Electrochemical and photoelectrochemical oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid and 2,5-diformylfuran
Photoelectrochemical cells for the oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid and/or 2,5-diformylfuran are provided. Also provided are methods of using the cells to carry out the electrochemical and photoelectrochemical oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid and/or 2,5-diformylfuran.
1. A method for the photoelectrochemical oxidation of 5-hydroxymethylfurfural using a photoelectrochemical cell comprising:
an anode in an anode electrolyte solution comprising 5-hydroxymethylfurfural; and
a cathode in a cathode electrolyte solution;
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 holes are transported to an interface between the anode electrolyte solution and the anode where they induce the oxidation of the 5-hydroxymethylfurfural to form 2,5-furandicarboxylic acid, 2,5-diformylfuran or both, and electrons are transported to an interface between the cathode electrolyte solution and the cathode where they induce a reduction reaction.
2. The method of claim 1 , wherein the photoelectrochemical cell further comprises a TEMPO mediator immobilized on the anode or dissolved in the anode electrolyte solution, and further wherein oxidation of the 5-hydroxymethylfurfural to form 2,5-furandicarboxylic acid, 2,5-diformylfuran or both is mediated by the TEMPO mediator.
3. The method of claim 2 , wherein the anode electrolyte solution is a single-phase anode electrolyte solution.
4. The method of claim 3 , wherein the anode electrolyte solution serves as an oxygen donor and the TEMPO-mediated oxidation of the 5-hydroxymethylfurfural forms 2,5-furandicarboxylic acid at a yield of at least 90%.
5. The method of claim 3 , wherein the anode electrolyte solution is an aqueous electrolyte solution and the TEMPO-mediated oxidation of the 5-hydroxymethylfurfural forms 2,5-furandicarboxylic acid at a yield of at least 99%.
6. The method of claim 3 , wherein the anode electrolyte solution is an aqueous solution having a pH of less than 12 and the TEMPO-mediated oxidation of the 5-hydroxymethylfurfural forms 2,5-furandicarboxylic acid at a yield of at least 90%.
7. The method of claim 3 , wherein the anode electrolyte solution does not serve as an oxygen donor and the TEMPO-mediated oxidation of the 5-hydroxymethylfurfural forms 2,5-diformylfuran at a yield of at least 94%.
8. The method of claim 1 , wherein the anode is the photoelectrode and the semiconductor comprises n-type BiVO 4 .