International Journal of Hydrogen Energy · 2025
Ultrasound-driven seawater splitting catalysed by TiO2 for hydrogen production
Cherie C. Y. Wong, Davide Bernardo Preso, Yi Qin, Pankaj S. Sinhmar, Zhiyuan Zong, and James Kwan
Seawater splitting presents a promising approach for sustainable hydrogen production, yet its application remains limited by competing side reactions and expensive catalysts in electrolysis. We present an alternative hydrogen production approach using ultrasound-driven seawater splitting catalysed by TiO2 at room temperature. A bespoke sonoreactor focusing pulsed, high-frequency ultrasound generated reactive radicals and achieved record sonochemical efficiencies in pure and natural seawater. Bubble-dynamics simulations and electron paramagnetic resonance measurements indicate that salt scavenging is the dominant factor reducing efficiency in seawater.
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Ultrasonics Sonochemistry · 2023
Enhancement of sonochemical production of hydroxyl radicals from pulsed cylindrically converging ultrasound waves
Cherie C. Y. Wong, Jason L. Raymond, Lillian N. Usadi, Zhiyuan Zong, Stephanie C. Walton, Adam C. Sedgwick, and James Kwan
Sonochemistry is a green alternative for hydrogen production, wastewater treatment, and chemical synthesis, but conventional reactors are often limited by dispersed acoustic energy. We constructed SonoCYL, a reactor that creates cylindrically converging ultrasound waves and an intense localised pressure field capable of spontaneously nucleating cavitation. Using a sensitive dosimetry technique, we quantified hydroxyl-radical yield, production rate, and sonochemical efficiency across operating conditions. SonoCYL achieved a substantially higher radical production rate and efficiency than conventional reactors reported in the literature.
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Chemical Communications · 2023
Fluorescence-based chemical tools for monitoring ultrasound-induced hydroxyl radical production in aqueous solution and in cells
Cherie C. Y. Wong, Lu-Lu Sun, Meng-Jiao Liu, Eleanor Stride, Jason L. Raymond, Hai-Hao Han, James Kwan, and Adam C. Sedgwick
We report the synthesis of hydroxyl-radical-responsive fluorescent probes that use a 3,5-dihydroxybenzyl functionality. The probes produced significant increases in fluorescence emission in the presence of hydroxyl radicals. Incubating Res-DHB in HeLa cells followed by therapeutic ultrasound also produced a significant fluorescence increase, enabling ultrasound-induced hydroxyl-radical production to be monitored in live cells.
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Materials Chemistry Frontiers · 2023
Molecular layer-by-layer re-stacking of MoS2–In2Se3 by electrostatic means: assembly of a new layered photocatalyst
Cherie C. Y. Wong*, Bryan K. Y. Ng*, Wentian Niu, Hector P. Garcia, Yiyang Li, Ping-Luen Ho, Winson C. H. Kuo, Robert A. Taylor, Keita Taniya, Qi Wei, Mingjie Li, Michail Stamatakis, and Shik Chi Edman Tsang
Two-dimensional transition-metal chalcogenides are useful semiconductors whose properties can be modified through heterojunction assembly, although weak interlayer interactions can cause phase segregation. We exfoliated MoS2 and In2Se3 into monolayer-containing colloids with oppositely charged surfaces. Their electrostatic attraction produced controllable AB-type layer stacking, supported by structural, spectroscopic, and computational analysis. This inexpensive bottom-up method enables a high-activity layered photocatalyst for water splitting.
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MSc by Research thesis · University of Oxford · 2021
In2Se3-based two-dimensional photocatalysts for water-splitting
Cheuk Yin (Cherie) Wong
Photocatalytic water splitting could help transform the world's fossil-based energy structure, but an ideal photocatalyst remains elusive. This work experimentally explored two-dimensional In2Se3 as a water-splitting photocatalyst for the first time. Exfoliation nearly doubled its activity, while Fe doping produced a nearly three-fold increase relative to the two-dimensional material. A self-assembled MoS2/In2Se3 heterojunction further improved activity through type-II band alignment and prolonged exciton lifetime.
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