http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Modified Electronic Structure Of Zinc Oxides For Photocatalytic Hydrogen Evolution
VUONG HOAI THANH 울산대학교 대학원 2022 국내석사
In this thesis, the concentration was put on the fabrication of ZnO-based heterojunction photocatalysts to improve photocatalytic activities of hydrogen generation from water. The studies have been divided into two parts, including p-n heterojunctions and type II heterojunctions. The mechanism of each type of catalyst under UV and visible light irradiation was clearly illustrated in the thesis. The first part describes the in-situ synthesis of multicomponent ZnO-based photocatalysts for hydrogen production. The fabricated ZnO coupled with Cu-Cu2O nanoparticles and modified reduced graphene oxide (mRGO) ameliorated hydrogen production. The simultaneous introduction of mRGO and Cu-Cu2O enhanced the generation rate of photocatalytic hydrogen to 3085.02 µmol g-1 h-1 due to significant alteration of the electronic structure. The bandgap energy of the prepared catalysts decreased from 3.2 eV for pristine ZnO to 2.64 eV for a composite containing 15% CuCu2O. The optimized designated heterostructure efficiently separates photo charge carriers and prevents charge carriers’ recombination by accelerating charge transfer with the help of mRGO and metallic Cu and as a result leading to efficient hydrogen yields. The second part obviously demonstrates the role of EDTA molecules to enhance the photocatalytic activity of CdS/ZnMn2O4. The composite strongly improved catalytic performance due to the low photo-resistance when bridging EDTA molecules between two materials. Besides that, the optimal composite showed superior hydrogen production at a rate of 26.34 mmol.g-1.h-1. Furthermore, the material possessed better photostability in both acid and basic environments for around 18 h under light irradiations. This research could be useful to validate the efficacy of organic-inorganic systems for photocatalysts because of the positive effect of organic factors in synthesizing heterojunction photocatalysts, promoting charge transfers, and reducing recombination of electron-hole pairs to increase photoactivity.