| 초록 |
Monoclinic bismuth vanadate (BiVO4) is a promising candidate for photoanodes of photoelectrochemical (PEC) water oxidation due to its relative low band gap energy, suitable valance band edge position for water oxidation and chemical stability under neutral and mild basic electrolyte conditions. Among various fabrication methods for BiVO4, two-step process including electrodeposition of bismuth precursor film followed by drop casting of V containing precursor solution to form BiVO4 has been shown to achieve high photoelectrochemical water oxidation performance. However, a careful removal of excess V2O5 formed on BiVO4 after annealing process is necessary in this fabrication method. The conventional method of removing excess V2O5 is chemical etching by highly basic solution. However, in often cases, unwanted dissolution of BiVO4 occurs during the etching of V2O5, which results in poor reproducibility and areal uniformity of the PEC performance. Here, we developed selective etching method for the removal of excess V2O5 without any damage to BiVO4, which is named as electrochemical etching. BiVO4 photoanodes prepared by our own electrochemical etching method shows higher reproducible PEC performance than conventional method. Physical and chemical analyses of BiVO4 films after different etching methods (ehemical vs electrochemical) revealed that the loss of vanadium at the surface cause the fluctuation in PEC performance of BiVO4. Details of material characterizations and electrochemical analyses will be delivered. |
