Transparent Stacked Photoanodes with Efficient Light Management for Solar-Driven Photoelectrochemical Cells

• Published in: ACS applied materials & interfaces 2021-03, Vol.13 (8), p.10181-10190
• Main Authors: Nguyen, Thanh Tai, Patel, Malkeshkumar, Kim, Sangho, Dao, Vinh-Ai, Kim, Joondong
• Format: Article
• Language: English
• Subjects: Functional Inorganic Materials and Devices
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.0c21405

Solar-driven hydrogen generation is one of the most promising approaches for building a sustainable energy system. Photovoltaic-assisted photoanodes can help to reduce the overpotential of water splitting in photoelectrochemical (PEC) cells. Transparent photoanodes can improve light-conversion efficiency by absorbing high-energy photons while transmitting lower energy photons to the photocathode for hydrogen production. In this work, transparent photoanodes were implemented by forming metal–oxide junctions of NiO/TiO2 heterostructures for creating the photovoltaic effect. The photovoltaic-induced transparent photoelectrode (PTPE) provides the photovoltage (0.7 V), which efficiently reduces the onset potential voltage by −0.38 V versus the reversible hydrogen electrode (RHE), as compared to 0.17 V versus RHE for a single-TiO2 photoanode. The PEC cell has a high photocurrent of 1.68 mA at 1.23 V with respect to the RHE. The chemical endurance of metal–oxides maintains the stability of the PTPE for over 100 h in an alkaline electrolyte of 0.1 M KOH. The results of this study reveal that combining multiple PTPE cells to create a stacked photoanode enhances the photocurrent roughly in proportion to the number of PTPE cells. This design scheme for optimizing the light-conversion efficiency in a PTPE–photoanode system is promising for creating robust systems for on-site energy producers.