Photoanode for photoelectrochemical water-splitting device and method of fabricating photoanode

Abstract

Proposed are a photoanode and method for fabricating a photoanode used as a photoelectrochemical water-splitting device. According to these specific implementation embodiments of this technique, a BiOI photoactive material is electrodeposited on the surface of the FTO photoanode through an electrodeposition process. Then, 60 μL of dimethyl sulfoxide (DMSO) solution containing vanadyl acetylacetonate (VO(acac) 2 ) is drop-cast on the FTO photoanode, and then the FTO photoanode is annealed at a temperature of 500° C. with a heating rate of 2° C./min., thus fabricating a BiVO 4 photoanode. The surface of the fabricated BiVO 4 photoanode is coated with a metal-organic complex (Co-DTPMP) cocatalyst through a SILAR process to fabricate a BVO/Co-DTPMP photoanode. Through this, it is possible to greatly improve photoelectrochemical performance and oxygen evolution reaction (OER) rate.

What is claimed is: 
     
         1 . A photoanode used as an electrochemical water-splitting device, for absorbing light and causing a water oxidation reaction to generate oxygen, the photoanode comprising:
 a photoelectrode on which a nanoporous material is grown a metal-organic complex cocatalyst coated on the surface of the photoelectrode by a successive ionic layer adsorption and reaction (SILAR) process.   
     
     
         2 . The photoanode of  claim 1 , wherein the photoelectrode comprises a bismuth vanadate (BiVO 4 ). 
     
     
         3 . The photoanode of  claim 1 , wherein the cocatalyst comprises a metal-organic diethylenetriamine penta (methylene phosphonic acid) (Co-DTPMP) bonded with cobalt (Co). 
     
     
         4 . The photoanode of  claim 1 , wherein the SILAR process comprises continuously performing a process of immersing the photoelectrode in a 15 mM DTPMP solution for 5 minutes, washing the photoelectrode with deionized water (DI water), and then immersing the photoelectrode in 15 mM Co(NO 3 ) 2 6H 2 O for 5 minutes a predetermined number of times. 
     
     
         5 . A method of fabricating a photoanode used as an electrochemical water-splitting device, the method comprising:
 fabricating a photoelectrode on which has a nanoporous material grown by electro-depositing a bismuth oxoiodide (BiOI) activating material on a surface of a fluorine-doped tin oxide (FTO), then cast-dropping a dimethyl sulfoxide (DMSO) solution containing vanadyl acetylacetonate (VO(acac) 2 ) on the surface, followed by annealing; and   coating a BiVO 4  by coating the surface of the photoelectrode with a metal-organic complex cocatalyst through a successive ionic layer adsorption and reaction (SILAR) process.   
     
     
         6 . The method of  claim 5 , wherein the photoelectrode comprises a bismuth vanadate (BiVO 4 ). 
     
     
         7 . The method of  claim 6 , wherein the fabricating of a photoelectrode comprises:
 a first step of producing a bismuth oxoiodide (BiOI) photoactive material by completely dissolving 1.66 g of Potassium Iodide KI and 0.485 g of Bismuth Nitrate (Bi(NO 3 ) 3 ) in 25 ml of de-ionized water (DI), and then adding nitric acid (HNO 3 ) dropwise to the solution for a pH concentration to be adjusted to 1.7, and adding 0.23 M benzoquinone in 10 mL ethanol solution is added to the pH adjusted solution; and a second step of fabricating a photoelectrode on which has a nanoporous material grown by electro-depositing a BiOI photoactive material on a surface of an FTO photoanode through an electrodeposition process, and then drop-casting 60 μL of dimethylsulfoxide solution containing vanadyl acetylacetonate (VO(acac) 2 ), followed by annealing.   
     
     
         8 . The method of  claim 7 , wherein the second step comprises:
 electrodepositing the BiOI photoactive material on the surface of the FTO photoanode by applying a constant potential of −0.1 V with respect to an Ag/AgCl reference electrode for 400 seconds at room temperature; and   fabricating a BiVO 4  by drop-casting 60 μL of dimethyl sulfoxide (DMSO) solution containing vanadyl acetylacetonate (VO(acac) 2 ) on the surface of the FTO on which the BiOI photoactive material has been electro-deposited, followed by annealing at a temperature of 500° C. at a heating rate of 2° C./min.   
     
     
         9 . The method of  claim 8 , wherein the second step further comprises removing excess vanadium pentoxide (V 2 O 5 ) by immersing the fabricated BiVO 4  in 1 M sodium hydroxide (NaOH) solution, and then washing the BiVO 4  with DI water and ethanol a predetermined number of times, followed by natural drying. 
     
     
         10 . The method of  claim 5 , wherein the cocatalyst comprises a metal-organic diethylenetriamine penta (methylene phosphonic acid) (Co-DTPMP) bonded with cobalt (Co). 
     
     
         11 . The method of  claim 10 , wherein the coating of a photoelectrode comprises fabricating a BVO/Co-DTPMP through coating of the surface of the photoelectrode with a metal-organic complex (Co-DTPMP) cocatalyst by repeating a successive ionic layer adsorption and reaction (SILAR) process a predetermined number of times. 
     
     
         12 . The method of  claim 11 , wherein the SILAR process comprises continuously performing a process of immersing the photoelectrode in a 15 mM DTPMP solution for 5 minutes, washing the photoelectrode with deionized water (DI water), and then immersing the photoelectrode in 15 mM Co(NO) 2 6H 2 O for 5 minutes a predetermined number of times. 
     
     
         13 . The photoanode of  claim 2 , wherein the cocatalyst comprises a metal-organic diethylenetriamine penta (methylene phosphonic acid) (Co-DTPMP) bonded with cobalt (Co).