Nanointerface Engineering of Photoactive Materials for Effective Water Splitting
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Date
2024-10-10
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Nazarbayev University School of Engineering and Digital Sciences
Abstract
With the depletion of the petroleum reserve and due to the approaching inevitable global warming, solar energy remains an ideal area for Kazakhstan to exploit due to its ample source and environmentally benign technology. Currently, the storage of solar energy during the day and night can be achieved through new battery technologies. However, taking into consideration the cost, production and recycling processes, the only efficient way for long-term storage (seasonal) is fuels. The simplest solar fuel is molecular hydrogen, obtained by splitting the water into its constituent elements using solar energy.
This study has examined Cu2O as a very effective photocathode, which has great potential for use in the process of photoelectrochemical water splitting. Its suitability depends on several factors such as the specific synthesis techniques, its optimization, and modification to the fabrication of a photoelectrochemical device. For Cu2O, semiconducting materials such as ZnO and TiO2 were utilized to enhance light absorption and create protection layers.
This work demonstrated a high-performance and stable nanostructured Cu2O photocathode with composite-zinc oxide (ZnO) engineered morphology. Material characterization confirmed the successful synthesis and modifications through X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), which verified the crystal structure and oxidation states. Scanning electron microscopy (SEM) revealed nanowire morphologies that improved both light absorption and charge separation compared to planar films. Electrochemical impedance spectroscopy (EIS) and linear sweep voltammetry (LSV) measured the improved photoelectrochemical performance, achieving up to 1.75 mA/cm2 under simulated sunlight.
Lastly, an infrared-to-visible photon upconversion (UC) system was employed in a photoelectrode made of Cu2O photocatalyst to construct a hybrid photoelectrochemical (PEC) water-splitting device. Throughout the system's development, various design aspects, such as the thickness and transparency of each layer, were analyzed for their impact on performance. A semi-transparent photoelectrode was used to construct a hybrid water-splitting device that has an expanded absorption range and a 56% enhancement in the produced photocurrent density.
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Type of access: Embargo, photoelectrochemical water splitting, green hydrogen, semiconductor, photon upconversion, heterostructure, cuprous oxide
Citation
Magazov, Yerbolat. (2024). Nanointerface Engineering of Photoactive Materials for Effective Water Splitting. Nazarbayev University School of Engineering and Digital Sciences