wherein the cathode comprises silver having a dendritic fractal morphology.
12. The method of claim 7 , wherein the cathode is a photocathode comprising a p-type semiconductor material partially coated with silver.