MOF기반 다층 이종접합 구조 설계를 통한 고효율 광전기화학적 수소 생산

다국어 초록 (Multilingual Abstract)

Photoelectrochemical water splitting has attracted considerable attention as a sustainable strategy for solar hydrogen production because it enables the direct conversion of solar energy into chemical energy using semiconductor photoelectrodes. Among various photoanode materials, TiO2 has been widely studied owing to its chemical stability, low cost, low toxicity, and suitable band-edge positions. However, its practical performance is limited by a wide band gap, poor visible-light utilization, rapid electron–hole recombination, and sluggish interfacial charge transfer. In this study, a MOF-derived TiO2/CdS/BiSbS3 multilayer heterojunction photoanode was designed to overcome these limitations by combining porous TiO2 scaffold engineering, anatase/rutile mixed-phase junction formation, and visible-light absorber integration.
NH2-MIL-125（Ti） was used as a sacrificial precursor to prepare MOF-derived TiO2 （M-TiO2）, and the calcination temperature was controlled from 400 to 700 ℃ to optimize the structure and PEC response of the TiO2 electrode. Among the prepared samples, M-TiO2 calcined at 500 ℃ maintained a porous MOF-derived morphology while forming anatase/rutile mixed-phase junctions, providing favorable pathways for charge separation, electrolyte penetration, and absorber deposition. To extend the photoresponse of TiO2, CdS and BiSbS3 were sequentially introduced as light-absorbing layers. Structural analyses confirmed that CdS and BiSbS3 were successfully deposited on the porous M-TiO2 electrode, increasing the interfacial contact between the TiO2 scaffold and absorber layers.
The optimized M-TiO2/CdS 6cy/BiSbS3 24h photoanode exhibited a photocurrent density of 1.40 mA cm-2, which was 4.52 times higher than that of the corresponding C-TiO2-based electrode. In addition, the M-based heterojunction photoanode showed a lower charge-transfer resistance of 1.495 kΩ compared with 4.694 kΩ for the C-based electrode. These results demonstrate that the enhanced PEC performance originates from the synergistic effects of MOF-derived porosity, anatase/rutile mixed-phase junctions, CdS/BiSbS3-induced visible-light absorption, and improved heterojunction charge transfer. Therefore, this study provides an effective design strategy for overcoming the intrinsic limitations of TiO2 photoanodes toward solar hydrogen production.

목차 (Table of Contents)

• 1. 서론 1
• 2. 실험 20
• 2.1. 시약 및 재료 20
• 2.2. NH2-MIL-125(Ti) 전구체 합성 21
• 2.3. NH2-MIL-125(Ti) 유래 TiO2 powder 및 paste 제조 23
• 2.4. 전극 제조 방법 24
• 2.5. 재료 특성 및 광전기화학적 특성 분석 27
• 3. 결과 및 논의 34
• 4. 결론 90
• 참고 문헌 93
• 부록(Appendix) 97