| 학회 | 한국재료학회 |
| 학술대회 | 2019년 가을 (10/30 ~ 11/01, 삼척 쏠비치 호텔&리조트) |
| 권호 | 25권 2호 |
| 발표분야 | 특별심포지엄8. 2차원 하이브리드 물질의 에너지·센서 응용 기술 심포지엄-오거나이저:이철호(고려대) |
| 제목 | Photoelectrocatalyst of 2D Metal Sulfide Layers grown by Atomic Layer Deposition |
| 초록 | 2D (2-dimensional) MoS2 have been shown to be efficient electrocatalysts and/or photoelectrocatalysts as well for the hydrogen evolution reaction (HER) replacing expensive noble metals, e.g., Pt, and Ir. MoS2 exhibits the non-ideal mode of ALD growth on planar surfaces. The non-ideality does not allow for the conventional linear relationship between the growth thickness and the number of cycles. Instead, it provides the ability to control relative ratios of the edge-sites and basal planes of MoS2 to the exposed surfaces. The number of edge sites produced was carefully characterized in terms of the geometric surface area and effective work function. It was correlated to the HER performance, including Tafel slopes and exchange current densities. We describe the direct formation of mixed-phase (1T and 2H) MoS2 layers on Si as a photocathode via atomic layer deposition (ALD) for application in the photoelectrochemical (PEC) reduction of water to hydrogen. Without typical series-metal interfaces between Si and MoS2, our p-Si/SiOx/MoS2 photocathode showed efficient and stable operation in hydrogen evolution reactions (HERs). The resulting performance could be explained by spatially genuine device architectures in three dimensions (i.e., laterally homo and vertically heterojunction structures). The ALD-grown MoS2 overlayer with the mixed-phase 1T and 2H homojunction passivates light absorber and surface states and functions as a monolithic structure for effective charge transport within MoS2. It is also beneficial in the operation of p-i-n heterojunctions with inhomogeneous barrier heights due to the presence of mixed-phase cocatalysts. The effective barrier heights reached up to 0.8 eV with optimized MoS2 thicknesses, leading to a 670 mV photovoltage enhancement without employing buried Si p-n junctions. The fast-transient behaviors via light illumination show that the mixed-phase layered chalcogenides can serve as efficient cocatalysts by depinning the Fermi levels at the interfaces. A long-term operation of ~70 h was also demonstrated in a 0.5 M H2SO4 solution. Refs.) Ho, T.A., Bae, C., Joe, J., Yang, H., Park, J.H., and Shin, H., “Heterojunction Photoanode of Atomic-Layer-Deposited MoS2 on Single Crystalline CdS Nanorod Arrays”, accepted for the publication (2019) Alqahtani, M., Sathasivam, S., Cui, F., Steier, L., Xueming, X., Alromaeh, A., Blackman, C., Kim, E., Shin, H., Benamara, M., Mazur, Y.I., Salamo, G.J., Parkin, I., Liu, H., and Wu, J., “Heteroepitaxy of GaP on Silicon for Efficient and Cost – Effective Photoelectrochemical Water Splitting”, J. Mater. Chem. A 7, 8550 – 8558 (2019) Joe, J., Yang, H., Bae, C., and Shin, H., “Metal Chalcogenides on Silicon Photoelectrodes for Efficient Water Splitting: A Mini Overview” Catalysts 9, 149 (2019) Joe, J., Bae, C., Kim, E., Ho, T.A., Yang, H., Park, J. H., and Shin, H., “Mixed-Phase (2H and 1T) MoS2 Catalyst for a Highly Efficient and Stable Si Photocathode”, Catalysts 8, 580 (2018) Ho, T.A., Bae, C., Lee, S., Kim, M., Montero Moreno, J. M. Park, J.H., and Shin, H., “Edge-On MoS2 Thin Films by Atomic Layer Deposition for Understanding the Interplay between the Active Area and Hydrogen Evolution Reaction”, Chem. Mater. 29, 7604 – 7614 (2017) |
| 저자 | 신현정 |
| 소속 | 성균관대 |
| 키워드 | electrocatalyst; photoanode; hydrogen evolution reaction; atomic layer deposition |
