Beyond ultraviolet: oxygen-vacant ZrO₂₋ₓ for visible-ir-light-driven water splitting
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Date
2024-11-01
Authors
Rajapakse, D. C.
Bandara, J.
Journal Title
Journal ISSN
Volume Title
Publisher
Postgraduate Institute of Science (PGIS), University of Peradeniya, Peradeniya ,Sri Lanka
Abstract
Solar energy conversion through photocatalysis offers a promising solution for the rising global demand for clean and sustainable energy. Low-cost, efficient photocatalysts for water splitting have emerged as a viable path for clean hydrogen production, driven by significant advancements in recent decades. Reduced transition metal oxides with oxygen vacancies (OV) have proven to be candidates for studying the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in photocatalytic water splitting. Their photocatalytic ability originates from the ideal properties of a narrow band gap and the existence of favourable trap states within the forbidden band due to the presence of OVs, which can facilitate the adsorption and activation of water molecules, promoting the HER. In this work, photocatalytic hydrogen production of highly reduced and oxygen-deficient ZrO₂₋ₓ was investigated under visible and IR light. The ZrO₂₋ₓ catalyst was synthesized by treating the ZrO₂ with NaBH₄ and annealing at 550 °C and 850 °C in a nitrogen atmosphere. Hydrogen evolution rates of 28.98 μmol g⁻¹h⁻¹ and 3.50 μmol g⁻¹ h⁻¹ under Vis-IR illumination at an intensity of 100 mW cm⁻² were noted for the 850 °C and 550 °C heated ZrO₂-x catalysts, respectively. Scanning electron microscopy analysis revealed micro-sized catalyst particles. Energy-dispersive X-ray spectroscopy confirmed the successful incorporation of Boron dopants within the ZrO₂ lattice. The concentration of dopants and the concentration of OVs have increased in the 850 °C catalyst compared to the 550 °C catalyst. The presence of these dopants and OVs is expected to promote the formation of small polarons, potentially leading to improved light absorption and charge separation. The current results warrant further studies on the photocatalytic activity of reduced ZrO₂.
Description
Keywords
Hydrogen evolution rates (HER) , Oxygen-vacancies , Photocatalysts , Reduced-compounds , ZrO2
Citation
Proceedings of the Postgraduate Institute of Science Research Congress (RESCON) - 2024, University of Peradeniya, P 184