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제128회 대한화학회 학술발표회, 총회 및 기기전시회 Enhanced Photoelectrochemical Water Splitting Efficiency of BiVO4 Based-Photoelectrode by Building Phase-Junction Configuration

2021년 8월 4일 09시 20분 46초
PHYS2-1 이곳을 클릭하시면 발표코드에 대한 설명을 보실 수 있습니다.
금 09시 : 00분
Physical Chemistry - Recent Advances in Physical Chemistry
저자 및
Woon Yong Sohn
Department of Chemistry, Chungbuk National University, Korea
Bismuth vanadate (BiVO4), one of the mineral forms of metal oxide, has been regarded as one of the best materials for a photoanode in a photoelectrochemical (PEC) cell due to its high earth abundance, non-toxicity, and the suitable value of the band gap for the absorption of visible light. However, the pure BiVO4 involves some drawbacks, which limit its use in the practical implementation, e. g. low conductivity. In order to make up for the weak aspects of BiVO4, building the heterojunction configuration has been regarded as one of the best methods to enhance the water splitting efficiency. However, because of the lattice mismatch between two difference species in the junction, the defect states could be generated, in which the charge recombination takes place. To solve this weak point of the heterojunction and enhance the photoelectrochemical performance of the BiVO4 photoanode, we designed the phase junction configuration including three types of the BiVO4 crystal structure. (Monoclinic Scheelite (MS), Tetragonal Scheelite (TS), Tetragonal Zircon (TZ)) We could prepare the film including three phases, MS, TS and TZ. The PEC performances of the as-prepared samples were evaluated by observing the current densities as a function of the applied bias voltage. We demonstrated that the film (MS&TS&TZ) shows both the high current density (1.2 mA/cm2 at 1.23 V vs RHE) and the low turn on voltage (0.44 V vs RHE), compared to those of bare BiVO4 (0.68 mA/cm2 at 1.23 V vs RHE, 0.6 V vs RHE). The origin of the improvement was revealed by using one of the time-resolved spectroscopic techniques, heterodyne transient grating method (HD-TG), and photo-electrochemical impedance spectroscopy (PEIS), which will be discussed in the presentation.